Genetic characterization of extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae collected from healthy turkeys.

INTRODUCTION

The spread of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-En) from turkeys via food chain and environmental contamination is a human health concern.

METHODOLOGY: Seventy fecal samples were collected from healthy turkeys and streaked on Tryptone Bile X-Glucoronide (TBX) supplemented with 2 mg/L of cefotaxime and on TBX supplemented with 1 mg/L of imipenem. ESBL production and susceptibility to antibiotics were studied according to CLSI guidelines. Genes encoding for ESBLs (SHV, CTX-M, TEM), carbapenemases (IMI, KPC, OXA48, NDM), tetracyclines (tetA, tetB, tetC), colistin (mcr-1 to mcr-5), sulphonamides (sul1, sul2), quinolones (qnr A/B/S, aac(6')-Ib-cr, qepA) resistance, and class 1 and 2 integrons were determined by PCR.

RESULTS

ESBL-En [n = 45 (64.3%): 41 E. coli and 4 K. pneumoniae] isolates were collected. In E. coli, blaCTX-M-1, blaCTX-M-14, blaCTX-M-15, blaCTX-M-27, and blaCTX-M-55 genes were identified in 23, 2, 5, 16, and one isolate, respectively. The blaCTX-M-15 gene was detected in two K. pneumoniae isolates, while each of blaCTX-M-1 and blaCTX-M-27 were detected in one isolate. Resistances to tetracyclines, sulfonamides, fluoroquinolones, and colistin were encoded by tetA (n = 21)/tetB (n = 1), sul1 (n = 8)/sul2 (n = 13), aac(6')-Ib-cr (n = 6), and mcr-1 (n = 2)/mcr-2 (n = 1) genes, respectively. Integrons of class 1 and class 2 were detected in 15 and six isolates, respectively. Five E. coli isolates belonged to the pandemic ST131 clone.

CONCLUSIONS

Our findings highlight the high occurrence of MDR/ESBL-En and demonstrate the possible transfer of these strains to humans via the food chain or direct contact.