PHENOTYPIC AND GENOTYPIC INVESTIGATION OF OXA23 AND OXA51 CARBAPENEMASES PRODUCING ACINETOBACTER BAUMANNII IN TRIPOLI HOSPITALS

Abstract

Acinetobacter baumannii is an opportunistic pathogen causing various nosocomial infections. The aim of this study was to characterize the molecular support of carbapenem-resistant A. baumannii clinical isolates recovered from four hospitals in Tripoli, Libya. Bacterial isolates were identified and antibiotic susceptibility testing was per-formed using automated system. Carbapenem resistance determinants were studied phenotypically using two dif-ferent techniques: E-test; chromogenic culture media. Polymerase chain reaction (PCR) amplification was used to determine the presence of bla OXA23 and blaOXA51 genes among isolates. A total of 119 isolates were characterized, overall the resistance prevalence was extremely high for aminoglycosides (79-96.6%), fluoroquinolones (94-96%), cephalosporins (96.6-100%) and carbapenemes (93.2-100%), all isolates were susceptible to colistin. In addition, 97.5% of isolates were identified as multidrug resistance (MDR). Varying degree of phenotypic detection of car-bapenemes was determined; highest levels of carbapenemes were detected using chromogenic media (76.5%) com-pared with E-test (45.4 %). The carbapenem resistance-encoding genes detected were blaOXA23 (84%) and blaOXA51 (73.1%); the highest occurrence of blaOXA23 was demonstrated in Tripoli’s Central Hospital (5/5; 100%) then in Tripoli Medical Center (44/51; 86.27%). The co-occurrence of these genes was demonstrated in (75/119; 63%) showing dissemination of carbapenemes resistance MDR A. baumannii in hospitals. This study shows that the high prevalence of OXA-23 contribute to antibiotic resistance in Libyan hospitals and represents the high incidence of the association of these two carbapenemases in an autochthonous MDR A. baumannii isolated from patients in Libya, indicating that there is a longstanding infection control problem in these hospitals.