Sewage and sewage-contaminated environments are the most prominent sources to isolate phages against Pseudomonas aeruginosa

Bahareh Lashtoo Aghaee,Mohammad Yousef Alikhani,Mohammadali Khan Mirzaei,Ali Mojtahedi

doi:10.1186/s12866-021-02197-z

Abstract

BackgroundP. aeruginosa is the primary source of hospital-acquired infections. Unfortunately, antibiotic resistance is growing to precariously high levels, making the infections by this pathogen life-threatening and hard to cure. One possible alternative to antibiotics is to use phages. However, the isolation of phages suitable for phage therapy— be lytic, be efficient, and have a broad host range —against some target bacteria has proven difficult. To identify the best places to look for these phages against P. aeruginosa we screened hospital sewages, soils, and rivers in two cities.ResultsWe isolated eighteen different phages, determined their host range, infection property, and plaque morphology. We found that the sewage and sewage-contaminated environments are the most reliable sources for the isolation of Pseudomonas phages. In addition, phages isolated from hospital sewage showed the highest efficiency in lysing the bacteria used for host range determination. In contrast, phages from the river had larger plaque size and lysed bacteria with higher levels of antibiotic resistance.ConclusionsOur findings provided additional support for the importance of sewage as the source of phage isolation.

Highlights

P. aeruginosa is one of the three bacterial pathogens listed as a critical priority for developing new antibiotics, and a leading cause of nosocomial infection [1, 2]
The lowest number of phages against P. aeruginosa were isolated from soil We isolated eighteen phages from eighteen samples collected from three different environmental sources- eight samples from rivers, six from sewages, and four from soil
Thousands of bacterial species are living on soil, including many human pathogens, suggesting soil as a viable source for phage isolation [41]

Summary

Introduction

P. aeruginosa is one of the three bacterial pathogens listed as a critical priority for developing new antibiotics, and a leading cause of nosocomial infection [1, 2]. P. aeruginosa causes infections in multiple organs, including skin, respiratory, urinary, and gastrointestinal tracts [3, 4]. Infections by this pathogen are often hard to treat due to the emergence of multidrug resistant strains and the fact that antibiotics are losing their effects [4,5,6]. Phages are highly specific, meaning beneficial bacteria stay unharmed during phage treatment [7, 10, 11]. They are ubiquitous- they outnumber their bacterial host in most ecosystems. To identify the best places to look for these phages against P. aeruginosa we screened hospital sewages, soils, and rivers in two cities

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