Use of genotypic selection to detect P53 codon 273 CGT>CTT transversion: application to an occupationally exposed population

CGT>CTT transversion in codon 273 of the P53 tumor-suppressor gene is one of the major mutations detected in human tumors. Within an epidemiological framework, we investigated the use of a genotypic selection method to measure this point mutation. The allele-specific polymerase chain reaction (AS-PCR) that was developed was able to detect 10 mutant copies of the gene among a total of 5 x 10(5) wild-type copies. We used this assay to detect CGT>CTT transversions in buccal cell DNA of production workers (n=76) from a viscose factory exposed to carbon disulfide (amongst other pollutants) and in the DNA of non-exposed office workers (n=67). The mutation appeared more frequently in the exposed than in the non-exposed worker who were smokers. The results of the study indicate that occupational exposure results in a significant increase in P53 CGT>CTT transversions and more especially identified occupational exposure in combination with smoking as a significant risk factor for the mutation. We conclude that AS-PCR of the P53 273rd codon transversions is a suitable technique for studying the effects of occupational exposure.

Pontiac fever: an operational definition for epidemiological studies

BACKGROUND

Pontiac fever is usually described in epidemic settings. Detection of Pontiac fever is a marker of an environmental contamination by Legionella and should thereby call for prevention measures in order to prevent outbreak of Legionnaire's disease. The objective of this study is to propose an operational definition of Pontiac fever that is amenable to epidemiological surveillance and investigation in a non epidemic setting.

METHODS

A population of 560 elderly subjects residing in 25 nursing homes was followed during 4 months in order to assess the daily incidence of symptoms associated, in the literature, with Pontiac fever. The water and aerosol of one to 8 showers by nursing home were characterized combining conventional bacterial culture of Legionella and the Fluorescence In Situ Hybridization (FISH) technique that used oligonucleotides probes specific for Legionellaceae. A definition of Pontiac fever was devised based on clinical symptoms described in epidemic investigations and on their timing after the exposure event. The association between incidence of Pontiac fever and shower contamination levels was evaluated to test the relevance of this definition.

RESULTS

The proposed definition of Pontiac fever associated the following criteria: occurrence of at least one symptom among headache, myalgia, fever and shivers, possibly associated with other 'minor' symptoms, within three days after a shower contaminated by Legionella, during a maximum of 8 days (minimum 2 days). 23 such cases occurred during the study (incidence rate: 0.125 cases per person-year [95% CI: 0.122-0.127]). A concentration of Legionella in water equal to or greater than 10(4).L(-1) (FISH method) was associated with a significant increase of incidence of Pontiac fever (p = 0.04).

CONCLUSION

Once validated in other settings, the proposed definition of Pontiac fever might be used to develop epidemiological surveillance and help draw attention on sources of Legionella.

Multiplication intra-amibienne de Legionella pneumophila et rôle potentiel des amibes dans la transmission de la légionellose

Legionnaires' disease is one of the major infectious risks related to hospital water systems. It is commonly accepted, that the disease is transmitted to man mostly by inhalation of water aerosols contaminated by Legionella pneumophila. The ability of L. pneumophila to multiply intracellularly within some amoebae better explains the ecology, the pathogenicity, and the virulence of this bacterium against human alveolar macrophages. The presence of these amoebae in water systems located where cases of Legionnaire's disease broke out, partly explains the difficulty in eradicating Legionella. Some studies also show that amoebae can play a major role in the transmission of the disease to man. Some other studies point out that inhaled amoebae could be involved in the pathogenesis of Legionnaire's disease. Future strategies to prevent the transmission of Legionella will probably have to include efficient treatments against amoebae.

Legionella anisa, a possible indicator of water contamination by Legionella pneumophila

Legionella anisa is one of the most frequent species of Legionella other than Legionella pneumophila in the environment and may be hospital acquired in rare cases. We found that L. anisa may mask water contamination by L. pneumophila, suggesting that there is a risk of L. pneumophila infection in immunocompromised patients if water is found to be contaminated with Legionella species other than L. pneumophila.

