Antimicrobial resistance of Salmonella serovars isolated from beef at retail markets in the north Vietnam.
Approximately 39.9% (63/158) of beef samples collected from retail markets in Hanoi from January to June 2009 were Salmonella-positive. Nine Salmonella serovars, Anatum (28.6%), Rissen (25.4%), Weltevreden (12.7%), Typhimurium (7.9%), Derby (7.9%), Lexington (7.9%), Dublin (4.6%), Newport (3.2%) and London (1.8%), were identified. Thirty-seven (58.7%) of the 63 Salmonella isolates were resistant to at least one antimicrobial tested, of which 29 (46%) isolates showed multidrug resistance (MDR). The isolates were commonly resistant to tetracycline (46.0%), sulphonamide (39.7%), ampicilline (31.7%), streptomycin (30.2%), trimethoprim (28.6%), kanamycin (28.6%) and chloramphenicol (22.2%). Fourteen (bla(TEMV), bla(OXA-1), aadA1, aadA2, sul1, tetA, tetB, tetG, cmlA1, floR, dfrA1, dfrA12, aac (3)-IV and aphA1-1AB) out of 22 antimicrobial resistance genes were detected by PCR from the resistant isolates. The catA1, Kn, blaPSE-1 genes and plasmid-mediated quinolones resistance (PMQR) genes such as qnrA, qnrB, qnrS, qepA and acc (6')-ib-cr were not detected. Mutations in the gyrA gene leading to the amino acid changes Ser83Phe and/or Asp87Asn were found in 6 out of the 11 quinolone-resistant isolates. The data revealed that multidrug resistant Salmonella strains were widely distributed in north Vietnam via the food chain and might contain multiple genes specifying identical resistant phenotypes. Thus, continuous studies are necessary to clarify the mechanisms of MDR in Salmonella and its spread in the livestock market.
Department of Veterinary Pathology, University of Miyazaki, Miyazaki 889-2192, Japan.
Truong Ha
TH
Thai
Takuya
T
Hirai
Nguyen Thi
NT
Lan
Akinori
A
Shimada
Pham Thi
PT
Ngoc
Ryoji
R
Yamaguchi
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology*; D027081:DNA Gyrase / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019450:Genes, MDR / Q000235:genetics; D008460:Meat / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D020125:Mutation, Missense / Q000235:genetics; D016133:Polymerase Chain Reaction; D012475:Salmonella / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D012481:Salmonella Infections, Animal / Q000453:epidemiology*; D017422:Sequence Analysis, DNA; D014744:Vietnam / Q000453:epidemiology
D000900:Anti-Bacterial Agents; D027081:DNA Gyrase