Microbiological quality of carbonated drinking water produced with in-home carbonation systems.

The microbiological quality of carbonated water produced with tap water in commercial in-home carbonation systems was determined, the results being discussed in the context of the microbiological quality of the tap water used, the properties of the drink makers, and the procedures of preparation and washing of various parts of the appliance. The last-mentioned data were received from each participant of the study by questionnaire. Escherichia coli, coliforms, fecal streptococci and spore-forming sulphite-reducing anaerobes were used as indicators for the hygienic quality of the water. Tap-water samples were collected according to the usual procedure when filling the carbonating bottle, i.e., without previous flushing and disinfection of the faucet. In 12% of tap-water samples, coliforms could be detected. On the other hand, in 20 of 52 carbonated waters (39%), coliforms as indicators of water pollution were found. By means of fecal streptococci and Pseudomonas aeruginosa, it was possible to establish additional contamination not involving E. coli or coliforms alone. Analysis revealed that, in addition to contaminated tap water, a bacterial biofilm on the inner surface of the re-usable bottles had a predominant influence on the microbiological quality of the carbonated water.

Evaluation of different primers for DNA fingerprinting of Legionella pneumophila serogroup 1 strains by polymerase chain reaction.

A DNA fingerprinting method for the characterization of Legionella pneumophila serogroup 1 strains was established. This method was based on the DNA extraction using Chelex 100 and subsequent PCR analysis using primers under conditions of low stringency. Sixteen single primers were tested for the typing of the 10 epidemiologically unrelated reference strains of L. pneumophila serogroup 1 as well as patient isolates and environmental strains isolated from the water system of a hospital where patients with legionellosis were treated. In addition, a combination of two primers (Lpm-1 and Lpm-2) originally established for the specific detection of Legionella strains was tested. The PCR results were compared with two further subtyping methods, i.e. monoclonal antibody analysis and pulsed-field gel electrophoresis. The type strains Philadelphia 1, Knoxville 1, Allentown 1, Benidorm 0303E, Bellingham 1, and France 5811 could be distinguished clearly in experiments using all of the primers. Depending on the primer used, Heysham 1 and Oxford 4032E showed different DNA profiles. The strains Olda and Camperdown 1 were nearly indistinguishable. In contrast, the analysis by PFGE and MAb subtyping revealed distinct types for all 10 reference strains. The discrimination of the patient isolates from two suspected cases of nosocomial legionellosis and environmental isolates was not possible with the 16 single primers used in the study. However, the PCR assay with the combination of Lpm-1 and Lpm-2 as well as the PFGE and MAb analysis were able to differentiate distinct types. The use of the sequence-specific primers under low-stringency annealing conditions allowed both simultaneous gene detection as well as epidemiological typing of Legionella strains.

No association between Helicobacter pylori genotypes and antibiotic resistance phenotypes within families.

BACKGROUND: Triple therapy combining a proton pump inhibitor with two antibiotics, e.g. clarythromycin (CLR), metronidazole (MTZ) or amoxicillin (AMX), represents the standard in Helicobacter pylori eradication regimens. Resistance to antimicrobial agents, particularly MTZ (up to 56% in Western countries) and CLR (up to 15% in southern Europe), is frequently observed and may be associated with treatment failure [1]. Recently, several studies indicated that individual H. pylori colonies from a single anatomic site may not always yield identical genotypes, or the identical patterns of susceptibility to antibiotics [2-5]. Representative for every single patient we analyzed 27 H. pylori antrum isolates for susceptibility to antimicrobial agents in order to test whether identical H. pylori genotypes exhibit a similar pattern of susceptibility to antibiotics. METHODS: PCR, RELP, PFGE, antibiotic susceptibility testing. RESULTS: H. pylori genotype and antibiotic susceptibility pattern in families do not segregrate. CONCLUSION: Molecular typing of H. pylori from family members does not predict antibiotic susceptibility pattern.