Which combination of test results would most strongly support identification of Vibrio vulnificus in a clinical lab case?

Which combination of test results would most strongly support identification of Vibrio vulnificus in a clinical lab case?

• A. Oxidase positive
• B. MacConkey pink colonies
• C. O/129 susceptibility
• D. All of the above

Answer: (D)

When identifying Vibrio vulnificus in a clinical lab, you look for a combination of features that together create a distinctive profile. Oxidase positive is a hallmark of vibrios, since they harbor cytochrome c oxidase, helping to distinguish them from many Enterobacterales that are oxidase negative. Seeing colonies that turn pink on MacConkey agar indicates lactose fermentation, which aligns with the lactose-fermenting pattern seen in this organism and helps separate it from non-lactose-fermenting Gram-negative bacteria. The O/129 susceptibility pattern provides another discriminating clue: vibrios are typically inhibited by 0/129, and this susceptibility is consistent with Vibrio species identification. When these three results occur together, they form a cohesive biochemical and phenotypic fingerprint that strongly supports identifying Vibrio vulnificus in a clinical case.

When identifying Vibrio vulnificus in a clinical lab, you look for a combination of features that together create a distinctive profile. Oxidase positive is a hallmark of vibrios, since they harbor cytochrome c oxidase, helping to distinguish them from many Enterobacterales that are oxidase negative. Seeing colonies that turn pink on MacConkey agar indicates lactose fermentation, which aligns with the lactose-fermenting pattern seen in this organism and helps separate it from non-lactose-fermenting Gram-negative bacteria. The O/129 susceptibility pattern provides another discriminating clue: vibrios are typically inhibited by 0/129, and this susceptibility is consistent with Vibrio species identification.

When these three results occur together, they form a cohesive biochemical and phenotypic fingerprint that strongly supports identifying Vibrio vulnificus in a clinical case.