ABSTRACT
Conventional diagnosis of infectious diarrhea caused by bacteria is time-consuming, labor-intensive, and has a suboptimal sensitivity. We have therefore developed a multiplex real-time polymerase chain reaction (PCR) for the simultaneous detection of Campylobacter jejuni, Salmonella spp., Shigella spp./enteroinvasive Escherichia coli (EIEC), and Yersinia enterocolitica in fecal samples. No cross reactivity between the different pathogens was observed, and the multiplex setup of the assay did not have an impact on the sensitivity of the PCR. The analytical sensitivity was 87 CFU/mL for C. jejuni, 61 CFU/mL for Shigella spp./EIEC, 5,528 CFU/mL for Salmonella spp., and 1,306 CFU/mL for Y. enterocolitica. An extensive validation of the assay was performed by testing 1,687 patient samples by both PCR and with conventional techniques. The use of PCR increased the overall clinical sensitivity from 78 to 100 % (p < 0.0001), the specificity was 99.4 % for the PCR, compared with 99.9 % for conventional culture. The novel PCR assay allows for rapid, sensitive, inexpensive, and high-throughput testing of the most common bacterial causes of gastroenteritis.
Subject(s)
Campylobacter Infections/diagnosis , Campylobacter jejuni/isolation & purification , Enterobacteriaceae Infections/diagnosis , Enterobacteriaceae/isolation & purification , Molecular Diagnostic Techniques/methods , Multiplex Polymerase Chain Reaction/methods , Real-Time Polymerase Chain Reaction/methods , Feces/microbiology , Humans , Sensitivity and SpecificityABSTRACT
Linear Alkylbenzenesulphonates (LAS), a major anionic surfactant used in laundry products, can be measured specifically in the environment by instrumental analysis. In addition to a desulphonation-gas chromatography approach, a method based on high performance liquid chromatography has been developed. The main features of the methods are outlined, and LAS concentrations measured in sewage sludge, sediments and sludge amended soils are reported. Knowledge of usage volumes, sewage treatment practices and environmental transport and transformation mechanisms has been used to predict concentrations of LAS. These calculated concentrations were found to agree well with those actually measured in the environment. Both measured and calculated ambient concentrations of LAS are below those which could produce potentially adverse effects in representative surface water, benthic and terrestrial organisms.