Genotypic Characterisation and Antimicrobial Resistance of Extended-Spectrum β-Lactamase-Producing Escherichia coli in Humans, Animals, and the Environment from Lusaka, Zambia: Public Health Implications and One Health Surveillance.

BACKGROUND

Extended-spectrum β-lactamases (ESBL) in Escherichia coli are a serious concern due to their role in developing multidrug resistance (MDR) and difficult-to-treat infections.

OBJECTIVE

This study aimed to identify ESBL-carrying E. coli strains from both clinical and environmental sources in Lusaka District, Zambia.

METHODS

This cross-sectional study included 58 ESBL-producing E. coli strains from hospital inpatients, outpatients, and non-hospital environments. Antimicrobial susceptibility was assessed using the Kirby-Bauer disk diffusion method and the VITEK® 2 Compact System, while genotypic analyses utilised the Illumina NextSeq 2000 sequencing platform.

RESULTS

Among the strains isolated strains, phylogroup B2 was the most common, with resistant MLST sequence types including ST131, ST167, ST156, and ST69. ESBL genes such as blaTEM-1B, blaCTX-M,blaOXA-1, blaNDM-5, and blaCMY were identified, with ST131 and ST410 being the most common. ST131 exhibited a high prevalence of blaCTX-M-15 and resistance to fluoroquinolones. Clinical and environmental isolates carried blaNDM-5 (3.4%), with clinical isolates showing a higher risk of carbapenemase resistance genes and the frequent occurrence of blaCTX-M and blaTEM variants, especially blaCTX-M-15 in ST131.

CONCLUSIONS

This study underscores the public health risks of blaCTX-M-15- and blaNDM-5-carrying E. coli. The strengthening antimicrobial stewardship programmes and the continuous surveillance of AMR in clinical and environmental settings are recommended to mitigate the spread of resistant pathogens.