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Emergence of blaTEM, blaCTX‑M, blaSHV and blaOXA genes in multidrug‑resistant Enterobacteriaceae and Acinetobacter baumannii in Saudi Arabia

Mutasim E. Ibrahim, Tarig Algak, Mohammed Abbas, Bahaeldin K. Elamin

Experimental and Therapeutic Medicine · 2021 · 48 citations · 40 references

Open access

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 blaTEM, blaCTX‑M, blaSHV and blaOXA ESBL resistance genes in MDREnterobacteriaceae and Acinetobacter baumannii (A. baumannii). 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. A. baumannii revealed the highest resistance rates for cefuroxime (100%), gentamicin (88%) and amikacin (86%). Klebsiella pneumoniae (K. pneumoniae) isolates had the highest resistance rates for cefuroxime (98%), aztreonam and trimethoprim/sulfamethoxazole (87% for each). Escherichia coli (E. coli) 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 blaTEM (84.7%), followed by blaCTX‑M (33.3%), blaSHV (2.7%) and blaOXA‑1 (1.4%). A single blaTEM gene was predominantly produced by K. pneumoniae (60.7%), A. baumannii (78.9%) and Proteus mirabilis (80%), whereas blaCTX‑M was harbored by E. coli (33.3%). The co‑existence of two different genes in a single bacterium was revealed in 22.2% of isolates, commonly between blaTEM and blaCTX‑M (19.4%). Sequencing analysis revealed that blaCTX‑M‑15 and blaTEM‑1 were predominant variants of the blaCTX‑M and blaTEM genes, respectively. The present study revealed a diversity of ESBL genes in Gram‑negative bacterial isolates, with blaTEM 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.