Mycobacterium tuberculosis

micro and structure 

• rod-shaped non spore, non encapsulated, slow growing, obligate aerob, acid fast (not going to be on gram stains nor culture) 
• complex cell wall with high lipid content (60% mycolic acid) (hydrophibic)
• has N glycolymuramic acid instead of N acetyl derivative
• cord factor important in pathogenisis (glycolipid)
• has glycolipids including LAM and PIM
• proteins in cell wall highly antigenic
• sufatides and is resistant to drying
• Runyon classification - MOTT

Acid Fast Bacterial Cell Envelope

• resists gram staining due to the presence of lipid coat
• strong staining with acid fast stain, counterstain with methylene blue (Red Snappers)
• chemically resistant to disinfectants, detergents and common antibiotics
• slow growing due to low nutrient permeability
• cell wall has outer lipids(waxes_ mycolic acid, peptidoglycan, plasma membrane and PIM and LAM

Other Mycobacterium

• Mycobacteria other than TB (MOTT) follow the Runyon classification
• slow growing, phtochromogens: M. Marinum
• Slow growing, scotochromogens:
• slow growing, nonpigmented: M avium, M intracellulaire
• Rapidly growing: M. fortuitum
• outlier one is mycobacterium leprae

Mycobacteria

Immune Response

• intracellular growing bacteria
• in unstimulated cells it prevents fusion of phagosome and grow in vacuoles
• cell mediated immunity required: CD4 T cells, interferon gamma (activation of macrophages) and TNF alpha (macrophage maintenance)
• granuloma formation = contaminment
• active infection: large number of CD4 T cells: DTH response to mycobacterial antigen
• cavities can be seen in these patients

Mycobacterium tuberculosis

Epidemiology

• principle risk factor-breathing, transmission by droplet nuclei
• human pathogen
• recent increases due to: HIV, homeless, IV drug abuse, decreased public health vigilance
• humans are susceptible to TB, but resistant to disease
• about 5% of those infected will develop (10% over life time) 
• asymptomatic transmission (if latent like this use single drug/only time you do this)

TB Primary

(Mycobacterium tb)

• incubation for 3-6 weeks after initial exposure (prolonged, espically compared to strep pneumo)
• no-pre-existing immunity (has to be initial)
• primary replication in lung (lower lobe in primary infection) and hematogenous spread to multiple organs
• sub clinical(often) or mostly systemic and n on specific symptoms: feverm anorexia, lethargy and unproductive cough
• most cases contained evidence of past infection: tuberculin sensitivity and Ghon complex
• 5-10% will develop active disease

TB Chronic (reactivation)

(Mycobacterium tb)

• previously infected patient (reactivation)(CD4 drops)
• cellular immunity contains, but does not eliminate, bacilli
• accumulation of large concentrations of TB antigen results in severe hypersensitivity
• caseous necrosis (destruction at center of cavitiy)
• tubercules liquify and cavity formation and spread
• fever, nigh sweats, weight loss, dyspne  a, cough and hemoptysis
• cellular immunity may eventually control but viable TB persists in healed granuloma and can recur
• reactivation is usually seen in upper lobe 

 T.B. Extrapulmonary

(Mycobacterium tb)

• Hematogenous spread (primary TB)
• pre disposing factors: immunsupprsion (HIV) chronic illness, diabetes
• any organ affected: brain, heart, kidney, lymph nodes (Pott's disease(skeletal-spine) and liver

Mycobacterium tb

screening and laboratory

• Skin Test (PPD): Tine test (not used) and Mantoux Method (inferior in people over five)
• Sputum (3x) - Acid-fast stain
• culture (3-6 weeks)
• chest radiograph
• new blood test for cytokine test (one of the best tests

M. tuberculosis Treatment

• isoniazid (INH), rifampin, pyrazinamide, streptomycin, ethambutol
• INH and rifampin, treatment of choice
• use 2 or more drugs to prevent emergence of resistant mutants
• 9 month therapy
• use four drugs for everything but latent (just INH)
• NO VACCINE???

