Molecular characterization of extended-spectrum beta-lactamase-producing <i>Enterobacterales</i> isolates collected from blood culture in patients with hematological malignancies
<b>Objective</b>. The objective of the study was to evaluate the prevalance of genes blaTEM, blaSHV and blaCTX-M among extended-spectrum beta-lactamase (ESBL)-producing <i>Enterobacterales</i> isolates collected from blood culture in patients with hematological malignancies. <b>Materials and Methods</b>. The prospective multicenter study included <i>Enterobacterales</i> 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. <b>Results</b>. A total of 499 ESBL-producing Enterobacterales were evaluated. Among them Klebsiella pneumoniae (43.9%) and <i>Escherichia coli</i> (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 <i>Enterobacterales</i>. Genes blaCTX-M were in 84.9% <i>K. pneumoniae</i>, 89.8% <i>E. coli</i> and 42.6% <i>Enterobacter cloacae</i>. 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. <b>Conclusions</b>. Among the ESBL-producing <i>Enterobacterales</i> isolates blaCTX-M genes were most common (82.6%), the majority of them belonged to the blaCTX-M-1 subtypes (88.8%). Most of <i>Enterobacterales isolates</i> (79%) harbored several types of beta-lactamases genes and 4.1% isolates carried two subtypes of blaCTX-M.