25 Unculturable Bacteria: Spirochetes and Rickettsia Flashcards
What are the 3 genera of spirochetes that cause human illnesses?
Treponema (syphilis)
Leptospira (leptospirosis)
Borrelia (relapsing fever and lyme disease)
T/F- Spirochetes are long slender rods that are related to gram negatives (LPS-like); they have endoflagella under a sheath (axial fibril-like flagella)
True
Treponemes species are defined by disease. Name 4 examples along with the diseases they cause.
T. pallidum-syphilis
T. pertenue-yaws
T. carateum-pinta
T. endemicum-bejel
T/F- normal flora do not contain treponemes
False. Normal flora may contain non-pathogenic treponemes
T/F- Treponemes have been kept alive in conditions with reduced oxygen, however, genomics predicts they are aerobes, but they have never been cultured on lab media
True
What facilitates dissemination of treponemes in the body?
readily attach to endothelial cells and pass through blood vessel walls
Treponema pallidum is responsible for disease?
Syphilis
-60% probability of transmission if sex with infected parter
-46x more common in gay men than straight men
-more common in men than women
-rates increasing in past several years
-Primary/Secondary disease are most infectious stages
Non-sexual transmission: congenital syphilis (400 cases/yr in U.S.) and Bejel/Siti are disease of children
T/F- syphilis does not change risk of transmitting or acquiring HIV
False, it increases risk:
- Indirect: a portal for HIV entry through lesions and attracting HIV target cells to lesions
- Direct: possibly upregulates HIV replication
Describe the natural course of a hard chancre in primary syphilis
- organism penetrates skin/mucous membrane and develops lesion and initial inoculation site
- organism replicates at this lesion and then spreads through blood stream (regional lymphadenopathy common). CD4 t cells and macrophages predominate.
- Chancre resolves without treatment while bacteria seeds other parts of body
When does secondary syphilis develop and what are the common manifestations?
- develops 6-8 weeks after resolution of primary lesion (CD8 response)
- maculopapular rash on flank, shoulder, arm, chest, back, hands, soles of feet, malaise, headache, generalized lyphadenopathy (lymphadenopathy resolves in 2 months)
What are some less common manifestations of secondary syphilis?
fever, anorexia, mucous patches, condylomata lata (infectious), alopecia, meningitis, myalgia, ocular complaints, hepatic, pulmonary or neuro involvement
What’s latent syphilis?
period of disappearance of secondary manifestations until therapeutic cure occurs OR until tertiary symptoms develop. Divided into early and late phases.
Important details of early latent phase (first year of latency)?
Many patients experience recurrence of secondary symptoms and remain INFECTIOUS to sexual partners
Important details of Late latent phase (>1 year of latency)?
Patients are not considered infectious and even without treatment 72% of T. palladium infected pts with remain symptom free forever. 28% progress to tertiary syphilis.
What is tertiary syphilis?
- few viable bacteria remain
- hypersensitivity to bacterial antigens causes GUMMA lesions
- cardio: aortic aneurysm, valvular insufficiency, coronary artery ostial stenosis
- Neuro: CN palsy, personality changes, delusions
- Outcome is death for tertiary syphilis
What are GUMMA lesions?
- small rubber granuloma infiltrates of monocytes
- any organ
- non-infectious
What is the underlying systemic pathophysiology of syphilis?
- lesions at all stages show vasculopathic changes (enderarteritis and periarteritis)
- dense local infiltrates (macrophages, lymphocytes, plasma cells, PMNs, histiocytes
- granulomata often present and assume necrotizing nature
Outcomes of congenital syphilis?
-Hutchinson’s teeth, Saddle nose, Saber shins, fulminant disseminated infections, lesions of skin and bone, deafness
T/F- syphilis bacteria can cross the placenta to infect the fetus
True
T/F- untreated syphilis in pregnancy can result in spontaneous abortion, still birth, premature delivery, or perinatal death
True
T/F- T. pallidum can be grown in culture
False. Cannot be grown in culture (makes no amino acids)
T/F- T. pallidum outer membrane does not contain LPS and contains very few proteins
True, this allows it to evade the immune system
T/F- binding between T. pallidum outer membrane proteins and host cell glycoproteins (fibronectin, laminin) occurs
True
T/F- Treponema is an intracellular pathogen that elicits weak stimulation of the innate, humoral, and cell-mediated defenses that eradicates the bacteria
False
- extracellular pathogen
- elicits STRONG immune response but it does NOT eradicate the bacteria. Lipoproteins play a crucial role in stimulating the innate mechanism during all stages.
Does microscopy help diagnose syphilis?
- Gram stain will not work
- can use phase contrast, dark field, or fluorescent microscopy
Are there screening assays for syphilis?
- -screening assays for non-treponemal antibodies detect IgG and IgM against cardiolipin (most sensitive in secondary and latent infection-100% vs 80% in primary and tertiary)
- rapid plasmid reagin test (RPR)
- venereal disease research laboratory test (VDRL) best for neurosyphilis
What confirmatory tests can be used for syphilis?
- Indirect Fluorescent Antibody (fluorescent treponemal antibody ‘FTA’)
- Treponema pallidum particle agglutination test (TP-PA)
How do you treat syphilis?
- treat at all stages of disease with parenteral penicillin injections
- no resistance to penicillin
- later stage=longer therapy needed
- if allergic to penicillin use ceftriaxone or doxycycline
- can be reinfected after treatment
T/F condoms always prevent syphilis infection
False. condom use is not necessarily helpful to prevent transmission of T. pallidum unless the infected area is completely covered and potential exposure site is protected
T/F- there is a vaccine for syphilis
False
