Emergence of <i>bla</i><sub>TEM</sub>, <i>bla</i><sub>CTX‑M</sub>, <i>bla</i><sub>SHV</sub> and <i>bla</i><sub>OXA</sub> genes in multidrug‑resistant <i>Enterobacteriaceae</i> and <i>Acinetobacter baumannii</i> in Saudi Arabia
Mutasim E. Ibrahim, Tarig Algak, Mohammed Abbas, Bahaeldin K. Elamin
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 <em>bla</em><sub>TEM</sub>, <em>bla</em><sub>CTX‑M</sub>, <em>bla</em><sub>SHV</sub> and <em>bla</em><sub>OXA</sub> ESBL resistance genes in MDR<em>Enterobacteriaceae</em> and <em>Acinetobacter baumannii (A. baumannii</em>). 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. <em>A. baumannii</em> revealed the highest resistance rates for cefuroxime (100%), gentamicin (88%) and amikacin (86%). <em>Klebsiella pneumoniae (K. pneumoniae</em>) isolates had the highest resistance rates for cefuroxime (98%), aztreonam and trimethoprim/sulfamethoxazole (87% for each). <em>Escherichia coli (E. coli)</em> 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 <em>bla</em><sub>TEM</sub> (84.7%), followed by <em>bla</em><sub>CTX‑M</sub> (33.3%),<em> bla</em><sub>SHV</sub> (2.7%) and <em>bla</em><sub>OXA‑1</sub> (1.4%). A single <em>bla</em><sub>TEM</sub> gene was predominantly produced by <em>K. pneumoniae</em> (60.7%), <em>A. baumannii</em> (78.9%) and <em>Proteus mirabilis</em> (80%), whereas <em>bla</em><sub>CTX‑M</sub> was harbored by <em>E. coli</em> (33.3%). The co‑existence of two different genes in a single bacterium was revealed in 22.2% of isolates, commonly between <em>bla</em><sub>TEM</sub> and <em>bla</em><sub>CTX‑M</sub> (19.4%). Sequencing analysis revealed that <em>bla</em><sub>CTX‑M‑15</sub> and <em>bla</em><sub>TEM‑1</sub> were predominant variants of the <em>bla</em><sub>CTX‑M</sub> and <em>bla</em><sub>TEM</sub> genes, respectively. The present study revealed a diversity of ESBL genes in Gram‑negative bacterial isolates, with <em>bla</em><sub>TEM</sub> 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.