Term
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Definition
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Term
| EXAM 3 - Etiologic Agents of Infectious Disease |
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Definition
infectious disease by organ system
Gram-positive rods
Gram-positive cocci
Gram-negative rods
Gram-negative cocci
Obligate intracellular pathogens
Fungi |
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Term
How do you get conjunctivitis?
Aka "pink eye" |
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Definition
most commonly due to an infection (either viral or bacterial) or allergies
can accur as a symptom of upper respiratory tract viral infection (common cold, sore throat)
Sx: inflammation of the eye conjunctiva |
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Term
| Where and how do you get keratitis? |
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Definition
predominately by viral (but also bacterial) infection, e.g. herpes simplex virus
the cornea becomes inflamed
Sx: moderate-intense pain, often w/ impaired eyesight
deep keratitis can be scar-forming |
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Term
| Is retinitis caused by bacterial or viral agents? |
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Definition
Viral
Sx: night blindness can proceed to tunnel vision, ultimately producing blindness in middle-age |
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Term
| All infections of the eye are due to ___ |
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Definition
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Term
How do you get otitis externa (OE)?
Aka "earache" |
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Definition
an infection of the outer ear canal due to trapped water
inflammation can be secondary to bacterial or fungal infection, often painful |
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Term
| Where do you contract myringitis? |
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Definition
| tympanic membrane of the ear |
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Term
| How and who gets otitis media w/ effusion? |
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Definition
irritants or viral infections or allergic reactions of nasal passages cause inflammation of inner ear and the eustachian tubes (which normally sweep mucous up and out) leading to accumulation of thick secretions
bacteria are then able to ascend up the inner ear cavity, produce overgrowth
OME = a biofilm |
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Term
| What is the most common sinusitis? |
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Definition
maxillary
(either viral or bacterial NF & FPs)
antecedent evens cause inflammation, accumulation, blockage overgrowth |
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Term
| What seems to be the general course of pathogenesis for bacterial infections of bady cavities? |
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Definition
(1) some antecedent event
(2) inflammation
(3) accumulation
(4) blockage
(5) overgrowth
3, 4, 5 may occur simultaneously? |
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Term
| How do you get rhinitis and why do symptoms manifest? |
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Definition
commonly caused by bacterial or viral agents of the upper respiratory tract
production of acute inflammatory mediators (immune response, vasodilation, excess mucous, inflammation) are primarily responsible for signs and symptoms (irritation, sneezing, rhinorrhea, leakiness, nasal congestion)
Infectious rhinitis = rhinorrhea (runny nose)
Allergic rhinits = clear discharge, swelling |
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Term
| How does bacterial growth produce dental caries? |
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Definition
bacteria form biofilm (plaque) on teeth that calcifies (calculus/tartar) and ferment sugar
the lactic acid solubilizes and demineralizes the enamel, producing caries - a chronic, slowly progressive, and not self-limiting disease |
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Term
| What is the difference b/w gingivitis and periodontitis? |
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Definition
in gingivitis, biofilm (plaque) buildup becomes calcified and produces inflammation of the gingiva (aka "gums")
periodontitis involves deeper tissue levels, of periodontal bone and ligament, and may result in teeth loss |
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Term
| Where does stomatitis occur? |
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Definition
in the mucous linings of the mouth, oral cavity incl. tongue
severe iron deficiency, or B-vitamin deficiency, can result in stomatitis
the diploid fungus Candida Albicans causes "thrush" on the tongue |
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Term
| Where does glossitis present? |
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Definition
on the tongue (alone)
may become swollen and block airways (medical emergency)
can be caused by iron deficiency, B-vitamin deficiency, or colonization by Candida Albicans (aka "thrush") |
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Term
| Where does parotitis present? |
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Definition
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Term
| Are infections/inflammations of the mouth and oral cavity due to NF or FP |
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Definition
NF
overgrowth of normal flora |
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Term
| In respiratory tract RTI, what is more likely the cause - NF or FP? |
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Definition
FPs
predominately
but also could be oral NF
bacterial, viral, fungal, or less commonly protozoal |
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Term
| How do you get diphtheria? |
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Definition
bacterial exotoxin
serious infection
upper RTI caused by Corynebacterium diphtheriae
