Environmental isolation and characterization of Escherichia coli phages from Burkina Faso

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Résumé

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 againstE. 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.
Results
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 exhibited 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.
Conclusion
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

Mots-clés

Escherichia coli phages, Genetic diversity, Wastewater, Animal feces, RAPD-PCR, Antibiotic resistance