Environmental isolation and characterization of Escherichia coli phages from Burkina Faso

Escherichia coli (E. coli) is a major cause of human and animal infections and is commonly treated with antibiotics, whose overuse promotes the emergence of resistant strains. The global rise of antimicrobial resistance has renewed interest in bacteriophages as alternative or complementary antibacterial agents. However, data on phage diversity and activity against E. coli in sub-Saharan Africa, particularly in Burkina Faso, remain limited. This study aimed to isolate and preliminarily characterize candidate E. coli bacteriophages and evaluate their in vitro lytic activity against two representative clinical and environmental E. coli isolates. E. coli strains were collected in Ouagadougou, Burkina Faso, between May and October 2021. Phages were isolated from wastewater and animal feces using E. coli ATCC 25922 as host for propagation. Lytic activity and phage titers were determined using standard spot and double-layer agar assays. Genetic diversity was assessed by RAPD-PCR as a preliminary fingerprinting approach to evaluate genetic similarity among isolates. A total of 28 phages were isolated from various sources, including wastewater and animal feces. Among them, 15/28 phages (53.57%) were recovered from slaughterhouse wastewater, representing the highest proportion. Phages from slaughterhouse effluents exhibit ed the highest titers ranging from 8.6 × 10⁹ to 2.6 × 10¹⁰ PFU/mL. All isolated phages demonstrated lytic activity against the single clinical E. coli strain tested, whereas their activity against the single environmental strain was variable. RAPD-PCR fingerprinting indicated genetic diversity among the isolates and suggested some variability according to their source of isolation. Slaughterhouse effluents appear to represent a promising reservoir of E. coli phages. The isolated phages exhibited lytic activity against a limited number of E. coli isolates, and their potential applications, as therapeutic and biocontrol agents against multidrug-resistant strains, require further investigation.