Sx: sore throat, fever, sometimes myocarditis, sometimes neuropathy
swelling can close off airways (req. tracheotomy) |
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Term
| Where does pertussis manifest? |
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Definition
in the bronchial tree
highly contagious bacterial disease caused by Bordetella Pertussis
Sx: severe chronic "whooping" cough |
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Term
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Definition
inflammation of lung tissue (alveoli)
common cause of death among elderly |
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Term
| What is the etiology of lower RTI (e.g. bronchitis, influenza, pneumonitis, pertussis) |
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Definition
allergens, chemicals
immune-mediated, or autoimmune
infection |
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Term
| Where and how does influenza manifest? |
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Definition
viral infection of the bronchial tree, lower RTI
Sx: fever, sore throat, muscle pains, severe headache, coughing, weakness/fatigue |
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Term
| How does bronchitis develop? |
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Definition
inflammatory condition w/o reference to infection
incl. bronchitis, bronchiolitis, chronic bronchitis, chronic obstructive pulmonary disease
although, inflammation causes further complications (one of the leading causes of death) and acute exacerbations can come in the form of bacterial/viral infection |
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Term
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Definition
viral infection of the trachea
primarily in younger children
Sx: swelling, "barking" cough, stridor |
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Term
| What are the different types of pneumonia we discussed? |
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Definition
Lobar (consolidation) pneumonia aka "typical" pneumonia: agent colonizes alveolar lining, multiplication, WBC infiltration, displacement
Interstitial pneumonia aka "patchy" or "atypical" or "walking" pneumonia: agent replicates in interstitium, fluid accumulation, inflammation here |
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Term
Cavitary lesions
aka lung abscess |
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Definition
necrotizing abscesses caused by microbial infection form a hole in lung tissue that does not grow back
often with aspiration, alcoholism |
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Term
| How do you get pneumonia? |
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Definition
viral, bacterial, fungal, protozoan infectious etiology
inflammation and immune response ensures there is fluid accumulation in the alveoli
caused by Strept. Pneumonia (50% of the time)
Sx: breathing problems, fever, cough, chest pain |
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Term
Tubercles
aka organized granulomas
aka solitary pulmonary nodule |
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Definition
round nodules surrounded by parenchyma
found in the lungs
opaque due to calcification
tubercles often develop as a result of infection by Mycobacterium tuberculosis (MTB): asymptomatic and latent |
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Term
| What causes emesis (vomiting)? Diarrhea? |
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Definition
ingestion of an enterotoxin aka exotoxin
or via systemic immune response to infection
diarrhea (liquid feces, increased fluid and electrolyte loss) is usually caused by these same enteroxtoxins |
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Term
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Definition
in situ toxin formation
leads to intestinal cell destruction and mucosal adherence, bleeding and pseudomembrane formation (necrotic cells, PMNs, monocytes, RBCs)
Sx: pain of lower abdomen and rectum |
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Term
| What is tenesmus a symptom of? |
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Definition
dysentery
tenesmus = strained, painful defecation w/ little fecal matter actually excreted
you can also get mucus/bloody stools and pain in dysentery |
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Term
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Definition
tissue invasion occurs in stomach or intestine
for gastrointestinal infections
bacterial agents that cause bacteremia though usually enter through the large intestine |
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Term
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Definition
immune response to foreign antigen is directed at host tissue instead
autoimmune attack on PNS myelin
often seen as a complication of GIT
most commonly caused by Campylobacter Jejuni
Sx: autoimmune ascending flaccid paralysis |
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Term
| Hemolytic-Uremic Syndrome (HUS) |
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Definition
a toxemia (exotoxoin in the blood)
where the toxin targets endothelial cells of GIT and kidney
predominately affects children
the "HUS triad" to look for one week after onset of diarrhea (e.g. infectious E. coli) includes:
(1) hemolytic anemia via RBC lysis
(2) acute renal failure via toxin action
(3) thrombocytopenia, failure to clot, bleeding
also can have CNS complications |
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Term
| Which UGTIs we discussed are STDs? |
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Definition
Pyelonephritis, Cystitis, Vaginitis = not an STD
Urethritis, Cervicitis = STDs |
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Term
| As a result of an STD agent, what are the Sx of urogential tract infection? |
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Definition
genital ulcers (3 FP agents)
papilloma (1 FP agent) |
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Term
| How does one contract meningitis? |
