RESUMO
This study was undertaken to identify and characterize amino acid substitutions in gyrA and parC related with quinolone resistance of 27 nalidixic acid-resistant (NaR) Salmonella isolates collected in poultry slaughterhouses in Korea. A total of 51 Salmonella isolates were detected from 44.8% (47/105) of the total samples from 15 poultry slaughterhouses examined, among which 27 (52.9%) NaR isolates were detected while ciprofloxacin (Cip) resistance was not present in the isolates. These 27 NaR isolates of DNA sequencing revealed that it contained three types of gyrA mutations in only D87 codon. Mutations in the D87 codon resulted in substitutions to G in most of the isolates, but D87Y and D87N exchanges were also detected. Although Cip resistance was absent, reduced susceptibility characterized by mutations in gyrA was apparent among Salmonella isolates from poultry slaughterhouses in Korea.
RESUMO
Poultry products have consistently been identified as important sources of Salmonella infection in humans, because vertical transfer of infection from breeding hens to progeny is an important aspect of the epidemiology of Salmonella spp. infection within the poultry industry. The aim of this study was to estimate the prevalence of Salmonella contamination in poultry products from 15 different located geographical areas from among the 50 poultry slaughterhouses authorized to operate in Korea and to characterize all the isolates by genotyping, phage typing and antibiotic resistance pattern. Salmonella was isolated from 10 (66.7%) of the first and 5 (33.3%) of the last chilling waters and from 32 (42.7%) carcasses originating from 9 slaughterhouses. The major prevalent serotypes of Salmonella originating from 2 duck slaughterhouses and 13 chicken slaughterhouses tested were S. Typhimurium and S. Enteritidis, respectively. Regarding the characteristics of their antibiotic resistance, 8 of the 11 ampicillin resistant (AmR) isolates carried blaTEM only, two carried blaTEM and blaCTX-M-14 and one carried blaCTX-M-3 and only one AmR isolate with the blaCTX-M-3 ß-lactamase gene was an ESBL-producing Salmonella strain. Twenty-seven Salmonella isolates showed nalidixic acid resistance with a mutation at amino acid codon Asp87 in gyrA and no mutation in the parC gene. In all the phenotypic and genotypic properties of the 18 S. Enteritidis and 8 S. Typhimurium based on PFGE, phage types and antibiotic resistance pattern, the predominant patterns were XEI/BEI-PT32a-NaR (n = 5) and XTI/BTI-RNDC-no resistant antibiotics (n = 6), respectively.
