Phenotypic and molecular epidemiology of Acinetobacter baumannii strains isolated in Rabta Hospital, Tunisia

Acinetobacter baumannii (A. baumannii) is often implicated in hospital outbreaks in Tunisia. It's a significant opportunistic pathogen that is usually associated with serious underlying diseases such as pneumoniae, meningitis and urinary tract infections. The aim of this prospective study was to evaluate the global state of its endemicity and the antibiotic resistance evolution. The possibility of nosocomial transmission of one or more epidemic strain(s) was investigated by means of 3 methods: biotyping, antibiotyping and Random Amplified Polymorphic DNA analysis (RAPD). MIC for imipenem by Ellipsometer-test strip (E-TEST). The presence of metallo-beta-lactamases (MBL) was detected according to the double synergy test of EDTA and imipenem disks. A. baumannii strains were mainly localized in intensive care (52.2%) and surgery units (23.6%). Among 224 strains that were studied, 4 biotypes were delineated with a predominance of biotype1. Resistance to beta-lactams was mostly associated with the production of cephalosporinases and penicilinases (84.3%). 45% of strains were resistant to imipenem which were associated with MBL production. RAPD gave 5 genomic groups. This study demonstrates the epidemic behaviour airborne spread of A. baumannii in hospital wards. The multiresistance was often responsible for failure of antibiotics therapy. The prevention of nosocomial infection and severe hygiene controls must be performed.