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Definition
meningeal inflammation can be caused by infection (bacterial & fungal are more serious than viral) or less commonly by drugs
the etiologic agent grows in the CSF subarachnoid space, edema, reduced cerebral blood flow, inflammation, irritation
which elicits a protective response (Nuchal rigidity) |
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Term
| What are the symptoms of meningitis? |
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Definition
meningeal inflammation
Sx: stiff neck, headache, fever, vomiting, petechiae, can result in cranial nerve injury, hypoxic-ischemic brain damage, catastrophic FX |
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Term
| What are the four major phyla of fungi? |
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Definition
Zygomycetes (sexual spores: zygospores)
Basidiomycetes (external spores: basidia)
Ascomycetes (internal spore sac: ascus)
Deuteromycetes (no known sexual state) |
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Term
| How do saprophytes obtain nutrients and energy? |
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Definition
| from dead plants and animals in soil and water |
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Term
| How are fungi different from bacteria at the cellular level? |
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Definition
Fungi are eukaryotic
They have a nucelus (or many) with a nuclear membrane, also have organelles (e.g. ER, mitochondria, 80S ribosomes)
They can reproduce sexually or asexually
& fungi have cell membranes that contain ergosterol (analogous to cholesterol in mammals), which makes ergosterol a common target for antifungal drugs like Amphotericin B |
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Term
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Definition
| Yeast that reproduce asexually produce blastoconidia via budding |
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Term
| Which species of yeast has a rigid polysaccharide capsule surrounding it? |
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Definition
Cryptococcus
this capsule helps explain some of its pathogenicity (cryptococcosis) |
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Term
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Definition
Yeast make up only 1% of fungal species
but they are unique b/c they are unicellular and mostly produce asexually (via budding: blastoconidia)
some species of yeast (e.g. Candida) elongate into chains called pseudohyphae. Candida is responsible for the oral and vaginal infections, known as candidiasis or simply "yeast infection", in humans |
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Term
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Definition
unconstricted tubular outpourings observed in germinating yeast and spore-forming fungi
A germ tube test is a diagnostic microscopy tool commonly used to confirm the presence of Candida Albicans |
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Term
| Do yeast reproduce sexually? |
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Definition
| Some species do, form ascospores (internal sacs) or basidiospores (external spores) |
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Term
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Definition
molds are fungi that grow in multicellular filaments: hyphae
they form fluffy, cottony colonies
& their cell wall consists of carbohydrate, chitin, chitosan, glucan and mannan |
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Term
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Definition
| yeast can form pseudohyphae as a result of incomplete budding |
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Term
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Definition
a mass of intertwined hyphae, sometimes called shiro
it is through the hyphae that fungus absorbs nutrients
they can be huge - one site in Oregon identified a contiguous mycelium growth 2,400-acres in size (1,665 football fields) |
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Term
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Definition
Hyphae can be
vegetative: growing adjacent/into the substrate
submerged: underground for nutrient absorbtion & food acquisition
aerial: extend above substrate (pictured) w/ fruiting bodies giving rise to spores/conidia
demiatiaceaous fungi: contain black pigmented hyphae containing melanin |
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Term
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Definition
| have black-pigmented hyphae which contain melanin |
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Term
| Asexual vs. Sexual reproduction in fungi |
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Definition
Asexual: via mitosis, can form Sporangiospores (sporangium cleavage) or Conidiophores (hyphae differentiation)
Sexual: via meiosis, can fuse two nuclei to form Zygospores, Ascospores, and Basidiospores
just remember,
"no sex on SportsCenter"
"Zoo Animals Bone" |
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Term
| What are the five thermally dimorphic fungi species that grow as mold/yeast? |
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Definition
Blastomyces dermatiditis
Histoplasma capsulatum
Cocciodoides immitis
Paracoccidoides brasiliensis
Sporothrix schenckii
"Historically, Spartacus Blamed Croccodiles from Paris to Brazil" |
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Term
| Mnemonic for thermally dimorphic fungi |
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Definition
"Historically, Spartacus Blamed Croccodiles from Paris to Brazil"
Histoplasma capsulatum, Sporothrix schenckii, Blastomyces dermatiditis, Cocciodoides immitis, Paracoccidoides brasiliensis |
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Term
| How do fungi find entry into humans to cause disease? |
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Definition
either by inhalation (of spores) or by traumatic introduction into tissue
