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Dr. Jyotsna AgarwalDr. Jyotsna Agarwal
Dept. MicrobiologyDept. Microbiology
Vibrio choleraeVibrio cholerae
Cholera: IntroductionCholera: Introduction
Transmitted to humans via Transmitted to humans via contaminated food and watercontaminated food and water
Part of normal flora of brackish water Part of normal flora of brackish water and estuariesand estuaries
Epidemiology of Vibrio cholerae
Cholera recognized for more than two millennia with sporadic disease and epidemics
Endemic in communities with poor sanitation
Seven pandemics (possible beginning of 8th) since 1817
Human carriers and environmental reservoirs
Historical PerspectiveHistorical Perspective::
1817-1820 1817-1820 First PandemicFirst Pandemic
spread out of India tospread out of India to
Europe Europe
spread from India -> spread from India -> MiddleMiddle
East (reaching Turkey & East (reaching Turkey &
Persia) -> Far EastPersia) -> Far East
(Singapore, Japan, (Singapore, Japan, PhilippinesPhilippines)
1829-1851 1829-1851
Second Second pandemicpandemicEntered US through Entered US through NY and New Orleans -NY and New Orleans -> proceeded through > proceeded through entire countryentire country
Historical Perspective: IdentificationHistorical Perspective: Identification
1854 - Filippo Pacini identified curved or comma 1854 - Filippo Pacini identified curved or comma shaped bacterium associated with this disease, shaped bacterium associated with this disease, which he called which he called Vibrio choleraeVibrio cholerae
1883- Rober Koch isolated the bacteria1883- Rober Koch isolated the bacteria
Historical Perspective:Historical Perspective:
1854- 1854- John SnowJohn Snow hypothesized water as hypothesized water as primary reservoir for primary reservoir for transmissiontransmission– Broad Street pump incidentBroad Street pump incident– 56 deaths in 2 days56 deaths in 2 days
Recent Cholera Pandemics
7th pandemic: V. cholerae O1 biotype El Tor Began in Asia in 1961
8th pandemic (??) V. cholerae O139 Bengal Began in India in 1992 and spread to Asia, Europe
and U.S.
Cholera affected countriesCholera affected countries
Similarities to Enterobacteriaceae Gram-negativeFacultative anaerobesFermentative bacilli
Differences from EnterobacteriaceaePolar flagella Oxidase positive
General Characteristics of Vibrio
Vibrio spp. (Family Vibrionaceae) Associated with Human Disease
Comma-shaped bacilli pH range for growth on media
pH 7.0 - 9.0 V. cholerae grow without salt, Most other
vibrios are halophilic
General Characteristics of Vibrio
Taxonomy of Vibrio cholerae >200 serogroups based on somatic O-
antigen O1 and O139 serogroups are
responsible for epidemic cholera O1 serogroup subdivided into
Two biotypes: El Tor and classicalThree serotypes: ogawa, inaba,
hikojimaNon-cholera vibrio (NCV) or non-agglutinating vibrios (NAG) or non-O1 vibrio cholerae)
Difference between El Tor & Difference between El Tor & classical Vibrio choleraeclassical Vibrio cholerae
Pathogenesis of V.cholerae
Incubation period: 2-3 days High infectious dose Abrupt onset of life-threatening
watery diarrhea Rice-water stools:
Colorless Odorless Speckled with mucus
Pathogenesis of V. cholerae
Cholera toxin leads to profuse loss of fluids and electrolytes (Na, K HCO3)
A-B type of toxin, receptor GM1, increase intracellular cAMP
Death attributable to: Hypovolemic shock Metabolic acidosis
Laboratory Identification of Vibrios
Transport medium or holding medium
- Cary-Blair-Venkatraman Ramakrishnan medium- liquid
Enrichment medium - alkaline peptone broth
Yellow colonies on TCBSYellow colonies on TCBS
Selective/differential culture medium - TCBS agar– V. cholerae grow as
yellow colonies– Gram stain– Biochemical and
serological tests– Motility- Darting
motility on hanging drop preparation
Treatment & Prevention of cholera
Untreated: 60% fatality Treated: <1% fatality Rehydration & supportive
therapy Oral Intravenous
Doxycycline or tetracycline
Water purification, sanitation & sewage treatment
Vaccines
SummarySummary
General characters of vibrio, historyGeneral characters of vibrio, history Vibrio choleraeVibrio cholerae Cholera: mode of spread, clinical Cholera: mode of spread, clinical
featuresfeatures Laboratory diagnosisLaboratory diagnosis Treatment/preventionTreatment/prevention