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Definition
| Gram(-), spirochete, too small to be seen by std microscopy, use darkfield, cannot be cultured. Virulence: no toxins, flagella (generates corkscrew motion), virulence based on immune evasion. Reservoir: transmitted sexually or congenitally. Disease: humans raise useless Ab to treponema. Syphylis has 4 stages (primary chancre; secondary body-wide rash, condylomata lata, and patchy alopecia; latent period; tertiary gummas [granulomas in skin, bone, liver], neurosyphilis, cardiac involvement. Neurosyphylis may be meningitis, tabes dorsalis (degeneration of sensory neurons via demyelination), general paresis (partial loss of voluntary movement), check for Argyll-Robertson pupil (constriction via accommodation, but no reaction to light). Congenital syphilis kills 50% fetus/newborn, survivors are infected, bone deformities, interstitial keratosis. Dx: depends on assembling accurate time course of varied symptoms. Syphilis serology for reagin (VDRL, RPR) confirm by testing for treponeme-specific Ab. Tx: penicillin G The spirochetes invade bloodstream right away! |
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Definition
| Gram(-), spirochete, too small to be seen by std microscopy, use darkfield, can sometimes be cultured from patient urine. Virulence: encode toxins, reasonably hearty (can survive outside host for weeks) Reservoir: pet & livestock, shed in urine; passed to humans by contact with contaminated H2O. Disease: 2 types-Anicteric disease: Phase 1- acute sepsis, circulate in blood and multiply in vasc endothelium. vasculitis from toxins (hemolysin&nephrotoxin) release blood into tissue and deprives target tissue of O2. a break (spirochetes are cleared from blood, but persist in privileged sites for weeks/months) and then Phase 2 (delayed or immune) mild organ symptoms (jaundice, kidney failure, hemorrhage in lungs, aseptic meningitis, HUS, DIC, TTP). Icteric disease - Phase 1-acute sepsis and with little or no break Phase 2 follows-with greater severity (major organ failures). Both phases include conjunctival suffusion (redness w/o exudate). Spirochetes invade lymphatics and blood stream right away! Tx: penicillin G, or alternatively doxycycline or 3rd gen cephalosporins. |
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Definition
| Yaws, transmitted via direct contact. |
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Definition
| Pinta, transmitted via direct contact. |
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Definition
Gram(-), flat waves, not spirochetes, large enough to see w/ std microscopy.
Reservoir: white footed mouse, wood rat, small rodents, and vectored by Ixode ticks.
Disease: Lyme requires 24h to transmit. 3 stages-1) flulike w/ erythema migrans rash, 2) musculoskeletal and/or neurologic symptoms, 3) additional neurologic symptoms, also post-lyme syndrome w/ lingering neurological sequela.
Dx: mostly by exam; serology can confirm exposure, but not disease and not promptly.
Tx: amoxicillin or doxycycline, alts ceftriaxone, cefuroxime axetil for 10-30 days.
Avoid ticks (protective clothing, DEET), possible prophylaxis w/ doxycycline. |
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Term
| Relapsing Fever - louse borne |
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Definition
| Borrelia recurrentis, more severe than tick-borne. Repeated high fevers with well periods between, complications of pregnancy. Average of one relapse. Borrelia immediately enter bloodstream from scratch site, sepsis ensues and cleared by stong IL-10 response + neutralizing Ab. Spirochetes then alter their surface antigen (antigenic variation) and new round of disease ensues w/ average of 3 relapses. Dx: peripheral blood smear, spirochetes are usually visible during febrile periods. Tx: tetracycline, doxycycline; for children/pregnant/nursing women use erythromycin. Avoid ticks (protective clothing, DEET), possible prophylaxis w/ doxycycline. |
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Term
| Relasping Fever - Tick borne |
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Definition
| less severe than louse borne, tick-borne is more common in US. (B. hermsii, B. turicatae, B. parkeri, B. duttoni, others) Repeated high fevers with well periods between, complications of pregnancy. Average of one relapse. Borrelia immediately enter bloodstream from scratch site, sepsis ensues and cleared by stong IL-10 response + neutralizing Ab. Spirochetes then alter their surface antigen (antigenic variation) and new round of disease ensues w/ average of 3 relapses. Dx: peripheral blood smear, spirochetes are usually visible during febrile periods. Tx: tetracycline, doxycycline; for children/pregnant/nursing women use erythromycin. Avoid ticks (protective clothing, DEET), possible prophylaxis w/ doxycycline. |
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Definition
| Gram(-)rods, requires silver stain or IF in tissue sections; free living form is motile(flagella) while intracellular form is non-motile, facultative intracellular parasite. Exposure is from aspiration or inhalation of contaminated water-NOT contagious. -Legionella survives endocytosis by monocytes/macrophages by altering endosome; can breed in them and then escape. -Cooling towers and whirlpool spas are NEW environments. -LD outbreaks trace to contaminated locations NOT people. -LD pneumonia is life-threatening even when tx with abx. -optimal Dx is by BOTH urine Ag test (ELISA) & culture of respiratory secretions. -Outbreaks in healthcare is common; vulnerable pts exposed to bad plumbing. |
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Term
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Definition
-urogenital infxn, can cause pneumonia.
