Antimicrobial resistance in nontyphoidal Salmonella from food sources in Colombia: evidence for an unusual plasmid-localized class 1 integron in serotypes Typhimurium and Anatum.
Seventy-two isolates representing 18 serotypes recovered from various food samples collected in Colombia were tested for antimicrobial susceptibilities. The collection was further characterized for extended-spectrum cephalosporin, aminoglycoside, and tetracycline resistance markers. Multidrug resistant (MDR) isolates were further investigated for class 1 integrons and were evaluated for the presence of conjugative plasmids along with a determination of the incompatibility group by polymerase chain reaction (PCR). Antibiogram analysis showed that the incidence rate of ceftiofur resistance was moderately high (15%). A similar level of resistance to neomycin and oxytetracycline (11% and 10%, respectively) was also observed. There was a high prevalence of gene cassettes as part of one or more class 1 integrons (61%), many of which contained determinants that contributed to the resistance profile. Class 1 integrons identified in MDR Salmonella enterica serotypes Typhimurium and Anatum isolates were characterized. Sequencing identified several incomplete open reading frames (ORFs) as part of a gene cassette (bla-( imp-13 ), dfr7, blr1088, and aac8) along with a complete gene cassette (bla-(oxa2)) in each case. A mosaic of gene cassettes was identical in the two Salmonella serotypes. These integrons were located to a conjugative replicon. Plasmid profiling and incompatibility typing identified three plasmids belonging to Inc groups A/C, P, and W. Our study highlights the role of integrons, contributing to a MDR phenotype that is capable of dissemination to other bacteria.
O'Mahony
Rebecca
R
Centre for Food Safety, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Dublin, Ireland.
Quinn
Teresa
T
Drudy
Denise
D
Walsh
Ciara
C
Whyte
Paul
P
Mattar
Salim
S
Fanning
Séamus
S
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003105:Colombia / Q000453:epidemiology; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D005506:Food Contamination; D005516:Food Microbiology; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D012475:Salmonella / Q000145:classification* / Q000187:drug effects / Q000235:genetics*; D012480:Salmonella Infections
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial