A Simple and Widely Applicable Method for Preparing Homogeneous and Stable Quality Control Samples in Water Microbiology

Test strains suspended in skim milk, quickly frozen in dry ice-ethanol, and stored at - 70°C can be used as quality control samples that are immediately available by quickly thawing at 37°C. The samples remain homogeneous and stable for at least 1 year, except for Aeromonas hydrophila, which decreases 20 to 30% in 1 year.     

Quality control of membrane filters for bacteriological examination of water

A standard protocol for quality control of membrane filters for bacteriological examination of water is presented. It is based on the screening test proposed by Brenner and Rankin (1990) making use of Enterobacter aerogenes ATCC 49701 as a test strain and tryptone soya agar as medium for incubation. The protocol is standardized to achieve adequate statistical power. A diluted culture of the test strain is filtered through samples of 20 filters of a test batch and a reference batch. Filters and colony morphology are screened for visual defects and criteria for acceptance are given. Variation in the colony counts within the batches is checked for randomness, because filters of a batch must be of equal quality and must not cause overdispersion. The protocol requires that the mean count of the reference batch should lie between 50 and 80 cfu. Homogeneity of the counts (i.e. variation no greater than random) between the batches is tested at a 99% confidence level. In this way an actual difference in recovery between filter batches of 13% to 16% can be detected with a probability of 90%. Results of several tests within this laboratory show good reproducibility.     

Risk of otitis externa after swimming in recreational fresh water lakes containing Pseudomonas aeruginosa.

OBJECTIVE--To determine whether an outbreak of otitis externa was due to bathing in recreational fresh water lakes and to establish whether the outbreak was caused by Pseudomonas aeruginosa in the water. DESIGN--Matched case-control study. SETTING--The Achterhoek area, the Netherlands. SUBJECTS--98 cases with otitis externa and 149 controls matched for age, sex, and place of residence. MAIN OUTCOME MEASURES--Odds ratios for type of swimming water and frequency of swimming; presence of P aeruginosa in ear swabs and fresh water lakes. RESULTS--Otitis externa was strongly associated with swimming in recreational fresh water lakes in the previous two weeks (odds ratio 15.5 (95% confidence interval) 4.9 to 49.2) compared with non-swimming). The risk increased with the number of days of swimming, and subjects with recurrent ear disease had a greatly increased risk. The lakes met the Dutch bathing water standards and those set by the European Commission for faecal pollution in the summer of 1994, but P aeruginosa was isolated from all of them, as well as from the ear swabs of 78 (83%) of the cases and 3 (4%) of the controls. CONCLUSIONS--Even when current bathing water standards are met, swimming can be associated with a substantial risk of otitis externa because of exposure to P aeruginosa. People with recurrent ear disease should take special care when swimming in waters containing P aeruginosa.     

Modeling Virus Adsorption in Batch and Column Experiments

Experiments with batch suspensions, recirculating columns and flow-through columns have been carried out involving a sandy soil and five bacteriophages: MS2, PRD1, X174, Q and PM2. In batch and recirculating column experiments, attachment and detachment rate coefficients were determined by fitting a two-parameter (attachment and detachment) model. In general, attachment and detachment rate coefficients were not found to be significantly different between the two kinds of experiments. There was one exception, however: MS2 appeared to detach faster in the presence of strong advective flow. In the case of flow-through column experiments, it is shown that a two-site model, with adsorption to equilibrium and kinetic sites, fits the breakthrough curves of all the phages, except PM2, satisfactorily. A one-site kinetic model was found to be appropriate for phage PM2. A small proportion of bacteriophages MS2, PRD1, and Q adsorbed to equilibrium sites, whereas a large proportion of X174 adsorbed to equilibrium sites. Such a distinction between adsorption to equilibrium and kinetic sites cannot be made in the case of batch or recirculating column experiments. Kinetic attachment rate coefficients were found to be significantly higher for the bacteriophages with presumably stronger negative charge. This may be ascribed to the presence of multivalent cations. Under these conditions, bacteriophage X174 appears to behave more conservatively than more negatively charged viruses, and may then be a better choice as a relatively conservative tracer for virus transport through the subsurface.     

First real-world experience with mobile health telemonitoring in adult patients with congenital heart disease

Background

Arrhythmias and heart failure are common and invalidating sequelae in adult patients with congenital heart disease (CHD). Mobile health (m-Health) enables daily monitoring and a timely response that might prevent deterioration. We present an observational prospective registry to evaluate feasibility of an m‑Health telemonitoring program for managing arrhythmia, heart failure and blood pressure in symptomatic adults with CHD.

Methods

Symptomatic adult patients with CHD are enrolled in an m‑Health telemonitoring program, which evaluates single-lead ECG, blood pressure and weight measurements. In case of symptoms extra measurements could be performed. Data are collected by mobile apps, matched with individualised thresholds. Patients are contacted if thresholds were exceeded or if arrhythmias were found, for treatment adjustments or reassurance. Data on emergency care utilisation, hospitalisation and patient-reported outcome measures are used to assess quality of life and self-management.

Results

129 symptomatic CHD patients were invited to participate, 55 participated. Reasons for refusing consent included too time consuming to participate in research (30) and to monitor vital signs (14). At baseline 22 patients were in New York Heart Association class ≥ II heart failure, 43 patients had palpitations or documented arrhythmias, and 8 had hypertension. Mean follow-up was 3.0 months, one patient dropped out, and adherence was 97%.

Conclusion

The first results indicate that this program is feasible with high adherence.

     

The impact of temperature on the inactivation of enteric viruses in food and water: a review

Temperature is considered as the major factor determining virus inactivation in the environment. Food industries, therefore, widely apply temperature as virus inactivating parameter. This review encompasses an overview of viral inactivation and virus genome degradation data from published literature as well as a statistical analysis and the development of empirical formulae to predict virus inactivation. A total of 658 data (time to obtain a first log(10) reduction) were collected from 76 published studies with 563 data on virus infectivity and 95 data on genome degradation. Linear model fitting was applied to analyse the effects of temperature, virus species, detection method (cell culture or molecular methods), matrix (simple or complex) and temperature category (<50 and ≥50°C). As expected, virus inactivation was found to be faster at temperatures ≥50°C than at temperatures <50°C, but there was also a significant temperature-matrix effect. Virus inactivation appeared to occur faster in complex than in simple matrices. In general, bacteriophages PRD1 and PhiX174 appeared to be highly persistent whatever the matrix or the temperature, which makes them useful indicators for virus inactivation studies. The virus genome was shown to be more resistant than infectious virus. Simple empirical formulas were developed that can be used to predict virus inactivation and genome degradation for untested temperatures, time points or even virus strains.     

Monitoring of waterborne pathogens in surface waters in amsterdam, the Netherlands, and the potential health risk associated with exposure to cryptosporidium and giardia in these waters

The water in the canals and some recreational lakes in Amsterdam is microbiologically contaminated through the discharge of raw sewage from houseboats, sewage effluent, and dog and bird feces. Exposure to these waters may have negative health effects. During two successive 1-year study periods, the water quality in two canals (2003 to 2004) and five recreational lakes (2004 to 2005) in Amsterdam was tested with regard to the presence of fecal indicators and waterborne pathogens. According to Bathing Water Directive 2006/7/EC, based on Escherichia coli and intestinal enterococcus counts, water quality in the canals was poor but was classified as excellent in the recreational lakes. Campylobacter, Salmonella, Cryptosporidium, and Giardia were detected in the canals, as was rotavirus, norovirus, and enterovirus RNA. Low numbers of Cryptosporidium oocysts and Giardia cysts were detected in the recreational lakes, despite compliance with European bathing water legislation. The estimated risk of infection with Cryptosporidium and Giardia per exposure event ranged from 0.0002 to 0.007% and 0.04 to 0.2%, respectively, for occupational divers professionally exposed to canal water. The estimated risk of infection at exposure to incidental peak concentrations of Cryptosporidium and Giardia may be up to 0.01% and 1%, respectively, for people who accidentally swallow larger volumes of the canal water than the divers. Low levels of viable waterborne pathogens, such as Cryptosporidium and Giardia, pose a possible health risk from occupational, accidental, and recreational exposure to surface waters in Amsterdam.     

