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Medical Microbiology
For course at University of Pittsburgh
159
Microbiology
Professional
02/18/2010

Additional Microbiology Flashcards

 


 

Cards

Term
Which bacteria do not have a cell wall?
Definition

Mycoplasma spp

Chlamydiae spp

Term
List 6 ways you can tell a eukaryotic pathogen from prokaryotic
Definition

1. Prokaryotes lack nucleus

2. Prokaryotes lack membrane-bound organelles (like mitochandria)

3. Prokaryote ribosome = 70S, Eukaryote = 80S

4. Bacteria (with 2 exceptions) have peptidoglycan cell wall

5. Bacteria (with a few exceptions) lack sterol in their cell membranes

6. Prokaryotes = 1 chromosome, eukaryotes >1

(7. Bacteria are much smaller - 1/5 to 1/10 the size)

Term
Periplasmic space
Definition
Space between inner cell membrane and cell wall in bacteria
Term
How does the membrane structure of gram + and gram - bacteria differ?
Definition

Gram +

cell membrane

thick peptidoglycan cell wall

 

Gram -

cell membrane

thin peptidoglycan cell wall

outer membrane (permeability barrier, containing porins and LPS)

Term
Mycobacteria spp
Definition

-waxy cell envelope: anti-phagocytic, helps disease transmission, gram stain doesn't work

 

-acid fast stain +

M. Leprae - obligate intracellular

M. Tuberculosis - facultative intracellular

 

Term
Escherichia coli
Definition
gram - rod
Term
Bacillus spp
Definition
gram +, has spores
Term
Streptococcus spp
Definition

mostly aerotolerants

pyogenes:

 

-group A strep

-gram + cocci in chains

 

pneumoniae

gram + diplococci

Term
Staphylococcus aureus
Definition

gram + cocci

 

Term

Neisseria spp

Definition

bind human transferrin/lactoferrin and import iron into cell

 

gonorrhoeae:

gram - diplococci

Term
What structures are unique to gram + bacteria?
Definition
lipotechoic acid, which mediates adherence to tissue, and techoic acid
Term

LPS

Definition

lipopolysccharide

-present on the outer membrane of some (mainly enteric) gram- bacteria

-three parts:

-lipid A - endotoxic activity

-polysaccharide core

-O antigen - provides resistance to bile and complement, very variable among different bacteria

Term
LOS
Definition
LPS without O antigen
Term
Spirochetes
Definition

So thin must use dark field microscopy to see. Can't gram stain, but have gram - structure

 

Borrelia burgdorferi - Lyme disease

Treponema pallidum - syphilis

Term
Salmonella spp.
Definition
gram -, facultative intracellular bacteria
Term
Vibrio cholerae
Definition
gram -, extracellular bacteria
Term
Chlamydiae spp
Definition

-obligate intracellular

-use host cell energy

-lack cell wall

-two membranes, like other gram (-)s

 

Chlamydiae trachomatis: blindness, nongonococcal urethritis pneumoniae

Chlamydiae psittacosis: psittacosis (a form of pneumonia)

Chlamydiae pneumoniae: pneumonia

 

Term

Mycoplasma pneumoniae

 

1. Characteristics

2. Pathogenesis/Manifestations

3. Diagnosis

4. Treatment

 

 

 

Definition

1. Very small, lacks a cell wall, tiny genome, sterols in membrane, does not grow easily on culture

2. Droplet transmission, colonizes the nasopharynx. Aspiration leads to bronchopneumonia (note mycoplasma cannot enter the alveoli). This results due to mycoplasma being very good at adhesion with a specialized organelle and because it releases peroxidase which damages the epithelial cells. 2 wk incubation period, illness lasts 3 weeks. Mainly occurs in adults, but kids can get it. ATYPICAL pneumonia (dry cough), erythema multiform, anemia

3. Diagnosis

Best way is PCR of sputum, since it does not grow well on culture

Cold agglutinins - put freshly drawn blood on ice - it will agglutinate due to presence of anti- Mycoplasma antibody. Not sensitive but very specific.

4. Treatment

- obviously not with beta lactam. Macrolides, tetracyclins, fluoroquinolones work well.

Term
Parts of the bacterial growth curve
Definition

lag - slow if any increase, bacteria preparing to proliferate

exponentional/log - maximal doubling speed

stationary - cells stop growing, number of viable cells decreases while total cells remains constant

Term
spectrum of oxygen requirement in bacteria
Definition

aerobes - must be in the presence of oxygen to survive

- microaerobes - the concentration of this oxygen must be > than that in air

facultative anaerobes - grow faster in the presence of oxygen (use respiration), but can survive without it (using fermentation)

aerotolerants - use fermentation only, but can survive in the presence of oxygen

obligate/strict anaerobes - cannot survive in the presence of oxygen

 

Term
Pseudomonas aeruginosa
Definition
aerobe
Term

Clostridium spp

Definition

strict anaerobes

gram + spore-forming rods

cause gas gangrene (have to remove the infected tissue), anaerobic cellulitis

 

Clostridium perfringens

- most common infection. Releases alpha toxin, a lecithinase that destroys plasma membranes

- associated with food poisioning

Clostridium septicum

- associated with GI tumors

Clostridium tetani

- spore is found in the soil, infects wounds and travels along the nerve

- commonly causes neonatal tetanus by infecting umbilical stump

- neurotoxin inhibits release of inhibitory neurotransmitters, causing muscle spasms.

- treatment = antitoxin, muscle relaxants, ventilator. Antibiotics don't help because the toxin is what is important

 

Term
Actinomyces spp
Definition

strict anaerobe

gram + rod (non-sporeforming)

Term
Peptococcus and Peptostreptococcus spp
Definition

strict anaerobes

gram + cocci

Term
Bacteroides spp
Definition

strict anaerobes

gram - rods (nonsporeforming)

normal flora in colon, vagina, mouth

bile-resistant. Bile sensitive species are Porphyromonas and Prevotella

not endotoxic

Bacteroides fragilis

 - most common anaerobic intra-abdominal and bloodstream infection, although only .5% of gut flora

- infection due to rupture of GI tract AND low redox environment

- cause peritonitis and abscess formation

- treated by abscess drainage and metronidazole

Term
Fusobacterium spp
Definition

strict anaerobes

gram - rods (nonsporeforming)

Term
Ways to get an anaerobic infection (5)
Definition

1. aspiration of normal mouth flora into lung

2. spillage of gut flora due to wound or tumor

3. bite wound (mouth secretions lower redox potential)

4. Tight cast restricts circulation

5. Antibiotic treatment alters normal flora and alters redox potential, can caus C. diff infection

Term
Characteristics of a non-clostridial, anaerobic infection (5)
Definition

1. Often polymicrobial (facultative anaerobes lower redox potential)

2. Form abscesses

3. Highly antibiotic resistant

4. low virulence, but can be lethal

5. slow-growing, fastidious, smelly (fermentation)

 

Term
Pseudomonas aeruginosa
Definition

gram -

treat with ciprofloxacin

Term
What is the etiology of sinusitis
Definition

Usually viral (rhinovirus). May be bacterial - which would cause a high fever and tenderness around the sinuses:

 

Bacterial:

Streptococcus pneumoniae

Haemophilus influenzae

Term
Haemophilus influenzae
Definition

gram -

cause of URI and pneumonia

Term

Moraxella Catarrhalis

1. Gram stain

2. Causes which diseases?

Definition

1. Gram -

2. acute bronchitis

Term
What are the common etiologies of rhinitis?
Definition

1. rhinovirus

2. coronavirus

3. respiratory syncitial virus (RSV)

Term

Acute bronchitis

 

1. symptoms

2. etiology

Definition

1. symptoms - productive cough, maybe accompanied by wheeze

 