MOTT

• Mycobacteria other than Tb
• M. avium and M intracellulare(MAI)
• most common non-TB mycobacterial species
• environment- major source of MAI
• requires multi-drug treatment
• exsize lymph nodes

M. avium and M. intracellulare

Complex (MAC)

• most common non-TB species
• environment - major source of MAI
• immunocompetent indivudals: middle aged male smokes (cavitary lung disease); elderly female nonsmokers (middle lobe infiltrates, lady windermere syndro)
• common infection in AIDs patients: extensive dissemination and growth in tissue
• requires multi-drug treatment different from TB
• ***didnt really cover this info****

Mycobacterium leprae

microbiology

• rod-shaped, nonspore forming, nonencapsulated, slow growing, aerobe, acid fast
• does not grow in culture
• generation time: 13 days in foot pad of mice
• armadillo-experimental animal (on feet)
• localizes in cooler parts of body (noose or ear) 
• obligate intracellular parasite

Leprosy

(mycobacteria)

• uncertain mode of transmission
• nasal mucosa of patients contain large numbers of M. leprae
• nasal may be source of infection and entry route
• animal reservoir??
• 2-4 year incubation after initial exposure
• indeterminate leprosy: freast lesions may heal or progress
• can become tuberculoid leprosy or lepromatous leprosy

Tuberculoid Leprosy

• few well circumscribed skin lesions, nerve damaged and enlarged, sensory loss, nerve damage- a distinct feature
• bacilli rare - not contagious
• granulomas form in skin and nerves
• Th1 response
• not highly contagious

Lepromatous Leprosy

• Variety of skin lesions, no granulomatous response
• diffuse aggregate of foamy macrophages apear in skin, mucus membranes, peripheral nerves
• lesions coalesce, skin thickening, cartilage destruction
• many bacilli, lesions usually involve cooler parts of body
• TH2
• contagious
• like the guy in kingdom of heaven

Mycobacterium leprae

Diagnosis and Treatment

• clinical signs and symptoms
• biopsy-acid fast stain
• lepromin reaction - not useful
• treated with dapsone, rifampin, and clofazimine
• combination of two or three of the above taken for 6 months to two years

Treponema Microbiology

• gram-negative, microaerophilic, long, thin, and tightly coiled spirochetes
• has endoflagella and is motile
• reproduce by transverse fission
• replication/doubling time is 30hours
• sensitive to drying and heat
• dows not grow in culture-dependent on host for purines, pyrimidines and most AA

Treponema pallidum

epidemiology

• syphillis  
• found worldwide, 3rd most common STD
• humans only natural host
• spikes of new cases correspond to social changes
• last decade showing trend among gay males
• sexual contact w/ primary or secondary syphilitic lesion (accounts for 30% of transmissions)
• less common methods of transmission: non genital contact, need sharing, transplacental transmission

T. pallidum

Virulence Factors

• syphillus
• host immune resposne-kye to clinical disease
• hyaluronidase: perivascular infiltration (?)
• outer membrane proteins: spirochete specific not exposed
• host fibronectin: adhere and directly interact w/ host tissue

Primary Syphilis

Secondary Syphilis

• T. pallidum disease
• occurs 2-10 weeks after primary lesion has healed (primary syphilis)
• maculopapular rash, sore throat, headache, fever, myalgia, anorexia, genralized lymphadenopathy, and the patient is infections
• rash and symptoms genearlly disappear

Tertiary Syphilis

• Treponema pallidum disease
• develops in approx 30% of patients w/ untreated syphilis
• appears 5-30 years later: meningovascular syphilis, cardiovascular syphilis(aneurysm) and isolated gumma in any organ
• neurosyphilis?

HIV and Syphilis

• patients infected w/ syphilis also at risk of acquiring HIV: address other high risk sexual behaviors and exposures
• presence of genital ulcers facilitates transmission of HIV
• Co-infected patients may present w/ secondary manifestions: neurosyphilis; uveitis
• treatment failures: rule out neurosyphilis (spinal tap)
• also if both secondary syphilis symptoms can show in primary stage

Latent Syphilis

• seroactivity but no active clinical diseaseclassified (possitive titer) as early latent and late latent
• early latent syphilis (preceeding 1 year) if only : documented seroconversion, unequivocal 1 or 2 shyphilis symptoms and sex partner with documended 1, 2 or 3 syphilis
• late latent syphilis is previous described conditions not met
• treatment: early latent: PCN 2.4 mi units(IM injection x 1)
• late latent syphilis: PCN 7.2 mil units (IM injection x 3 weeks)

Treponema pallidum laboratory diagnosis

• darkfield (not practical) or fluorescent Ab. microscopy
• non-treponemal antigen tests:VDRL, RPR(rapid plasma reagin) or CF (these are screen tests)
• treponemal tests: FTA-ABS, TPHA, or TPI (more specific, less sensitive test)
• treatment with penicilin (benzathine or benzyl)

Borrelia burgdorferi

microbiology and epidemiology

• (quasi) gram neg spiral organism
• motile with endoflagella
• microaerophilic
• difficult to culture
• found world wide (NE, Upper MW and Pacific west in US)
• transmitted by Ixodes ticks
• reservoir is white footed mouse and white tail deer
• no person to person spread
• leading vector borne disease in US

