• It contains 3 genera:
Vibrio
Aeromonas
Plesiomonas
• VIBRIO:
• GENERAL CHARACTERS:
Gram negative, rigid, curved rods.
vibratory motility – charecteristic feature
asporogenous, non-capsulated
• VIBRIO SPECIES:
V.cholerae
V. mimicus
• HALOPHILIC VIBRIOS:
V.parahaemolyticus
V.alginolyticus
V. vulnificus
GARDNER AND VENKATRAMAN’S CLASSIFICATION:
VIBRIO
GROUP A
GROUP B
(biochemically and antigenically
heterogenous )
OSUB GROUP
O1
Non-01
(SERO GROUPS)
(SERO VARS)
BIOTYPES : CLASSICAL
SEROTYPES : Ogawa
(up to 0-13)
El Tor
Inaba
Hikojima
• TEST
CLASSICAL
• Hemolysis
_
+
• VP test
_
+
• Chick erythrocyte
agglutination
_
+
• polymyxinB sensitivity
+
_
• GroupIV phage
Susceptibility
+
_
• El Tor phage V
Suceptibility
_
El Tor
+
VIBRIO CHOLERAE
MORPHOLOGY
• Short ,curved ,cylindrical rods
• V.comma
• S-shaped or spiral forms
• Pleomorphism
• Fish in stream appearance
• Darting motility
• Swarm of gnats
CULTURAL CHARACTERISTICS
•
•
•
•
•
Strongly aerobic
Temp 16-40 C,PH :6.4-9.6
Requirement of Nacl
Grows well on ordinary media
Nutrient agar:
moist,translucent,rounddiscs,1-2mm in
diameter with bluish tinge in transmitted light
Mac conkeys agar:Late lactose fermenters
Blood agar:hemodigestion
Gelatin stab culture:infundibuliform or napiform liquefaction
Peptone water:forms surface pellicle-in 6hrs
• SPECIAL MEDIA:1.Holding or transport media:a.Venkatraman-Ramakrishnan medium
b.Cary-Blair medium
c.Autoclaved sea water
2.Enrichment media:a.Alkaline peptone water
b.Monsur’s taurocholate tellurite peptone water
3.Plating media:a.alkaline bile salt agar
b.monsur’s gelatin taurocholate trypticase
tellurite agar
c.TCBS medium
• BIOCHEMICAL REACTIONS:catalase
-positive
oxidase
- positive
Indole
- positive
methyl red -negative
voges-proskauer test -negative
citrate test - positive
nitrate test - positive
• Sugar fermentation tests
ferments glucose
mannitol
maltose
mannose
sucrose with the production of acid only
not ferments inositol
arabinose or lactose
• Vibrios decarboxylate lysine and ornithine but not
arginine
• Vibrios elaborate several enzymes
• CHOLERA RED REACTION
RESISTANCE
•
•
•
•
•
Susceptible to heat ,drying and acids & disinfectants
Resist high alkalinity
Destroyed at 55 C in 15 min
Affected by vibriophages
Killed in the gastric juice of normal acidity with in
min
• El Tor vibrios survive longer than classical cholera
vibrio