2. Usually viral:

-influenzae virus

-rhinovirus

-adenovirus

Can be bacterial, esp on top of chronic:

Streptococcus pneumoniae (GPC)

Haemophilus influenzae (GN)

Moraxella catarrhalis (GN)

Term

Pharyngitis/tonsilitis

 

etiology

Definition

usually viral (rhinovirus, coronavirus)

the main bacterial cause is Streptococcus pyogenes (GAS)

Term

Influenza

 

1. Etiology

2. Presentation

3. Diagnosis

Definition

1. Etiology - influenza virus A or B

2. sudden onset of chills, sever muscle aches, fever, and cough

3. PCR

Term

Community Acquired Pneumonia

 

1. Manifestation

2. Etiology

Definition

1. Manifestation: fever, cough (often productive), CXR white, sharp pain on inspiration

2. 40%  Streptococcus pneumoniae

    20%  Haemophilus influenzae

    25% Atypical: Mycoplasma pneumoniae

                        Chlamydophila pneumoniae

                        Legionella pneumophila

    15% Viral

 

 

Term
Etiology of ventilator associated pneumonia
Definition

"PEAKS"

 

Pseudomonas aeruginosa (GNR)

Enterobacter coacae (GNR)

Acinetobacter (GNR)

Klebsiella pneumoniae (GNR)

Straphylococcus aureus (GPC)

Term

Cystitis

 

1. Symptoms

2. Etiology

Definition

= lower urinary tract infection (infection of bladder)

 

1. dysuria, increased frequency of urination

2. Escherichia coli (by far most common)

Staphylococcus saprophyticus

Term
etiology of encephalitis
Definition

mainly viral:

Herpes simplex virus

vector borne viruses (ex. West Nile)

Term
etiology of meningitis
Definition

1. Streptococcus pneumoniae (GPC)

Neisseria meningitidis (GNC)

Enteroviruses

Listeria monocytogenes (GPR)

Term
Etiology of Diarrhea
Definition

Bacteria:

Salmonella spp. (GNR)

Shigella spp. (GNR)

Campylobacter spp. (GNR

Escherichia coli (GNR)

Clostridium difficile - in hospitalized patients

Protozoa

Giardia lamblia

Cryptosporidium

Viruses

Rotavirus

Norovirus

Term
Etiologies of common skin infections
Definition
1. cellulitis
Streptococcus pyogenes (GAS)
Staphylococcus aureus (NOT S. epidimeridis)
2. abscesses
Staphylococcus aureus
3. chronic ulcers in diabetics
progress from Strep/Staph to gram neg. to drug resistant gram - (Pseudomonas)
4. dermatitis
Candida albicans
dermatophytes (tinea, ex.)
Term
FOR EACH immunodeficiency, give a. the reasons it might occur, b. the OIs that tend to occur

1. opsonization, RES
2. B cell deficiency
3. T cell deficiency
4. granulocyte abnormalities
Definition
1.
a. complement deficiency (SLE), liver cirrhosis, splenectomy, SCD
b. encapsulated pathogens:
S. pneumoniae
H. influenzae (GNR)
N. meningitidis (GNC)

2.
a. multiple myeloma, CVID
b. IgA def. - Giardia lamblia. IgG - encapsulated pathogens: S. pneumoniae (GPC), H. influenzae (GNR), Neisseria meningitidis (GNC)

3.
a. HIV, immunosuppresants such as cyclosporine, azathioprine, glucococorticoids, anti-TNF, anti-lymphocyte Abs
b. toxoplasmosis, Candida, PCP, CMV, mycobacteria

4.
a. neutropenia (chemo), CGD
b. Remember "spa" for the catalase + infections
PSeudomonas Aeruginosa
ASPergillus
StaPhylococcus Aureus
Term
What are the major food-borne pathogens and what is special about them?
Definition
Norovirus - most common, onset 1-2 days
Staphylococcus aureus (GPC) - intoxication, heat stable enterotoxin. Causes vomiting.
Clostridium botulinum (GPR) - intoxication with neurotoxin that can take at least a day to take effect, causes paralysis. Rare.
Clostridium perfringens (GPR) - in vivo produced enterotoxin, onset 12 hrs. Causes diarrhea and cramps.
EHEC (GNR) - produces shiga toxin which causes diarrhea, but also enters into the circulation and causes kidney failure
non-typhoid Salmonella (GNR) - causes inflammation. Onset 12-48 hrs)
Shigella (GNR) - causes inflammation. Onset 12-72 hrs. Causes dysentery
Campylobacter jejuni - causes inflammation. Onset 3-5 days
Hepatitis A virus - onset 10-45 days. Invades systemically, causing the hepatitis.
Term
Name the major water-borne pathogens
Definition
Vibrio cholerae
Various gram (-) rods (Shigella, E. Coli)
Giardia lamblia (1-4 wk onset, chronic diarrhea)
Cryptosporidium (5-10 day onset)
Entamoeba histolytica (2-4 wk onset)
HAV
Norovirus
Rotavirus
Enterovirus
Term
List 5 ways pathogens adapt to survive in the GI tract
Definition
1. Novel pili help them find spots despite normal flora
2. Seek shelter in mucus
3. Adherence
4. O antigen provides bile resistance
5. Ingestion of a large number at a time
6. Production of urease to increase pH
Term
Campylobacter jejuni

1. characteristics
2. source
3. how does it cause infection?
4. treatment/aftermath
Definition
1. gram (-) microaerophilic oxidase + curved (seagull-shaped) rod, grows best at 42 degrees
2. zoonotic reservoir (chickens), also fecal-oral, handling pets
3. Invades lower SI/upper colon, main virulence factor is LPS endotoxin, causing diarrhea, fever
4. self-resolves after 5 days, so just provide fluids. Sequelae may include Guillain-Barre syndrome (molecular mimicry)
Term
Giardia spp.

1. life cycle
2. source/transmission
3. manifestation
4. Diagnosis and treatment
Definition
1. cysts are in feces: highly infectious, resistant to chlorination.
2. Source = zoonotic reservoir. Water-borne, so occurs in campers/hikers or when treatment plant breaks
3. Often asymptomatic. Acute form occurs about 1-3 wks after infection and self-resolves 1-4 weeks later. Chronic form is also possible, as are relapses. People with IgA deficiency are especially susceptible. Sudden-onset of explosive, greasy, foul-smelling diarrhea
4. Dx: cysts in stools, Treatment: Metronidazole
Term
Cryptosporidium parvum

1. Life cycle
2. Source/transmission
3. Manifestations
4. Diagnosis/Treatment
Definition
1. Complex. Know that oocysts are infectious and in the feces, and that trophozoites are in the intestine
2. Like Giardia, zoonotic reservoir, waterborne pathogen. fecal/oral possible
3. Invades enterocytes, causing diarrhea about 1 week after ingestion. Or can be asymptomatic. Usually self-resolves after a week or two EXCEPT in immunocompromised people, who may develop serious disease and die.
4. Dx: oocysts can be detected by modified acid-fast stain
Tx: none, but recent approval of nitrazoxanide
Term
Rotavirus

1. Characteristics
2. Source/transmission
3. Manifestations/Epidemiology
4. Diagnosis, prevention, treatment
Definition
1. dsRNA virus (reovirus family) with icosahedral capsid and no envelope (resistant to acid)
2. source = human reservoir. transmission = fecal/oral
3. most common cause of infectious diarrhea in children <2, symptoms are worse in children. Vomiting followed by diarrhea, appearing within 48 hrs and self-resolving.
4. Diagnosis is by EM or serologic testing, prevention is by an oral vaccine which is recommended for infants now, and there is no treatment except fluids.
Term
Hepatitis A Virus