Lyme Disease

• Borrelia burgdorferi
• 3 day to 4 week incubation after tick bite
• primary stage: erythema chronicum migrans, flatted red area near bite that expands with central clearing, fever, chills, myalgia, haeadache and lasts 4 weeks
• Secondary stage: occurs wks to months later: arthritis, neurologic manifestationa nd cardiac disease
• thrid stage: months to years later: arthritis, chronic skin, nervous system or join involvement

Relapsing Fever

(Borrelia)

• Borrelia recurrentis
• small pruritic eschar at site of tick bite
• incubation about 1 week with abrupt onset of shaking chills, fever, myalgia and headaches
• hepatosplenomegaly common

Lyme Disease Lab ID, treatment

and prevention

• ID with serology and barbour stoenner kelly medium
• clinical presentation is very important in diagnosis
• Tetracyclin, penicillin, chloramphenicol, doxycline
• avoid exposure to ticks
• educate public

Leptospira Microbiology and

Epidemiology

• gram-neg small thinly coired spirochete
• motility by two periplasmic flagella
• aerobic and cultured on Fletchers medium
• reservoir hosts: rodents, small mammals
• incidental hosts: humans and farm animals
• can survive for several weeks in water
• water contaminated with infected animal urina
• humans infected by: recreational exposure to contaminated water and occupational exposure to infected animals
• peak incidence in summer and causes leptospirosis (leptospirosis interrogans)

Leptospirosis Disease

• Leptospira interrogans
• ingestion or exposure to contaminated food or water
• 1-2 week incubation
• fever, myalgia, malaise and rash
• infection can either clear in one week (most common result) or go to advanced disease

Leptospirosis advanced disease

• Leptospira interrogans
• lasts three weeks or more
• aseptic meningitis and/or generalized illness-headache, rash, vascular collapse, thrombocytopenia, hemorrhage, hepatic and renal dysfunctino
• called Weil's Disease?
• high mortality: 10%

Leptospirosis Lab ID

Treatment and Prevention

• serology (prefered): microscopic agglutination tests (MAT)
• culture (growth can be very slow)
• penicillina nd tetracycline is used
• vaccination of livestock and pets
• rodent control
• prevent exposure to contaminated water

Clostridia Characteristics

• Gram positive bacilli
• spore formers and can be motile
• predominately obligate anaerobes 
• found in soil, intestinal flora in animals and humans and contaminated water areas
• six species cause disease in humans and 4 are important
• C. botulinum, C. difficile, C. perfringens. C tetani
• non invasive opportunistic pathogen and disease secondary to toxins
• all clostridium have toxins (like how all strep does)

Clostridium botulinum

• strict anaerobe
• spore former that prefers an alkaline environment
• produces neurotoxisn A through G: important ones are A, E, and F and inhibit the release of ACh (less nueral activity)
• there is food borne, infant and wound (similar to food borne and extremely rare) causes of botulinum

Clostridium botulinum

Food Borne

• uncooked or inappropriately preserved foods
• sequence of symptoms: GI disturbances/ slurred speech, difficulty swallowing and descending paralysis
• symptoms present 24-72 hours after ingestion
• treatment with antitoxin

Clostridium botulinum

infant

• floppy head syndrome
• commonly btw 2-6 months
• ingestion of spores: usually honey
• Immature Gi track = perfect for proliferation
• symptoms: Gi disturbances (mostly constipation) and flaccid paralysis
• treatment: supportive care

Clostridium difficile

• normal flora of GI track (colon)
• cannot be cultured
• drug resistant, aero-tolerant
• produces two toxins: A and B
• opportunistic: has own set of antibiotics against it
• if you acquire a pathogenic C. difficile and fail to mount an anamnestic toxin A antibody response you get CDAD
• can cause leukocytosis and pseudomembrane colitis (causes malabsorption of water)

Clostridium difficile 

symptoms, diagnosis and treatment

• symptoms are watery diarrhea (yellow), abdominal pain/discomfort and loss of appetite
• diagnosis: toxin immunoassay, antigen assay and PCR (looking for genes that code for toxin)
• treatment: supportive care and antibiotics
• colon inflates like a balloon (toxic megacolon) and this is the biggest fear (instant death)
• metronidazole and vancomycin are first line antibiotics for this

