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Detailed information of VIBRIO CHOLERAE
VIBRIO CHOLERAE
DEFINITION:
A bacterial infection of the small intestine caused by Vibrio
Cholerae resulting in a secretory diarrhea.
EPIDEMIOLOGY:
- incidence: ?
- risk factors:
- age: ?
- season: ?
- route: direct: fecal-oral, (animals play no role) indirect:
water, food (shellfish)
- environ: epidemic: nosocomial
- endemic: developing countries, panendemics
- incubation period: 6 hours -> 2 days
PATHOGENESIS:
- Vibrio Cholerae is a gram negative rod
- 70 serotypes known and while many cause acute diarrhea
only the 01 serotype causes cholera
- two biotypes of 01 serotype: classic and El Tor
- after ingestion, the vibrios multiply in the lumen &
adhere to the surface of the epithelial cells underneath the
mucous layer where they release an enterotoxin which has two
subunits:
- attaches to a GM1 ganglioside receptor on the surface
of the epithelial cells
2. Active Subunit
- enters the cell & activates adenylate cyclase ->
increases cAMP -> decreases the active absorption of
sodium and water in villus cells and increases the active
secretion of chloride by crypt cells -> net loss of water
& electrolytes into the lumen
- both human and nonhuman reservoirs exist and V.
cholerae may be transmitted as a subclinical infection
- the El Tor biotype may survive for prolonged periods
in water
CLINICAL FEATURES:
- variable
- mild - yellow stool
- severe - cholora gravis
- sudden onset of painless and profuse watery diarrhea
- up to 200-350 cc/kg/day
- stool passed frequently and effortlessly
- rice-water appearance (clear fluid with flecks of mucous)
- slight fish-like odour of stool
- may continue for 7 days
- early sign of recovery is reappearance of bile pigment in
stool
- associated symptoms:
- periumbilical cramps (50%), nausea/vomiting, no tenesmus,
- severe dehydration and hypotonia
- fever > 38 C (25%)
- cyanosis and painful muscle cramps
- lethargy, slurred speech, coma
- glucose malabsorption rare
- mortality (< 1%)
2. Complications
- tetany, coma, seizures
- pulmonary edema
- arrhythmias (due to low K+)
- paralytic ileus (due to low K+)
- acute renal failure (ATN), hypokalemic nephropathy
- hypokalemia, hypoglycemia
INVESTIGATIONS:
- cultures - on TCBS agar
- diarrheal fluid - isotonic with elevated bicarbonate & K+
2. Biopsy
- small bowel (jejunum)
- intact epithelium with minimal cellular response
- slight edema of lamina propria
- moderate dilation of capillaries and lymphatics
- empty goblet cells (of mucous)
3. Serum
- metabolic acidosis with severe dehydration
- low K+, low glucose
- serology:
- vibriocidal and agglutinating antibody titres peak (4x or
greater rise) at 1-2 weeks after the onset of illness and
return to baseline 8-12 weeks after onset (diagnostic)
- antitoxin titres remain elevated for up to 12-18 months
MANAGEMENT:
- oral rehydration fluid (ORF) and isotonic IV rehydration
- replace HCO3, K+, glucose
2. Medications
- Tetracycline 50mg/kg/day po q6h for 2-3 days
- shortens duration and volume of diarrhea by 50-70%
- shortens duration of carriage of Vibrio
- others: doxycycline, furazolidone. erythromycin, TMP-SMX,
chloramphenicol
3. Prevention:
- avoid contaminated food and water
- breastfeeding provides vibriocidal antibodies - VC rare in
breast-fed infants
- high potency cholerae vaccines offer 50-80% protection for
up to 6 months in endemic regions but does not protect against
transmission
- chemoprophylaxis - with tetrcycline or doxycycline for 2
days decreases infection rates in household contacts
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Pediatric Database - VIBRIO CHOLERAE
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