oa Development of a molecular assay For rapid detection of six major enteric pathogens

"Golden" standard laboratory diagnostic tests for enteric pathogens are generally time and labor intensive. Over the last ten years, advances in molecular biology have paved the way for the development of highly specific and sensitive real-time polymerase chain reaction (RT-PCR) detection assays. Worldwide adoption of RT-PCR machines have lowered the cost of conducting such assays to where it became the standard diagnostic tool in detection of enteric pathogens. Herein, we developed a molecular method to screen the stool specimens from food workers and housemaids in Qatar for the presence of several common enteric bacteria and parasites using RT-PCR. A total of 200 samples were collected from apparently healthy subjects during a routine health check-up. The stool specimens were collected over the period of 4 months and screened for the presence of Salmonella spp., Shigella spp., Campylobacter jejuni, Entamoeba hystolytica, Cryptosporidium parvum, and Giardia lamblia using multiplex real-time polymerase chain reaction (RT-PCR). The technique allows simultaneous detection of either the bacteria or the parasites in a single reaction tube within 3 hours of receiving the sample. The specificity and sensitivity of the assay was established using a serial dilution of DNA extracted from a stool sample spiked with the corresponding pathogen. For each of Salmonella and Campylobacter only one sample was found to be positive (0.5% prevalence), while two samples were positive for Shigella, Cryptosporidium, and Entamoeba (1% prevalence), and 14 for Giardia (7% prevalence).These initial results give an indication that food workers in Qatar are shedding several important enteric pathogens and their role in spreading the infection requires further investigation. The development of the assay reported here will allow for an in-depth investigation of these pathogens in the future.