Clostridium perfringens

• found in soil and GI tract
• oxygen tolerant
• spore forming in environment
• produces many toxins: collagenase, proteinase, deoxyribonuclease, alpha toxin phospholipase C and θ toxin
• traumatic tissue, vascular damage, necrotic tissue, and decrease oxygen supply (kills tissue around wound to make anaerobic environment)
• types of infection: anaerobic cellulitis and anaerobic myonecrosis
• disease gas gangreen
• no person to person transmission
• diagnosed by culture
• treatment: surgical intervention, antibiotics, HBO

Gas Gangrene

• Clostridium perfringens
• localized edema
• production of H2 and CO2
• skin color changes
• fever
• extremely painful
• spreads to adjacent healthy tissue
• shock and death

Food Borne

Clostridium perfringens 

• common cause of food poisoning
• ingestion of spores and viable cells
• enterotoxin production: breaks down Intestinal mucosa, leakage of cellular contents, and osomotic equilibrium disruption
• symptoms: diarrhea, abdominal discomfort
• treatment

Clostridium tetani

Microbiology

• small gram positive rods and motile
• spores are found everywhere
• conditions: puncture wound, necrotic tissue and decreased oxygen
• toxin: tetanospasmin or spasmogenic toxin/irreversibly binds to gangliosides of neural tissue preventing release of neuroinhibitors glycine and gamma aminobutyric acid (GABA) (inhibiting gaba causes constant excitation)

Clostridium tetani

symptoms

• cramping/twitching at wound site
• sweating
• pain around wound site
• trismus "lock jaw" risus sardonicus "sarcastic grin"
• opisthotonos
• violent spasms of trunk and back
• death
• descending order of neurological problems
• treatment: debribement, anti-toxin, human tetanus immune globulin and toxoid booster shot, antibiotics and anti-spastic medication

Precipitation

• reaction of soluble antigen and soluble antibody
• can occur in liquid or solid phase
• antibody excess = Prozone
• clinical examples: immunodiffusion, immunofixation
• not very sensitive
• most precipitation when antigen and antibody are at similiar concentrations
• if too much antibody you might get a false negative becuase not goo precipitation

Immunodiffusion

• a precipitation assay where one or both reactants move through a solid phase, usually agar
• double (Ouchterlony) diffusion: qualitative or semi quantitative 
• one way to tell fungii in laboratory
• can have partial identity

Agglutination

• reaction of a soluble antibody and a particulate antigen, e.g. red cells or latex beads coated with an antigen
• clinical examples: Rapid plasma reagin(RPR), cryptococcal ag, rhematoid factor and blood bank typing
• RPR is screening test for syphillis because it doesnt grow well in culture

ELISA

• Enzyme linked immunosorbet assay
• to quantitate Antibody: antigen coated onto wells of microtiter plate
• to quantitate Antigen: antibody can be coated to plate
• add substrate that changes color in presence of the enzyme 
• usually yellow or blueish collor of plates
• used to test multiple specimens (100 of patients)
• indirect assay
• can be used w/ Herpes or HIV
• can be qualitative or quantitative

Western Blot

• set up on actual membrane so cant be automated very well
• a technique that detects antibodies to specific antigens, classified by their molecular weight (seperation based on size)
• combines elements of electrophoresis and ELISA
• good for diagnosis less sensitive, more specific (must test positive for HIV on ELISA first and than this)
• can be used to detect antigens or antibody: antibody tested when used to confirm LYME ELISA

Rapid Enzyme Immunoassays

• antigens are coated onto a membrane
• patients serum is added, antibodies, if present, bind to the antigens
• enzyme labeled antihuman Ig is added
• wash solution is added followed by enzyme substrate that will change color if the enzyme is present
• test can be completed in 10-20 minutes
• clinical examples: pregnancy test, mycoplasma IgM testing, HIV screening and HIV conformation (second tier assay)

Protein Electrophoresis

• separation of serum or urine proteins based on charge
• agarose medium
• visual inspection of the elctrophoretic pattern and densitometric quantitation of the % of protein in each region, eg albumin, alpha 1, alpha 2 beta and gamma
• right side increase is immunoglobulin increase (chronic illness or w/e)
• cirrosis has beta gama bridging

Immunofixation Electrophoresis

• begin with a protein electrophoresis
• overlay the electrophoresed serum w/ an antibody to a particular protein (IgG, IgM, IgA, kappa and lambda
• stain for immune complex precipitation bands

Indirect Immunofluorescence

• detecting an antibody
• patients antibody binds to a solid substrate (cell)
• add an anti human Ig coupled to a fluorescent molecule (FITC, usually)
• look for fluorescence under appropriate light