1. Characteristics
2. Source/Transmission
3. Course of disease
4. Diagnosis, Prevention, Treatment
Definition
1. HAV = picornavirus, singlestrand+ RNA, no envelope, only known serotype
2. Transmission = oral/fecal (human reservoir), through contaminated food or water
3. Course of disease
more than 50% are asymptomatic, others will develop flu-like symptoms 2-4 weeks after ingestion.
the body can make neutralizing antibodies at this point against HAV; if it does then the infection stops here
if the body fails to do this, then HAV will spread into the blood and infect the liver, leading to hepatitis and jaundice
this will last 2 months, and then go away. NOT a chronic condition like Hep B and C. very few people will die from it because they develop fulminant hepatitis
infection confers permanent immunity
4. Diagnosis - only by presence of IgM antibodies against HAV
Prevention - HAV vaccine post-exposure or to high risk folks such as travelers
Treatment - no anti-virals available. May give passive immunity post-exposure
Term
Characteristics of Treponema pallidum
Definition
spirochete, must see by dark field microscopy.
gram (-) structure
microaerophilic
corkscrew movement
slowly replicating (doubling time >30 hrs)
Term
Course of syphilis
Definition
Primary:
Chancre occurs within 3 weeks of infection, self-resolves. Maybe some lymphadenopathy
Secondary:
Within 3-6 weeks the bacteria has disseminated to liver, brain, skin. You have a rash (on palms and soles), fever, malaise, condyloma lata, hair loss. RARELY neurosyphilis
Latent:
Secondary syphilis resolves, and you can have latent syphilis for 3 to 30 years
Tertieary:
gummas - large granulomatous lesions, can be anywhere
neurosyphilis
Term
Syphilis diagnosis and treatment
Definition
Dx: can be by microscopy from skin scrapings
Usually done by serology
Non-treponemal:
VDRL, RPR tests for Ab to cell membrane lipids and lecithin. The levels of these can be used to track how therapy is going
Treponemal:
Antibodies to the bacteria itself - are positive for life and therefore can't be used to track

Algorithm:
ELISA for treponemal Ag, then if + RPR. If RPR- do treponemal Ab.

Tx:
Penicillin - highly effective
Term
Hantavirus

1. Characteristics
2. Reservoir/Transmission
3. Manifestations
4. Diagnosis/Treatment
Definition
1. Bunyavirus family, segmented (3) (-) strand RNA with RNA pol, spherical, enveloped
2. Reservoir in deer mice (and other rodent species) - virus is in saliva, urine and feces, aerosolized and inhaled.
3. Often asymptomatic. Hemorrhagic Fever = fever, malaise, chills, GI problems, myalgia. Can be accompanied by renal distress. Hantavirus Pulmonary Syndrome can arise: build up of fluid in lungs leads to respiratory failure. Mainly a T Cell infiltrate without marked necrosis. Mortality is ~52%.
4. Diagnosis by PCR of lung tissue, serology. No treatment available except fluids, dialysis for kidney failure
Term
Rabies virus

1. Characteristics
2. Reservoir/Transmission
3. Pathenogenesis/Manifestations
4. Diagnosis/Treatment
Definition
1. Rhabdovirus family, single (-) strand with RNA pol, helical capsid, enveloped. Large bullet shaped virus
2. Reservoir = many mammalian hosts. Transmitted through a bite or a scratch
3. Virus replicates in muscle cells, then enters peripheral neurons through AchR. Travels to CNS, other organs (e.g. saliva). Incubation period of 12 months. Causes lethargy, confusion, paresis, increased salivation, behavioral changes.
4. Diagnosis by symptoms, history of animal contact. Immunofluorescence of suspected animal's brain tissue. No anti-viral treatment available, fatal. High-risk people given HDC vaccine. Post-exposure: HRIG injected around wound to neutralize, HDCV given in other arm.
Term
Rickettsiae spp.

1. Characteristics
2. Reservoir/Transmission
3. Pathenogenesis/Manifestations
4. Diagnosis/Treatment
Definition
1. Small, obligate intracellular bacteria with gram (-) structure (but too small to stain)
2. Reservoir is ticks with transovarian transmission to offspring. Transmission to humans through tick bites
3. Rickettsiae virulence factors include filopodia and toxins. Invade many cells, but particularly capillary endothelial cells, leading to lysis and capillary destruction, which in turn causes the spots. Manifestations occur within 2-12 days. Generalized symptoms: severe headache, malaise, fever, GI problems, abdominal pain, myalgia, meningitis, respiratory and renal problems, conjunctivitis. Note 10% do not have the spots.
4. Dx by history and manifestation. Can do culture on specimens, or Weil-Felix test = Ab against Proteus vulgaris antigen (cheaper). Treatment is tetracycline, which is successful if given early enough.
Term
Borrelia Burgdorferi

1. Characteristics
2. Reservoir/Transmission/Location
3. Pathenogenesis/Course of Disease
4. Diagnosis and Treatment
Definition
1. Spirochete
2. Ticks. Tick bite must be 48 hrs. Coastal areas of southern NE and New York, Midwest (Wisconsin, Minnesota, Michigan), Coastal woodlands of Calif and Oregon
3. Osps = surface lipoproteins: tropism and tissue attachment
Invades skin and widely disseminates, getting into the blood and the CSF. 3 stages:
a early:
bulls-eye rash (erythema migrans) - absent in 50%
general symptoms
b early disseminated:
10% have cranial neuropathy, meningitis. Some have iritis, retinitis
c late:
oligoarthritis in large joints (60%), which continues post-Lyme disease
ECM lesions lead from fatigue to dementia
Chronic Lyme/Post-Lyme disease: resembles fibromyalgia and chronic fatigue, not caused by the infection.

4. Diagnosis: by tissue culture from ECM. Serology - problem is you need to treat before you can see the Abs. ELISA followed by WB (similar to HIV test). Treatment: Early - amoxicillin or doxycycline. Late - IV ceftriaxone
Term
What is the risk of transmission in needlestick injury for the following diseases:

1. HIV
2. HCV
3. HBV
Definition
1. HIV = .3%
2. HCV = 3%
3. HBV = 30%
Term
For HAV thru HDV give the route of transmission and whether it causes chronic hepatitis and leads to liver cancer
Definition
HAV. Transmission = fecal-oral. No chronic disease/HCC
HBV. Transmission = parenteral, sexual, and perinatal. Chronic disease + HCC
HCV. Transmission = parenteral. Chronic disease + HCC
HDV. Transmission = parenteral. Chronic disease + HCC
Term
What prophylaxis is available for HAV thru HDV
Definition
HAV - HAIG + vaccine
HBV = HBIG + vaccine
HCV = none
HDV = HBV vaccine
Term
Hepatitis B virus

1. Family
2. Structure/contents
3. Genome
Definition
1. Family - Hepadnaviridiae
2. consists of an envelope with the embedded protein HBsAg, an icosachedral core made up of the protein HBcAg, a DNA molecule that has one incomplete strand, and a DNA polymerase with RT activity
3. HBV encodes 4 genes: HBsAg, HBcAg, Pol, and X (a transcription regulator)
Term
Hepatitis B

1. Pathogenesis
2. Manifestations
3. Diagnosis
4. Treatment
Definition
1. "S" ORF protein attaches to hepatocytes -> invasion. Multiplies without killing the hepatocyte. Makes the cell produce excess HBsAg as a decoy. Damage as a result of CTL response (inflammation). Oncogenesis possible if integrates into DNA. "X" ORF thought to play a role.
2. Within 1-6 months, 3 possibilities:
Asymptomatic, Acute (RUQ pain, jaundice, malaise), fulminant. After this, 90-98% of adults will clear the infection. 2-10% of adults and 90% of newborns will develop a chronic persistent infection that may be asymptomatic, or may develope into chronic hepatitis, cirrhosis, and hepatocellular carcinoma (any of these can develop from the asymptomatic stage)
3. elevated LFTs. Serology: HBV DNA, HBsAg are always present during infection. HBeAg is present during acute infection - if it is present in chronic infection it indicates increased virulence. Anti-HBsAG is the antibody conferring protective immunity. It, along with Anti-HBcAg and Anti-HBeAg will appear if the person has ever been infected. Anti-HBsAg only will show up if the person was vaccinated.
4. Prevention: Vaccine
Acute Treatment: HBIG
Chronic Treatment: Interferon, lamivudine (an RTI)
Term
Hepatitis D

