Statistical adjustment of culture-independent diagnostic tests for trend analysis in the Foodborne Diseases Active Surveillance Network (FoodNet), USA

Performance Evaluation of the Novodiag Bacterial GE+ Multiplex PCR Assay

The bacteriological diagnosis of intestinal bacterial infections has historically been based on culture on agar plates. However, culture may lack sensitivity, and some enteropathogens, such as pathovars of Escherichia coli, may escape routine diagnosis. Our goal was to evaluate the analytical performance of the Novodiag Bacterial GE+ kit for the detection of enteropathogenic bacteria in acute community diarrhea. We included 251 stools in this study (198 retrospective and 53 prospective). The analytical performance was calculated using a composite reference standard (CRS) in the absence of a perfect gold standard (lack of sensitivity of culture). The CRS was defined as positive if culture was positive or, in case of a negative culture, if the BD Max extended enteric bacterial panel and/or other real-time PCR (RT-PCR) tests were positive. Of the 251 samples, 200 were positive, and 51 were negative. Overall sensitivities of the Novodiag Bacterial GE+ kit for Campylobacter sp., Salmonella sp., Shigella sp./enteroinvasive E. coli (EIEC), Yersinia enterocolitica, enterohemorrhagic E. coli (EHEC), and enterotoxigenic E. coli (ETEC) ranged from 98.98 to 100%, specificities ranged from 98.08 to 100%, positive predictive values (PPVs) ranged from 88.24 to 100%, and negative predictive values (NVPs) ranged from 99.36 to 100%. The analytical performance of the Novodiag Bacterial GE+ kit is excellent. It can be used as a routine tool in the rapid diagnosis of bacterial gastroenteritis. Despite the eNAT tube dilution of the primary sample, the detection of Salmonella sp. and EHEC was perfect. The kit has the advantage of only detecting pathogenic Y. enterocolitica Its performance for Campylobacter is very satisfactory.