Flow cytometry

• cross btw a fluorescent microscope and a hematology analyzer (uses laser)
• measures: light scatter and granularity of cells
• measure fluorescence: antibody binding
• sorting capabilites based on cellular parameterr possible
• forward scatter mesures cells shadow (size )
• side scatter measures internal complexity (neutrophils have large size scatter and lymphocytes have low): nuclear: cytoplasm ratio (higher, higher scatter)

Mycoplasma 

Microbiology

• smallest free-living organism (150 to 200nm), pleomorphic, prokaryote
• fastidious, require sterols for growth
• Ureaplasmas split urea for metabolism
• facultative anaerobes (except M. pneumoniae, which is strict aerobe)
• divide by binary fission 
• grow slowly, lack cell wall, single pla sma membrane, P1 adhesin protein, smallest organism able to grow on cell free media

Mycoplasma

Mechanisms of immune evasion

• mycoplasmas enter host cell in which they multiply and exist for long periods of time
• they have evolved molecular mechanisms to deal with the host immune response: mimicry of host antigens, survival w/i phagocytes and non phagoctyes, and generation of phenotypic plasticity (1 gene, multiple phenotypes)
• produce peroxide and superoxide anion
• differ from viruses and chlamydia (contain RNA and DNA, divide and produce energy)
• evolved from gram positive ancestor (clostridia)
• colonies have fried egg shape
• chlamydia cannot produce energy

Mycoplasma

pneumonia epidemiology

• transmitted by respiratory secretions
• peak incidence in individuals 5 to 20 yrs old
• introduced into household by children
• account for 5-15% of pneumonias but 40% of ones ommited to hospital
• human only reservoir
• not highly infectious
• intensive exposure to infected person required 
• pneumonia develops in 3-10 % of those infected
• less than 5% of patients require hospitilization
• if pneumonia can be underlying immunodefficiency

Mycoplasma pneumonia

pathogenesis

• diagnosis not routinely confirmed in clinical practice (rarely fatal, cultures take too long, responds to empirical treatment for CAP and and usually not even considered)
• cause infections primarily as extracell parasites
• attach to surface of ciliated and nonciliated epithelial cells
• lipid associated membrane proteins present on the mycoplasmal surface are recognized by TLRs for host response
• mycoplasma organisms are very common contaminants of tissue cultures
• cause pneumonia milder upper resp disease, bronchitis, laryngitis, pharyngitis and otitis media

Mycoplasma pneumonia

progression

• exposure to respiratory droplets
• attaches to respiratory bronchial epithelium
• incubation 1-3 weeks
• onset insidious, chills, fever, headache, sore throat, malaise, and cough (paroxysmal)
• not severe (walking pneumonia), resolves in 10-14 days, but may last several weeks

Mycoplasma pneumonia

radiographic findings 

• lung involvement tends to be unilateral, but can be bilateral
• diffuse reticulonodular or interstitial infiltrates involving the lower lobes
• pleural effesion may develop in 25% of cases
• chest x ray is typically more impressive than phsycial findings

Mycoplasma pneumonia

Complications

• rashes: erythema multiforme or stevens-johnson syndrome occurs in approximately 7% of cases
• pericarditis
• hemolytic anemia
• arthritis
• meningoencephalitis
• peripheral neuropathy
• Guillain-Barre Syndrome

Mycoplasma encephalitis

• causes 5-10% of cases of encephalitis in pediatric patients and up to 60% of them show neurologic sequelae
• recent evidence suggests it is a post-infections phenomenon that manifests after clearance of the bacteria from the CNS or respiratory tract by the immune system
• intrathecal antibodies are positive in 74% of cases
• he has never seen an adult case of this

Ureaplasma

Epidemiology

• common inhabitant of the genitourinary mucous membrane
• closely associated w/ sexual activity
• 80% colonization in those w/ 3 or more sexual partners

Ureaplasma Disease

• nongonococcal urethritis (NGU)
• in pregnant women, cervical carriage of U urealyticum has been associated w/ chorioamnionitis and post partum fever, low birth weight and chronic lung disease in newborn
• pyelonephritis, struvite kidney stones
• preterm labor and spontaneous abortion
• prostatitis

Mycoplasma hominis

Disease

• fever- post abortal, post partum
• pelvic inflammatory disease
• septicemia
• wound infections
• pyelonephritis
• meningitis
• osteomyelitis
• arthritis in association w/ hypogammaglobulinemia

mycoplasma genitalium

Disease

• first isolated in 1980 from urethral specimens in men w/ urethritis
• smallest genome of an organism capable of growing in a microbial culture
• accounts for 15% to 20% of NGU in males
• pelvic inflammatory disease and cervicitis

