Spiral Bacteria Flashcards
1
Q
Classification of spiral bacteria
A
Spirochaetes
- Treponema pallidum
- Borrelia
- Relapsing Fever Group - B. recurrentis, B. duttoni
- Lyme Disease Group - B. burgdorferi - Leptospira interrogans
- Spirillum minus & Streptobacillus monilformis - causes of rat bite fever
Spiral
- Campylobacter - jejuni, coli, fetus
- Helicobacter - pylori, cinaedi, fennelliae
2
Q
Features of campylobacter & helicobacter
A
- Oxidase positive
- Gram negative short spirals
- Grow under microaerophilic conditions (less O2)
- will not grow at normal atmospheric conc of O2/in its absence
3
Q
Transmission of T. pallidum
A
- natural syphilis infections only occur in man
1. Sexually transmitted disease - organism is sensitive to drying, only by intimate contact
4
Q
Clinical presentations of T. pallidum (6)
A
- Primary syphilis
- Chancre (painless ulcer) + enlargement of local lymph nodes
- often on genitals, also extragenital sites (mouth, lips, anal canal, fingers of HCW)
- may have multiple, not always painless, increasesd risk of concomitant HIV inf - Secondary syphilis
- Treponemes spread throughout body - rash (macular, papular, pustular), very infectious, usually involves palms & soles
- Mucous patches (lesions on mucous membranes), snail track ulcers, oral/genital
- Condylomata lata (warty lesions) around anus, genitals, warm moist areas
- generalised enlargement of lymph nodes (lymphadenopathy)
- fever, acute meningeal involvement - Latent syphilis
- signs disappear but secondary lesions may relapse
- 70% never develop further disease, the rest develop chronic symptomatic inf - Meningeal syphilis
- present within a few months to a year of infection
- chronic meningitis - headache, nausea, neck stiffness, other neuro signs - Late complications (tertiary, quaternary syphilis)
- Neurosyphilis - Meningovascular syphilis, General paresis/general paralysis of the insane (GPI), Tabes dorsalis (demyelination of posterior columns of spinal cord & dorsal roots/ganglia - loss of pain & proprioception - ataxic gait, lightning/sudden pains, Charcot’s joint, foot ulcers, Argyll Robertson pupils)
- Gummatous syphilis/tertiary - granulomatous lesions which become necrotic - gumma on skin, mucous membranes, bone
- Cardiovascular syphilis - aortitis of thoracic aorta - narrowed origin of coronary arteries, angina, MI, stretching of aortic valve ring, aortic incompetence, aortic aneurysm, weakened/stretched aortic wall - Congenital syphilis (T. pallidum can cross the placenta)
- may kill the baby, induce abortion
- bullous rash at delivery (may be absent) - early lesions (resemble sec syphilis) - later lesions (gummatous, neurosyphilis)
- Hutchinson’s triad: 8th nerve deafness + interstitial keratitis (corneal clouding - blindness) + Hutchinson’s teeth (notched incisors)
5
Q
Diagnosis of T. pallidum (3)
A
- Dark Ground Illumination (DGI)
- thin, cannot be seen using routine dye staining methods
- not for oral lesions - other bacteria in flora - not specific - Neurosyphilis: CSF sample - abnormalities in cell count, chemistry, syphilis antibody tests
- Serology
(A) Non-treponemal antibody tests (non specific)
- VDRL (venereal disease reference laboratory), RPR (rapid plasma reagin)
- +: titre fluctuates with intensity of disease, falls w successful treatment, -: false positive reactions, VDRL/RPR titres decay naturally without treatment
(B) Treponemal antibody tests (specific)
- TPHA (T. pallidum hemagglutinin test), TPPA (TP particle/agglutination test), FTA-Abs (fluorescent treponemal antibody test - absorbed)
- +: less false positives & fluctuations, -: stay raised for a long time even after successful treatment
- VDRL + TPHA - if either is positive do FTA-Abs
6
Q
Treatment of T. pallidum
A
- Penicillin/azithromycin
- supervised by experienced STD physicians to manage Jarisch-Herxheimer reactions & careful follow up
7
Q
Prevention of T. pallidum
A
- Antenatal screening
- Serology for all STD patients
- Contact tracing
- Screening of donors
- Education
8
Q
Transmission & virulence factors of relapsing fever (borrelia)
A
- louse (B. recurrentis), tick (B. duttoni)
- antigenic variation - relapsing nature of infections
9
Q
Clinical presentations of relapsing fever (borrelia)
A
- periods of fever alternate with afebrile intervals
- fevers cease when bacterium has run out of new antigens & immune system catches up
10
Q
Diagnosis & treatment of relapsing fever (borrelia)
A
- Peripheral Blood Films
- Doxycycline (watch out for Jarisch-Herxheimer reaction)
11
Q
Transmission of lyme disease (borrelia)
A
Bite of hard ticks, extensive animal reservoir
12
Q
Clinical presentations of lyme disease (borrelia) (3)
A
- Stage 1: Rash, erythema chronicum migrans - begins at site of bite (macule/papule) - spreads out in a ring (sometimes with central clearing), may be assoc w systemic disease
- Stage 2: neurological, cardiac, MSK disease, arthritis (weeks to months later)
- Stage 3: chronic skin, joint, neurological disease (months to years later)
- congenital infection may occur
13
Q
Diagnosis & treatment of lyme disease (borrelia)
A
- Serology
- culture is difficult
- Treatment depends on stage of disease
- ECM: Doxycycline
14
Q
Features & transmission of Leptospira interrogans
A
- many serovars depending on surface Ag
- chronically excreted in urine of rats & other animals
- Entry through skin, mucous membranes of URT, eyes
15
Q
Clinical presentations of Leptospira interrogans (3)
A
Leptospirosis
- Septicaemic phase, bacteraemic leptospirosis - flu-like, high fever, muscle pain, possible conjunctival congestion
- Immune phase - bacteria cleared from blood as antibodies appear, signs of meningeal irritation (headache, vomiting)
- Weil’s disease: Icteric leptospirosis - jaundice, hemorrhage, renal failure, conjunctival congestion, may be fatal
