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Isolation of Lytic Bacteriophages of Escherichia coli and Their Combined Use with Antibiotics Against the Causative Agents of Colibacillosis in Calves
by
, , and
Pavel G. Alexyuk
,
Andrey P. Bogoyavlenskiy
, 
Kuralay S. Akanova
,
Yergali S. Moldakhanov
,
Timur T. Kerimov
,
Nadezhda S. Sokolova
,
Vladimir E. Berezin
and
Madina S. Alexyuk
* Research and Production Center for Microbiology and Virology, Almaty 050010, Kazakhstan
*
Author to whom correspondence should be addressed.
Vet. Sci. 2025, 12(9), 817; https://doi.org/10.3390/vetsci12090817
Submission received: 5 August 2025
/
Revised: 25 August 2025
/
Accepted: 26 August 2025
/
Published: 26 August 2025
(This article belongs to the Section Veterinary Biomedical Sciences)
Simple Summary
Colibacillosis is a serious infectious disease caused by Escherichia coli, which commonly affects calves and can result in significant economic losses in livestock production. The reduced effectiveness of antibiotics due to increasing bacterial resistance necessitates the development of alternative therapeutic approaches. In this study, we isolated four bacteriophages—viruses that infect and lyse bacteria—from wastewater samples collected in various cities across Kazakhstan. These phages demonstrated strong lytic activity against pathogenic bacterial strains, rapid replication, environmental stability, and high efficacy in bacterial destruction. Furthermore, the combined application of bacteriophages and conventional antibiotics resulted in a synergistic effect, leading to more rapid suppression of bacterial growth in most cases. Whole-genome sequencing revealed that the isolated phages lacking any genes associated with bacterial virulence or antibiotic resistance, indicating their biosafety for potential therapeutic use. Taken together, our findings support the possible potential of newly isolated bacteriophages as effective and safe agents for the control of bacterial infections in animals, and suggest their utility in reducing antibiotic dependency in livestock production.
Abstract
The spread of antibiotic-resistant pathogenic Escherichia coli poses a serious threat to calf health on livestock farms. With the decline in antibiotic therapy effectiveness, alternative approaches such as phage therapy are urgently needed. This study aimed to isolate lytic E. coli bacteriophages, characterize their properties, and evaluate the synergistic effects of their combined use with veterinary antibiotics against colibacillosis pathogens in calves. As a result of the work, 4 bacteriophages were isolated from wastewater from various cities of Kazakhstan: vB_EcoS_ABO/4, vB_EcoM_PL/4, vB_Eco_CWW/26, vB_EcoM_ShWW/46. Morphological, biological, and genomic analyses showed that the phages belong to different genera of the Caudoviricetes class, possess high lytic activity, broad host range, environmental stability, and lack genes associated with lysogeny, antibiotic resistance, or virulence. Interaction studies with antibiotics revealed synergistic or additive effects in over 75% of cases. These findings highlight the strong potential of the isolated bacteriophages for independent or adjunctive use in the treatment and prevention of colibacillosis in calves. However, further in vivo studies are required to definitively confirm their therapeutic efficacy.
