Antimicrobial resistance (AMR) is a public health problem threatening human, animal, and environmental safety. This study assessed the AMR profiles and risk factors associated with Escherichia coli in hospital and environmental settings in Lusaka, Zambia. This cross-sectional study was conducted from April 2022 to August 2022 using 980 samples collected from clinical and environmental settings. Antimicrobial susceptibility testing was conducted using BD Phoenix^TM 100. The data were analysed using SPSS version 26.0. Of the 980 samples, 51% were from environmental sources. Overall, 64.5% of the samples tested positive for E. coli, of which 52.5% were from clinical sources. Additionally, 31.8% were ESBL, of which 70.1% were clinical isolates. Of the 632 isolates, 48.3% were MDR. Most clinical isolates were resistant to ampicillin (83.4%), sulfamethoxazole/trimethoprim (73.8%), and ciprofloxacin (65.7%) while all environmental isolates were resistant to sulfamethoxazole/trimethoprim (100%) and some were resistant to levofloxacin (30.6%). The drivers of MDR in the tested isolates included pus (AOR = 4.6, CI: 1.9–11.3), male sex (AOR = 2.1, CI: 1.2–3.9), and water (AOR = 2.6, CI: 1.2–5.8). This study found that E. coli isolates were resistant to common antibiotics used in humans. The presence of MDR isolates is a public health concern and calls for vigorous infection prevention measures and surveillance to reduce AMR and its burdens.

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 bla_TEM-1B, bla_CTX-M,bla_OXA-1, bla_NDM-5, and bla_CMY were identified, with ST131 and ST410 being the most common. ST131 exhibited a high prevalence of bla_CTX-M-15 and resistance to fluoroquinolones. Clinical and environmental isolates carried bla_NDM-5 (3.4%), with clinical isolates showing a higher risk of carbapenemase resistance genes and the frequent occurrence of bla_CTX-M and bla_TEM variants, especially bla_CTX-M-15 in ST131. Conclusions: This study underscores the public health risks of bla_CTX-M-15- and bla_NDM-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.