Affiliations: *WHO Collaborating Centre for Antimicrobial Resistance in Bacteria from Food animals and Food of Animal Origin, Danish Veterinary Institute, Biilowsvej 27, DK-1790 Copenhagen V, Denmark
**Center for Antimicrobial Resistance Monitoring in Food-borne Pathogens. Faculty of Veterinary Science, Chulalongkorn University, Bangkok;
***WHO International Salmonella and Shigella Centre, National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Bangkok, Thailand
Source: Journal of Antimicrobial Chemotherapy (2003); 52: 715-718
Language : English
Objective: This study was conducted to investigate the occurrence of antimicrobial resistance among Salmonella Weltevreden isolates from different sources in South-East Asia (Indonesia, Laos, Malaysia, Taiwan, Thailand, Vietnam), Australia, Denmark, New Zealand and the USA.
Methods: A total of 503 isolates were examined for susceptibility to antimicrobial agents, and resistant isolates were examined for the presence of selected resistance genes by PCR.
Results: Only 48(9.5%) of the isolates were resistant to one or more of the antimicrobial agents tested. A low frequency of resistance was found towards ampicillin (1.8%), chloramphenicol (1.6%), florphenicol (0.4%), nalidixic acid (1.6%), neomycin (0.6%), streptomycin (4.4%), sulfamethoxazole (4.2%), tetracycline (4.0%) and trimethoprim (1.4%), whereas all isolates were susceptible to co-amoxiclav, ceftiofur, ciprofloxacin, colistin and gentamicin. All nine ampicillin-resistant isolates contained a sequence similar to the blaTEM-1b gene, one of the eight chloramphenicol-resistant isolates a sequence similar to the catA1 gene, all three neomycin-resistant isolates a sequence similar to the aphA-2 gene, 16(73%) of the 22 streptomycin-resistant isolates a sequence similar to the addA gene, the remaining six (27%) a sequence similar to the strA gene, and all 21 sulfamethoxazole-resistane isolates a sequence similar to the sul2 gene. Thirteen (65%) of the 20 tetracycline-resistant isolates contained the tet(A) gene, four (20%) the tet(B) gene and one (5%) the tet(C) gene.
Conclusions: This study showed a low frequency of resistance among Salmonella Weltevreden isolated from humans and other reservoirs in South-East Asia and elsewhere. There was no major difference in the occurrence of resistance between source or geographical origin.