Antimicrobial Susceptibility and Molecular Characterization of Clinical Strains of <i>Acinetobacter baumannii</i> in Western Saudi Arabia

Abstract

<i>Acinetobacter baumannii</i> has emerged as a problematic multidrug-resistant (MDR) pathogen worldwide. The aim of this study was to characterize clinical isolates of <i>A. baumannii</i> 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 <i>A. baumannii</i> 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 <i>A. baumannii</i> 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 <i>bla</i>_OXA-23-like gene and IS<i>Aba1</i> upstream of <i>bla</i>_OXA-23-like were detected in 92% of the carbapenem-resistant isolates, while all carbapenem-resistant isolates were found to carry <i>bla</i>_OXA-51-like, and <i>bla</i>_ADC-type cephalosporinase gene. The <i>bla</i>_IMP gene was detected in 84% isolates, and two isolates carried the <i>bla</i>_NDM-1 gene. Data demonstrate the coexistence of multiple carbapenem resistance determinants in <i>A. baumannii</i> from the western region of Saudi Arabia.