Isolation and Characterization of Two Lytic Bacteriophages Infecting a Multi-Drug Resistant Salmonella Typhimurium and Their Efficacy to Combat Salmonellosis in Ready-to-Use Foods

Abstract

Foodborne salmonellosis is a global threat to public health. In the current study, we describe the isolation and characterization of two broad-spectrum, lytic Salmonella phages: SPHG1 and SPHG3 infecting a multidrug-resistant Salmonella Typhimurium EG.SmT3. Electron microscopy and whole genome analysis identified SPHG1 as a Myovirus, while SPHG3 as a new member of the genus “Kuttervirus” within the family Ackermannviridae. SPHG1 and SPHG3 had a lysis time of 60 min. with burst sizes of 104 and 138 PFU/cell, respectively. The two phages were robust at variable temperatures and pH ranges that match the corresponding values of most of the food storage and processing conditions. A phage cocktail containing the two phages was stable in the tested food articles for up to 48 h. The application of the phage cocktail at MOIs of 1000 or 100 resulted in a significant reduction in the viable count of S. Typhimurium by 4.2 log10/sample in milk, water, and on chicken breast. Additionally, the phage cocktail showed a prospective ability to eradicate and reduce the biofilm that formed by S. Typhimurium EG.SmT3. A phage cocktail of SPHG1 and SPHG3 is considered as a promising candidate as a biocontrol agent against foodborne salmonellosis due to its broad host ranges, highly lytic activities, and the absence of any virulence or lysogeny-related genes in their genomes.

Bacteriophage Cocktail Can Effectively Control Salmonella Biofilm in Poultry Housing

“…In this study, we found that UPWr_S1, UPWr_S3, and UPWr_S4 phages alone and the UPWr_S134 phage cocktail exhibited a great ability to decrease the number of Salmonella from biofilm structures in a 96-well microtiter plate and on stainless steel washers formed by strong and moderate biofilm producers, S. Enteritidis ATCC 13076 and 372 lux strains, respectively. A previous study on S. Typhimurium and S. Enteritidis showed significant biofilm eradication by phage cocktail at titers of 7 log 10 and 8 log 10 PFU/mL in a 96-well microplate with the reduction levels varying between 44 and 63% (Gong and Jiang, 2017;Islam et al, 2019;Esmael et al, 2021). The ability of UPWr_S1, UPWr_S3, and UPWr_S4 phages and the UPWr_S134 phage cocktail to eliminate bacteria from biofilm formed by S. Enteritidis 372 lux corresponds to the average reduction level of most Salmonella-targeting phage cocktails, whereas monophage and phage cocktail treatment of biofilm formed by the strong biofilm producer S. Enteritidis ATCC 13076 resulted in almost complete biofilm eradication.…”

SGP-C: A Broad Host Range Temperate Bacteriophage; Against Salmonella gallinarum

“…EOP was calculated through the previously reported method ( Khawaja et al, 2016 ) using SG-C as a reference strain. EOP values from 0.5 to 1 were classified as highly efficient, values between 0.2 to < 0.5 as moderately efficient and 0.0001 to < 0.2 as least efficient while < 0.0001 as in-efficient ( Mirzaei and Nilsson, 2015 ; Esmael et al, 2021 ).…”

An Overview of Salmonella Biofilms and the Use of Bacteriocins and Bacteriophages as New Control Alternatives

“…This is important as there are different temperatures in the food chain and this study would indicate that phage treatment could be used over a wide temperature range. In the same way, Esmael et al [114] tested to S. Typhimurium lytic phages against 72 h-old biofilms formed in microtiter plates. Concentrations of 8 log10 PFU/mL reduced more than three times biofilm formation.…”