Occurrence of environmental carbapenem-resistant Klebsiella species isolates at Mulago National Referral Hospital, Uganda

Carbapenem-resistant Klebsiella species have emerged as a major global public health threat, and hospital sewage acts as a crucial environmental reservoir for resistant strains that are known to cause infections associated with high rates of treatment failure and mortality. We aimed to characterize carbapenem-resistant K. pneumoniae isolated from sewage sites at Mulago National Referral Hospital. Isolated K. pneumoniae from sewage sites were subjected to antimicrobial susceptibility assays to determine their resistance to carbapenems. Multiplex PCR was performed on selected carbapenem-resistant isolates to detect the presence of five carbapenemase-encoding genes and to identify seven major serovars. The overall prevalence of carbapenem-resistant K. pneumoniae isolated from hospital sewage was 15.4%. Overall, the resistance rates to meropenem and imipenem were 81.3% and 62.5%, respectively. Multiplex PCR revealed that 68.8% of the isolates were positive for one or more carbapenemase-encoding genes, and the most predominant gene was bla NDM (36.4%), followed by bla IMP (27.3%), bla VIM (23.7%), and then, bla OXA-48 , at 13.6%. No bla KPC gene was detected. Capsular multiplex PCR revealed that 37.5% of the isolates were pathogenic, whereas 62.5% of the isolates were non-pathogenic; the predominant capsular antigen gene was wzyK2 (25%), followed by wzyK1 (6.25%), wzyK5 (6.25%), and wzyK54 (6.25%). This study detected the presence of carbapenem-resistant pathogenic and non-pathogenic Klebsiella environmental isolates, which pose a significant threat to the control of antimicrobial resistance. Further studies examining clinical isolates to identify sources of antimicrobial resistance and wider surveillance systems are required.