Aims: To make a preliminary assessment of the incidence of Salmonella in Egyptian dairy products, and to investigate the effectiveness of various protocols for the detection of the pathogen in these products. Methods and Results: Samples of milk and related dairy products were randomly collected from local markets and examined for the presence of Salmonella. While most samples were free of the organism, isolates of Salmonella enterica subsp. enterica serovar Typhimurium PT 8 could be recovered from 'matared' cream specimens. These isolates were susceptible to antibiotics usually used to challenge infections caused by Salmonella. A combination of buffered peptone water, Muller-Kauffman tetrathionate broth, and brilliant green phenol red agar gave the best results for the detection of the pathogen. Selenite-cystine broth and Hektoen enteric agar were ineffective as an enrichment and a plating medium, respectively, in the isolation of Salmonella. A modified identification strategy that reduces the burden of serological testing of presumptive isolates is proposed. Conclusions, Significance and Impact of the Study: 'Matared' cream could be a vehicle for transmitting Salmonella. Using the above combination of media, beside the suggested modified confirmatory procedure, should increase the effectiveness and ease of the detection of Salmonella in milk and dairy products.

Aims:  To examine the presence of Enterobacter sakazakii in milk and milk‐related products produced/distributed under Egyptian conditions and to probe possible transmission routes of the pathogen during the preparation of dairy products. Methods and Results:  One hundred and thirty‐seven samples of milk and milk‐related products were randomly collected from Egyptian markets and examined for the presence of Ent. sakazakii. The pathogen could be detected only in skimmed milk powder (SMP) and its related product, imitation recombined soft (IRS) cheese. Enterobacter sakazakii isolates recovered from these products were phenotypically similar and sensitive to all antibiotics examined in this study. They also showed indistinguishable banding patterns when subjected to macro‐restriction profiling using pulsed‐field gel electrophoresis (mrp‐PFGE). One Ent. sakazakii isolate was inoculated into SMP that was used in the preparation of IRS cheese using two cheese making procedures. The pathogen could survive for up to 1 month in the IRS cheese prepared by either procedure. Conclusions:  The simultaneous presence of Ent. sakazakii in SMP and IRS cheese samples collected within the same local market besides the phenotypic and genotypic similarities of isolates recovered from these samples suggested the possibility of Ent. sakazakii being transmitted from SMP into IRS cheese. This hypothesis was supported by the observation that the pathogen could survive in the IRS cheese prepared from contaminated SMP. Significance and Impact of the Study:  The study highlights SMP and IRS cheese as potential transmission vehicles of Ent. sakazakii. It also raises concern on the microbiological safety of IRS cheese prepared from SMP.

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Changes occurring in the viability of Salmonella enterica subsp. enterica during the preparation and cold storage of Domiati cheese, Kariesh cheese and ice‐cream were examined. A significant decrease in numbers was observed after whey drainage during the manufacture of Domiati cheese, but Salmonella remained viable for 13 weeks in cheeses prepared from milks with between 60 and 100 g/L NaCl; the viability declined in Domiati cheese made from highly salted milk during the later stages of storage. The method of coagulation used in the preparation of Kariesh cheese affected the survival time of the pathogen, and it varied from 2 to 3 weeks in cheeses made with a slow‐acid coagulation method to 4–5 weeks for an acid‐rennet coagulation method. This difference was attributed to the higher salt‐in‐moisture levels and lower pH values of Kariesh cheese prepared by the slow‐acid coagulation method. A slight decrease in the numbers of Salmonella resulted from ageing ice‐cream mix for 24 h at 0°C, but a greater reduction was evident after one day of frozen storage at −20°C. The pathogen survived further frozen storage for four months without any substantial change in numbers.

Viability of dairy‐borne Salmonella enterica ssp. enterica serovar Typhimurium PT8 was studied during the fermentation of skim milk by thermophilic lactic acid bacteria (LAB). Longer generation times of Salmonella were found in mixed cultures of skim milk containing Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus or a mixture of them (1:1), as compared with single cultures of the pathogen. Salmonella was less able to survive in mixed cultures with these LAB during prolonged incubation at 41°C and also during cold storage of the fermented milk. Lactobacillus ssp. bulgaricus and its mixture with S. thermophilus were more inhibitory to the growth and survival of Salmonella than was S. thermophilus. This was associated with higher ability of L. ssp. bulgaricus and the mixture to develop acidity in milk than S. thermophilus. Examining the antibacterial activity of these LAB towards Salmonella showed that other factors including heat‐resistant and heat‐labile compounds were involved in inhibiting the pathogen by these cultures. The viability of the same Salmonella strain during the preparation and cold storage of buffalo's yogurt was also examined. Salmonella was found to survive longer in yogurt made with starter containing probiotic bacteria than in that prepared with the traditional starter. This was ascribed to the development of lower pH by the traditional starter.