Detection of hospital wastewater genotoxicity with the SOS chromotest and Ames fluctuation test.

The genotoxic potential of Rouen University Hospital wastewater was evaluated by the SOS chromotest (on Escherichia coli PQ37) and Ames fluctuation test on Salmonella typhimurium strains TA 98 and TA 100 without metabolic activation. The samples were taken during the hospital maximal activity period (8:00 a.m. to 6:00 p.m.) over three one-week periods of the year. The simultaneous use of SOS chromotest and Ames fluctuation test allows us to carry out a preliminary screening of the hospital wastewater and to gain some insight by which mechanism the genotoxic compounds act. Out of a total of 18 daytime unconcentrated samples tested, 10 (55%) are positive in at least one assay. The two tests have different sensitivity. Indeed, nine genotoxic samples (50%) are detected by the Ames test, and four (22%) by the SOS chromotest. Distribution and intensity of the genotoxic response are different at the three periods. In order to explain this phenomenon, the influence of the rain levels is discussed. This work showed that the hospital wastewater samples tested were overall genotoxic, the response intensity being inflected by the pluviometry. Efforts are now under way to try to identify one or several genotoxic compounds in order to take precautionary measures to limit their release in hospital wastewaters.

Glutaraldehyde in hospital wastewater.

Glutaraldehyde (GA) solutions are widely used in hospitals to disinfect reusable fiber-optic endoscopes. These solutions are dumped after use in the aquatic environment without any particular safety precautions. Taking into account the quantity of GA consumed daily and the released water volume, the predicted hospital wastewater concentration was estimated at 0.50 mg/L. To measure the real GA concentration present in hospital wastewater, we developed an analytical technique that is simple, sensitive, and reliable. This method consists of a water sample concentration and purification by solid phase extraction and then a spectrophotometric determination. This analytical method was used for a 1-week surveillance program at Rouen University Hospital (2,600 beds). The wastewater tested showed the presence of a concentrated peak approximately eight times higher than the predicted wastewater concentration. The environmental impact of GA release into the aquatic environment was then studied. A predicted no-effect concentration (PNEC) < 1 microg/L was calculated. In most situations the predicted environmental concentration (PEC) was found to be <0.5 microg/L taking into account the hospital wastewater dilution in its way to the sewage treatment plant and GA biodegradation. The PEC/PNEC ratio is then < 1, showing that this release are not expected to present a significant risk to the aquatic environment. However in situations of insufficient dilution or of major release, the PEC/PNEC ratio become > 1, and an environmental risk should be expected. An internal prevention program of the various hospital departments to assure GA rational use, and a release spreading would give an additional safety margin to consider GA as safe in terms of environmental risk.

Microbiologic contamination study of nebulizers after aerosol therapy in patients with cystic fibrosis.

BACKGROUND: To evaluate the contamination of delivery systems after an aerosol therapy session in patients with cystic fibrosis who have chronic Pseudomonas aeruginosa infection. METHODS: Fifty-three patients with cystic fibrosis were enrolled in the study from March 1996 to June 1997. All patients were age 7 years or older and had P aeruginosa infection. They also had been treated with recombinant deoxyribonuclease and were capable of producing sputum for culture. RESULTS: Nine devices were excluded for the study. A total of 44 nebulizers were included: 37 from patients with P aeruginosa colonization with a count of 10(6) colony-forming units/mL or more and 7 with a count of between 10(5) colony-forming units/mL and 10(6) colony-forming units/mL. CONCLUSION: This study demonstrates that in the absence of cleaning, nebulizers of patients with cystic fibrosis who are infected with P aeruginosa are likely to be contaminated by a pathogenic flora.

Hydrogen peroxide gas plasma sterilization is effective against Cryptosporidium parvum oocysts.

The aim of this work was to evaluate in an immunosuppressed rat cryptosporidiosis model a new method that combines vacuum and low-temperature hydrogen peroxide gas plasma for sterilization of endoscopic material contaminated by Cryptosporidium parvum. Rats were challenged with oocysts either air-dried or air-dried and treated with vacuum alone or associated with gas plasma. No rat was found infected after gas plasma exposure of oocysts, whereas vacuum or air-drying alone resulted only in a decreased infectivity.

[Microbiological aspects of nosocomial risks of suction bottles]. / Aspects microbiologiques des risques nosocomiaux des flacons d'aspiration.

The suction and collection of more or less contaminated biological fluids or regurgitated matter in reusable glass bottles may be responsible for nosocomial infections. Based on a study conducted in 49 cases, the authors try to demonstrate the microbiological risks in the operating theatre of changing and transport of these bottles and the risks for the environment and the hospital staff in the cleaning of these bottles. The connection to the vacuum system was found to be contaminated in 26.1% of cases, the environment of the waste evacuation and cleaning zone was contaminated in 59.2% of cases and, in 28.6% of cases, the microorganism detected was identical to that in the bottle. All of these factors suggest that a disposable system, although apparently more expensive, ensures a greater degree of safety, avoiding the problems related to transport emptying and elimination of these bottles.