1. Characteristics
2. Manifestations
3. Diagnosis/Prevention/Treatment
Definition
1. Deficient virus - RNA virus with core comprised of delta antigen, with HBV envelope containing HBsAg. Must be a co-infection or superinfection of an HBV patient.
2. More severe version of HBV, increased risk of chronic hepatitis and cancer
3. Serology: Anti-Delta Ag
4. Prevention - protection from HB vaccine, treated with interferon 2 alpha
Term
Hepatitis C

1. Characteristics
2. Manifestations
3. Diagnosis/Prevention/Treatment
Definition
1. Single + strand RNA virus of flavivirus family. Error-prone RNA pol means lots of errors, evasion of immunity
2. Similar to HBV with a sub-clinical acute phase but a much higher risk of contracting chronic infection, and a much higher risk of developing cirrhosis and cancer
3. Diagnosis by serology - anti-HCV Ab or RT-PCR. No vaccine or IG therapy possible because of rapid mutations. Treatment is interferon and ribavirin.
Term
Epstein-Barr Virus

1. Family?
2. Course of disease
3. Diagnosis
Definition
1. Herpesvirus
2. Spread by saliva, infects epithelial cells and spreads to B cells (naive and memory). CTL response to B cells responsible for IM. Asymptomatic in children. In adolescents, you have extreme pharyngitis, lymphadenopathy, fatigue. Also can get a beta-lactam rash and there is a significant risk of splenic rupture in traums to the area. The CTL kills almost all the infected B cells except a few memory B cells, where the virus remains latent. Chronic infection, where the T cells fail to kill it, or it comes back from the memory cells is associated with many human cancers - Burkitt's lymphoma, etc. PTLD is a significant risk for people who are in latency or who are receiving an EBV+ organ: the immunosuppressant drugs reduce the T cells, allowing the memory B cells to expand and this can lead to cancer.
Diagnosis:
Acute is by monospot - an agglutination test with antibodies to sheep, cow RBCs. "Heterophile antibodies"
To detect a past infection you use specific anti-EBV antibodies
If PTLD is suspected, you do PCR to detect the viral load, or do a biopsy and look at the tissue in question.
Term
What infections commonly occur in cystic fibrosis?
Definition
Pseudomonas aeruginosa
Term
What are the most common inhalation-associated pathogens in the following situations?

1. CNS injury
2. T cell deficiency
3. IgG deficiency
Definition
1. aspiration pneumonia, abscesses. Caused by anaerobic streptococci, fusobacteria
2. PCP, CMV
3. infection by encapsulated microbes, e.g. pneumococcus
Term
What common inhalation-acquired pathogens are generally NOT aspirated (i.e. - they come from an exogenous source and cause a LTI)
Definition
Legionella
Histoplasma
Tuberculosis
Anthrax
F. Tularensis
Term
Adenovirus

1. Structure
2. What accounts for the different serotypes?
3. Why are the serotypes significant?
4. What factors would lead you to suspect adenovirus in the diagnosis?
5. Transmission?
6. Pathogenesis (including virulence factors)
7. What manifestation tends to appear in the summer? Which manifestation is associated with nosocomial infections?
8. What are the options for diagnosis and pros and cons
9. Treatment? Prevention? Vaccine?
Definition
1. dsDNA virus, non-enveloped
2. Fiber protein (a surface protein) variation determines serotype
3. Different fiber proteins are specific for different cellular receptors, and so different serotypes are associated with different disease
4. epidemic outbreak + patient immunocompromised
5. host-restricted. Droplets -> URI infection, aspiration -> LRI. GI secretions/stool. Rarely waterborne
6. Invades epithelial cells and lymphoid tissue (ex. tonsils). Early genes (E1A and E1B) inhibit host mRNA transport to the cytoplasm and translation, leading to viral mRNA accumulation. Early genes also block apoptotic signals, interferon signals, and inhibit MHCI expression. The disease remains latent in immunocompromised hosts and is shed for a long time
7. summer - pharyngocunjunctival fever. nosocomial - epidemic keratoconjunctivitis
8. Culture (shell vial method)- expensive, can't do for GI serotypes. Serum Ab (many false positives because they last a long while). Ag detection - false (-) because you need a lot of antigen. PCR - on specimen or serum.
9. Treatment - none. Prevention = isolate infected people and get their contacts. Vaccine - military one was effective and discontinued, now being reinvestigated.
Term
What are coccobacilli
Definition
Technically rods, but are short and wide so are somewhere in between rods and cocci
Term
Haemophilus influenza
1. Characteristics
2. Virulence factors
3. Diagnosis
Definition
1. gram (-) coccobacilli, pleomorphic
2. LOS, IgA protease, CAPSULE promoting invasion/bacteremia, can get iron from lactoferrin and heme, adhesins
3. toddlers + lack of immunization = H. flu
gram stain of CSF, ear fluid, sputum
culture: grows on chocolate agar, not on blood
Term
Characteristics of the Enterobacteriaceae
How you tell them apart
Members and what diseases they cause
Definition
Gram (-) rods, facultative anaerobes, can use glucose as sole carbon source, can be isolated on MacConkey agar, oxidase (-).

Tell them apart with triple sugar iron medium. E. coli uses lactose, while Salmonella and Shigella do not. Salmonella produces H2S gas.

E. coli - diarrhea, dysentery, UTI
Salmonella - diarrhea, typhoid (enteric fever)
Shigella - dysentery, diarrhea,
Yersinia - dysentery, plague, lymphadenitis

in immunocompromised people, many members of this family can cause UTIs, bacteremias (E. Coli, Proteus, Klebsiells (which can also cause pneumonia), Enterobacter, Citrobacter, Serratia)
Term
What do the following serotypes of E. Coli correspond to?

O148:H28
O26:H11
O157:H7
O4:H5
K1
Definition
O148:H28 = ETEC
O157:H7 = EHEC
O26:H11 = EPEC
O5:H4 = UTI
K1 = meningitis
Term
Describe the toxins made by various E. Coli strains
Definition
Endotoxin (LPS): common to all E. Coli
Hemolysin (Hly): a surface toxin, causes kidney damage in pyelonephritis
Heat-Stable Toxin (STa): A small polypeptide, causes diarrhea.
Heat-Labile Toxin (LT): A large protein, causes diarrhea
Shiga Toxin (Stx): A large protein, blocks ribosomal activity, affects kidney cells
Term
Describe the different strains of E. Coli that cause GI illness
Definition
1. ETEC (O148:H28)
- attaches to cells with unique CFA pili (colonizes novel sites)
- produce STa or LT
- responsible for diarrhea in infants and traveler's diarrhea in adults, causes food poisoning
2. EPEC (O26: H11)
- attaches to epithelial cell with bundle-forming pilus. Using a T3SS, secretes factors into the cell that promote pedestal formation; also secretes TIR into the cell. It then produces intimin on its surface, causing it to adhere tightly to the surface.
- no enterotoxin; causes attachment and effacement (A/E) lesions
- infant diarrhea in developing countries
3. EAEC
- forms a biofilm on top of the epithelial cells, gets trapped there by mucus production
- may secrete a toxin: EAST
- mild disease, responsible for traveler's diarrhea, infant diarrhea in U.S., common in HIV+. No blood or leukocytes in stool, low fever.
4. EIEC
- no unique pili, just afimbrial adhesions
- gets endocytosed, breaks out of endosome, replicates intracellularly, spreads laterally to neighboring cells (similar to Shigella)
- stool has blood, leukocytes
5. EHEC (O157:H7, but can be other serotypes)
- the same as EPEC, but produces Shiga toxin
- Shiga toxin will cause hemmorhagic colitis (leading to a bloody stool) and it can also cause hemolytic uremic syndrome (HUS), = acute kidney failure, in about 5-10% of those infected, most often in children
- associated classically with eating undercooked meat, petting zoos

e
Term
In uropathogenic E. Coli, what allows them to cause pyelonephritis
Definition
P-pili or Pap-Pili - binds to the P blood group antigen, also known as Forssman's antigen, on kidney epithelial cells
Term
What does the K1 strain of E. Coli cause and how
Definition
Causes meningitis - K1 antigen is associated with a capsule that helps it evade phagocytosis and complement, leading to invasion.

