TRANSMISSION OF R FACTOR BY CONJUGATION FROM A NATURALLY-ISOLATED, MULTIPLE DRUG-RESISTANT STRAIN OF VIBRIO ELTOR TO SHIGELLA AND SALMONELLA

Out of the four multiple drug-resistant strains of El Tor vibrio which were isolated in the Philippines in 1964 and 1965, one strain (D226) was confirmed to transmit its quadruple drug-resistance to sensitive strains of Salmonella and Shigella. The recipients maintained their resistance after repeated subcultures in drug-free media, and are able to transfer their resistances to sensitive strains of Vibrio and Aeromonas. The resistant strains thus obtained lost easily their transmitted resistance after a few subcultures in drug-free media. The remaining three triple-resistant strains of El Tor vibrio failed to transmit their resistance. These strains maintained their resistance quite stably during several years, although the strain D226 lost its resistance about one year afterisolation. © 1969, JAPAN ANTIBIOTICS RESEARCH ASSOCIATION. All rights reserved.