Antimicrobial Resistance and Virulence Genes of Escherichia coli Isolates from Swine in Ontario

Abstract

A total of 318 Escherichia coli isolates obtained from diarrheic and healthy pigs in Ontario from 2001 to 2003were examined for their susceptibility to 19 antimicrobial agents. They were tested by PCR for the presence of resistance genes for tetracycline, streptomycin, sulfonamides, and apramycin and of 12 common virulence genes of porcine E. coli. Antimicrobial resistance frequency among E. coli isolates from swine in Ontario was moderate in comparison with other countries and was higher in isolates from pigs with diarrhea than in isolates from healthy finisher pigs. Resistance profiles suggest that cephamycinases may be produced by >8% of enterotoxigenic E. coli (ETEC). Resistance to quinolones was detected only in enterotoxigenic E. coli (<3%). The presence of sul3 was demonstrated for the first time in Canada in porcine E. coli isolates. Associations were observed among tetA, sul1, aadA, and aac(3)IV and among tetB, sul2, and strA/strB, with a strong negative association between tetA and tetB. The paa and sepA genes were detected in 92% of porcine ETEC, and strong statistical associations due to colocation on a large plasmid were observed between tetA, estA, paa, and sepA. Due at least in part to gene linkages, the distribution of resistance genes was very different between ETEC isolates and other porcine E. coli isolates. This demonstrates that antimicrobial resistance epidemiology differs significantly between pathogenic and commensal E. coli isolates. These results may have important implications with regards to the spread and persistence of resistance and virulence genes in bacterial populations and to the prudent use of antimicrobial agents.

Contribution of Multi‐Antimicrobial Resistance to the Population of Antimicrobial ResistantEscherichia coliIsolated from Apparently Healthy Pigs in Japan

“…The present result showed that the resistance frequency of antimicrobials in porcine E. coli isolates in Japan is considered to be moderate compared with the results in several countries such as Denmark, the Netherlands, Spain, Sweden, Korea, Australia and the United States: resistance frequency of ampicillin (3.4-76.5%), oxytetracycline (10.3-99.2%) and trimethoprim (/sulfonamide) (7.5-59.1%) (3,4,8,10). As these results may reflect the differences in antimicrobial regimens in each country, a risk-management strategy for antimicrobial resistance in bacteria of animal-origin is necessary on the basis on the situation of antimicrobial-resistant bacteria in each country.…”

Distribution of SCCmec-associated phenol-soluble modulin in staphylococci

“…Associations of virulence factors with mobile genetic elements (MGEs) conferring drug resistance have been observed in E. coli [13,14] and enterococci [15], but in staphylococci, the connection of PSM-mec to SCCmec is rather unique [2]. PSM-mec can be found in diverse staphylococcal species, and these staphylococci originated from different host species.…”

“…This can be attributed to the insertion of a 1865 bp long IS1182 element and between the primers, M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 within mecI [11,12]. It was also negative in a S. vitulinus strain, which was mecR1-negative by array hybridisation.Associations of virulence factors with mobile genetic elements (MGEs) conferring drug resistance have been observed in E. coli [13,14] and enterococci [15], but in staphylococci, the connection of PSM-mec to SCCmec is rather unique [2]. PSM-mec can be found in diverse staphylococcal species, and these staphylococci originated from different host species.…”

Effect of oxytetracycline as well as an acid-based feed supplement on the prevalence and abundance of selected antibiotic resistance genes in weaned piglets

“…Genetic linkage of selected antibiotic resistance genes is common. For E. coli, respectively, association of tetA and sul1 is more frequently reported [9].…”

“…Among Gram-negative tet genes, the widespread tetA and tetB genes have been shown to be linked to other resistance genes. They are frequently associated with genes conferring resistance to streptomycin (strA, strB) and/or sulfamethoxazole (sul1, sul2) [9].…”