Emergence of <i>bla</i>_TEM, <i>bla</i>_CTX‑M, <i>bla</i>_SHV and <i>bla</i>_OXA genes in multidrug‑resistant <i>Enterobacteriaceae</i> and <i>Acinetobacter baumannii</i> in Saudi Arabia

Abstract

Multidrug-resistant (MDR) patterns due to extended-spectrum β-lactamase (ESBL) production in pathogenic bacteria are now becoming prevalent in hospitals worldwide, posing a public health challenge. The aim of the present study was to determine the antibiotic susceptibility patterns and distribution of the <i>bla</i> _TEM, <i>bla</i> _CTX-M, <i>bla</i> _SHV and <i>bla</i> _OXA ESBL resistance genes in MDR<i>Enterobacteriaceae</i> and <i>Acinetobacter baumannii (A. baumannii)</i>. A cross-sectional study was conducted between September 2017 and August 2018 in the King Abdullah Hospital (Bisha, Saudi Arabia). Bacterial isolates were collected from the clinical samples of patients; these were identified and screened for ESBL production and their antibiotic susceptibility was examined using standard microbiology methods. Multiplex-PCR runs were performed to identify genes encoding ESBL producers. DNA sequencing analysis was used to identify the specific gene variants. Of the 274 isolates, 173 (63.1%) exhibited MDR patterns to different antibiotics. <i>A. baumannii</i> revealed the highest resistance rates for cefuroxime (100%), gentamicin (88%) and amikacin (86%). <i>Klebsiella pneumoniae (K. pneumoniae)</i> isolates had the highest resistance rates for cefuroxime (98%), aztreonam and trimethoprim/sulfamethoxazole (87% for each). <i>Escherichia coli (E. coli)</i> exhibited high resistance rates for trimethoprim/sulfamethoxazole (92%) and cefuroxime (87%). Of the 173 MDR isolates, 78 (45.1%) exhibited ESBL production. Of these, 88.9% (72/78) carried ESBL genes. The most prevalent gene-encoding isolates were <i>bla</i> _TEM (84.7%), followed by <i>bla</i> _CTX-M (33.3%), <i>bla</i> _SHV (2.7%) and <i>bla</i> _OXA-1 (1.4%). A single <i>bla</i> _TEM gene was predominantly produced by <i>K. pneumoniae</i> (60.7%), <i>A. baumanni</i>i (78.9%) and <i>Proteus mirabilis</i> (80%), whereas <i>bla</i> _CTX-M was harbored by <i>E. coli</i> (33.3%). The co-existence of two different genes in a single bacterium was revealed in 22.2% of isolates, commonly between <i>bla</i> _TEM and <i>bla</i> _CTX-M (19.4%). Sequencing analysis revealed that <i>bla</i> _CTX-M-15 and <i>bla</i> _TEM-1 were predominant variants of the <i>bla</i> _CTX-M and <i>bla</i> _TEM genes, respectively. The present study revealed a diversity of ESBL genes in Gram-negative bacterial isolates, with <i>bla</i> _TEM being the most prevalent type. The emergence of various ESBL genes with several co-existing genotypes is alarming, rendering extensive surveillance studies necessary to understand the transmission and epidemiology of such resistant gene-carrying isolates.