Microb Drug Resist. 2021 Jul 14. doi: 10.1089/mdr.2020.0530. Online ahead of print.
Infectious complications caused by multidrug-resistant bacteria are a serious clinical and therapeutic problem. Our study aimed to analyze the genetic characteristics of extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) that cause multidrug-resistant infections in patients with solid tumors. Identification of ESBL-encoding genes was performed by polymerase chain reaction (PCR) and sequencing. The clonal relationship of the isolates was evaluated by pulsed-field gel electrophoresis. Multilocus sequence typing (MLST) was carried out for selected Escherichia coli and Klebsiella pneumoniae isolates. All E. coli strains were classified into phylogenetic groups using the PCR-based approach. There were 735 patients with clinical symptoms of infections tested, of which 44 (6.0%) were positive for ESBL-E on genotypic testing. The most frequent organism was E. coli (n = 24, 54.5%), followed by K. pneumoniae (n = 13, 29.5%), Proteus mirabilis (n = 3, 6.8%), Enterobacter cloacae cplx (n = 2, 4.5%), and Klebsiella oxytoca (n = 2, 4.5%). Overall, 31 (70.5%) of the ESBL-E isolates carried only blaCTX-M-1-like genes, and the genes were found to be blaCTX-M-15 (n = 30, 68.2%) or blaCTX-M-3 (n = 1, 2.3%). Eleven strains (25%) had blaCTX-M-9-like genes, mostly blaCTX-M-27 (n = 10, 22.7%) and unique blaCTX-M-65 (n = 1, 2.3%). One isolate possessed both blaCTX-M-15 and blaCTX-M-27 genes, and another one produced TEM-12 ESBL. MLST analysis revealed E. coli sequence type (ST) 131 and ST361, and K. pneumoniae ST16, ST307, and ST437. Among E. coli isolates, the B2 phylogenetic group was predominant. Most of the strains showed resistance to third-generation cephalosporins and fluoroquinolones, and susceptibility to aminoglycosides and carbapenems. Patients with solid cancer and ESBL-E infections require special management since they are a population with a high threat of antibiotic-resistant infections. Carbapenems and aminoglycosides remain active antibiotics against these infections.