Mycoplasma fermentans

• often isolated from previously healthy patients
• symptoms are acute flu like
• identified in necrotizing lesions in lymph, spleen, liver, heart and brain
• tissue necrosis, lymphocyte depletion, lack of cellular reaction in infected tissue
• antibiotic treatment similar to M. hominis
• incriminated in rheumatoid arthritis (antibodies for it more common in RA patients)
• variability in surface antigens is believed to contribute to the chronic nature of RA

Mycoplasma Colonization

• M. pneumoniae following symptomatic disease: not normal flora
• infacts are colonized w/ M. hominis and genitalium and URAplasma although it doesnt persist
• aprox 15% of sexually active men and women are colonized w/ hominis and 45-75% are colonized w/ ureaplasma

Diagnosis

Mycoplasma/ureaplasma

• normally slow growings (except M hominis) on culture
• PCR ampliction tests have been developed for mycoplasma and ureaplasma
• commercial PCR assays not available so testing restricted to research setting
• antibody specific tests only avaiable for M. pneumoniae
• IgM and IgG antibodies detected by complement fixation have low sensitivity and specificity (too low to use)
• cold agglutinis are IgM antibodies that bind I antigen on surface of RBCs
• dont order cold agglutinis?

M. pneumoniae

treatment

• appropriate antimicrobial therapy wills horten symptomatic period and hasten radiologic resolution
• penicillins, cephalosporins and vancomycin are ineffective because the organism has no cell wall
• M. pneumonia is usually susceptible to macrolides, tetracycline and fluoroquinolones
• empiric therapy w/ a macrolide is preferred to avoid collateral damage to gram neg enteric flora
• macrolide resistance in mycoplasma is rare in US but has been reported in Asia

Mycoplasma prevention

• prolonged period of contagion even when on therapy
• no vaccine
• M. hominis, M. genitalium and Ureaplasma infections can be prevented by avoiding sexual activity or using proper barrier precautions

"Rickettsia"

• Rickettsia, Orientia, Ehrlichia, Anaplasma and Coxiella (some have rashes some do not)
• genetically distinct classes of bacteria: historically linked, related disease etiologies
• zoonoses transmitted by arthropods (coxiella does not require this)
• important include: rocky monuntain spotted fever, and epidemic typhus
• more than 45 other pathogens of rickettsia
• ehrlichia and anaplasma are part of emergin pathogens

"Rickettsia"

General features

• small gram negative coccobacilli (grow only in euk cells and mistaken for viruses)
• contain peptidoglycan and LPS - little endotoxin activity   (absent in ehrlichia)
• sensitive to antibacterial chemotherapy
• slow growing and can produce a slime layer/capsule
• obligate intracellular parasites: possess leaky cell membranes (they can make there own ATP though)
• unstable outside fo cells except Coxiella burnetti
• rickettsia and orientia grow in cytoplasm of endothe
• ehrlichia grow in the endosomes of monocytes 
• anaplasma grow in the endosomes of granulocytes and neutrophils
• coxiella grow in the phagolysosomes of monocytes

Rickettsial Diseases

• acute disease: sudden onset 1-4 weeks after exposure; severe headache, fever, chills muscle pain, vomiting followed by rash and joint pain
• diagnosis- difficult: fever + rash + tick exposure triad uncommon (3% of patients)
• history and laboratory datat typically not helpful during acute phase
• acurrate testing via PCR or immunofluorescence of biopsy-done at reference labs only
• treatment decisions should be based on epidemiologic and clinical clues, should neverbe delayed while waiting for confirmation 

Rickettsial Diseases

• predilection for endothelial cells of small blood vessels: petechial/hemorrhagic rash and thrombi both surface and w/i organs
• rupture of endethelial cells is responsible
• weil-felix test antigens of rickettsiae cross react with proteus OX: agglutination of proteus antigens by patients serum confirms diagnosis: determined after treatment and recovery has begun
• treatment: bacterial protein synthesis inhibitors: doxycyclin(drug of choice) than chloramphenicol and quinolones (Q fever)

Rickettsial Disease Classification

• Spotted Fever group: polymerize actin to move/escape
• RMSF: R rickettsii
• rickettsialpox -R akari
• Boutonneuse fever: R conorri
• Typus Group: lyse cells or wait for cell death to release
• epidemic typhus - R prowazekii
• endemic typhus (murine): R typhi
• Scrub typus group: distict from rickettsia
• spread by chiggers and mites and found in east asia

Epidemic Typhus

• Rickettsia prowazekii
• rash- moves from trunk to extremities
• fever, headach myalgia and 40% untreated mortality
• disease of crowding and poor: forced napolean retreat from moscow
• reservoir: lice release bacteria in feces and die, human innoculation through scratching (also flying squirell)
• Brill-Zinsser disease: mild disease w/o rash leading to a carrier state
• recrudescence of R prowazekii in carriers reinitieates disease spread w/i population (lice)