[Study of 12 epidemical cases of legionnaire's disease occurred in Meurthe-et-Moselle (France) between July and August 2004]

PATIENTS AND METHOD

To describe epidemiological, clinical, biological, radiological data and therapeutic features of legionnaire's disease during an outbreak occurring in Meurthe-et-Moselle between July-August 2004.

RESULTS

12 cases were recorded including 11 men, 6 smokers, 4 alcoholo-nicotinic, 3 diabetics, 3 with hemopathy, 1 with corticotherapy; in one case no risks factors were found; mean age was 68.5 years [minimum=48; maximum=96]. Nine cases had sudden symptoms. Nine cases had a fever up to 40 degrees C, 9 with dyspnoea, 7 with cough, 7 with a relative bradycardia, 3 with diarrhoea, 3 felt faint, 3 with confusion. Radiology: unilateral unilobe localisation in 10 cases. Biological data: cytolysis in 8 cases, CRP >300 mg/l in 8. The diagnosis confirmed with urinary antigen of Legionella pneumophila serogroup 1 (UrAgLp1) in 12 cases. In 2 cases, UrAgLp1 appeared negative between 3rd and 10th day after the beginning of a treatment although UrAgLp1 was positive before the treatment. In all cases, the first serology realised during first days following occurrence the first symptoms remained negative. Two serology of control in four were positive. One search of L. pneumophila serogroup 1 in sputum was positive in 7. Bitherapy was used in 7 cases with preferential association: fluoroquinolone+rifampicin. Two patients died. Origin of the contamination remains unknown.

CONCLUSION

Culture of Legionella is essential, in epidemic context, to compare clinical and environmental Legionella and to locate the origin of contamination.

Prevention and control of health care-associated waterborne infections in health care facilities

The current article is a review of the public health risks attributable to waterborne pathogens in health care. The consequences of health care-associated infections (HAIs) are discussed. Not only are Legionella spp involved in HAIs, but also Pseudomonas aeruginosa, other gram-negative microorganisms, fungi, and amoeba-associated bacteria. This is particularly noteworthy among immunocompromised patients. New prevention strategies and control measures brought about through advanced planning, facility remodelling and reconstruction, disinfection, and filtration have resulted in a significant reduction of the incidence of waterborne HAIs. The positive consequences of a comprehensive multibarrier approach including prevention and control programs in health care facilities are discussed. Environmental cultures are now integrated within the infection control program of some European countries. In high-risk areas, the application of disposable sterile point-of-use filters for faucets and shower heads appears to be the practice of choice to efficiently control waterborne pathogens and to prevent infections.

Escherichia coli behavior in the presence of organic matter released by algae exposed to water treatment chemicals

When exposed to oxidation, algae release dissolved organic matter with significant carbohydrate (52%) and biodegradable (55 to 74%) fractions. This study examined whether algal organic matter (AOM) added in drinking water can compromise water biological stability by supporting bacterial survival. Escherichia coli (1.3 x 10(5) cells ml(-1)) was inoculated in sterile dechlorinated tap water supplemented with various qualities of organic substrate, such as the organic matter coming from chlorinated algae, ozonated algae, and acetate (model molecule) to add 0.2 +/- 0.1 mg of biodegradable dissolved organic carbon (BDOC) liter(-1). Despite equivalent levels of BDOC, E. coli behavior depended on the source of the added organic matter. The addition of AOM from chlorinated algae led to an E. coli growth equivalent to that in nonsupplemented tap water; the addition of AOM from ozonated algae allowed a 4- to 12-fold increase in E. coli proliferation compared to nonsupplemented tap water. Under our experimental conditions, 0.1 mg of algal BDOC was sufficient to support E. coli growth, whereas the 0.7 mg of BDOC liter(-1) initially present in drinking water and an additional 0.2 mg of BDOC acetate liter(-1) were not sufficient. Better maintenance of E. coli cultivability was also observed when AOM was added; cultivability was even increased after addition of AOM from ozonated algae. AOM, likely to be present in treatment plants during algal blooms, and thus potentially in the treated water may compromise water biological stability.

