engleski

Co-production of CTX-M-15 and CMY-2 in animal Escherichia coli isolate from Croatia

Escherichia coli resistant to expanded-spectrum cephalosporins was isolated from a wound swab of a dog admitted at Veterinary clinic in Zagreb. Antimicrobial susceptibility to a wide range of antibiotics was determined by broth microdilution method according to CLSI. Double-disk synergy test (DDST) and combined disk test with addition of clavulanic acid and PBA (3-aminophenylboronic acid) were performed as described previously. Transferability of ceftazidime resistance was tested by conjugation. Transconjugant was selected on plates containing cefotaxime (1 mg/L) and rifampicin (256 mg/L). The frequency of transconjugation was expressed relatively to the number of donor cells. Isoelectric focusing (IEF) was performed according to Matthew et al. The presence of genes broad and extended-spectrum beta-lactamases (blaSHV, blaTEM, blaCTX-M and blaPER-1) and plasmid-mediated ampC genes in clinical isolate and transconjugant strain was examined as described previously. The isolate was resistant to amoxicillin alone and combined with clavulanate, piperacillin alone and with tazobactam, cefpodoxime, cefuroxime, cefazoline, ceftazidime, cefotaxime, ceftriaxone, cefoxitin, cefoperazone, cefovecin, ciprofloxacin, enrofloxacin and moxifloxacin, intermediate susceptible to cefepime and susceptible to imipenem, meropenem, gentamicin, amikacin, chloramphenicol, tetracycline and trimethoprim/sulphamethoxazole. MICs of the selected antimicrobials are shown in Table 1. DDST was negative but combined disk test with clavulanic acid and PBA was positive indicating the production of an ESBL and plasmid-mediated AmpC, respectively. Resistance to ceftazidime was transferred to E. coli recipient strain with the frequency of 10-6. IEF revealed two bands with the pI of 8.9 and >9 corresponding to CTX-M-15 and AmpC. PCR and sequencing of bla genes identified CTX-M-15 and CMY-2. ISEcp1 was not found upstream or downstream of the blaCTX-M gene. Plasmid extractions were positive for blaCTX-M and blaCMY genes. PCR for qnr genes was negative. The strain was assigned to FIB repA PBRT.To our knowledge this is the first report of co-production of CTX- M-15 and CMY-2 β-lactamase in canine E. coli in Europe and the first report of an ESBL and plasmid-mediated AmpC in animal isolate from Croatia.

CTX-M-15; CMY-2; Escherichia coli; dog

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