CTX-M, TEM, and SHV Genes in Escherichia coli, Klebsiella pneumoniae, and Enterobacter spp Isolated from Hematologic Cancer Patients with Bacteremia in Uganda

Abstract

Purpose We determined the phenotypic resistance to third-generation cephalosporins, phenotypic extended spectrum beta-lactamase (ESBL) prevalence, and genotypic prevalence of ESBL-encoding genes bla CTX-M , bla TEM , and bla SHV in Enterobacteriaceae isolated from hematologic cancer patients with febrile neutropenia and bacteremia at the Uganda Cancer Institute (UCI). Patients and Methods Blood cultures from hematologic cancer patients with febrile neutropenia were processed in BACTEC 9120. E. coli, K. pneumoniae, and Enterobacter spp . isolates were identified using conventional biochemical methods. Antimicrobial susceptibility tests, phenotypic ESBL characterization, and genotypic characterization of the ESBL-encoding genes bla CTX-M , bla TEM , and bla SHV were determined for pure isolates of E. coli, K. pneumoniae, and Enterobacter spp . Results Two hundred and two patients were included in the study. Median age of patients was 19 years (IQR: 10–30 years). Majority (N=119, 59%) were male patients. Sixty (30%) of the participants had at least one febrile episode due to Enterobacteriaceae. Eighty-three organisms were isolated with E. coli being predominant (45, 54%). Seventy-nine (95%) Enterobacteriaceae were multidrug resistant. The ESBL phenotype was detected in 54/73 (74%) of Enterobacteriaceae that were resistant to third-generation cephalosporins. A higher proportion of Enterobacteriaceae with ESBL-positive phenotype were resistant to piperacillin-tazobactam (p=0.024), gentamicin (p=0.000), ciprofloxacin (p=0.000), and cotrimoxazole (p=0.000) compared to Enterobacteriaceae, which were sensitive to third-generation cephalosporins. The organisms were more susceptible to carbapenems and chloramphenicol than resistant. ESBL-encoding genes ( bla CTX-M , bla TEM , and bla SHV ) were detected in 55 (75%) of the 73 Enterobacteriaceae that were resistant to third-generation cephalosporins. Bla CTX-M , was the most common ESBL-encoding gene identified with 50 (91%). Conclusion ESBL-producing Enterobacteriaceae are a predominant cause of bacteremia in hematologic cancer patients at UCI. The most common ESBL-encoding gene identified in the ESBL-PE was bla CTX-M . Resistance to imipenem and meropenem was low.