-Chlamydia is a small intracellular bug, so must use drugs that penetrate cell membrane.
-replicate in a unique manner beginning with tiny, infectious, rugged elementary bodies which "unpack" into reticulate bodies after infxn.
-reticulate bodies form intracellular inclusions that are visible on microscopy. Require ATP from host.
Dx-tissue culture for C. trachomatis in rape victims(can only grow in cells!), serology, or MIF(microimmuno fluorescence) to differentiate pneumonias, but tx can be based on physical findings.
Tx-doxycycline, except preg/peds/allx, use erythromycin. Pts who use alternatives may need follow-up testing and retreatment. |
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Definition
can cause pneumonia
Dx: MIF, serology, CXR
Tx: doxycycline, if preg/ped/allx use erythromycin. if alternate is used follow-up may be required. |
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Definition
-exposure to birds, especially sick birds.
Dx: complement fixing or MIF Ab test, serology, CXR, culture is hazardous.
Tx: doxycycline, if preg/ped/allx use erythromycin. if alternate is used follow-up may be required. |
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Term
| Mycobacteria tuberculosis |
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Definition
acid-fast bacillus, obligate aerobe, very slow growing
transmission: lung by inhalation; to lymph node, kidney, bone, CNS by hematogenous spread; to GI by swallowing infected sputum. immunocompetent host raises strong CMI response & hold infxn latent for decades.
Hematogenous spread by intracellular infxn of naive macrophages; activated macro can clear it. CD8 cells kill infected macrophages & establish caseating granulomas. TNF-alpha also important for containment.
Classic pulmonary TB (75%): cough, weight loss, fever, night sweats, hemoptysis, chest pain. Dx- check sputum & CXR.
Determine exposure by PPD or quantiferon; perform abx resistance testing as soon as cultures grow; MDR & XDR strains are public health nightmares.
Isolate infexious pt and begin multi drug course feat. isoniazid. Direct oberve thx is recommended.
BCG vaccine (live attenuated M. bovis) is used abroad, not cost-effective here. |
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Term
| Mycobacterium tuberculosis, extrapulmonary diseases |
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Definition
Scrofula-infxn of cervical lymph nodes; dx-fine needle aspirate.
genitourinary-dx: iv urography, urine culture.
CNS-dx: MRI, lumbar puncture
GI-dx: x-ray, CT of abdomen
Skeletal-dx: MRI, joint fluid culture.
Miliary-dx: CXR w/ bright spotlight, lateral CXR, chest CT.
Pediatric: must have been recently acquired (trace source), watch for miliary & meningitis, culture from gastric lavage. |
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Term
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Definition
-Environmentally acquired infxn that cause neither TB nor leprosy.
-Atypical mycobacterial infxn in immunocompetent adult is usually cutaneous; scrofula in children; immunosuppressed host may have systemic symptoms, particularly from M. kansasii or MAI, MAC (M. avium or M. intracellulare).
-Atypical mycobacterial infxn may be difficult to tx once established; require multiple abx. |
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Term
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Definition
Acid-fast rod, impossible to culture, slowest growing human pathogen, prefers 30 C (extremities).
Reservoir: humans & armadillos
transmission: extremely long incubation period, doesn't transmit easily, only 5-10% of humans believed to be susceptible.
Leprosy presents on a range from Tuberculoid (paucibacillary, vigorous CMI both contains infxn, and damages nerves, PPD+) to Lepromatous (multibacillary, weak CMI, extensive cutaneous symptoms, PPD-).
-Lepromatous easily tested by skin smear, biopsy, molec probe, serology; tuberculoid may be detected by biopsy or serology, but sensitivity is low - phys exam/hx.
-Lepromin PPD tests anti-leprosy immunocompetence, NOT exposure.
Tx: 2 years dapsone+rifampin
-Lepromatous pt may develop erythema nodosum leprosum, severe cases can require immunomodulant tx like thalidomide. |
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