Prevalence and antibiotic resistance of Enterococcus faecium and Enterococcus faecalis in municipal wastewater integrated with hospital effluent in northern Malaysia

Antibiotic resistance is a growing global health threat, with Enterococcus faecium and Enterococcus faecalis emerging as significant multidrug-resistant pathogens in both clinical and environmental settings. Malaysia’s NSAR 2023 report highlights the presence of antibiotic-resistant strains in hospital environments, raising concerns about their potential spread. However, data on their resistance profiles in wastewater systems remain limited. This study investigates the prevalence and antibiotic resistance patterns of E. faecium and E. faecalis in municipal wastewater impacted by hospital effluent in northern Malaysia. Samples were cultured on ECOFA agar, and CFU/mL was quantified. Presumptive E. faecalis counts (3.60 × 10² to 2.00 × 10⁴ CFU/mL) exceeded those of E. faecium (5.00 × 10¹ to 8.00 × 10³ CFU/mL). PCR targeting the ddl gene identified E. faecium as the predominant species (68.89%), followed by E. faecalis (27.78%) and other Enterococcus spp. (3.33%). Antibiotic susceptibility testing of 87 isolates revealed highest resistance in E. faecium to ampicillin (15.00%) and in E. faecalis to chloramphenicol (16.00%). Both species showed resistance to linezolid (E. faecium: 6.00%; E. faecalis: 8.00%). The Multiple Antibiotic Resistance (MAR) index ranged from 0 to 0.83 (E. faecium) and 0 to 0.5 (E. faecalis), with E. faecium exhibiting higher MAR values and more multidrug-resistant isolates. These findings underscore the need for enhanced monitoring and targeted interventions to mitigate the environmental dissemination of antibiotic-resistant enterococci and reduce associated public health risks.