We conducted environmental surveillance of antimicrobial resistance (AMR) bacteria in the Msimbazi river basin in Tanzania to determine the occurrence of extended-spectrum β-lactamase (ESBL)-producing, carbapenem resistant Enterobacteriaceae (CRE) and quinolone resistant Escherichia coli and Klebsiella spp. A total of 213 Enterobacteriaceae isolates were recovered from 219 samples. Out of the recovered isolates, 45.5% (n = 97) were Klebsiella pneumoniae and 29.6% (n = 63) were Escherichia coli. K. pneumoniae isolates were more resistant in effluent (27.9%) compared to the E. coli (26.6%). The E. coli had a higher resistance in river water, sediment and crop soil than the K. pneumoniae (35 versus 25%), respectively. Higher resistance in K. pneumoniae was found in nalidixic acid (54.6%) and ciprofloxacin (33.3%) while the E. coli isolates were highly resistant to ciprofloxacin (39.7%) and trimethoprim/sulfamethoxazole (38%). Resistance increased from 28.3% in Kisarawe, where the river originates, to 59.9% in Jangwani (the middle section) and 66.7% in Upanga West, where the river enters the Indian Ocean. Out of 160 E. coli and K. pneumoniae isolates, 53.2% (n = 85) were resistant to more than three classes of the antibiotic tested, occurrence being higher among ESBL producers, quinolone resistant and carbapenem resistant strains. There is an urgent need to curb environmental contamination with antimicrobial agents in the Msimbazi Basin.
Keywords: Enterobacteriaceae; Msimbazi river basin; antimicrobial resistance; crop soil; effluent; river sediment; river water.