A randomized controlled trial assessing infectious disease risks from bathing in fresh recreational waters in relation to the concentration of Escherichia coli, intestinal enterococci, Clostridium perfringens, and somatic coliphages.

We performed epidemiologic studies at public freshwater bathing sites in Germany to provide a better scientific basis for the definition of recreational water quality standards. A total of 2,196 participants were recruited from the local population and randomized into bathers and nonbathers. Bathers were exposed for 10 min and had to immerse their head at least three times.

Development and test for long-term stability of a synthetic standard for a quantitative Cryptosporidium parvum LightCycler PCR assay.

A recently described quantitative rapid cycle real time PCR (LightCycler) assay detects Cryptosporidium parvum after in vitro excystation, which is a surrogate marker for the viability of the organisms. In the original assay the quantification standard is a dilution series of C. parvum oocysts with a microscopically determined excystation rate.

Improved detection of Salmonella spp. in foods by fluorescent in situ hybridization with 23S rRNA probes: a comparison with conventional culture methods.

This report describes a new technique for the detection and identification of Salmonella species in food with the use of fluorescent in situ hybridization (FISH) with 23S rRNA-targeted oligonucleotide probes. Two species-specific 23S rRNA-targeted oligonucleotide probes (Sal-1 and Sal-3) were selected, and one (Sal-544) was newly designed. The relative specificities of these probes were compared with those of bacterial 23S rRNA sequences from the GenBank database and tested by in situ hybridization with bacterial cell smears of pure cultures.

DNase pretreatment of master mix reagents improves the validity of universal 16S rRNA gene PCR results.

DNase I pretreatment of 16S rRNA gene PCR reagents was tested. The DNase I requirement for the elimination of false-positive results varied between 0.1 and 70 IU per master mix depending on the applied Taq polymerase.

Effects of reduced mucus oxygen concentration in airway Pseudomonas infections of cystic fibrosis patients.

Current theories of CF pathogenesis predict different predisposing "local environmental" conditions and sites of bacterial infection within CF airways. Here we show that, in CF patients with established lung disease, Pseudomonas aeruginosa was located within hypoxic mucopurulent masses in airway lumens. In vitro studies revealed that CF-specific increases in epithelial O(2) consumption, linked to increased airway surface liquid (ASL) volume absorption and mucus stasis, generated steep hypoxic gradients within thickened mucus on CF epithelial surfaces prior to infection.

The effect of human serum DNAases on the ability to detect antibiotic-killed Escherichia coli in blood by PCR.

PCR has proved superior to conventional blood culture for diagnosing bacteraemia in the presence of antibiotics. Nevertheless, even PCR might yield false-negative results if the template DNA were to be cleaved by serum DNAases after antibiotics had induced bacterial death. To evaluate the cleavage of bacterial template DNA by human serum DNAase I, serum samples inoculated with purified Escherichia coli DNA were incubated with increasing amounts of recombinant human DNAase (rhDNAase) and then examined by a PCR specific for E.