Huge Diversity of TEM and SHV β-Lactamases Types Among CTX-M-15-Producing Enterobacteriaceae Species in Tunisia.

Abstract

The aim of our study was to characterize third-generation cephalosporin (3GC)-resistant Enterobacteriaceae isolated over two different periods from patients hospitalized in the Military Hospital of Tunis with special focus to class A β-lactamases. This study included 180 Enterobacteriaceae resistant to 3GC isolated from samples of patients hospitalized in various services of the hospital. Enterobacteriaceae species detected by the Vitek 2 Compact® (BioMérieux®) automated system showed the dominance of Klebsiella pneumoniae followed by Escherichia coli during both periods. These strains were mainly isolated from urine samples and rectal swabs of patients hospitalized mostly in neonatology service and intensive care unit. The molecular research of genes encoding CTX-M, TEM, and SHV β-lactamase types showed a high rate of strains producing CTX-M β-lactamases, all of them harbored the blaCTX-M-15 gene. However, a huge diversity of SHV and TEM β-lactamases types was discovered in our study. In fact, nine various subvariants of blaSHV gene (blaSHV-1, blaSHV-11, blaSHV-12, blaSHV-27, blaSHV-28, blaSHV-31, blaSHV-38, blaSHV-79, and blaSHV-81) and eight subvariants of blaTEM gene (blaTEM-70, blaTEM-71, blaTEM-76, blaTEM-77, blaTEM-79, blaTEM-105, blaTEM-148, and blaTEM-186) were identified among our Enterobacteriaceae species during both periods. All subvariants of blaTEM gene and some subvariants of blaSHV gene (blaSHV-31, blaSHV-38, blaSHV-79, and blaSHV-81) have not been previously detected in our country.