Responsible mainly for neonatal meningitis (second leading cause).
Term
When do you not use antibiotics in treating E. Coli?
Definition
In the case of HUS, and in the case of most of the GI infections like ETEC.
Term
Helicobacter pylori

1. Describe it
2. Name the virulence factors
3. Normal disease progression
4. Diagnosis
5. Treatment
Definition
1. similar to Campylobacter jejuni, is a curved gram (-) rod that is motile.
2. Urease = allows it to survive in stomach acid by locally raising the pH
Motility = It has a flagella that propels it through the mucus layer in the stomach
VacA - secreted, damages epithelial cells
CagA - secreted via a T4SS directly into stomach epithelial cells, causes inflammation

3. At first, causes mild NVD symptoms. Then cases chronic gastritis (mild stomach inflammation). In more than 1%, causes an ulcer (mainly due to the toxin activity). All duodenal ulcers and most gastric ulcers have this as the cause.

4. Diagnosis is commonly done by breath test

5. Treatment is antibiotic + ppi (excample Clarithromycin + omeprazole)
Term
Clostridium difficile

1. Characteristics
2. Pathogenesis (virulence factors)
3. Progression of disease
4. Diagnosis
5. Treatment
Definition
Term
Enterococcus faecalis/faecium

1. Characteristics
2. What diseases does it cause and how?
3. Prevention/Treatment?
Definition
1. Gram (+) cocci, facultative anaerobe, frequently in chains
2. It is normal gut flora that can infect the skin of sick patients -> contact transmission by transient hand infection, etc. The major diseases it causes are vascular-line related bacteremia, endocarditis, and catheter-related UTI.
3. Prevention = swab patients rectum for VRE - if they have it then they get isolated/contact precautions
Treatment. Many strains of E. faecium are vancomycin resistant, also ampicillin resistant. Against VRE you have linezolid, tigecycline, daptomycin.
Term
Klebsiella

1. Characteristics
2. What diseases does it cause and how does it cause them?
3. Treatment
Definition
1. GNR, facultative anaerobe
2. Like Enterococcus, normal gut flora that colonizes the skin of sick people -> person to person transmission. Causes bloodstream infection through vascular line, catheter-related URI, and pneumonia.
3. ESBL strains are resistant to all beta lactams except carbapenems.
Term
Airborne precautions
- what are you protecting against
- what diseases do you use this in
- what are the precautions
Definition
protection against fomites
you use it in TB, measles, chicken pox
N95 dusk mask, negative pressure room
Term
Droplet precautions
- what diseases do you use this in
- what are you protecting against
- what are the precautions
Definition
mumps, rubella, influenza, meningococcus
droplets from sneezes
surgical mask, private room
Term
Contact precautions
-what diseases do you use this in
- what are the precautions
Definition
- a lot: MRSA, VRE, C. diff, enteritis, hepatitis A, RSV, lice and scabies
- gown and gloves required, private room, patient-dedicated stethoscopes and thermometers
Term
Name some pathogens that invade the epithelium but do not go deeper.

Resp -
Skin -
Urogenital -
GI -

Why is this the case?
Definition
Resp - rhinovirus, influenza
Skin - HPV
Urogenital - Chlamydia trachomatis, HPV
GI - rotavirus, Shigella

Could be because it gets too hot past the epithelium, or the pathogen has specific adhesins for epithelial cells only
Term
Name some example organisms that invade through the epithelium and then just keep going

Skin
GI tract
Respiratory
Urogenital
Definition
Skin - Stapholococcus aureus
GI - Salmonella typhi, Poliovirus
Resp - Measles, VZV, Mycobacteria Tuberculosis
Urogenital - HSV, Treponema pallidum
Term

Complete the following table

 

Yersinia spp            Shigella spp              Salmonella spp

 

Genes

Mode of Entry

Cells/Tissues invaded

Site of replication

Definition
Genes:
Yersinia - 3, the main one is invasin
Shigella - 30, all of which are on plasmids
Salmonella - 30, all of which are chromosomal

Mode of entry
Yersinia - invasin binds to beta-1 integrin on epithelial cells, resulting in changes in the host cell through signal transduction. This causes the host cell membrane to adhere to the bacterium at multiple points, leading to the host cell "zippering it up"
Shigella - Temperature triggers expression of Ipa, which is released from the bacterium and forms a complex on the host cell surface, causing massive actin polymerization and ruffling - this results in macropinocytosis
Salmonella - same as above except the released protein is Sip

Cells/Tissues invaded
Yersinia - M Cells of colon and ileum only, then spreads through lymph, ending at mesenteric lymph nodes. Resists phagocytosis with Yops
Shigella - M cells only, does not breach epithelium, mainly infects colon
Salmonella - M cells or enterocyes - some species breach epithelium, mainly infects ileum

Site of replication
Yersinia - extracellular
Shigella - Cytoplasm
Salmonella - Endosome
Term
List of example pathogens that disseminate via the blood
Definition
Extracellular:
Strep pneumoniae
Hepatitis B
Trypanasoma spp


In RBCs: malaria
In leukocytes: Listeria monocytogenes
In leukocytes: Measles
Term
Shigella

1. Pathogenesis
2. Diagnosis
3. Prevention and treatment
4. Which are the most virulent?
Definition
1. Using a Mxi-Spa translocon needle, it secretes Ipa (T3SS), which assembles on the surface of M cells in the colon and causes membrane ruffling, leading to uptake by macropinocytosis. It is transcytosed and picked up by a macrophage which it kills. It either enters another macrophage, or it enters the basal surface of a colonocyte. Once in the colonocyte it can spread from cell to cell using the IcsA (gives it motility via cells actin) or IcsB (forms a projection onto the next cell). The macrophages will recruit polys to the site, resulting in inflammation, fecal leukocytes. Inflammation and hemmorhagic colitis also caused by Shiga toxin, released by some strains (mainly S. dysenteriae)
2. Diagnosis is by fecal leukocytes + culture (MacConkey agar, grows yellow because lactose -)
3. Prevention by good hygiene, a vaccine is in the works. Treatment can be by antiobiotics, but make sure not to use anti-motility agents
4. S. sonnei is mild, S. flexneri and S. dysenteriae are bad
Term
Name 3 organisms that have prevalent beta-lactamase activity-against which drugs?
Definition
35% of H. flu and 100% of M. catarrhalis have beta lactamase activity against amoxicillin. It is also extremely common in Staphylococcus aureus
Term
In what species are ESBLs commonly found?
Definition
Klebsiella, E. Coli, and other GNR
Term
Which organisms mount resistance to beta lactams by altering their PBP?
Definition
Staph aureus (MRSA), E. faecium, S. pneumoniae
Term
How does Pseudomonas aeruginosa mount resistance to quinolones?
Definition
Combination of 2 mechanisms:

1. Downregulation of OprD porin, by which quinolones enter the cell
2. Increased efflux pump
Term
Which drugs is E. Coli commonly resistant to?
Definition
It has beta-lactamase, ESBL is mounting. Also commonly resistant to TMP/SMZ
Term
Describe resistance in Enterococci spp
Definition
Naturally resistant to many antibiotics.
All we have is ampicillin and vancomycin - resistance to these is mounting
Term
How does HA-MRSA differ from CA-MRSA?
Definition
It has different genes: MecA which encodes its altered PBP, Panton-Valentine Leukocidin which is a cytotoxin.