Mobile health in adults with congenital heart disease: current use and future needs

ObjectiveMany adults with congenital heart disease (CHD) are affected lifelong by cardiac events, particularly arrhythmias and heart failure. Despite the care provided, the cardiac event rate remains high. Mobile health (mHealth) brings opportunities to enhance daily monitoring and hence timely response in an attempt to improve outcome. However, it is not known if adults with CHD are currently using mHealth and what type of mHealth they may need in the near future.MethodsConsecutive adult patients with CHD who visited the outpatient clinic at the Academic Medical Center in Amsterdam were asked to fill out questionnaires. Exclusion criteria for this study were mental impairment or inability to read and write Dutch.ResultsAll 118 patients participated (median age 40 (range 18–78) years, 40 % male, 49 % symptomatic) and 92 % owned a smartphone. Whereas only a small minority (14 %) of patients used mHealth, the large majority (75 %) were willing to start. Most patients wanted to use mHealth in order to receive more information on physical health, and advice on progression of symptoms or signs of deterioration. Analyses on age, gender and complexity of defect showed significantly less current smartphone usage at older age, but no difference in interest or preferences in type of mHealth application for the near future.ConclusionThe relatively young adult CHD population only rarely uses mHealth, but the majority are motivated to start using mHealth. New mHealth initiatives are required in these patients with a chronic condition who need lifelong surveillance in order to reveal if a reduction in morbidity and mortality and improvement in quality of life can be achieved.     

Long-Term Inactivation Study of Three Enteroviruses in Artificial Surface and Groundwaters, Using PCR and Cell Culture

Since the transmission of pathogenic viruses via water is indistinguishable from the transmission via other routes and since the levels in drinking water, although significant for health, may be too low for detection, quantitative viral risk assessment is a useful tool for assessing disease risk due to consumption of drinking water. Quantitative viral risk assessment requires information concerning the ability of viruses detected in drinking water to infect their host. To obtain insight into the infectivity of viruses in relation to the presence of virus genomes, inactivation of three different enteroviruses in artificial ground and surface waters under different controlled pH, temperature, and salt conditions was studied by using both PCR and cell culture over time. In salt-peptone medium, the estimated ratio of RNA genomes to infectious poliovirus 1 in freshly prepared suspensions was about 10⁰. At 4°C this ratio was 10³ after 600 days, and at 22°C it was 10⁴ after 200 days. For poliovirus 1 and 2 the RNA/infectious virus ratio was higher in artificial groundwater than in artificial surface water, but this was not the case for coxsackievirus B4. When molecular detection is used for virus enumeration, it is important that the fraction of infectious virus (based on all virus genomes detected) decays with time, especially at temperatures near 22°C.     

Gene mapping by chromosome spot hybridization

A method is described for the localization of cloned single-copy genes to flow-sorted chromosomes. Chromosomes were sorted directly onto nitrocellulose filters and the chromosomal DNA was subsequently hybridized with gene-specific radioactively labeled DNA probes. Mild aspiration of the filters during sorting was applied to collect the deflected chromosomes in a small spot. Sorting of 10,000-30,000 chromosomes was sufficient to detect gene-specific hybridization with single-copy DNA probes. Using this technique, we have sublocalized the human c-myb oncogene to 6q21-q23 by sorting translocated chromosomes with breakpoints in the q21 and q23 region of chromosome 6. Chromosome spot hybridization appears to be a rapid and simple method to assign cloned genes to chromosomes. Hybridization of an unlocalized gene probe to spots of chromosomes pre-enriched by velocity sedimentation can quickly narrow the choice of chromosomes which need to be sorted. Conversely, individual chromosomes in a flow karyotype can be identified by hybridizing sorted chromosomal DNA with chromosome-specific DNA probes.