Abstract
Background: The objective was to investigate the phenotypic and genotypic resistance and the horizontal transfer of
resistance determinants from Salmonella isolates from humans and animals in Vietnam.
Methodology/Principal Findings: The susceptibility of 297 epidemiologically unrelated non-typhoid Salmonella isolates
was investigated by disk diffusion assay. The isolates were screened for the presence of class 1 integrons and Salmonella
genomic island 1 by PCR. The potential for the transfer of resistance determinants was investigated by conjugation
experiments. Resistance to gentamicin, kanamycin, chloramphenicol, streptomycin, trimethoprim, ampicillin, nalidixic acid,
sulphonamides, and tetracycline was found in 13 to 50% of the isolates. Nine distinct integron types were detected in 28%
of the isolates belonging to 11 Salmonella serovars including S. Tallahassee. Gene cassettes identified were aadA1, aadA2,
aadA5, blaPSE-1, blaOXA-30, dfrA1, dfrA12, dfrA17, and sat, as well as open reading frames with unknown functions. Most
integrons were located on conjugative plasmids, which can transfer their antimicrobial resistance determinants to
Escherichia coli or Salmonella Enteritidis, or with Salmonella Genomic Island 1 or its variants. The resistance gene cluster in
serovar Emek identified by PCR mapping and nucleotide sequencing contained SGI1-J3 which is integrated in SGI1 at
another position than the majority of SGI1. This is the second report on the insertion of SGI1 at this position. High-level
resistance to fluoroquinolones was found in 3 multiresistant S. Typhimurium isolates and was associated with mutations in
the gyrA gene leading to the amino acid changes Ser83Phe and Asp87Asn.
Conclusions: Resistance was common among Vietnamese Salmonella isolates from different sources. Legislation to enforce
a more prudent use of antibiotics in both human and veterinary medicine should be implemented by the authorities in
Vietnam.
resistance determinants from Salmonella isolates from humans and animals in Vietnam.
Methodology/Principal Findings: The susceptibility of 297 epidemiologically unrelated non-typhoid Salmonella isolates
was investigated by disk diffusion assay. The isolates were screened for the presence of class 1 integrons and Salmonella
genomic island 1 by PCR. The potential for the transfer of resistance determinants was investigated by conjugation
experiments. Resistance to gentamicin, kanamycin, chloramphenicol, streptomycin, trimethoprim, ampicillin, nalidixic acid,
sulphonamides, and tetracycline was found in 13 to 50% of the isolates. Nine distinct integron types were detected in 28%
of the isolates belonging to 11 Salmonella serovars including S. Tallahassee. Gene cassettes identified were aadA1, aadA2,
aadA5, blaPSE-1, blaOXA-30, dfrA1, dfrA12, dfrA17, and sat, as well as open reading frames with unknown functions. Most
integrons were located on conjugative plasmids, which can transfer their antimicrobial resistance determinants to
Escherichia coli or Salmonella Enteritidis, or with Salmonella Genomic Island 1 or its variants. The resistance gene cluster in
serovar Emek identified by PCR mapping and nucleotide sequencing contained SGI1-J3 which is integrated in SGI1 at
another position than the majority of SGI1. This is the second report on the insertion of SGI1 at this position. High-level
resistance to fluoroquinolones was found in 3 multiresistant S. Typhimurium isolates and was associated with mutations in
the gyrA gene leading to the amino acid changes Ser83Phe and Asp87Asn.
Conclusions: Resistance was common among Vietnamese Salmonella isolates from different sources. Legislation to enforce
a more prudent use of antibiotics in both human and veterinary medicine should be implemented by the authorities in
Vietnam.
| Original language | English |
|---|---|
| Article number | e9440 |
| Number of pages | 8 |
| Journal | PLoS One |
| Volume | 5 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2010 |