Ehrlichiosis and Anaplasmosis

• emerging diseases (1980s) transmitted by ticks
• disease named based on type of blood cells infected (monocytes, neutrophils, eosinophils and/or platelets)
• Human monocytic ehrlichiosis (HME): lone star ticks
• Human granulocytic anaplasmosis (HGA): ixodes ticks
• deer ticks can transmit both 
• initial: fever, headache, malaise and muscle aches
• similar to RMSF except few rashes (except peds)
• multi organ system involvement and low leukocytes and platelets
• Immunofluorescensce assay 
• serology and DNA tests becoming more common

"Query Fever" (Q Fever)

• coxiella burnettii
• most infections are asymptomatic to mild
• acute dis3ease: influenza like febrile illness 
• treat w/ tetracyclines
• chronic disease associated w/ preexisting heart valve disease or immunosuppression (pregnancy): complication is endocarditis (65% mortalitiy)
•  most often in sheep farmers, vets and meat workers
• spread by aerosols but can be through ticks
• extracell organism is spore forming (bioterror)
• replicates in phagolysosomes of moncytes
• phase II acute, Phase I and II chronic
• vaccine for phase I (spore phase) 

Rickettsial diseases

Treatment and prevention

• all the normal stuff including elimination of reservoir and vector and exposure
• treat with doxycycline
• 
  can also treat with quniolones and tetracyclines

Chlamydiaceae

• gram negative coccobacilli (2 forms)
• virus like properties: infections form, elementary (small) body) 
• undergo a noninfections eclipse phase-reticulate body
• obligate for intracullular growht (energy parasite)
• contain both NA, fission, peptidoglycan and LPS (limited endotoxin) and sensitive to select antibacterial drugs

Chlamydiaceae 2 forms

• Elementary Body (EB)-0.3-0.4: 

rigid infections body
specialized for extracellular survival
survives phagocytosis and attack by lysosomal enzymes

• Reticulate Body(RB) - 0.8 - 1.0

large irregularm non infections form

specialized for intracellular cell division

metabolically active and osmotically fragile 

Chlamydial Diseases

general characteristics

• subclinical infection is the rule and over disease the exception (evolution toward symbiosis)
• predilection for mucus membranes: infection nonciliated columnar, cuboidal and transitional epithelial cells: eyes, genitourinary tract and resp tract
• disease is chronic and relapsing: limitied but not eliminated by immunes system
• immune response responsible in large part for the damage - delayed type hypersensitivity (DTH)
• carrier state - persistent infection
• Ab is produced but offers limited protection, but is diagnostic (serology)

Chlamydial Diseases

Virulence Factors

• EB binding and endocytosis in epithelial cells
• prevention of phagosome-lysosome fusion by EB outer membrane
• intracellular replication of RBs
• chronic immune activation through cellular persistence and reinfection
• variations in the major outer membrane proteins (MOMPSs) determine serovars and thus pathogenesis
• inhibition of programmed cell death
• environmental survival of infections EBs- sulfhydryl cross linkage of major outer membrane proteins

Chlamydial Disease

Diagnosis

• clinical signs Chlamydia vs Chlamydophila and biovars-serovars
• bacterial ID: isolation of organisms in tissue culture
• histological observation of cytoplasmic inclusion bodies in patient samples - giemsa, iodine, IF
• serological tests for Ab response is important for determing serovars-ELISA
• immunofluorescence

Chlamydial Diseases

• treatment: tetracyclin,   and other protein synthesis inhibitors(azithromycin)
• erythromycin in children
• C trachomatis treatable w/ sulfonamides
• no reversal of scarring
• C trachomatous found in 45% of gonoccal infections so if you find one treat both
• cell wall inhibitors cause abnormal bacterial morphology but no clinical relief
• prevention: safe sex, sanitation, vaccines?

