BIOTYPE TRAITS AND ANTIBIOTIC SUSCEPTIBILITY OF VIBRIO-CHOLERAE SEROGROUP O1 BEFORE, DURING AND AFTER THE EMERGENCE OF THE O139 SEROGROUP

Sixty-nine strains of Vibrio cholerae O1 isolated at different times w ere analysed to investigate if there were any differences among the O1 strains isolated before, during and after the advent of the O139 sero group. Of the 69 O1 strains examined, 68 belonged to the Ogawa serotyp e while one belonged to the Inaba serotype. With the exception of one strain all other strains of V. cholerae O1 belonged to the eltor bioty pe. A single O1 strain isolated before the emergence of the O139 serog roup could not be classified as either eltor or classical biotype beca use it was resistant to both classical and eltor specific bacteriophag es. Marked variations in the susceptibility to antibiotics of V. chole rae O1 isolated during the different periods were observed. In additio n, strains of V. cholerae isolated after the epidemic of serogroup O13 9 in Calcutta showed an expanding R-type with resistance to a variety of drugs as compared to the O1 strains isolated before the advent of t he O139 serogroup. From this study, it is clear that there is a substa ntial mobility in genetic elements of V. cholerae O1 which necessitate s a continuous monitoring to keep abreast of the changing traits of th e etiologic agent of cholera.