Detection of INVA Gene and Cytotoxin of Salmonella entertidis in Food Samples Using Molecular Methods

Salmonella entertidis is a foodborne pathogen that causes various diseases in human beings worldwide. The toxin of Salmonella can cause infectious diseases. In this research project, Salmonella was detected through various microbial, biochemical and molecular tests in diverse food samples collected from highly populated, moderately populated and less populated areas of Lahore, Pakistan. Enriched cultures of all food samples such as apples, tomatoes, yogurt and mayonnaise was streaked on violet-red bile glucose agar, Simmon’s citrate agar and eosin-methylene blue agar (EMB).  Salmonella isolates were screened for the presence of toxin encoding gene through PCR. 27% apples, 19% tomatoes, 5% mayonnaise and 7% yogurt were found to be positive for INVA genes (invasion protein genes). In medical and pharmaceutical point of views the INVA gene can also help to develop specific medicines against salmonella. The cytotoxin that is protein in nature was confirmed by SDS PAGE in mayonnaise samples. This study illustrates that foods of highly populated areas are reservoir for Salmonella entertidis in Pakistan. There is need to develop specific drugs, precautionary measures to control salmonella and its disease.