Multi-Drug Resistant Acinetobacter-Derived Cephalosporinase and OXAsetC Genes in Clinical Specimens of Acinetobacter spp. Isolated From Teaching Hospital

Hospital-acquired infections caused by multi-drug resistant Acinetobacter spp. are often extremely difficult to treatand this has proved to be a serious problem worldwide.

The aim of this study was to determine the incidence rates and distribution patterns of multi-drug resistant (MDR) Acinetobacter spp. strains and the occurrence of Acinetobacter-derived cephalosporinase (ADC-7) and OXA-type carbapenemases (OXAsetC genes) in clinical specimens in the Beheshti Teaching Hospital in Kashan, Iran.

This descriptive study was carried out on sixty isolates of Acinetobacter spp. and clinical samples collected from patients. The level of antibiotic resistance was determined by the disc diffusion method and the results were interpreted according to the Clinical and Laboratory Standards Institute (CLSI) procedure. Polymerase chain reaction (PCR) amplification of the genetic determinants of resistance was also determined.

The resistance rates were; amikacin (80%), tobramycin (68.3%), ceftazidime (60%), ciprofloxacin (55%), piperacillin/tazobactam (51.7%), doxycycline (50%), SXT/TMP (sulfamethoxazole / trimethoprim)(48.3%), levofloxacin (43.3%), gentamicin (40%), imipenem (25%), and sulbactam/ampicillin (20%). The frequency of MDR Acinetobacter spp. strains isolated was found to be 56.7%. These isolates were most sensitive to imipenem followed by ampicillin/sulbactam and gentamicin. The prevalence of genes for ADC-7 and OXAsetC in the Acinetobacter spp. was; 34 (56.7%) and 32 (53.3%), respectively. The positive percentages of MDR isolates for ADC-7 were 82.4% and for OXAsetC they were 73.5%.

Our phenotypic analysis demonstrated that Acinetobacter spp. isolates were resistant to most clinically significant antibiotic classes. This is the first report concerning Acinetobacter-derived cephalosporinase, blaADC, enzymes in Acinetobacter spp. isolates from Iran.