Spirochetes Flashcards
(28 cards)
Spirochetes
Bacteria shaped like coils
5-20 microns long, <1 micron across
Gram negative - don’t stain with Gram stain but structurally negative
Have outer membrane, periplasmic space, thin cell wall, cell membrane, and flagella, including endoflagella (flagella inside periplasmic space)
Treponema pallidum
Treponema pallidum pallidum –> syphilis
Other species involve skin and bone and spread by direct contact
Syphilis Transmission
Sexual but also mother-to-child (congenital)
No other natural hosts - relies on host for nutrients; minimal surface proteins allows for immune evasion
Primary Syphilis
Painless chancre at infection site (anywhere where spirochete enters body)
10-90 days after initial infection
Heals on its own after a month
Secondary Syphilis
Spirochete disseminated throughout body, symptoms all over
Flu-like: sore throat, fever, malaise, adenopathy (swelling of lymph nodes)
Disseminated rash - contagious; includes palms, soles, and mucous membranes; can have condyloma lata (wart-like)
Begins weeks to months after infection, resolves slowly on its own
Latent Phase Syphilis
After rash and systemic symptoms resolve
No symptoms but 1/3 progress to tertiary syphilis (over years to decades)
Dormant
Tertiary Syphilis
Gumma: effects of long-term tissue destruction; anywhere on body but typically mouth; start as mass that is caused by spirochetes –> immune response –> ulcer and erosions
Vascular problems: Aortitis, aortic aneurysm
Neurologic problems: Tabes dorsalis
Tabes dorsalis
From Tertiary Syphilis
Demylination of dorsal spine
Loss of position sense –> wide-based gait
Neurological Syphilis
Spirochetes invade CNS early in infection
Early: Can cause tabes dorsalis
Later: Can cause tabes dorsalis or dementia
Anytime: Can cause uveitis (eye pain and blurry vision)
Treponema pallidum Diagnosis
Cannot be cultured in lab - has no genes for tricarboxylic acid cycle; dependent on host cells for purines, pyridimines, and amino acids
Cannot be seen on traditional microscope
Relies on clinical impression, dark-field microscopy, and serology
Treponema pallidum Diagnosis: Dark-field Microscopy
Shine light from side and look for deflected light
Treponema pallidum Diagnosis: Serology: Screening enzyme immunoassay
AKA EIA and ELISA
Quick and easy
Good sensitivity and specificity - but requires confirmation test
Once positive, always positive - can’t tell if currently have syphilis or just in the past
Enzyme Immunoassay EIA
- Syphilis antigen in bottom of test tube
- Patient serum added, antibodies bind if present
- Anti-human Ig antibody with attached enzyme added; binds to bound antibody
- Enzyme substrate added
- Enzymatic reaction produces color change if positive for antibodies for syphilis
Treponema pallidum Diagnosis: Serology: Non-treponemal tests
Doesn’t detect antibodies to spirochete - detects antibodies to lipids released from damaged cells
Mix serum with cardiolipin and look for clumping
Non-specific but quantitative - can monitor response to treatment and check for re-infection
Antibody titer
Indicates concentration of antibody present, measure by testing serial dilutions of serum
Expressed as ratio - Indicates highest dilution of patient’s serum that gives postive result (titer of 1:64 has more antibody present than someone with 1:2)
Treponema pallidum Diagnosis: Serology: Treponemal tests
High specificity
Slow and difficult
Tie-breaker
Syphilis Treatment
Penicillin
Primary: 1 dose of intramuscular penicllin
Secondary: 1 dose of intramuscular penicillin
Latent/Tertiary: 1 or 3 weekly doses of intramuscular penicillin
Neuro including ocular: 2 weeks of intravenous penicllin
Jarisch-Herxheimer Reaction
Inflammatory responses to toxins released by dying spirochetes –> fever, flu-like symptoms
Syphilis Prevention
Sexual transmission: condoms, monogamy, abstinence, partner treatment
Mother-to-child (congenital): testing and treatment during pregnancy (initial visit, repeat in 3rd trimester if high risk)
Lyme Disease: Borrelia burgdorferi
Spirochete
Tiny genome - linear chromosome; 9 circular and 12 linear plasmids
Depends on host for nutrition
Makes no toxins that we know of
Lyme Disease Transmission
Vector: Ixodes tick (especially nymphs)
Reservoir: White footed mice
Early Localized Lyme Disease
Erythema migrans rash at site of tick bite - expanding, not usually painful or itching
May also have fever, aches, lymph node swelling
3-30 days after bite
Will resolve on its own, within weeks
Early disseminated Lyme disease
Weeks after infection
Dermatologic - multiple erythema migrans
Days to weeks after infection
Neurologic: meningitis, Bell’s palsy
Cardiac: heart block
Musculoskeletal: arthralgias, arthritis
Can resolve without treatment
Late Lyme disease
Months to years after infection
Large joint arthritis (can relapse)
Neurological symptoms: Neuropathy, encephalopathy (short-term memory problems, word-finding difficulty)