Effet du chlore sur la colonisation bactérienne d'un réseau expérimental de distribution d'eau

La contamination bactérienne de la phase eau d'un réseau de distribution résulte d'une multiplication des bactéries sur les parois des canalisations d'eau (biofilms) suivie de leur arrachage et de leur transport dans le flux circulant. Ce travail met en évidence l'effet du chlore, d'une part, sur la formation des biofilms et, d'autre part, sur des biofilms déjà constitués. Des éprouvettes de matériaux neufs introduites dans des eaux présentant des concentrations en chlore total variant de 2,4 à 0,02 mg/l et véhiculant entre 0,5 x 106 et 5 x 105 cellules bactériennes/mi (dont 1 à 10 % de bactéries cultivables) sont rapidement colonisées (106 à 108 cellules/cm2). L'effet du chlore est sensible sur les cellules totales pour des concentrations de l'ordre de 1 à 2,4 mg/l. Sur les bactéries cultivables, un ralentissement de la croissance du biofilm est observé dès 0,3 mg/1 de chlore total. Par contre, des résiduels de 0,02 ou 0,05 mg/l sont sans effet sur la cinétique de formation des biofilms. Des résiduels moyens de chlore total compris entre 2,3 et 3,4 mg/l appliqués en continu pendant 14 jours sur un biofilm constitué d'environ 8,7 x 106 cellules par cm2 (1,7 % de bactéries cultivables), entraînent l'élimination d'environ 90 % des bactéries fixées (abattement d'1 logarithme) durant les premiers jours d'exposition. L'altération du biofilm exposé à un résiduel de chlore total de l'ordre de 1,3 mg/l est identique, mais toutefois plus étalée dans le temps. Ces essais réalisés sur des éprouvettes de PVC, PE et mortier de ciment n'ont pas permis la mise en évidence de comportements différents de ces 3 supports..

Mycobacterium xenopi and drinking water biofilms

The ability of Mycobacterium xenopi to colonize an experimental drinking water distribution system (a Propella reactor) was investigated. M. xenopi was present in the biofilm within an hour following its introduction. After 9 weeks, it was always present in the outlet water (1 to 10 CFU 100 ml(-1)) and inside the biofilm (10(2) to 10(3) CFU cm(-2)). Biofilms may be considered reservoirs for the survival of M. xenopi.

Carbon disulfide cytotoxicity on cultured cardiac myocyte cell of rats

Although mostly epidemiological studies suggested that carbon disulfide produces cardiovascular effects in occupationally exposed workers, little is known about its cellular mechanism. The purpose of the present study was to evaluate the functional and histological effects on cardiac myocytes cultured under the condition of carbon disulfide exposure. Cardiac myocytes were isolated from neonatal rat ventricles by trypsin dispersion and cultured for 3 days in a full (Dulbecco's modified eagle medium) medium containing 2% calf serum. Thereafter the myocytes (10(6) myocytes/culture flask) were incubated with carbon disulfide at (CS(2)) the concentrations of 0, 20, 40, and 80 micromol/mL) for 24h. The beating arrest rate of myocytes for each group was examined and succinodehydrogenase (SDH) activity in the myocardial cells was also assessed by cytochemical method, and morphological examination was also performed. We found that the beating arrest rate of cardiac myocytes increased with increasing exposure levels. Vacuolization and pseudopodia may be seen in the cytoplasm of exposure group. SDH activity decreased with increasing exposure levels. The results suggested that CS(2) has a direct cytotoxic effect which is dose dependent. The biochemical mechanism may be a reduction of the availability of energy of the cardiac cytocyte in the form of ATP, resulting in a decrease of contractility by lacking of energy.

Cardiovascular effects of carbon disulfide: meta-analysis of cohort studies

Objectives were to review the evidence of cardiovascular effects of carbon disulfide (CS2) on exposed workers from different cohort studies. Databases searched included MEDLINE, TOXLINE, and OSHtM Database (CD-ROM). Reference lists of reports and reviews were also searched. To be included in the analysis, a study had to have been a cohort study on cardiovascular effects of carbon disulfide with at least one outcome of interest. Every report was independently read using the Lichtenstein scale, General information of each study and relative risk estimates were calculated with 95% confidence intervals using the fixed-effects model. Pooled relative risks were calculated by the Dersimonian-Laird method basing on the random-effects model. Eleven cohort studies were identified in an extensive literature review. Pooled RR value was 1.56 and its 95% confidence interval was from 1.12 to 2.1, which showed CS2 exposure has feeble correlation with the prevalence of cardiovascular diseases. It is proved that meta-analysis is a sensitive method for combining different results in occupational epidemiology.

