Surveillance and genotyping ofEnterobacter sakazakiisuggest its potential transmission from milk powder into imitation recombined soft cheese

Abstract

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. 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. 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. 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.