First Report of DHA-1 Producing Enterobacter cloacae Complex Isolate in Bulgaria

Abstract

The aim of the present study was to reveal the characteristics of an Enterobacter cloacae complex isolate producing DHA-1 AmpC enzyme recovered from a patient hospitalized in St Marina Hospital, Varna.Materials and methods: Susceptibility testing, conjugation experiments, isoelectric focusing, PCR and sequencing were carrying out.Results: Of 176 Enterobacter spp. isolates only one isolate was positive for blaDHA. The sequencing revealed the presence of blaDHA-1 and blaCTX-M-3. The antimicrobial susceptibility testing showed higher resistance rates to almost all beta-lactams (ceftazidime, cefotaxime, cefepime, amoxicillinclavulanic acid, piperacillin/tazobactam), tobramycin, gentamycin, trimethoprim/sulphomethoxazole and quinolones (ciprofloxacin and levofloxacin). The isolate was susceptible to imipenem, meropenem and amikacin. The isoelectric focusing showed a band at pI 5.4 without ceftazidime and cefotaxime activity; a band at pI 7.8 with cefoxitin activity and another - with pI 8.4 with cefotaxime activity. Conjugation experiments were successful only for blaCTX-M-3 carrying determinants. Conclusions: To the best of our knowledge this is the first report of DHA-1 producing isolate in Bulgaria. The emergence of DHA-1 producing E. cloacae complex demonstrates the possibility for further dissemination of the gene encoding this enzyme. Infectious control measures are needed for the prevention of this phenomenon.

Keywords

• Bulgaria
• AmpC
• DHA-1
• <i>Enterobacter cloacae</i>