Antimicrobial Agents and Chemotherapy, May 2000, p. 1315-1321, Vol. 44, No. 5
0066-4804/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Department of Veterinary Microbiology, Royal Veterinary and Agricultural University, Frederiksberg, DK-1870 Frederiksberg C,1 and Danish Veterinary Laboratory, DK-1790 Copenhagen V,3 and Armed Forces Research Institute of Medical Sciences, Bangkok 10400, Thailand2
Received 1 June 1999/Returned for modification 26 July 1999/Accepted 8 February 2000
In this study, 176 clinical and environmental Vibrio
cholerae strains of different O serotypes isolated in Thailand
from 1982 to 1995 were selected and studied for the presence of class 1 integrons, a new group of genetic elements which carry antibiotic resistance genes. Using PCR and DNA sequencing, we found that 44 isolates contained class 1 integrons harboring the aadB,
aadA2, blaP1, dfrA1, and
dfrA15 gene cassettes, which encode resistance to
gentamicin, kanamycin, and tobramycin; streptomycin and spectinomycin;
-lactams; and trimethoprim, respectively. Each cassette array contained only a single antibiotic resistance gene. Although resistance genes in class 1 integrons were found in strains from the same epidemic, as well as in unrelated non-O1, non-O139 strains isolated from children with diarrhea, they were found to encode only some of the
antibiotic resistance expressed by the strains. Serotype O139 strains
did not contain class 1 integrons. However, the appearance and
disappearance of the O139 serotype in the coastal city Samutsakorn in
1992 and 1993 were associated with the emergence of a distinct V. cholerae O1 strain which contained the aadA2
resistance gene cassette. A 150-kb self-transmissible plasmid found in
three O1 strains isolated in 1982 contained the aadB gene
cassette. Surprisingly, several strains harbored two integrons
containing different cassettes. Thus, class 1 integrons containing
various resistance gene cassettes are distributed among different
V. cholerae O serotypes of mainly clinical origin in Thailand.
This article has been cited by other articles:
| Clin. Vaccine Immunol. | Clin. Microbiol. Rev. |
|---|---|
| J. Clin. Microbiol. | ALL ASM JOURNALS |