Importantly, while HA-MRSA is only susceptible to vancomycin, CA-MRSA has broader susceptibility, including clindamycin
Term
Mechanism of resistance in S. pneumoniae?
Definition
Altered PBP
Term
What type of resistance is commonly seen in group A strep and how does it work?
Definition
Macrolide resistance: 3 mechanisms.

1. Altered target - methylation of the ribosome. Phenotype is called MLSi or MLSc, caused by erm(A) and erm (B) genes.
2. Altered target - ribosomal mutations
3. Increased efflux pumps. MefA is the gene responsible
Term
Define the following terms:

Transformation
Transduction
Conjugation
Definition
Transformation - picking up of naked DNA
Transduction - picking up DNA from a virus (bacteriophage)
Conjugation - two bacteria contact one another and plasmid is transferred
Term
Describe the process of transformation
Definition
- only occurs between bacteria of similar species
- cell lyses and the DNA floats away
- a single strand is picked up by a surface DNA receptor and endocytosed - it goes to the nucleus and recombines homologously with chromosome
Term
Deescribe the process of transduction
Definition
A bacteriophage infecting a cell accidentally puts a piece of bacterial DNA in its capsid instead of its own, then it infects another bacteria. That piece of DNA does homologous recombination with the host genome.
- phages are usually host-restricted (i.e. happens between similar/same species)
- host must have phage receptor
Term
What do all plasmids contain?
Definition
- an origin of replication
- Cop - a gene determining copy number (larger plasmids tend to make fewer copies)
- a protein that initiates replication known as "rep" gene. Aside from this gene, relies on the host machinery for replication
Term
What does comes compatible mean in regard to plasmids?
Definition
Two plasmids are compatible if they can reside together in the same cell
Term
What does it mean to say that a plasmid is conjugative? What genes does a conjugative plasmid have? Are R plasmids typically conjugative?
Definition
Conjugative = it encodes genes to initiate conjugation (formation of sex pilus). These are encoded by the Tra genes. R plasmids are generally conjugative.
Term
What does oriT refer to? Describe the process of conjugation
Definition
- the site where the plasmid is nicked during conjugation. A sex pilus is formed, the plasmid is nicked, and one strand is transferred across. Then replication in both bacteria restores the plasmids to dsDNA
Term
Describe integrons
Definition
Mobile DNA elements that capture genes and insert in various sites via homologous recombination. Associated with carrying multiple drug-resistant cassettes.
Term
Transposons:

Insertion sequences vs. transposons
conservative vs. replicative
What do they have at their ends?
Definition
Insertion sequence: a short piece of DNA that only carries genes necessary for its own movement. Transposon: carries the transposase protein, needed for its movement, along with other unrelated genes, for example antibiotic resistance

Conservative = cut and paste. Replicative = copy and paste

Inverted repeats
Term
Types of antibiotic therapy and their descriptions, examples of when used if applicable
Definition
1. Prophylaxis:
- malaria
- immunocompromised, against PCP, CMV, fungal
- on burns and wounds
- ascites
- inducing bacteremia, to prevent endocarditis (controversial as transient bacteremia occurs daily)
2. pre-emptive
- means you are looking at lab results, but there are no clinical symptoms. Ex. bone marrow transplant patient who is immunosuppressed, you see CMV PCR titer increasing
3. empiric
- means patient is sick, but you don't know the organism
- use in CAP, VAP, neutropenic fever. DO NOT use in the following situations: URI, chronic illness, cultured MRSA or VRE or coag negative staph in the blood. The patient must be sick.
4. pathogen-directed
- means you know the organism, but not what antibiotic it's susceptible to. Hospitals have charts of what % of isolates of a given organism are susceptible to what
5. susceptibility - directed
- you know the organism and its susceptibility - could have been determined by disk-diffusion assay or MIC. Then you choose the antibiotic that is the most effective, is the cheapest, has the least toxicity, and is the narrowest spectrum
Term
Definition of MIC, explain procedure, is low good or bad?
Definition
Minimum inhibitory concentration- you put different dilutions of the antibiotic in a test tube with culture broth and observe the minimum concentration at which there is no growth. Low MIC = low concentration needed to inhibit = good.
Term
How can you stain fungi? Does gram staining work?
Definition
silver stain, calcofluor stain, periodic acid-Schiff test. Gram-staining does not work
Term
What is in the fungal cell wall?
Definition
glucans
sometimes chitin
Term
Describe the 3 types of fungi
Definition
molds - composed of hyphae, which are long rods of tubular cell(s). Mycelium = mass of branching hyphae
yeasts - resemble bacteria when grown on a plate. Unicellular, although can become pseudohyphae if elongated. Reproduce by budding
dimorphic - mold-like in the environment, hyphae-like in the body
Term
Amphotericin

1. Mechanism
2. Activity
3. Toxicity
Definition
1. Binds to ergosterol, increasing membrane permeability
2. against practically all fungi
3. Severe nephrotoxicity limits its use
Term
Nystatin

1. MEchanism
2. Uses/Activity
Definition
1. Binds to ergosterol, increasing membrane permeability
2. Topical only
Term
-azoles

1. Mechanism
2. types and uses
3. What can fluconazole NOT be used against
Definition
1. Prevent the production of ergosterol from lanosterol.
2. imidazoles = topical
triazoles = for severe fungal infections
3. molds
Term
echinocandins

1. Mechanism
2. Activity/Uses (what is it not good against?)
3. Names of specific drugs
Definition
1. prevent synthesis of 1, 3 beta glucan (cell wall component)
2. Good against candida and aspergillus, NOT against cryptococcus
3. Caspofungin, micafungin, anidulafungin
Term
Flucytosine

1. Mechanism
2. Uses
Definition
1. Inhibits thymitidyl snythetase, which is necessary for fungal DNA synthesis
2. Never used alone because resistance crops up rapidly, generally in combination with amphotericin. Common usage in this way for cryptococcal meningitis
Term
Terbanifine

1. Characteristics
2. Mechanisms
3. Uses
Definition
1. Allylamide
2. Inhibits squalene epioxidase, which inhibits lanosterol and those ergosterol synthesis.
3. Oral or topical use for treatment of superficial fungal infections (i.e. dermatophytes)
Term
Under what conditions only do fungi cause infections in humans?
Definition
immunocompromised
Term
Name (and categorize, if applicable) the major fungal pathogens, and if applicable, what disease they cause
Definition
Candida spp (yeasts)
Cryptococcus neoformans (yeast)
Aspergillus spp (molds)
Zygomyces spp (molds)
Sporotrichosis - sporothryx schenckii (dimorphic)
Geographic dimorphics:
-Histoplasma capsulatum (Dimorphic)
-Coccidioides immitis (Dimorphic)
-Blastomyces dermatitidis (Dimorphic)
Pneumocystis jiroveci (Yeast)
Dermatophytes:
- zoophilic: microsporum canis (causes tinea capitis - ringworm)
- geophilic
- anthrophilic: Trichophyton rubrum (causes tinea pedis and tinea cruris). Various ones case Onychomycosis - nail infections.
Term
Candida spp

