Download Micro--Spirochaetes

The Amazing World of Spirochaetes
(nope. just the clinically relevant stuff)
GENERAL INFO: gram negative, helical shaped bacteria with periplasmic flagella (between outer
membrane and cytoplasmic membrane) for motility.
3 Genera: Treponema, Borrelia, Leptospira
----------------------------------------------------------------------------------------------T. pallidum ssp. pallidum (hereafter called T. pallidum) is the causal agent of SYPHILIS
- micro-aerophilic, motile, cannot be seen under brightfield microscope
- transmitted btwn humans by intimate contact (~90% genital, ~10% oral)
- Infection through intact mucosa or skin micro-abrasions
*This is an obligate human pathogen. There are no known environmental or zoonotic reservoirs.
This organism cannot be cultured on cell-free media. As a result very little is known about T.
pallidum’s virulence factors and the pathophysiology of syphilis.
Virulence Factors
- no LPS and largely devoid of transmembrane proteins
- hyaluronidase producer (used to penetrate mucosal linings)
- fibronectin covering to evade macrophages
- highly immunogenic proteins are anchored below outermembrane where Ab can’t reach
12 million cases of infection worldwide. ~23%-32% of sex trade workers infected
CLINICAL PRESENTATION – infection and spread occurs before presentation
Stage
Time period
Symptoms
Resolution
10-90 days
1 or more chancres at site of penetration Naturally resolve
Primary
(Infections) after infection creating rash appearance.
within 2 months
Secondary 2-10 wks after Rash all over body including palms and Naturally resolves
(Highly
primary heals
soles. Flu-like symptoms (sore throat,
over weeks to months
infectious)
headache, fever, lymphadenopathy)
4-10yrs
Diffuse, chronic inflammation in
Can go through
Tertiary
virtually any organ/tissue (arteritis,
periods of limited
dementia, blindness, gumma lesions in
resolve or progress to
bone, skin, and other tissue)
greater morbidity and
Cardiosyphilis in 10%, neurosyphilis 8% death
Diagnosis and Treatment: Primarily identified through serological assays (Ab tags) but
darkfield microscopy can be used on fresh samples from primary lesions. Treated with forms of
penicillin at all stages unless allergy prohibits (doxycycline used)
---------------------------------------------------------------------------------------------Borrelia burgdorgeri –
-
occurs in forests of Europe, Asia and North America.
Causes LYME DISEASE
tick-borne illness that takes 24-48hrs to transfer to humans
animal reservoirs are deer and rodents
organism can be cultured and viewed under brightfield microscope
CLINICAL PRESENTATION
1. Early localized Stage:
- 10 days after bite, lasts 4 weeks, classic ‘bullseye’ lesion (red, clear, or necrosed tissue center)
- lesions called Erythma Chronicum Migrans – ECM
- Flu-like symptoms and lymphadenopathy
2. Early Disseminated Stage: can occur with stage 1
- spread to skin, nervous system (meningitis, cranial nerve palsy, peripheral neuropathies), joints
(arthritis), and heart.
3. Late Stage
- symptoms from previous stage are now chronic (chronic arthritis, chronic encephalopathy, etc.)
- chronic fatigue also noted
Diagnosis and Treatment: rash can be sampled and cultured for Borrelia. Blood and CSF can
be assayed (ELISA, Western blot) for Ab. Penicillin is the main antibiotic but doxycylcine can
be used as well.
------------------------------------------------------------------------------------------------Leptospira interrogans
- causes LEPTOSPIROSIS
- tightly coiled, simplest of spirochaetes
- found in urine of dogs, rats, livestock and wild animals
Transmission: Penetrates abraded skin or intact mucous membrane
Risk factors:
Occupational exposure (veterinarians, workers in slaughterhouses, animal
caretakers, etc.) or recreational activities in contaminated water
CLINICAL PRESENTATION
1. Septicemic phase
- abrupt fever, headache, malaise, and severe muscle aches
- conjunctiva are red, patient is photophobic.
2. Weil’s disease (severe form)
– renal failure, hepatitis with jaundice, mental status changes, and hemorrhage in many organs
Diagnosis and Treatment:
• Culture (on special media) blood and CSF during first febrile period
• During second phase, organisms may be cultured from the urine
• Treated with penicillin-type drugs or doxycyclin