This study was conducted to evaluate the combined disc test and the double disc synergy test for
MBL detection among imipenem sensitive and resistant A. baumanni strains, to study the co-resistance to other
classes of antibiotics and to determine the prevalence of some antibiotic resistance determinants (bla OXA 51 like
gene and class I integron) among these isolates. We isolated a total of 51 A. baumannii strains. The antibiotic
sensitivity pattern was determined by Kirby Bauer disc diffusion method. For imipenem, the minimum
inhibitory concentrations (MICs) were determined using the Epsilometer (E test). The isolates were tested for
the presence of MBLs by the combined disc test (CDT) and the double disc synergy test (DDST). For all
isolates, PCR was performed for the detection of the bla OXA-51-like and Class I integrase genes. The highest rates
of resistance were against ciprofloxacin (64.7%), amoxacillin clavulanic acid (58.8%), amikacin (58.8%),
ceftriaxone (56.9%) and chloramphenicol (52.9%). Lower rates of resistance were to imipenem (31.4%) and
tetracyclines (25.5%). MBLs were detected in both imipenem sensitive and resistant A. baumannii isolates. The
CDT had a sensitivity ranging from 92% to 100% , while the DDST had a sensitivity ranging from 86.2% to
100%. The bla OXA-51 like gene was detected in 96.1% and Class I integrase gene was detected in (72.5%) of
A. baumannii strains . The later conferred significantly higher resistance rates to various antibiotics.