Tetracycline resistant and polymyxin B sensitive vibrio cholerae O1 E1 tor isolated from the recent epidemics.

Abstract

By examining 99 Vibrio cholerae 01 isolates from cholera epidemics in a variety of areas in Laos in 1998, we found two unusual characteristics of the organisms. All except 4 isolates were moderately resistant to tetracycline without having plasmids, and susceptibilities to the other drugs were as expected. Eleven isolates showed the same level of susceptibility to polymyxin B as classical V. cholerae 01. With the exception of 4 tetracycline-susceptible strains, all the isolates were resistant to or poorly sensitive to the vibriostatic agent 0/129 (2,4-diamino-6,7-di-iso-propyl pteridine phosphate) . All isolates, including those susceptible to polymyxin B, produced El Tor hemolysin which was neutralized by anti-El Tor hemolysin and were resistant to cholera phage IV, indicating that they were of the El Tor biotype.

Antibiotic Resistance Conferred by a Class I Integron and SXT Constin in Vibrio cholerae O1 Strains Isolated in Laos

“…In the Lao People's Democratic Republic (Lao PDR), Vibrio cholerae isolates are collected at the Center for Laboratory and Epidemiology, and their cholera toxin and hemolysin production are studied, as well as their susceptibility to phages and antimicrobials. In the period between 1993 and 2000, although the pathogens were sensitive to the therapeutic antimicrobials as expected until 1996, a change in the drug sensitivity pattern started in 1998 after a period without cholera (13,17,20). Strains isolated after 1997 were found to be moderately resistant to tetracycline and chloramphenicol and highly resistant to trimethoprim-sulfamethoxazole (20).…”

“…Among a collection of 284 V. cholerae O1 biotype El Tor strains recovered from cholera patients from 1993 to 2000, 50 strains were included in the present study for further analysis. The various phenotypic characteristics of the strains were studied previously (13,17,20,25). Before PCR analysis, antibiotic resistance was confirmed in these isolates by MIC determination, and the results were compared with the initial MIC results (13,17,20).…”

“…The various phenotypic characteristics of the strains were studied previously (13,17,20,25). Before PCR analysis, antibiotic resistance was confirmed in these isolates by MIC determination, and the results were compared with the initial MIC results (13,17,20). V. cholerae O139 strain MO45 (ATCC 51394), isolated in Madras, India, in 1992, and V. cholerae O1 strain CRC182, isolated in India in 2000, were included for comparison purposes.…”

“…However, no plasmid was detected in 20 randomly selected tetracycline-resistant Laotian strains in 1998 (17). Recently, other genetic elements, such as a class I integron and an SXT constin, have also been reported to be associated with the spread of genetic determinants of resistance to antimicrobial agents (9,10,15,16,24).…”

Phenotypic and Genotypic Characteristics and Epidemiological Significance ofctx+Strains ofVibrio choleraeIsolated from Seafood in Malaysia

“…An epidemic or outbreak due to O1 strains resistant to TC is recognized very infrequently. In the last decade, O1 Ogawa strains resistant to TC were isolated from epidemics in south-ern Thailand in 1997 and 1998 (22) and in Laos in 1998 (16). The strains isolated from an epidemic in southern Thailand in 1998 were included in this study, and they showed the profile A1 (Table 3).…”