Characterization and optimization of bacteriophage cocktails to control Clostridium perfringens in vitro and in curry roux.

Clostridium perfringens is a major cause of foodborne disease in developed countries. The aim of this study was to isolate and characterize phages specific to C. perfringens to evaluate the most efficient phage cocktail for the biocontrol of C. perfringens, both in vitro and in curry roux. In this study, four phages were isolated from chicken meat and were morphologically and genetically characterized along with two phages previously isolated in our laboratory that display different host lysis spectra. Phage cocktail CP11, consisting of phages CPQ3, 7, 8, and 10, showed the broadest host range. Electron micrograph images suggested that all four phages belong to the Podoviridae family, and none of them carry any antibiotic resistance or toxin genes. Notably, the phages were stable at various pH values and in curry roux. Cocktails consisting of six, five, and four phages at the same concentrations were examined to determine the most effective phage cocktail. Phage cocktail PC11 significantly decreased the viable count of C. perfringens to a value less than the lower detection limit up to 48 h at both 8 and 37 °C in broth and at 24 °C in the curry roux. These results suggest that phage cocktail PC11 is a promising natural biocontrol agent against C. perfringens in vitro and in curry roux.

Characterization of Clostridium perfringens bacteriophages and their application in chicken meat and milk.

Clostridium perfringens is one of the most important foodborne pathogens in developed countries. It causes severe food poisoning outbreaks worldwide, along with mortality and economic losses. Recently, bacteriophages have been investigated as an alternative tool to control pathogenic bacteria in the food industry. In this study, 19 Clostridium perfringens and 6 Clostridium perfringens bacteriophages were isolated from chicken meat. According to host range and stability tests, bacteriophage CPQ1 showed high thermostability and the broadest host range. The electron micrograph image of this bacteriophage suggested that it belongs to the Picovirinae subfamily of the Podoviridae family. Nucleotide sequence analysis of the genomic DNA indicated the absence of any antibiotic resistance, toxin, or virulence genes. In broth, CPQ1 showed strong lytic activity with a low MOI of 1, decreasing the OD600 of Clostridium perfringens cell suspension from 0.2 to 0.02 at 37 °C in 2 h. In pasteurized milk and chicken meat, CPQ1 with an MOI of 10 also caused a significant decrease in viable counts of Clostridium perfringens compared to the bacteriophageless control at both 24 °C and 37 °C. This is the first report on the application of bacteriophage to control Clostridium perfringens in foods.

Serotypes, Pathogenic Potential, and Antimicrobial Resistance of Escherichia coli Isolated from Subclinical Bovine Mastitis Milk Samples in Egypt.

Subclinical mastitis (SCM) is regarded as both a problem for dairy producers and a threat to human health worldwide owing to the potential bacterial contamination of milk and dairy products, particularly those made from raw milk. In the present study, we isolated Escherichia coli from 14 (9.3%) SCM milk samples. We serotyped each E. coli isolate (n = 14), and investigated its potential pathogenicity and antimicrobial resistance (AMR). The serotyping results showed that the E. coli isolates belonged to serotypes O55:H7 (n = 2), O111:H4 (n = 2), O127:H6 (n = 2), O128:HUT (n = 2), O26:HUT (n = 1), O44:H18 (n = 1), O114:H21 (n = 1), O86:HUT (n = 1), O124:HUT (n = 1), and O127:H7 (n = 1). Potential pathogenicity was detected in 93% (13/14) of the isolates. In particular, 13 isolates possessed at least one of the examined virulence genes. Ten isolates (71%) exhibited AMR to at least one of the tested antimicrobials, four (40%) were multidrug-resistant, and one isolate produced extended-spectrum ß-lactamases. The obtained results indicate that SCM acts as a source for the spread of potentially pathogenic E. coli strains that are resistant to many groups of antimicrobials, and may constitute a hazard to both public and animal health.