it is thought their ability to cause disease is an accidental phenomenon for fungi, though (175 species out of hundreds of thousands) |
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Term
| What temperature range do fungi like to grow at? |
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Definition
most fungi are mesophilic
& prefer mild temperatures between 20-45*C
which is below that of the average human body |
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Term
| What is the best defense against fungal infection? |
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Definition
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Term
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Definition
Relatively low virulence in fungi
which helps explain why disease/infection often occurs in debilitated immunocompromised hosts |
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Term
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Definition
type of fungi: feed off keratin in hair, skin, nails
they include the following (3) genera:
Epidermophyton
Microsporum
Trichophyton
dermatophytes do not usually invade host tissue, but rather colonize the outer layer of skin (epidermis)
these are the most common fungal infections in man (ringworm, tinea, "jock itch")
"Microsporum no nails, Epidermiphyton no hair, Trichophyton everywhere"
"you can't spell Dermatophytes without E-M-T" |
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Term
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Definition
A quick, inexpensive fungal test to differentiate between dermatophytes and Candida albicans from other skin disorders (psoriasis, eczema)
Normal (negative) result = no fungi
Septate, segmented hyphae = possible ringworm
Spore-formers show arthroconidia
Tinea versicolor shows curved hyphae
Yeast cells are round, oval, budding |
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Term
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Definition
binds strongly to cellulose and chitin (found in fungal cell walls, as well as yeast buds)
Calcofluor is also the dye used in white-colored clothing which fluoresces under "black-lighting" |
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Term
| Periodic Acid Schiff (PAS) stain |
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Definition
used to detect glycogen and polysaccharides, stains fungal elements (hyphae & yeast) with a purple-magenta color
(picture: esophageal candidiasis) |
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Term
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Definition
a diagnostic tool used in dermatology to identify/diagnose fungal infections
(via UV light) |
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Term
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Definition
simple stain for the microscopic identification of fungi
organisms in the slide mount stain are killed by the high concentration of phenol |
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Term
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Definition
a chronic, mild mycosis of the stratum corneum
Sx: tiny spots (on chest, abdomen, upper limbs, back) eventually grow in size forming branny, discolored or depigmented lesions
Risk Fx: poor health, chronic infections, excessive sweating, pregnancy
Dx: Wood's Lamp (fluoresces golden-yellow) or KOH stain (shows clusters of round, budding yeast, short branching hyphae) |
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Term
| What fungi species causes Pitaryiasis versicolor? |
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Definition
Malassezia furfur
which is NF of the skin
"malasSEZIA b/c tiny spots on chest/back grow in SIZE to depigmented lesions"
"FURFUR b/c it FLUOResces golden-yellow under Wood's Lamp" |
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Term
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Definition
a superficial mycosis of the stratum corneum caused by dermatiaceous fungi
usually, a tropical disease in equatorial regions
Sx: painless macules on palms of hands
Dx: KOH stain (shows brown, branching septae & budding yeast) |
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Term
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Definition
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Term
| What fungi species of fungi causes Tinea nigra? |
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Definition
Hortaea (exophiala) werneckii
which is dermatiaceous (black pigmented hyphae containing melanin)
Dx: Hortaea werneckii stains brown and shows multiple hyphae and budding yeast on KOH stain |
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Term
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Definition
fungal infection of the hair shaft
Sx: irregular nodules |
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Term
| White piedra vs. Black piedra |
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Definition
White piedra: softer granule
caused by Trichosporon
"white trash"
Black Piedra: hard, darkly colored, varies in size
caused by Pedraia hortai
"black president" |
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Term
| Where do you find dermatophytes? And what families are responsible for human disease |
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Definition
combs, brushes, theater seats, hats
they can be anthropophilic (human reservoirs) or zoophilic (animal carriers) or geophilic (live in soil)
Microsporum = no nails
Epidermiphyton = no hair
Trichophyton = everrrrywhere |
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Term
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Definition
cutaneous mycosis of the head, scalp, eyebrows
caused by Microsporum or Trichophyton
Sx: itching, dandruff, hair breaks off, leaving patches
Dx: KOH mount or Wood's Lamp (in which Microsporum spp. Fluoresce green) |
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Term
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Definition
differential types of Tinea Capitis
Ecothrix = forms mycelia and conidia around hair shaft, destroys the cuticle
usually resolves, but spreads to other tissues
"grey patch ringworm"