[Drinking water and urinary stones. Which drinking water and which modalities of diuresis?]

Urologists frequently advise a high fluid intake to their patients with calcium stones, but apart from this simple advice, they often have few convincing arguments. This article describes the various types of drinking water available in France (mineral water, spring water, tap water), the legislation concerning drinking water, and the ions that must be taken into account for long-term forced diuresis. After studying their composition and adapting the dietary advice (particularly concerning dairy foods) to this ionic composition, various types of water can be advised to patients, including tap water, most types of spring water, but not all mineral waters.

Carbon disulfide cytotoxicity on cultured cardiac myocytes of rats

Although epidemiological studies have suggested that carbon disulfide produces cardiovascular effects in occupationally exposed workers, little is known about its cellular mechanism. The purpose of the present study was to evaluate the functional and histological effects on cardiac myocytes cultured under a condition of carbon disulfide exposure. Cardiac myocytes were isolated from neonatal rat ventricles by trypsin, dispersed and cultured for 3 days in a full Dulbecco's Modified Eagle Medium containing 2% calf serum. Then the myocytes (10(6) myocytes/mL) were incubated with carbon disulfide at concentrations of 0, 20, 40, and 80 micromol/mL for 24 h. The beating arrest rate of myocytes for each group was examined, succinodehydrogenase (SDH) activity in the myocardial cells was assessed using a cytochemical method, and a morphological examination was performed. We found that the beating arrest rate of cardiac myocytes increased with increasing exposure levels. Vacuolization and pseudopodia could be seen in the cytoplasm of the exposed group. SDH activity decreased with increasing exposure levels. The results suggest that CS2 has a direct and dose-dependent cytotoxic effect. The biochemical mechanism may be a reduction of the availability of energy (adenosine triphosphate) to cardiac myocytes, resulting in a decrease of contractility by lack of energy.

Hygiene and health - the need for a holistic approach

The holistic principles of hygiene and public health have contributed substantially to an increase in life expectancy by more than 30 years and in life quality since the beginning of the 20th century. Frank, Pettenkofer, Nightingale, Pasteur, Lister, and Koch have been pioneering protagonists of the holistic approach to hygiene and public health. Socioeconomic development and related factors such as nutrition status and food hygiene, housing conditions, water supply and sewage systems, and education (including motivation for personal hygiene) have obviously been of more importance for life expectancy and life quality than progress in curative medicine, such as availability of microbial diagnosis, vaccination, and antibiotics. Today, new risk factors for infectious diseases arise, even in developed countries. These risk factors arise from emerging pathogens, antibiotic-resistant microorganisms, changing demographic patterns, an increasing amount of ambulatory and home care, socioeconomic and environmental changes, technical environments, worldwide distribution of food, and changing human behavior with a decreased awareness of microbial threats. These new challenges worldwide make a renewal of the holistic approach of hygiene and public health both urgent and necessary. On the basis of historic experience, policies that focus on surveillance and control, diagnosis, and therapy only can be assumed to be both insufficient and inefficient in controlling the new challenges in infectious diseases. Experiences in Germany with a holistic hospital hygiene strategy since 1976 provide encouragement for the promotion of holistic health concepts. Risk assessment, risk management, and risk communication are basic steps of a modern holistic strategy. Hygiene has the potential to act as a moderator of diverging positions of different disciplines within this renewed approach.

A new analytical tool to assess health risks associated with the virological quality of drinking water (EMIRA study)

This work assessed the risks associated with the virological quality of tapwater using a molecular analytical tool manageable in a field survey. It combined a daily epidemiological follow-up of digestive morbidity among a panel of volunteers and a microbiological surveillance of drinking water. RT-PCR was used for detection of enterovirus, rotavirus and astrovirus. 712 cases of acute digestive conditions occurred in the 544 volunteers. 38% (9/24) raw water and 23% (10/44) tap water samples were positive for at least one virus marker with 9/10 positive tap water samples complying with bacterial criteria. No statistically significant association was found between the presence of viral markers and observed incidence of digestive morbidity. However, when an outbreak occurred, enterovirus and rotavirus RNA was detected in the corresponding stored tap water samples. Sequencing of the amplified fragments showed that the rotavirus detected was of bovine origin. This work demonstrated that enteric virus markers were common in tapwater of the study communities (characterised by a vulnerable raw water) despite absence of bacterial indicators. Tangential ultrafiltration coupled to RT-PCR allowed a simultaneous and fast detection of the study viruses from environmental samples. This process is a promising tool usable for virological water surveillance, in as much the corresponding know-how is transferred to the field professionals.

