Bacteriophage Cocktails Protect Dairy Cows Against Mastitis Caused By Drug Resistant Escherichia coli Infection.

Mengting Guo,Hengan Wang,Ya Gao,Yuanping Liu,Yuqiang Cheng,Yaxian Yan,Zhaofei Wang,Xiaoyan Zeng,Jingjiao Ma,Yibing Xue,Jianhe Sun

doi:10.3389/fcimb.2021.690377

Abstract

Mastitis caused by Escherichia coli (E. coli) remains a threat to dairy animals and impacts animal welfare and causes great economic loss. Furthermore, antibiotic resistance and the lagged development of novel antibacterial drugs greatly challenge the livestock industry. Phage therapy has regained attention. In this study, three lytic phages, termed vB_EcoM_SYGD1 (SYGD1), vB_EcoP_SYGE1 (SYGE1), and vB_EcoM_SYGMH1 (SYGMH1), were isolated from sewage of dairy farm. The three phages showed a broad host range and high bacteriolytic efficiency against E. coli from different sources. Genome sequence and transmission electron microscope analysis revealed that SYGD1 and SYGMH1 belong to the Myoviridae, and SYGE1 belong to the Autographiviridae of the order Caudovirales. All three phages remained stable under a wide range of temperatures or pH and were almost unaffected in chloroform. Specially, a mastitis infected cow model, which challenged by a drug resistant E. coli, was used to evaluate the efficacy of phages. The results showed that the cocktails consists of three phages significantly reduced the number of bacteria, somatic cells, and inflammatory factors, alleviated the symptoms of mastitis in cattle, and achieved the same effect as antibiotic treatment. Overall, our study demonstrated that phage cocktail may be a promising alternative therapy against mastitis caused by drug resistant E. coli.

Highlights

Mastitis remains a devastating disease in dairy animals worldwide
Eighteen E. coli (12 Food-borne strains and six strains isolated from the milk of dairy cows with mastitis) and two E. coli reference strains of MC1061 and MG1655 from the American Type Culture Collection (ATCC) were used in this study were stored in our laboratory (Table 1)
Spot assay showed that SYGD1 and SYGMH1 had a wide host range with a similar spectrum (12 of 20, 60%), and SYGE1 could lyse more strains (16 of 20, 80%) (Table 1)

Summary

Introduction

Mastitis (intramammary inflammation) remains a devastating disease in dairy animals worldwide. It adversely threatens the health of udder, decreases the quality and production of milk, impedes the growth of bovine, increases rearing and prevention costs, and negatively impacts animal welfare (Khan et al, 2021). Bacterial culture was done on milk samples from 161 large Chinese (>500 cows) dairy farms, the most frequently isolated pathogens were Escherichia coli (14.4%), Klebsiella spp. E. coli is the most common Gram-negative bacteria causing acute clinical mastitis in dairy cows during early lactation (Cortinhas et al, 2016). E.coli mastitis incurs subclinical phenotypes, including an increase in somatic cell count (SCC) in milk (Abdi et al, 2021) and the production of proinflammatory cytokines in blood (Cobirka et al, 2020). Due to the abuse of antibiotics, multidrug-resistance bacteria have emerged which is projected to be the greatest challenges of the 21st century (Streicher, 2021)

Methods

Results

Discussion

Conclusion