Gram Negative Bacilli
V. cholerae, is best described by which of the following statements? (AIIMS Nov 2011)
|A||Cause of gastroenteritis; reservoir in birds and mammals, optimal growth at 42oC|
|B||Human pathogen, halophilic, lactose-negative, sucrose-negative; cause gastrointestinal diseases primarily from ingestion of cooked seafood|
|C||Human pathogen, halophilic, lactose-positive; produces heat-labile, extracellular toxin.|
|D||“String-test” – positive isolate; three serotypes-Ogawa(AB), Inaba (AC), hikojima (ABC)|
a. Some organisms originally thought to be vibrios, such as C. jejuni, have been reclassified. C. jejuni, which grows best at 42°C, has its reservoir in birds and mammals and causes gastroenteritis in humans.
b. V cholerae causes cholera, which is worldwide in distribution. The three serotypes for cholera are Ogawa (AB), Inaba (AC), and Hikojima (ABC). The isolate of V ckolerae is “string-test”-positive.
c. V parahaemolyticus is a halophilic marine vibrio that causes gastroenteritis in humans, primarily from ingestion of cooked seafood. It is lactose- negative and sucrose-negative.
d. V vulnificus is also halophilic. It has been suggested that these halophilic vibrios do not belong in the genus Vibrio but in the genus Beneckea. V vulnificus is lactose-positive and produces heat-labile, extracellular toxin. Organisms that, unlike V cholerae, do not agglutinate in 0-1 antiserum were once called nonagglutinable (NAG), or noncholera (NC), vibrios. Such a classification can be confusing because V vulnificus, which is an NCV, nevertheless causes severe cholera-like disease. In addition, V vulnificus can produce wound infections, septicemia, meningitis, pneumonia, and keratitis.