Investigation of Salmonella spp. and Escherichia coli prevalence and antimicrobial resistance in pigs at Korean Abattoirs

Abstract

The objective of this study was to ascertain the nationwide prevalence and antimicrobial resistance rates of
Salmonella spp. and Escherichia coli amongst domesticated finisher pigs. Fecal samples (n=840) were collected at 84
slaughterhouses in Korea in May 2009. Salmonella spp. was isolated from 21 of the 840 samples (2.5%), and
comprised the following isolated serotypes: Salmonella rissen, Salmonella derby, Salmonella typhimurium.
Antimicrobial susceptibility testing was performed for eight antimicrobials. Salmonella resistance was tetracycline
(76.19%); nitrofurantoin (38.10%); kanamycin (33.33%); chloramphenicol, sulfamethoxazole/trimethoprim and
cephalothin (28.57%); polymyxin B (9.52%); and ampicillin/sulbactam (4.76%), and E. coli resistance was tetracycline
(87.11%); chloramphenicol (66.24%); kanamycin (51.68%); sulfamethoxazole/trimethoprim (51.29%); cephalothin
(8.38%); nitrofurantoin (5.15%); ampicillin/sulbactam (4.64%); and polymyxin B (0.52%). Tetracycline resistance was
most common. Surprisingly, 28.57 and 66.24% of the Salmonella spp. and E. coli isolates, respectively, were resistant
to chloramphenicol, which has been banned from agricultural use in Korea for some time. A wide range of strains
displayed multi-antimicrobial resistance: 14 out of 21 (66.66%) and 611 out of 776 (78.72%) of the Salmonella and E.
coli isolates, respectively. Salmonella spp. and E. coli demonstrate an appreciable broad-spectrum, (multi)-
antimicrobial resistance, which is a potential public health concern. A continuous antibiotic surveillance program may
be worthwhile.