ESBL-producing E. coli and K. pneumoniae in Al-Ahsa, Saudi Arabia: antibiotic susceptibility and prevalence of blaSHV and blaTEM.

Introduction Antibiotic resistance is a serious problem in clinical medicine [1]. Production of inactivating enzymes is one of the most common mechanisms by which different microorganisms can acquire resistance against several antimicrobial agents, especially βlactams. Extended spectrum β-lactamases (ESBLs) mediate resistance against different broad spectrum cephalosporins and monobactams [2]. There are different types of ESBLs, namely TEM, SHV, and CTX, but most of these enzymes are mutants of TEM1, TEM2, and SHV1 that are caused by point mutation of the original encoding genes [3]. These genes are carried on plasmids that may harbor other genes encoding resistance against different antimicrobial agents. These plasmids are easily transferred among different bacterial species, leading to widespread of multi-drug resistant bacteria [4]. E. coli and Klebsiella spp. are the most common producers of ESBLs and are responsible for many hospitaland community-acquired infections. Due to the extensive use of cephalosporins for treatment of different bacterial infections, the prevalence of ESBLproducing bacteria became significantly high worldwide [5]. In Saudi Arabia, limited data are available on the susceptibility patterns of ESBL-producing bacteria. The aim of the current study was to evaluate the susceptibility of ESBL-producing K. pneumoniae and E. coli clinical isolates to different antimicrobial agents and to estimate the prevalence of blaSHV and blaTEM in the tested isolates.