Chlamydia trachomatis

Diseases

• lymphagranuloma venereum (LGV): inguinal lymph node swelling=buboes, L serovars-tropism for mononuclear phagocytes
• trachoma can cause ocular tachoma, Urogenital disease, and infant pneumonia
• Trachoma serovars are A, B, Ba, C, and D-K  

Ocular Trachoma

• Chlamydia trachomatis
• Trachoma 
• the leading causes of preventable blindness worlwide-A, B, Ba, and C servars
• Adult inlusion conjunctivitis - usually preceeded by genital infection - A, B, Ba , C and D-K serovars

Urogenital Disease

• Chlamydia trachomatis
• trachoma
• D-K serovars
• epididymitis
• Urethritis
• endocervicitis, pelvic inflammatory Disease (PID) - may lead to sterility due to scarring
• D-K is in the Dick

Infant pneumonia

• Chlamydia trachomatis
• trachoma
• B, Ba, and D-K serovars
• contracted from infected mothers during birth
• 2-3 week eclipse phase, rhinitis, afebrile, distinctive staccato cough

Chlamydia trachomatis

transmission

• sex: msot frequent bacterial pahtogen in US (4mil/y)
• tansmission by infected patients who may be asymptomatic: 75% women and 50% men
• inoculation throuhg a break in skin or membranes
• passage to newborn at birth
• trachoma spread to eye by hand, dorplet, clothing and flies
• gays, newborns of infected moms, and children in crowed living and poor sanitation (trachoma)
• young white males w/ HLA-B27 are at risk for Reiter's syndrome- a sexually acquired reactive polyarthritis assocated w/ urethritis, conjunctivitis and mucocutaneous lesions

Chlamydophila pneumoniae

• resp disease: mild pneumonia, sinusitis, pharyngitis, bronchitis, signs indistiguishable from other types of mild pneumonia
• found in artherosclerosis/CAD plaques (association)
• Virulence: same os C trachomatis- MOMPs, phag/lysosome fusion inhibition
• also infects and dstroys ciliated resp epithelia, smooth muscle, endothelia and macrophages
• transmission: person to person spread through inhalation of infections aerosols. no animal reservoir
• everyone at risk: 50% by age 18, > 75% by 30
• infection prevalent throughout life w/ disease common in adults
• usually treatment not needed, though use tetracycline, azithromycin
• treatment failure can be common

Chlamydophila psittaci

parrot fever or ornithosis

Macrophages

(innate host protections)

• TLR activated: phagocytic but not efficient killers, IL01, TNFa, and IL6
• IFNgamma/TNFa activated ANGRY macrophages: ROS, RNS, IL1, TNFam and IL6

Neutrophils and Chronic Inflammation

• normally they are quick, attack and die off
• however!!!
• if continuous C5a or Th17 (from t cells) than this leads to chronic inflammation

Myeloid Dendritic Cells

(phagocytes)

• blood derived DCs and Langerhans cells in skin
• gobble PAMP sitmulated to start secreting IL1, TNFa and IL6
• also IL12 and IL23 so that dendritic cell can direct T cell to what should be done
• move to lymph node for presentatin of processed peptides to T cells
• plasmactyoid Dcs in blood streat use PAMP to recognize and cytokines to facilitate systemic response to infection in the Blood (IFNalpha and TNFa)

Innate Lymphoid Cells

• includes Natural killer cells
• produce IFNg (macrophage/DCs)
• or produce IL4 (facilitate antibody and mucous production
• IFNg makes macrophages angry

T cell Dependent Protection from

Intracellular Bacteria (TB)

• Mycobacterium tuberculosis hides in unactivated macrophages
• response to tubrculosis as follows:
• sacrifice infected macrophage
• activate other macrophages: CD4 T cell production of IFNg and macrophage and T cell production of TNFa
• chronic/frustated activation of the macrophage into giant and epitheloid cells
• granuloma to wall of infection: dependent upon constant cytokine irritation of macrophages
• at risk for TB if lose ability to make TNFa 

Host Protections:

Immune B cells

• IgM, highest avidity but low afinity: important for capsular bacteria and strong complement activator
• IgG much more affinity, 6-10 days primary and 2-3 secondary: facilitates phagocyte function (complement, opsin, and neutralizing)
• IgE has no contribution to antibacterial response
• IgA same timetable as IgG, continous for normal flora: secreated across mucosal epithelium and only functions in neutralizing

Bacteria w/ Intracellular mechanisms

for surviving w/i phagocytes

• Listeria, Rickettsia, shigella (cytoplasm livers)
• Chlamydia, legionella, mycobacteria (ihibit formation of phagolysosome)
• Brucella, salmonella and catalase + organisms: resistance to acidic/oxidative env w/i phagolysosome

Complement Defect Susceptibility

• pyogenic bacteria: staphy and strep because C3a and C5a attrach neutrophils
• Encapsulated bacteria: opsonin
• neisseria: its the LOS
• and viruses: holes in envelopes and opsonin

Phagocyte/Spleen Susceptibility

• Bacteria (esp these): 
• catalase-positive: staph, neisseria and enterobacteria
• encapsulated bacteria
• spleen= filter=macrophage hangout