Endothrix = within the hair shaft, no cuticle destruction, esp. from T. tonsurans
tendency to become chronic
"black dot ringworm" |
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Term
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Definition
cutaneous mycosis of the body
most commonly from Trichophyton rubrum and Trichophyton mentagrophytes
Sx: horny layers of skin that spread
hair follicles act as reservoirs |
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Term
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Definition
cutaneous mycosis of the groin
usually tropical regions, more in males
in the US, most commonly caused by T. rubrum
Sx: severe itching |
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Term
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Definition
cutaneous mycosis of the nails
is the form most resistant to treatment
Organism: T. rubrum
Sx: brittle, yellow crumbly nails |
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Term
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Definition
cutaneous mycosis of the feet
aka "Athlete's Foot", common in institutions
can become chronic, drug-resistant
Organisms: T. rubrum, T. mentagrophytes, E. floccosum
Sx: small vesicles form and rupture |
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Term
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Definition
cutaneous mycosis of the beard
Organisms: T. mentagrophytes, T. rubrum |
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Term
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Definition
cutaneous mycosis of the hands
Organisms: T. rubrum, T. mentagrophytes, E. floccosum |
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Term
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Definition
| involves the dermis, subcutaneous tissues, muscles and fascia |
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Term
Sporotrichosis
"Rose gardener's disease" |
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Definition
subcutaneous mycosis involving traumatic inoculation into the skin
mostly tropical, especially farmers and gardeners
Organism: the dimorphic fungus Sporothrix schenckii
Sx: nodular skin lesions that ulcerate, pulmonary can be inhaled, can spread in immunosuppressed pt's to form disseminated sporotrichosis
Dx: culture, biopsy (cigar-shaped yeast)
"sporo :: sporo" |
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Term
| How is the dimorphism of Sporothrix schenckii evident in sporotrichosis? |
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Definition
| S. schenckii goes from colonies of hyphae at room temperature to forming cigar-shaped budding yeast at body temp (which can be seen after culture and biopsy) |
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Term
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Definition
take advantage of immunocompromised host
greatly increased w/ organ transplants, radiation therapy and AIDS |
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Term
| What three fungi families are mainly responsible for opportunistic infections? |
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Definition
Candidiasis
Aspergillus
Rhizopus/Absidia/Mucormycosis
Cryptococcus
"What an opportunity - CARCAM!" |
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Term
|
Definition
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Term
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Definition
Candida yeast can enter through any break in the skin, overgrowth of the fungus results in disease (so cell-mediated immunity is key)
to infect, C. albicans transforms from unicellular yeast to invasive multicellular filament
Sx: thrush (white patches on tongue), candidal vaginitis (itchy cottage cheese), chronic mucocutaneous candidiasis (skin, hair, nails & mucous membrane infection),
or can become disseminated candidiasis (kidney, braine, myocardium, eye) |
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Term
| How do you identify Candida albicans? |
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Definition
Germ tube (+)
pseudohyphae
blastoconidia |
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Term
| What cells play an important role in suppressing Candidiasis infection? |
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Definition
PMNs, monocytes, eosinophils, dendritic cells
& lymphocytes play an important role
this helps explain why patients who are immunosuppressed or have T-lymphocyte dysfunction may end up with chronic mucocutaneous candidiasis |
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Term
| Indwelling catheters are a contributing factor for |
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Definition
Candidiasis infection
(probably more) |
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Term
| Why would extended antibiotic use be a contributing factor of Candidiasis? |
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Definition
| b/c many Candida sp. are NF |
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Term
| What is in the "pseudomembrane" of thrush? |
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Definition
it's composed of Candida cells, epithelial cells, WBC, food debris, necrotic tissue, bacteria
all lumped together
in white curdlike patches on tongue
prevalent in pt's on inhaled steroids for asthma and AIDS patients |
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Term
| What is the most common cause of vaginits? |
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Definition
Vaginal candidiasis
Sx: thick cottage cheese, severe itching
Risks: diabetes, pregnancy, antibiotic Rx |
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Term
| What increases risk of disseminated candidasis? |
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Definition
neoplasms, burns, transplants, low birth weight
dissemination to kidney, brain, myocardium produces high mortality (~40%) |
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Term
| What is the usual POE for Aspergillus? |
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Definition
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