Sensitivity of Vibrio parahaemolyticus, V. alginolyticus and V. cholerae to Cephalexin and the Elongation Phenomenon

Sensitivity of 15 strains in Vibrio parahaemolyticus, 3 strains in V. alginolyticus and 6 strains in V. cholerae to cephalexin(CEX), was examined, and the minimum inhibitory concentrations (MICs) against them were determined. Cellular elongation in each species was observed using light microscope and the morphological characteristics were described. Details of the results are as follows : 1) MICs against all of the strains of V. parahaemolyticus and V. alginolyticus were in the range from 25 to 100μg/ml, and those against the strains in V. cholerae were in the range from 6.25 to 50μg/ml. 2) Cellular elongation was able to be seen in each culture incubated with CEX. The concentrations for the elongation was different in each strain and ranged from one eighth to one half of each MICs. 3) Occurence of the elongated cells in several incubation preiods were various