1. 1st and 2nd most common infectious species
2. Pathogenesis (normal habitat, etc.)
3. Disease manifestations
4. Treatment
Definition
1. C albicans (most common) and C Galbrata
2. Normal flora of GI tract, mouth, vagina.
- kept in check by local flora (AB therapy -> candidiasis)
- kept in check by mucus membrane integrity (chemotherapy breaking down membranes and GI surgery -> candidiasis)
- kept in check by immune system (corticosteroids and other IS -> candidiasis)
3. A wide spectrum. Superficial infections of mouth (thrush), skin (diaper rash), esophagus, vagina. More seriously, can disseminate, causing blood infection, endocarditis, abscesses in multiple sites.
4. Amphotericin, echinocandins, or azoles
Term
Cryptococcus neoformans

1. Geographic location
2. Where does it live?
3. How does it get into the host?
4. Virulence factors
5. Presentation
6. Diagnosis
7. Therapy
Definition
1. Ubiquitous
2. Soil, bird droppings, trees, rotted wood
3. Inhaled
4. Polysaccharide capsule - antiphagocytic, antidetection, source of the cryptococcus antigen. Melanin - protects it against radical oxygen species. It grows best at 37 degrees C.
5. Most common and seriously is cryptococcal meningitis - usually a subacute meningitis (headache, vague neurological complaints, +/- fever). Also can cause pneumonia, cryptococcemia, skin lesions, prostatitis
6. India ink stain of CSF, culture of CSF, or detection of cryptococcus antigen in blood or CSF
7. Amphotericin + flucytozine, followed by fluconazole for maintenance
Term
Aspergillus spp

1. Common organisms causing infection
2. Risk factors
3. Presentation
4. Diagnosis
5. Treatment
Definition
1. A fumagatus, A flavus are common, A niger is rarer
2. Neutropenia, corticosteroids
3. most mild: ABPA (allergic bronchopulmonary aspergillosis) - an allergic reaction to the spores colonizing. Generally the person will have underlying asthma or CF - complains of asthma worsening. IgE and IgG against aspergillus are present, eosinophilia.
aspergilloma - a ball of fungus in the lungs, can be asymptomatic or can cause pneumonia-like symptoms, hemoptysis. Can also occur in maxillary and ethmoid sinuses
invasive aspergillosis - 90% mortality rate in some populations (transplant recipients). Mainly occurs in the immunocompromised
Can also colonize external ear (mainly A niger here) - otomycosis.
4. Difficult. Can be by BAL -> culture, microscopy, detection of galactomannan antigen in BAL, blood.
5. Voriconazole = drug of choice. Also amphotericin, caspofungin, posiconazole, but NOT fluconazole (doesn't work on molds)
Term
Zygomycete

1. How does it get into the body?
2. What does it cause?
3. Prognosis?
Definition
1. Inhaled
2. Pneumonia-like symptoms
3. High mortality because it is resistant to antifungals
Term
Sporotrichosis

1. Causative organism. Mold or yeast?
2. Source of organism and how it gets into the body
3. Symptoms
Definition
1. Sporothryx schenckii (dimorphic)
2. Found in soil, plants that are woody and thorny (think of a rose gardener). Infects the skin
3. Erythema nodulosa. Can spread by lymph and cause inflamed subcutaneous nodles
Term
Histoplasma capsulatum

1. Where?
2. Source of organism, route of entry
3. Clinical manifestation
4. Diagnosis
5. Treatment
Definition
1. Ohio and Mississippi river valleys
2. Soil, bird droppings. Inhaled
3. ->Histoplasmosis. 90% are asymptomatic or have mild flu-like symptoms. Can progress to chronic pulmonary histoplasmosis or cavitary pulmonary histoplasmosis, and disseminate.
4. Culture, Histoplasma Ag in blood and urine
5. Amphotericin B, Itraconazole
Term
Coccidioides immitis

1. Where and what does it cause (popular term)
Definition
SW US. Valley fever
Term
Blastomyces dermatitides

1. Where?
2. Progression of disease and manifestation
Definition
1. Ohio and Mississippi river valleys (much rarer than histoplasmosis)
2. Inhaled, colonizes lungs, then disseminates. Causes serious lung and skin lesions (plaques, etc.)
Term
Pneumocystis jiroveci

1. Characteristics
2. What disease does it case and describe it. How can it be prevented?
Definition
1. Yeast-like, lacks ergosterol in membrane
2. Pneumocystis pneumonia - subacute pneumonia, unproductive cough, low oxygen saturation). Prevent with bactrim prophylaxis
Term
Dermatophytes

1. Yeast or mold?
2. Where do they infect?
3. Diagnosis
Definition
1. Molds
2. Superficial keratin layer
3. Skin scrapings ->culture or microscopy.
Term
List all of the pathogenic parasites and their classification
Definition
Protozoa:
Plasmodium spp
Babesia spp
Trichomonas vaginalis
Toxoplasma gondii
Trypanosoma
Cryptosporidium parvum
Microsporidium spp
Giardia lamblia
Leishmania
Entamoeba hystolytica
Acanthamoeba
Intestinal roundworms:
Ascaris lumbricoides
Hookworm (Necator americanus, ancylostoma duodenale)
Pinworm (enterobius vermicularis)
Whipworm
Strongyloides stercoralis
Tissue roundworms:
Wuchereria bancrofti (-> elephantiasis)
Brugia malayi (-> elephantiasis)
Onchocerca volvulus (->river blindness)
Loa loa spp
Mansonella spp
Tapeworms (cestodes)
Taenia solium
Taenia saginata
Echinococcus granulosus
Flukes (trematodes)
Schistosoma spp
Term
Definitive host vs. Intermediate host
Definition
Definitive host = where the parasite reproduces sexually
Intermediate host = where the parasite reproduces asexually
Term
Entamoeba hystolytica

1. Life cycle
2. Pathogenesis and manifestations
3. Epidemiology
4. Treatment
Definition
1. Trophozoites are in the gut, they can come together to form infectious cysts which are in the feces - they are ingested and then enter the next person's gut, where they mature into trophozoites
2. 90% just cruise through, asymptomic. 10% trophozoites will invade the colonic mucosa, causing bloody diarrhea. They can migrate to the liver through the portal blood causing a liver abscess
3. Rare in the us except MSM and facilities
4. Metronidazole
Term
Acanthamoeba spp.

What do you need to know about them?
Definition
They swim around in fresh water and infect your eyes if you if you use that water to wash your contacts. ->keratitis (infection of the cornea)
Term
What are the four protozoa that cause diarrhea, and what is notable about each of them? Where do they occur?
Definition
1. Entamoeba hystolytica - mostly abroad, a bit in the U.S. Can cause liver abscesses
2. Giardia lamblia - everywhere. People with IgA deficiency are susceptible. Leads to frothy, smelly diarrhea and abdominal bloating
3. Cryptosporidum parvum - everywhere. Prolonged diarrhea
4. Microsporidium spp. - everywhere. Common in immunocompromised (AIDS)
Term
Trichomonas vaginalis

1. Route of transmission
2. Symptoms/Manifestations
3. Diagnosis
4. Treatment
Definition
1. STI
2. Male - asymptomatic. Female - Vaginal irritation, soreness. Frothy discharge with characteristic fish odor
3. Wet mount = pear shaped protozoa with flagella twitching around
4. Metronidazole
Term
Babesia

-vector
-geography
Definition
- ticks
- U.S - esp. Northeastern (Martha's Vineyard, Cape Cod, Nantucket Island)
Term
Leishmania spp

