Detection and characterization of carbapenemase-producing Enterobacteriaceae in cancer patients: first Sri Lankan report of blaVIM in Enterobacteriaceae

Abstract

Background: Carbapenem-resistant Enterobacteriaceae (CRE) are an important cause of infections in cancer patients. The proportion of carbapenem resistance and the types of carbapenemase-encoding genes in Enterobacteriaceae isolated from cancer patients were determined in this study.

Methodology: Bacteria isolated from adult, in-ward cancer patients with lower respiratory tract infections (LRTI), skin and soft tissue infections (SSTI), or urinary tract infections (UTI) were included in the study. Enterobacteriaceae were identified up to the species level by API^® 20E test kits. Carbapenem resistance was defined as non-susceptibility to either imipenem or meropenem in the disc diffusion test. Major carbapenemase-encoding genes (blaKPC, blaNDM, blaOXA-48, blaIMP, and blaVIM) were detected by the GeneXpert^® Carba-R real-time PCR instrument.

Results: Enterobacteriaceae comprised 57% (94/165) of the bacterial isolates. Carbapenem resistance among Enterobacteriaceae was 46.8% (44/94). Klebsiella pneumoniae (65.9%, 29/44) was the predominant CRE isolate followed by Escherichia coli (25%, 11/44). The majority of CRE isolates (72.7%, 32/44) had a meropenem MIC of ≥ 32 µg/mL. Carbapenemase-encoding genes were identified in 43 of the 44 CRE isolates. blaNDM was the most prevalent carbapenemase-encoding gene and was detected in 67.4% (29/43) of Enterobacteriaceae isolates. No isolate was positive for blaIMP_. Sixteen (37.2%) isolates co-harbored more than one carbapenemase-encoding gene. Two Enterobacteriaceae isolates were found to harbor blaVIM.

Conclusions: Nearly all CRE isolated in this study were carbapenemase producers. This study documented the emergence of blaVIM harboring Enterobacteriaceae for the first time in Sri Lanka.