Antimicrobial resistance and molecular characterization of ESBL-producing Enterobacterales from Parirenyatwa Hospital wastewater in Harare

Abstract

Background The hospital environment is a proven hotspot for antimicrobial-resistant bacteria, which may be released through hospital wastewater into the environment and municipal wastewater. The aim of this study was to monitor the occurrence of and perform molecular characterization of MDR ESBL Enterobacterales isolated from Parirenyatwa Hospital wastewater, Harare, Zimbabwe.

Methods This was a cross-sectional study. Enterobacterales from sixty-four 500 mL samples of hospital wastewater from three drainage sites of Parirenyatwa Hospital were isolated. A modified double disc synergy test was used to confirm ESBL Enterobacterales before genotyping with multiplex PCR.

Results The majority of isolates came from the main hospital drainage site. All the isolated Enterobacterales showed MDR. Of the 33 Enterobacterales isolated from hospital wastewater, 8 (24%) were ESBL-producing: 5/8 (63%) Escherichia coli, 2/8 (25%) Klebsiella pneumoniae, and 1/8 (12%) Citrobacter freundii. The multiple antibiotic resistance index (MARI) obtained from the ESBL-producing Enterobacterales isolates ranged from 0.5 to 0.75. Seven (87.5%) isolates harboured the blaCTX-M gene and five (62.5%) isolates had the blaTEM gene, with four (50%) isolates containing both genes. Three isolates contained the blaCTX-M gene only and one contained only blaTEM. The blaSHV gene was not detected. Conclusions MDR ESBL-producing Enterobacterales were identified from Parirenyatwa Hospital wastewater. The MARI greater than 0.2 indicated that these isolates were from a high-risk source of contamination.