G. JOST¹, N. LIASSINE¹, F. DE MARVAL<sup>1

1</sup>Laboratoire Dianalabs, Geneva, Switzerland

Objective: This study was aimed to evaluate the BD MAX Enteric Bacterial Panel (EBP) PCR assay, in comparison with the standard stool culture.
Methods: Stool culture was performed using standard procedures. BD MAX EBP (BD, Sparks, MD) is a multiplex real-time PCR assay which targets Campylobacter jejuni/coli, Salmonella spp., Shigella spp./EIEC and EHEC.
Results: Shigella spp./EIEC: a total of 157 stools were tested: 150 were negative and 2 were positive both by PCR and culture; 5 specimens were positive by PCR but negative by culture, and therefore presumed to be EIEC. Campylobacter spp.: of the 3259 specimens tested, all C. jejuni/coli detected by culture were positive by PCR, whereas 9 Campylobacterales, other than C. jejuni/coli, were diagnosed only by culture (8 Arcobacter spp., 1 Helicobacter pullorum). Discrepant results were observed in 110 (3.4 %) specimens which were tested positive by PCR and remained negative by culture. Salmonella spp. : A total of 3259 specimens were analysed, of which 67 (2%) were Salmonella spp.-positive and 3174 were Salmonella spp.-negative by culture and PCR. Eleven specimens that were positive by culture for Salmonella spp. remained negative by PCR, whereas 7 PCR-positive Salmonella spp. remained negative by culture. EHEC: 45 out of 3259 stool specimens (1.4%) were tested positive by PCR; 28 of these specimens were sent to the NENT for confirmation, 20 of which were confirmed as EHEC.
Conclusion: Introduction of PCR allows a more rapid and sensitive diagnosis. In the present study, maximum benefit was obtained for the detection of C. jejuni/coli and Shigella spp./EIEC. However, the culture allows a more extended spectrum of Campylobacterales than PCR. Surprisingly, culture detected more often Salmonella spp. than PCR in our routine practice. These features prompt us to maintain the culture of Salmonella spp. and Campylobacter spp. The multiplex PCR assay allows the routine detection of pathogens (EIEC and EHEC) that were formerly investigated only in particular situations, which leads to more positive results; this can be disturbing for clinicians and epidemiological analysis.