Spiral Bacteria Flashcards
Classification of spiral bacteria
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
Features of campylobacter & helicobacter
- Oxidase positive
- Gram negative short spirals
- Grow under microaerophilic conditions (less O2)
- will not grow at normal atmospheric conc of O2/in its absence
Transmission of T. pallidum
- natural syphilis infections only occur in man
1. Sexually transmitted disease - organism is sensitive to drying, only by intimate contact
Clinical presentations of T. pallidum (6)
- 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)
Diagnosis of T. pallidum (3)
- 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
Treatment of T. pallidum
- Penicillin/azithromycin
- supervised by experienced STD physicians to manage Jarisch-Herxheimer reactions & careful follow up
Prevention of T. pallidum
- Antenatal screening
- Serology for all STD patients
- Contact tracing
- Screening of donors
- Education
Transmission & virulence factors of relapsing fever (borrelia)
- louse (B. recurrentis), tick (B. duttoni)
- antigenic variation - relapsing nature of infections
Clinical presentations of relapsing fever (borrelia)
- periods of fever alternate with afebrile intervals
- fevers cease when bacterium has run out of new antigens & immune system catches up
Diagnosis & treatment of relapsing fever (borrelia)
- Peripheral Blood Films
- Doxycycline (watch out for Jarisch-Herxheimer reaction)
Transmission of lyme disease (borrelia)
Bite of hard ticks, extensive animal reservoir
Clinical presentations of lyme disease (borrelia) (3)
- 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
Diagnosis & treatment of lyme disease (borrelia)
- Serology
- culture is difficult
- Treatment depends on stage of disease
- ECM: Doxycycline
Features & transmission of Leptospira interrogans
- many serovars depending on surface Ag
- chronically excreted in urine of rats & other animals
- Entry through skin, mucous membranes of URT, eyes
Clinical presentations of Leptospira interrogans (3)
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
Diagnosis & treatment of Leptospira interrogans
- Microscopy: DGI of blood, urine
- Serology
- culture difficult
- Benzylpenicillin
Features of rat bite fever
- rare, local lesion (skin ulcer, abscess), local lymphadenopathy, fever, skin rash
- may be acquired by oral route (Haverhill fever) via contaminated milk/water (S. moniliformis)
- caused by Spirillum minus (gram neg spiral, mostly in far east esp Japan, Africa); Streptobacillus moniliformis (pleomorphic gram neg non-spiral)
Transmission of campylobacter jejuni & coli
Faecal-oral, contaminated food & milk (from animals, poultry meat)
Clinical presentations of campylobacter jejuni & coli (5)
- C. jejuni is an impt cause of GI inf, C. coli is less common
1. incubation 1-7 days, initial flu-like prodromal illness
2. Sever abdominal pain (sometimes suspected as appendicitis)
3. Diarrhea (sometimes frank blood w faeces)
4. usually self limiting
5. complications: sever local hemorrhage, reactive arthritis, Guillain Barre syndrome)
Diagnosis of campylobacter jejuni & coli (2)
- Stool culture on selective medium w antibiotics to suppress faecal flora
- microaerophilic conditions, 42C
- grey spreading oxidase positive colonies
- gram stain - typical spiral morphology - Serology
Treatment of campylobacter jejuni & coli (2)
- Supportive therapy: rehydration
2. Erythromycin/Ciprofloxacin - for severe symptoms
Prevention of campylobacter jejuni & coli (3)
- eliminate from poultry farms
- safe food handling & cooking practices
- safe water supplies, pasteurise milk
Clinical presentations of campylobacter fetus (3)
- causes abortion in sheeps, cows
1. Occasional cause of diarrhea
2. Septicaemia in immunocompromised
3. Rare cause of septic abortion
Features of H. pylori
- Urease positive
2. Only infects gastric-type mucosa
Transmission of H. pylori
- Faecal-oral
2. Oral-oral
Clinical presentations of H. pylori (3)
- Symptoms ~2 weeks: abdominal pain, flatulence, nausea, bad breath
- Chronic active gastritis - provoked by bacterial antigens, may be asymptomatic, stomach pain (non-ulcer dyspepsia) & eventual atrophic gastritis
- H. pylori gastritis is linked to 1. peptic ulceration 2. gastric cancer 3. gastric MALT lymphoma
Diagnosis of H. pylori (6)
Non-invasive - in younger patients with dyspepsia (no alarm symptoms) - if not scope (risk of cancer)
- Urea Breath Test - drink solution of urea with 14C, H. pylori breaks down urea into CO2 & NH3, CO2 absorbed into bloodstream & excreted rapidly through lungs
- Faecal Antigen Test
- false negs due to antibiotics, PPIs, acute bleeding - Serology (serum, blood urine, saliva) - false pos in recently treated patients
Invasive
- Culture from gastric biopsies taken through fibre-optic endoscope
- grows micro-aerophilically at 37C
- colonies are rapidly urease positive - Histology/Microscopy
- Rapid Urease Test
- biopsy added to urease broth
- positive result seen in a few min because bacterium makes a lot of enzymes
Treatment of H. pylori
- several agents to eliminate colonisation
- more complex regimes - higher clearance rates, but expect relapse
Prevention of H. pylori (3)
- Improved living conditions - lower infection rates
- Careful disinfection of endoscopes to prevent nosocomial transmission
- No vaccine
Features of H. cinaedi & fennelliae
- associate with proctitis in homosexual men
- can also cause bacteremia
