Antibiotic resistance genes in class 1 integron-positive STEC strains isolated from cattle, pigs and food

COLELLO, ROCÍO; KRÜGER ALEJANDRA; ROSSEN, JWA; FRIEDRICH, AW; ETCHEVERRÍA, ANALÍA I.; PADOLA, NORA L.

Boston

Simposio; 9th International Symposium On ShigaToxin (Verocytotoxin) Producing Escherichia coli Infections (VTEC 2015); 2015

VTEC 2015

IntroductionThe emergence of antimicrobial resistant bacteria is a problem of public health.Antimicrobial resistance also becomes more common in STEC. Integron is one of the elements that can facilitate this emergence of antibiotic resistance and its dissemination among STEC. Furthermore, integron-positive strains were shown to be more resistant to antibiotics compared with integron-negative strains.The aims of this study were to investigate the presence of intl1 in STEC strains isolatedfrom different origins and to identify antibiotic resistance genes in integron-positive isolates.MethodsA collection of 542 STEC isolates recovered from cattle, pigs and food was screened forthe presence of intl1 by PCR. Integron-positive isolates were evaluated for antimicrobial resistance with a commercial oligonucleotide microarray for E. coli.Results and Discussion Seven STEC isolates were positive for intl1, of which four had been isolated from dairy calves (O26:H11, O103:H2, O103:H18; ONT:H18), two from pigs (O8:H32; ONT:H32), and one from a chicken hamburger (O130:H11). Most of the isolates carried four or more antimicrobial resistance genes. All isolates were positive for sulfonamide resistance genes(sul1 alone or in combination with sul2) and for tetracycline resistance genes (tetA and/or tetB). All except one (86%) also had genes associated with aminoglycoside resistance (aadA alone or in combination with strA-strE), β-lactamases resistance (blaTEM) and chloramphenicol resistance (floR or catA1). In addition, four isolates presented the drfA1 gene encoding resistance to trimetropin.ImplicationsMulti-resistant STEC present in animals represents a risk for animal and human health, as they can transfer their resistance elements to other bacteria. The use of inappropriate antimicrobial treatment should be reduced in food-producing animals to limit the dissemination of bacteria resistant to antimicrobial agents