Extended-Spectrum<i>β</i>-Lactamases among Enterobacteriaceae Isolated from Urinary Tract Infections in Gaza Strip, Palestine

Abstract

Background . Extended-spectrum β -lactamase-producing organisms causing urinary tract infections are increasing in incidence and pose a major impendence to health-care facility, having limited therapeutic options. This study aimed to assess the prevalence of ESBLs in Enterobacteriaceae isolates causing urinary tract infections in Gaza strip, Palestine, and to characterize β -lactamase types and associated resistance genes. Methods . Eighty-five Enterobacteriaceae isolates were recovered from urinary tract infections within three months in Gaza Strip hospitals. The characterization of β -lactamase genes and the genetic environments of CTX-M, the identification of associated resistance genes, and the presence and characterization of integrons were tested by PCR and sequencing. Results . The occurrence rate of ESBL among tested isolates was 30 (35.3%), and among ESBL-positive isolates, bla CTX-M was the highest followed by bla TEM . ESBL-CTX-M-1 group was confirmed in 93.3%, and the remaining carried CTX-M-9 group. CTX-M-15, CTX-M-3, CTX-M-1, CTX-M-14, CTX-M-27, and CTX-M-37 enzymes were demonstrated among the isolates with the majority (73%) being CTX-M-15. IS Ecp-1 was demonstrated in 27 (90%, high incidence) of ESBL isolates. Class 1 integrons have been detected in higher rates (53.3%) in ESBL-positive isolates in comparison with non-ESBL isolates (6, 33.3%). Cassettes of integron-1 contain ( aadA1 , aadA2 , aadA5 , dfrA5 , dfrA7 , dfrA12 , and dfrA17 ) genes. The aac(6′)-Ib-cr gene was demonstrated in 36.7% of ESBL-positive isolates. Conclusions . This study indicates that bla CTX-M-15 was the most prevalent β -lactamase in this region. Our study demonstrates for the first time in Palestine the identification of bla CTX-M-15 in P. rettgeri and S. liquefaciens , also bla CTX-M-37 in E. cloacae. The coexpression of multiple β -lactamase genes with aac(6′)-Ib-cr and qnr in the presence of IS Ecp-1 and integrons in individual strains will increase the dissemination of highly resistant strains. ESBL producers were more resistant than non-ESBLs producers for almost all tested antibiotics.