Detection of integrons class 1 and class 2 in VTEC strains isolated from pigs.

COLELLO, ROCÍO; MOREDO, FABIANA; ETCHEVERRÍA, ANALÍA I.; LEOTTA, GERARDO; PARMA, ALBERTO E.; PADOLA, NORA L.

Amsterdam

Simposio; 8th International Symposium on Shiga Toxin (Verocytotoxin) producing Escherichia coli infections.; 2012

Introduction: In the last 10 years, approximately 500 HUS annual cases were reported in Argentina, with an incidence of 17/100,000 children under five years old. The production of Stx1, Stx2 and/or their variants is the primary virulence trait responsible for human disease. Stx2e is typically associated with pig edema disease and has been detected only rarely in STEC of human origin. Some studies have shown that STEC serotypes have developed resistance to antibiotics used in human and veterinary medicine. Humans may obtain antibiotic-resistant E. coli by contact with animals, foods, or environment. The widespread use of antiibiotics creates a reservoir of resistant bacteria and antibiotic resistance genes. Integrons are elements that contain the genetic determinants of the components of a site-specific recombination system that recognize and capture the mobile resistance antibiotic genes cassette. Integrons includes a gene for an integrase (int), an adjacent recombination site (attl), and a strong promoter/s that ensure expression of the integrated cassettes. Aim: The aim of this study was to detect integrons in STEC strains with antibiotic multiresistance. Materials and Methods: Twenty-one STEC strains isolated from pig faeces from ten farms (named A to J) from Argentina were analysed to detect integrons (int1 and int2) by PCR. Results: Out of twenty-one analysed strains, 8 (38 %) carried integrons enconding genes. These strains belonged to 4 different farms. The results of PCR and antibiotic resistance are shown in table 1. Farm Toxin subtype Integrons class Antibiotic resistance A stx2e intl1 S-AMP-TET-CMP-TMP/SMX-DOX-FLOR B stx2e Intl2 S-T-CMP-TMP/SMX-DOX-FLOR B stx2e intl2 S-TET-CMP-TMT/SMX-DOX-FLOR B stx2e intl2 TET-DOX-FLOR-CIP-NAL B stx2e intl2 S-TET-CMP-TMP/SMX-DOX-FLOR C stx2 intl2 S-TET-TMP/SMX-DOX-FLOR C stx2 intl2 S-TET-TMP/SMX-DOX-NAL D stx1 intl2 S-TET-DOX-NAL CIP:Ciprofloxacin-AMP:Ampicillin-TMS:Trimethoprim/Sulfamethaxazole-DOX:Doxycyline-CMP:Choramphenicol-FLOR:Florfenicol-TET:Tetracycline-NAL:Nalidixic acid-S:Streptomycin Table 1: presence of integrons and antibiotic resistance in STEC strains Discussion: The use of antibiotics in animal production systems has determined that bacteria could develop resistance mechanisms originating strains with risk for human if entering a food chain. Integrons are not only associated with resistance to antibiotics, but also with the horizontal transfer of resistance gene. Some studies have informed of the presence of integrons in Enterobacteriaceae and Escherichia coli in samples isolated from pigs, not being registered data in STEC strains so far. Conclusion: In this study integrons class 1 and class 2 were detected in STEC strains isolated from pigs showing that inadequate use of antibiotic as therapeutic agents or growing promoter in veterinary, implies a risk for public health because the acquisition and the horizontal transfer of integrons among strains.