Feasibility of same-day identification of members of the family Vibrionaceae by the API 20E system

Sixty isolates, comprising nine species of the family Vibrionaceae, were tested with the API 20E 5-h same-day procedure (Analytab Products, Plainview, N.Y.). Included were 27 Aeromonas hydrophila isolates, 10 Aeromonas sobria isolates, 7 Aeromonas caviae isolates, 3 Plesiomonas shigelloides isolates, 3 Vibrio alginolyticus isolates, 3 Vibrio cholerae isolates, 1 Vibrio fluvialis isolate, 5 Vibrio parahaemolyticus isolates, and 1 Vibrio vulnificus isolate. The 5-h profile numbers were specific for the five Vibrio species and the Plesiomonas isolates. The three Aeromonas species shared seven 5-h profile numbers. Of the 63 5-h profile numbers generated by testing each isolate twice, 22 were identical to those found in the overnight analytical profile index. Of these, 20 were correct identifications, and two were incorrect. The remaining 41 5-h profile numbers were not found in the overnight analytical profile index. Because the 5-h analytical profile index does not contain any oxidase-positive organisms, the oxidase value was subtracted from the 63 5-h profile numbers to determine whether misidentifications could occur if the oxidase test was either not performed or not performed correctly. Only five of these factored profile numbers resulted in a possible misidentification. It is feasible, within limitations, to use the 5-h API 20E same-day procedure to identify the more commonly occurring members of the Vibrionaceae. The manufacturer should develop a data base for this purpose.