Efficacy of diversely isolated lytic phages against multi-drug resistant isolates in Kenya.

Background: causes nosocomial infections in 15% of patients in low- and middle-income countries with emergence of carbapenem resistance. The utilisation of bacteriophages for therapeutic purposes is crucial for eradicating these resistant bacterial strains.

Objective: This study evaluated the efficacy of lytic phages on bacterial isolates of and determined their stability in various physicochemical conditions.

Methods: Twenty-nine lytic phages were isolated from the waste water of six informal settlements in Nairobi County, Kenya, from July 2019 to December 2020 and cross-reacted with 30 anonymised clinical isolates of Six phages were then selected for physicochemical property studies. Phages were described as potent upon lysing any bacterial strain in the panel.

Results: Selected phages were stable at 4 °C - 50 °C with a 5.1% decrease in titre in four of six phages and a 1.8% increase in titre in two of six phages at 50 °C. The phages were efficient following two weeks incubation at 4 °C with optimal activity at human body temperature (37 °C) and an optimal pH of 7.5. Phages were active at 0.002 M and 0.015 M concentrations of Ca ions. The efficiency of all phages decreased with increased exposure to ultraviolet light. All phages ( = 29) showed cross-reactivity against anonymised clinical isolates of strains ( = 30). The most potent phage lysed 67.0% of bacterial strains; the least potent phage lysed 27.0%.

Conclusion: This study reveals the existence of therapeutic phages in Kenya that are potent enough for treatment of multi-drug resistant