ABSTRACT
Figure 202 Slightly curved, uniformly staining bacilli with rounded ends in smear from 5% sheep blood agar
Figure 203 Vibrio parahaemolyticus Phase-contrast of wet preparation of agar slant condensate showing marked pleomorphism with filaments containg round (spheroplast) bodies. Pleomorphism with formation of spherical forms may occur spontaneously or induced by cultivation on media with suboptimal sodium chloride concentration
e.g. El Tor biotype of V. cholerae, V. parahaemolyticus, and V. fluvialis. Thiosulfate citrate bile salts sucrose (TCBS) medium is used for the isolation of vibrios when suspected. This medium allows for differentiation of Vibrio species based upon sucrose fermentation (yellow colonies), e.g. V. cholerae, form sucrosenegative (green colonies) species, e.g. V. parahaemolyticus. Vibrio species are inhibited by the vibriostatic agent 0129, (2,4-diamino-6,7-diisopropylpteridine). Vibrio species also render a positive ‘string’ test after emulsification of colonies in 0.5% sodium desoxycholate. Epidemiologic clues suggesting a Vibrio infection include a recent history of raw or undercooked seafood consumption, especially shell fish (oysters), trauma-induced wounds contaminated with fresh or sea water, and foreign travel, particularly to endemic areas.
