Characterization of Carbapenem-resistant Acinetobacter baumannii Isolated from Intensive Care Unit, Egypt

Background: Carbapenem resistant Acinetobacter baumannii has emerged worldwide in the hospitals especially in Intensive care units (ICU). Objectives: to detect carbapenems resistance and characterization of some carbapenem resistant genes among acinetobacter baumannii isolated from patients in ICU unit in Giza Chest Hospital, Egypt. Methodology: This study was designed to detect the prevalence of carbapenem resistance among A. baumannii species isolated from patients having nosocomial infections in Egypt. Antimicrobial susceptibility pattern was done. Identification and susceptibility testing was confirmed by VITEK® 2 Compact system. Isolates were further tested by the modified Hodge test (MHT) to detect carbapenem resistance. PCR was used to detect some carbapenem resistant genes. Results: A. baumanniii represent 22(16.1%) of total isolates causing nosocomial infection in ICU. A. baumanniii were resistant to sulfamethoxazole-trimethoprim, amoxicillin/ clavulanicacid, ciprofloxacin, piperacillin/tazobactamandceftazidime 100%, 90.9%, 90.9, 90.9%, 81.8% and 81.8% respectively. Imipenem resistance was 14/22(63.6%). Colistin showed the highest activity against A. baumannii isolates; the resistance rate was 4.5%. Total number of carbapenem-resistant gram-negative isolates was (38.9%). Regarding A. baumanniii 14 out of 22(63.6%) were carbapenem resistant as detected by the antibiotic susceptibility test. According to this antibiogram result, 14 A. baumanniii isolates screened for carbapenemase production by MHT, carbapenemase activity was detected among 10(71.4%) of carbapenem-resistant A. baumanniii isolates. Molecular detection of carbapenem resistant genes showed that BlaOXA-23 was the common detected gene 6/14 (42.8%). BlaOXA-58 was detected among 1/14(7.1%) of isolates. Conclusion: A. baumannii with multidrug resistance become a problem especially in immunocompromised patient. Resistance among A. baumannii caused by several mechanisms. OXA-23-like carbapenemase-producing strains have been among the most detected patterns.