SPIROCHETES!!! MICROM 442 Deck 14 Flashcards
B.hermsii disease=
relapsing fever
B. burgdoferi disease =
Lyme disease
T. pallidum disease =
syphilis
L. interrogans disease =
leptospirosis
structure is distinctively
corkscrew shaped with Lipid-rich outer membrane covering periplasmic
flagella; thin peptidoglycan layer covering
cytoplasmic membrane
what is special about the leptospira shape?
has hooked ends
B. hermsii + B. burgdorferi have what type of chromosome structure
linear
all expect one has high genetic variability?
T. pallidum/syphillis
which two do not have confirmed plasmids (the other 2 have both circular and linear)?
syphillis and leptospirosis
all have a small genome size except?
L. interrogans which makes sense because she is able to infect people although we are accidental hosts
One circular chromosome in
T. pallidum
Two circular chromosomes in
Leptospira
Syphilis manifestations
- Chronic bacterial infection, sexually transmitted
- Early manifestations involve primarily skin
- Late manifestations involve virtually all organs
and tissue sites, including the central nervous
system
Syphilis habitat
Human only
Syphilis: Transmission
- Direct, usually sexual, contact with infectious
person (1⁰ or 2⁰ stage) - Organism is highly invasive; gains access to blood
stream and disseminates throughout body,
including central nervous system - May also cross placenta to cause congenital
syphilis
Congenital Syphilis
- Infection of fetus during
pregnancy - Results in prematurity,
spontaneous abortion,
stillbirth, neonatal illness
or death, latent infection
Syphilis: Pathogenesis
- Immune response ultimately clears primary
and secondary lesions, but infection is not
eradicated systemically - Causes lifelong persistent, chronic infection
in untreated persons - Antigenic variation if pivotal to persistence
Antigenic Variation of TprK
- Surface-exposed protein
- Has 7 variable regions
- Antigenic variation by
segmental gene conversion
o One expression site
o 53 variable region donor
sites
Accounts for development of SECONDARY stage,
lifetime persistence
Syphilis: Treatment
- Penicillin –first line
- Alternatives: doxycycline, tetracycline, amoxicillin
- Macrolides – high rates of resistance in circulating strains – no
longer recommended
Syphilis: Lab Diagnosis
– PCR, RT-PCR not commercially available
– Darkfield microscopy
– No culture technique available (in vitro
cultivation system is not yet adapted)
relapsing fever passed on by two arthopods which are?
louse-bourne and tick-borne
Tick borne (B. hermsii) relapsing fever
Humans infected via tick saliva (or feces) during tick bite—
only short feeding is required for transmission
Louse borne (B. recurrentis) relapsing fever
‒ No invasion of louse tissue (stay in the hemolymph). No
transovarial transmission
‒ Humans are infected by hemolymph/feces when parasite is
crushed (mechanical transmission only)
ultimately relapsing fever has a decreasing burden but reinfections because of the
different serotypes and the the antibodies having to compensate
Relapsing Fever has which genes for antigenic variation?
vlp and vsp
Lyme Disease surface proteins
OspA, OspB, OspC
lyme disease major resevoir=
small rodents mostly but also birds and deer and TRANSMITTED via TICK bite
Lyme Disease: Pathogenesis
- Organism is very invasive, reaches blood
stream and disseminates to many organs,
including central nervous system - Persistent, chronic infection (due to antigenic
variation of surface antigens?)
Lyme Disease: Clinical Course
1: Erythema chronicum migrans (ECM)
and secondary lesions
2: Neurologic and cardiac abnormalities:
headache, stiff neck, conjunctivitis,
muscle pain, (weeks to months
after ECM)
3: Arthritis (weeks to years after ECM) -
intermittent or chronic
Lyme Disease: Treatment
Penicillin, ceftriaxone, tetracyclines
* Later treatment may not be successful:
chronic inflammation in absence of bacteria
(Autoimmunity, chronic inflammation due to
PG fragments?)
Leptospirosis: Habitat
- Most widespread zoonosis in the world
- Free-living in water
- Animal reservoir–domestic and wild animals
Leptospirosis: Transmission
- Source of infection is water contaminated with the
infected urine of “carrier” animals - Portal of entry is skin, mucous membranes
- Carrier state persists for months to years
Leptospirosis: Pathogenesis
- Invasive
- Disseminates to infect multiple organs,
including central nervous system
Clinical Outcomes of Leptospiral Infection
inapparent infx -> undifferentiated fever -> Complex, multi-system disease (Aseptic meningitis
Renal failure
Jaundice
Myocarditis
Pulmonary hemorrhage
Refractory shock)
Leptospirosis: Clinical Course
- Sudden onset of fever (spiking), severe
myalgia, headache - Bacteria present in blood, CSF, urine
- Usually self-limited, but can be protracted and severe
