CARBAPENEM resistant Acinetobacter baumannii (CRAB) now leads the WHO's critical priority list of nosocomial pathogens worldwide. Carbapenem Hydrolysing Class D β-lactamases (CHDL) -“OXA-type β-lactamases"- is of great concern. In this study, bacterial isolates recovered from different clinical samples collected from three different hospitals in Cairo from October 2014 to May 2015. The isolates were identified using Vitek 2 and partial 16S rRNA gene sequencing. Acinetobacter baumannii isolates represented 16.1% of the total Gram negative isolates. Susptibility test revealed that 88.9% were CRAB, 65% of imipenem resistant isolates and 57.5% of meropenem resistant isolates had chromosomal mediated resistance. Forty CRAB isolates were identified and screened for blaOXA-23-like, blaOXA-24-like, blaOXA-51-like and blaOXA-58-like genes.
The most prevalent gene was blaOXA-51-like which was detected in 95% of the isolates followed by blaOXA-23-like and blaOXA-24-like in 90% of the isolates. However, blaOXA-58-like was not detected in any of the isolates. The absence of blaOXA-51-like in 5% of CRAB isolates proving the inconvenience of using blaOXA-51-like as a species specific region for identification of CRAB by PCR. In addition, all isolates harbored more than one OXA gene, 75% were blaOXA-23/OXA-24/OXA-51 carriers while 25% harbored two OXA genes. This study revealed the emergence of blaOXA-24-like gene in CRAB for the first time in Egyptian hospitals.