Salmonella contamination in foods and their formation of biofilms in food processing facility are the primary bacterial cause of a significant number of foodborne outbreaks and infections. Broad lytic phages are promising alternatives to conventional technologies for pathogen biocontrol in food matrices and reducing biofilms. In this study, 42 Salmonella phages were isolated from environmentally-sourced water samples. We characterized the host range and lytic capacity of phages LPSTLL, LPST94 and LPST153 against Salmonella spp., and all showed a wide host range and broad lytic activity. Electron microscopy analysis indicated that LPSTLL, LPST94, and LPST153 belonged to the family of Siphoviridae, Ackermannviridae and Podoviridae, respectively. We established a phage cocktail containing three phages (LPSTLL, LPST94 and LPST153) that had broad spectrum to lyse diverse Salmonella serovars. A significant decrease was observed in Salmonella with a viable count of 3 log₁₀ CFU in milk and chicken breast at either 25 °C or 4 °C. It was found that treatment with phage cocktail was able to significantly reduced biofilm on a 96-well microplate (44–63%) and on a stainless steel surface (5.23 to 6.42 log₁₀). These findings demonstrated that the phage cocktail described in this study can be potentially used as a biological control agent against Salmonella in food products and also has the effect to reduce Salmonella formed biofilms.

Salmonella, one of the most common food-borne pathogens, is a significant public health and economic burden worldwide. Lytic phages are viable alternatives to conventional technologies for pathogen biocontrol in food products. In this study, 40 Salmonella phages were isolated from environmentally sourced water samples. We characterized the lytic range against Salmonella and among all isolates, phage LPST94 showed the broadest lytic spectrum and the highest lytic activity. Electron microscopy and genome sequencing indicated that LPST94 belongs to the Ackermannviridae family. Further studies showed this phage is robust, tolerating a wide range of pH (4–12) and temperature (30–60 °C) over 60 min. The efficacy of phage LPST94 as a biological control agent was evaluated in various food products (milk, apple juice, chicken breast, and lettuce) inoculated with non-typhoidal Salmonella species at different temperatures. Interestingly, the anti-Salmonella efficacy of phage LPST94 was greater at 4 °C than 25 °C, although the efficacy varied between different food models. Adding phage LPST94 to Salmonella inoculated milk decreased the Salmonella count by 3 log₁₀ CFU/mL at 4 °C and 0.84 to 2.56 log₁₀ CFU/mL at 25 °C using an MOI of 1000 and 10000, respectively. In apple juice, chicken breast, and lettuce, the Salmonella count was decreased by 3 log₁₀ CFU/mL at both 4 °C and 25 °C after applying phage LPST94 at an MOI of 1000 and 10,000, within a timescale of 48 h. The findings demonstrated that phage LPST94 is a promising candidate for biological control agents against pathogenic Salmonella and has the potential to be applied across different food matrices.

Foodborne diseases represent a major risk to public health worldwide. In this study, LPST153, a novel Salmonella lytic phage with halo (indicative of potential depolymerase activity) was isolated by employing Salmonella enterica serovar Typhimurium ATCC 13311 as the host and had excellent lytic potential against Salmonella. LPST153 is effectively able to lyse most prevalent tested serotypes of Salmonella, including S. Typhimurium, S. Enteritidis, S. Pullorum and S. Gallinarum. Morphological analysis revealed that phage LPST153 belongs to Podoviridae family and Caudovirales order and could completely prevent host bacterial growth within 9 h at multiplicity of infection (MOI) of 0.1, 1, 10 and 100. LPST153 had a latent period of 10 min and a burst size of 113 ± 8 PFU/cell. Characterization of the phage LPST153 revealed that it would be active and stable in some harsh environments or in different conditions of food processing and storage. After genome sequencing and phylogenetic analysis, it is confirmed that LPST153 is a new member of the Teseptimavirus genus of Autographivirinae subfamily. Further application experiments showed that this phage has potential in controlling Salmonella in milk and sausage. LPST153 was also able to inhibit the formation of biofilms and it had the ability to reduce and kill bacteria from inside, including existing biofilms. Therefore, the phage LPST153 could be used as a potential antibacterial agent for Salmonella control in the food industry.

Antimicrobials have been used to improve animal welfare, food security, and food safety that promote the emergence, selection, and dissemination of antimicrobial-resistant (AMR) bacteria. In this study, 50 E. coli were isolated from frozen chicken meat samples in Dhaka city. Antibiotic sensitivity patterns were assessed through the disk diffusion method and finally screened for the presence of antimicrobial resistance genes (ARG) using the polymerase chain reaction (PCR). Among the 160 samples, the prevalence of E. coli was observed in fifty samples (31.25%). All of these isolates were found resistant to at least one antimicrobial agent, and 52.0% of the isolates were resistant against 4–7 different antimicrobials. High resistance was shown to tetracycline (66.0%), followed by resistance to erythromycin (42.0%), ampicillin and streptomycin (38.0%), and sulfonamide (28.0%). In addition, the most prevalent ARGs were tet(A) (66.0%), ereA (64.0%), tet(B) (60.0%), aadA1 and sulI (56.0%), blaCITM (48.0%) and blaSHV (40.0%). About 90.0% of isolates were multidrug resistant. This study reveals for the first time the current situation of E. coli AMR in broilers, which is helpful for the clinical control of disease as well as for the development of policies and guidelines to reduce AMR in broilers production in Bangladesh.

Escherichia coli O157:H7 is a recognized food-borne pathogen causing severe food poisoning at low doses. Bacteriophages (phages) are FDA-approved for use in food and are suggested as natural preservatives against specific pathogens. A novel phage must be identified and studied to develop a new natural preservative or antimicrobial agent against E. coli O157:H7. The phage SPEC13 displayed broad host range and was classified within the Ackermannviridae family based on its observed characteristics by a TEM and genome analysis. In 10 min, this phage achieves a remarkable 93% adsorption rate with the host. Its latency period then lasts about 20 min, after which it bursts, releasing an average of 139 ± 3 PFU/cell. It exhibited robustness within a pH range of 4 to 12, indicating resilience under diverse environmental circumstances. Furthermore, SPEC13 demonstrated stability at an ambient temperature up to 60 °C. A whole genome and phylogenetics analysis revealed that SPEC13 is a novel identified phage, lacking a lysogenic life cycle, antibiotic resistance genes, or genes associated with virulence, thereby presenting a promising biological agent for therapeutic application. Animal studies showed that SPEC13 effectively controlled the growth of harmful bacteria, resulting in a significant improvement in colon health, marked by reduced swelling (edema) and tissue damage (mucosal injury). The introduction of SPEC13 resulted in a substantial decrease in quantities of E. coli O157:H7, reducing the bacterial load to approximately 5 log CFU/g of feces. In conclusion, SPEC13 emerges as a promising inclusion in the array of phage therapy, offering a targeted and efficient approach for addressing bacterial infections.