Multiplex PCR for bacterial, viral and protozoal pathogens in persistent diarrhoea or persistent abdominal pain in Côte d'Ivoire, Mali and Nepal

In contrast to acute diarrhoea, the aetiology of persistent digestive disorders (≥ 14 days) is poorly understood in low-resource settings and conventional diagnostic approaches lack accuracy. In this multi-country study, we compared multiplex real-time PCR for enteric bacterial, parasitic and viral pathogens in stool samples from symptomatic patients and matched asymptomatic controls in Côte d'Ivoire, Mali and Nepal. Among 1826 stool samples, the prevalence of most pathogens was highest in Mali, being up to threefold higher than in Côte d'Ivoire and up to tenfold higher than in Nepal. In all settings, the most prevalent bacteria were EAEC (13.0-39.9%) and Campylobacter spp. (3.9-35.3%). Giardia intestinalis was the predominant intestinal protozoon (2.9-20.5%), and adenovirus 40/41 was the most frequently observed viral pathogen (6.3-25.1%). Significantly different prevalences between symptomatic and asymptomatic individuals were observed for Campylobacter, EIEC and ETEC in the two African sites, and for norovirus in Nepal. Multiple species pathogen infection was common in Côte d'Ivoire and Mali, but rarely found in Nepal. We observed that molecular testing detected multiple enteric pathogens and showed low discriminatory accuracy to distinguish between symptomatic and asymptomatic individuals. Yet, multiplex PCR allowed for direct comparison between different countries and revealed considerable setting-specificity.

Experiences with pre-travel diagnostic PCR testing for SARS-CoV-2: challenges and opportunities

This study explores challenges and opportunities arising from pre-travel severe acute respiratory syndrome coronavirus 2 diagnostics for the conduct of travel medicine clinics. We found that such testing might offer huge opportunities to reach individuals who would otherwise not present to travel medicine clinics, such as individuals visiting friends and relatives in malaria-endemic countries.

Immunological characterization of two major proteins isolated from the outer membrane of Proteus mirabilis

Two proteins with apparent molecular weights of 39,000 and 36,000 (M(r) 39,000 and M(r) 36,000, respectively) were isolated from the outer membrane of Proteus mirabilis 19. M(r) 36,000 was shown to be free of detectable amounts of the M(r) 39,000 protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and free of lipopolysaccharide according to gas chromatographic analyses of 3-hydroxymyristic acid content. The M(r) 39,000 protein contained no detectable amount of lipopolysaccharide and only a trace of M(r) 36,000. Both isolated proteins gave strong reactions in antisera produced to purified P. mirabilis 19 cell walls (outer membrane proteins in the native state). This suggested that the proteins isolated by our methods essentially retained their native configuration upon resolubilization. Antisera produced in rabbits to the isolated proteins showed strongest reactions with the homologous antigen, but some cross-reactions with the heterologous protein and with P. mirabilis 19 lipopolysaccharide were observed. These cross-reactions could be attributed to specific responses to traces of the heterologous (contaminant) proteins present in the purified proteins used as immunizing antigens. The M(r) 39,000 and M(r) 36,000 proteins have no major antigenic determinants in common. Reactions with P. mirabilis 19 lipopolysaccharide in antisera to the outer membrane proteins could be completely removed by absorption of the antisera with the M(r) 36,000 protein.