Molecular characterization of extended-spectrum beta-lactamase-producing <i>Enterobacterales</i> isolates collected from blood culture in patients with hematological malignancies
Objective. The objective of the study was to evaluate the prevalance of genes blaTEM, blaSHV and blaCTX-M among extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales isolates collected from blood culture in patients with hematological malignancies. Materials and Methods. The prospective multicenter study included Enterobacterales isolates collected from blood culture in hematological patients from 10 Russian hospitals (2003-2015). The isolates were screened for ESBLs by the phenotypic methods (CLSI 2017). Genes encoding TEM, SHV and CTX-M were detected using polymerase chain reaction (PCR) by specific primers. Results. A total of 499 ESBL-producing Enterobacterales were evaluated. Among them Klebsiella pneumoniae (43.9%) and Escherichia coli (43.3%) predominated. The tested genes were present in combination (79%) and alone (19.6%). Genes of blaCTX-M were most common (82.6%), followed by blaTEM (73.7%) and blaSHV (53.7%). The genes (blaTEM, blaSHV and blaCTX-M) were not detected in 1.4% (n=7) ESBL-producing Enterobacterales. Genes blaCTX-M were in 84.9% K. pneumoniae, 89.8% E. coli and 42.6% Enterobacter cloacae. The blaCTX-M genes belonged to the subtypes blaCTX-M-1 (88.8%), blaCTX-M-9 (14.8%) and blaCTX-M-2 (0.2%). Two different subtypes of blaCTX-M were in 4.1% Enterobacterales isolates. Conclusions. Among the ESBL-producing Enterobacterales isolates blaCTX-M genes were most common (82.6%), the majority of them belonged to the blaCTX-M-1 subtypes (88.8%). Most of Enterobacterales isolates (79%) harbored several types of beta-lactamases genes and 4.1% isolates carried two subtypes of blaCTX-M.