6.1. Most probable number
The most probable number (MPN) method described in
the US Food and Drug Administration Bacterial Analytical
Manual (FDA, 1998) is commonly used for the
detection of V. parahaemolyticus in foods. However, the
MPN method is labor-intensive and time-consuming.
A major disadvantage of the method is that thiosulfate–
citrate–bile salts–sucrose agar (TCBS) cannot differentiate
V. parahaemolyticus from some strains of Vibrio vulnificus
or Vibrio mimicus. Growth of V. parahaemolyticus as well
as a few strains of V. vulnificus and V. mimicus that do not
ferment sucrose all appears on TCBS as round (2–3 mm in
diameter) and green or blue-green colonies. Therefore,
several presumptive positive colonies formed on a TCBS
plate need to be analyzed with lengthy biochemical tests for
confirmation and results may not be available for 4–5 day