Antimicrobial Susceptibility and Molecular Characterization of Clinical Strains of Acinetobacter baumannii in Western Saudi Arabia

Acinetobacter baumannii has emerged as a problematic multidrug-resistant (MDR) pathogen worldwide. The aim of this study was to characterize clinical isolates of A. baumannii from Jeddah, a coastal city in the western region of Saudi Arabia that has an ∼50% expatriate population. In this study, 135 nonrepetitive clinical isolates of A. baumannii were identified through MALDI-TOF and susceptibility was determined with VITEK-2 systems and broth microdilution method. Genotypic characterization of the isolates was performed by using M13 primer typing and polymerase chain reaction screening was performed for carbapenemase genes, insertion sequences, metallo-β-lactamases, and cephalosporinase genes. The isolates were recovered from heterogeneous clinical specimens, and the majority of the cases of A. baumannii infection were acquired in the hospital and predominantly involved patients who were older than 50 years. Total, 58.5% of the isolates were MDR, and 55.6% isolates were resistant to carbapenem antibiotics. Approximately half of the isolates were resistant to ceftazidime, and cefepime among the β-lactam antibiotics and ciprofloxacin from the quinolone group. The bla OXA-23-like gene and IS Aba1 upstream of bla OXA-23-like were detected in 92% of the carbapenem-resistant isolates, while all carbapenem-resistant isolates were found to carry bla OXA-51-like, and bla ADC -type cephalosporinase gene. The bla IMP gene was detected in 84% isolates, and two isolates carried the bla NDM-1 gene. Data demonstrate the coexistence of multiple carbapenem resistance determinants in A. baumannii from the western region of Saudi Arabia.