1. Vector
2. Geography
3. Manifestations
Definition
1. Sandfly
2. Central and South America, Middle East and Africa (Iraq - think veterans)
3. Varies depends on the organism and host immune system. Can cause disfiguring skin ulcers, or can have visceral effects (=Kala azar - hepatosplenomegaly)
Term
Diseases, reservoirs, and vectors of the Trypanosoma spp.
Definition
Chagas disease = American trypanosoma. Vector = Kissing bug reduviid. Causes colonic/esophageal dysmotility, cardiac arrhythmia, myocarditis. May cause neuronal damage as sequelae due to autoimmune molecular mimcry

Sleeping sickness = African trypanosoma. Vector = Tsetse fly. Reservoir = cattle. Severe meningo-encephalitis. Fatal.
Term
Ascaris lifecycle and treatment
Definition
Ascaris.
adult worm in gut lays eggs. Contaminated feces are then consumed, the eggs hatch and the larvae enter the bloodstream. There they travel into the lungs and throat, where they are coughed up and swallowed into the gut for the second time, where they mature into an adult. Treated with mebendazole, albendazole, ivermectin
Term
Pinworm symptoms, diagnosis, and treatment
Definition
Pinworm (enterobius vermicularis)
- perianal itch
- perianal scotch tape, test it in the morning for eggs
- treat whole family with albendazole, mebendazole, or pyrantel
Term
Hookworm and strongyloides lifecycle

ancylostoma disease course vs. strongyloides disease course.
strongyloides treatment.
Definition
In soil, eggs and hatch and larvae penetrate the skin. They swim to the gut, where they mature and lay eggs.

Ancylostoma = not a human disease (from dog poop). Therefore just causes a rash on the feet that self resolves.
Strongyloides = lifelong infection. Waits around for the immune system to be deficient, then causes pneumonia, GI rupture by the worms perforating membranes. Treatment is with ivermectin.
Term
Filariasis

1. Causative organisms and their lifecycle
2. Clinical manifestations
3. Organisms and what they cause
Definition
1. Wuchereria bancrofti, Brugia malayi, Onchocerca volvulus, Loa loa spp, Mansonella spp. Larvae are transmitted through insect bite, they mature into adult worms in the lymphatics, causing elephantiasis and blindness if it occurs in the eye.
The organisms are tissue nematodes. EB and BM cause elephantiasis. OV = river blindness
Term
Schistosoma spp.

1. Lifecycle
2. Manifestations
3. Diagnosis
4. Treatment
Definition
1. Adult worms in the veins of the GI tract and bladder lay eggs, which are passed out by urine or feces. These get into fresh water, where they infect a snail (intermediate host). In the snail they turn into cerceriae, which then penetrate the skin of humans. They turn into larvae which swim to the liver and lungs, mature into worms, and then swim into the veins of the bladder and GI tract.
2. acute schistosomiasis = Kataya fever. chronic schistosomiasis -> liver cirrhosis, bladder cancer.
3. Diagnosis is by detecting the eggs in feces and urine. Also see eosinophilia
4. Treatment = praziquantel
Term
T. solium lifecycle
Definition
Adult tapeworms in gut lay eggs, that humans can ingest, or more commonly are ingested by animals. In the pigs GI tract the eggs hatch to become oncospheres and then create cysts all over the body. The cysts are then ingested when you eat undercooked pork - the larvae then invade your GI tract and do the same hting as well as maturing into worms. Cysts all over body = cysticercosis. Neurocysticercosis = seizures.
Term
What is the beef tapeworm called
Definition
Taenia saginata
Term
Echinoccocus granulosus

1. What disease does it cause
2. Lifecycle
3. Treatment
Definition
Hiyatid fever
2. Dogs are the definitive hosts, eggs can be ingested by sheep and humans. Invades and causes cysticercosis
3. Albendazole
Term
Lice

-Genus and species of different spots infected
- treatment
Definition
Pediculosis capitus
Pediculosis corporis
-permethrin, ivermectin, malathion
Term
Scabies

1. Causative organism
2. Pathogenesis
3. Where?
4. Treatment
Definition
1. Sarcoptes scabei
2. Feces cause the itching
3. Webbing of hands. 5% immunocompromised = Norwegian scabies.
4. Permethrin cream or PO ivermectin.
Term
Thayer-Martin media
Definition
Grows Neisseria spp exclusively
Term
Neisseria meningitidis

1. Characteristics
2. How can you tell it apart from N. Gonorrhoeae?
3. Virulence Factors
4. Pathogenesis
5. Presentation
6. Diagnosis, Prevention, Treatment
7. Why hasn't vaccine reduced the incidence in infants?
Definition
1. Gram (-) diplococci, oxidase (+), grow on Thayer-Martin media, non-motile
2. It has a capsule and turns maltose into acid - N. Gonorrhoeae does neither
3. Capsule - anti-phagocytic, anti-complement. Comes in different serotypes - A,B,C,W135. Pili, Outer membrane proteins - aid in adhesion, have some antigenic variation. IgA protease, transferrin, LOS
4. Colonizes nasopharynx (many carriers). Invades into blood, spreads to skin and brain. Destroys capillaries in skin, causing purpura, infects brain meninges. Also can cause arthritis and osteomyelitis
5. High fever, headache, nuchal rigidity, purpura.
6. Gram stain of CSF fluid. If it's diplicocci gram (-) you can be sure it's N. meningitidis. Prevention - give antibiotics to contacts, immunize college students, children, those who are susceptible (complement deficiency, asplenics). Treatment - a wide range of antibiotics work - penicillins, fluoroquinolones, cephalosporins. Latest vaccine = Menactra.
7. Organisms with the B capsule - the body won't make antibodies against them because they look like the sialic acid residues on neuronal cells. This B capsule accounts for 80% of neonatal infections (also some younger kids, college students).
Term
Streptococcus pyogenes

1. Characteristics
2. How do you differentiate S. pyogenes from S. agalactiae?
3. Reservoir and spread?
4. Bacteremia?
5. Virulence Factors
6. Disease Manifestations
7. Diagnosis
8. Treatment
9. Prevention
Definition
1. Gram (+) cocci in chains, catalase (-), non motile, non spore forming
2. PYR test, susceptibility to bacitracin (pyogenes is)
3. Human reservoir - spread through fomites
4. Yes, it can occur. Less likely in pharyngitis because there is more competitive local flora to inhibit it.
5. M protein - lots of variation. A protein that sticks out through the cell wall. Binds to Factor H -> molecular mimcry. W/ LTA, adheres to the fibronectin around epithelium. Causes rheumatic fever and poststreptococcal glomerulonephritis (PSGN). Lipotechoic acid (LPA) -> adhesion to fibronectin. Hyaluronic capsule -> anti-phagocytic, looks like ECM (momecular mimicry). C5a peptidase. Streptolysin O and Sterptolysin S = hemolysins. Destroy RBCs mainly, also WBCs and tissue. Streptokinase A = dissolves blood clots that the body tries to make to wall it off. Streptodornase = DNAse. Hyaluronidase - digests ECM. Erythrogenic toxins -> get into blood and cause toxic shock syndrome by activating T Cells
6. Suppurative = pharyngitis with abscesses, cellulitis, abscesses, pyoderma, necrotizing fasciitis. Toxogenic - erythrogenic toxin gets into blood stream, causing scarlet fever. Non-suppurative = Rheumatic fever, PSGN (hematuria, edema, HTN, self resolves)
7. gram stain pus from wound, culture throat swab (too many other streps to gram stain)
8. Penicillin, other antibiotics
9. No vaccine, penicillin prophylaxis if rheumatoid fever.
Term
Streptococci classification scheme
Definition
Beta (complete)
Group A: pyogenes
Group B: agalactiae

Alpha (partial)
Pneumoniae
Viridans

Gamma (Non)
Enterococcus
Viridans
Term
What is fabulation?
Definition
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