Genotoxic activity of five haloacetonitriles: comparative investigations in the single cell gel electrophoresis (comet) assay and the ames-fluctuation test

Halogenated acetonitriles (HANs) are known to be water disinfectant by-products. Their mutagenicity and carcinogenicity have been shown in different test systems in vivo and in vitro. They also have clastogenic properties. In this study, the ability of HAN to induce single-strand breaks on the DNA of HeLa S3 cells was investigated using the single-cell gel electrophoresis (SCGE) assay, which could be a good tool with which to evaluate the genotoxicity of chlorinated water. The results were compared to those obtained in the Ames fluctuation test using the Salmonella typhimurium TA 100 strain without activation. With the Ames fluctuation test, a mutagenic effect was observed for chloroacetonitrile (MCAN), dichloroacetonitrile (DCAN), and trichloroacetonitrile (TCAN). No mutagenic effect was found with bromoacetonitrile (MBAN) or dibromoacetonitrile (DBAN). In the SCGE assay, all five HANs induced DNA damage in HeLa S3 cells, increasing the mean tail moment significantly. For each compound, a dose-effect relation was observed. This study shows that the SCGE assay has greater sensitivity for assessing the genotoxicity of HAN than does the Ames-fluctuation test. Brominated acetonitriles were more genotoxic than chlorinated acetonitriles in the SCGE assay, and the genotoxicity increased with the number of halogenated atoms of the compound. This behavior had already been found with other genotoxicity tests.

Comparison of membrane filtration methods for the recovery of legionellae from naturally contaminated domestic drinking water supplies

We compared four methods for the cultural recovery of legionellae from naturally contaminated water samples: (A) inoculating 1 and 0.1 ml directly on the selective solid growth medium, (B) filtration through cellulose nitrate membrane filters and inoculating the resuspended residue corresponding to 100 and 10 ml of the original sample on the medium, (C) filtration through polycarbonate filters and inoculating the resuspended residue corresponding to 100 and 10 ml of the original sample, and (D) filtration of 100 and 10 ml through cellulose nitrate filters and incubating the filter directly on the medium. Of the water samples tested in parallel, 103 samples tested positive for legionellae in at least two of these methods. The mean number of CFU/ml recovered by methods A, B, C, and D werte 5.45, 1.85, 1.70, and 2.26, respectively. The differences between the methods proved to be highly significant except for methods B and C (p = 0.112), the results of which correlated closely with each other (r = +0.96). In comparison with method A the recovery rates of methods B, C, and D were found to be 60, 57, and 69%, respectively. We recommend the use of method A for the recovery of legionellae at concentrations of > or = 1 CFU/ml. If legionellae below this concentration are to be detected we recommend method D as the easiest and most sensitive technique.

[Waterborne microbiological risk assessment: a state of the art and perspectives]

Microbiological contamination is the most common threat related to drinking water. In developed countries, the current health system provides a good level of protection. However, some facts point out the need to develop further tools for better management of the waterborne risk. Several outbreaks have occurred in the United-States in the past decade. They were most often caused by tap water contamination associated with parasites and viruses, despite good compliance of the water treatment procedures. The chemical risk assessment methodology set up at the end of the 70's can now be applied for microbiological risks. This approach allowed the US authorities to improve their control on waterborne infection risks. Although limited, surveillance data suggest that to date. France has not encountered such outbreaks. However, the baselines and principles of risk management in that area should be also be optimized and updated. This work underlines the limits of the current risk management system. A literature review on microbiological risk assessment is first presented. Applications of this methodology are then commented, advantages and limits of the microbiological risk assessment approach in France are discussed.