Beta-lactamases conferring resistance to third generation cephalosporins in Escherichia coli from pets in Argentina

RUMI MARÍA VALERIA; DI CONZA JOSÉ; GENTILINI ELIDA; GUTKIND GABRIEL

Boston

Congreso; ASM Microbe 2016; 2016

American Society for Microbiology

Introduction: The spread of antimicrobial resistance and the emergence of multidrug-resistant (MDR) pathogens increased in the last decade. The production of extended spectrum β-lactamases (ESBL) is a common cause of resistance to third generation cephalosporins (TGC) and it is considered a concern problem both in human and veterinary medicine. Genes encoding resistance to TGC are usually found in transmissible plasmids and are often associated to other resistance determinants. The aim of this study was to determine the resistance profile of E. coli isolated from pet and to characterize the resistance mechanisms to TGC.Material and Methods: A total of 54 E. coli isolates were collected from clinical samples in dogs and cats. Resistance was determined by the disk diffusion method according to CLSI VET01-A4 and VET01-S2 recommendations. Screening for ESBL and plasmid AmpC β-lactamases (AmpCp) were conducted by double disk synergy tests. ESBL and AmpCp determinants were investigated by PCR. Clonal relatedness was investigated by REP/ERIC-PCR. The main phylogenetic groups in E. coli isolates were assessed by PCR according to Clermont et al.Results: Of the 54 strains, 31 (57%) were resistant to AMP and 20/31 (64%) isolates were also resistant to TGC. No carbapenem resistance was observed. Seven isolates were characterized as ESBL producers, while 13/20 as AmpC carriers. Most of these isolates belong to the phylogenetic group D (14/20) and to a lesser extent B2 (4/20) and B1 (2/20).In ESBL-producing isolates were detected the blaCTX-M-2 group (4), blaCTX-M-1 group (2) and blaCTX-M-9 group (1) genes. Thirteen AmpC-producing strains were positive for blaCMY-like genes and all of them were clustered in a single electropherotype.A significant proportion of AMP resistant strains were also resistant to quinolones [NA: 80.6% (25), CIP: 67.7% (21) and LEV: 61.3% (19)] and TMS [64.5% (20)]. Finally, 58.1% (18) isolates showed a profile of MDR.Conclusions: AmpCp constitute the main TGC resistance mechanism in E. coli isolated from pets in our region. Cefotaximases belonging to three genetically different groups were also found being CTX-M-2 group the commonest amongst E. coli. It is important to highlight the high level of resistance to different families of antimicrobial (commonly used in pets) associated with AMP resistance.