Zentralblatt fur Bakteriologie, Mikrobiologie und Hygiene. 1. Abt. Originale B, Hygiene最新文献

For several years formaldehyde-gas-underpressure procedures are increasingly used for disinfection and sterilization of medical thermolabile instruments. In many places, however, uncertainty and sceptism, if these methods are sufficient in the medical field, are existing. This is understandable, since no generally test instructions are available. The principal suitability of gaseous formaldehyde for disinfection and sterilization, however, had been demonstrated by several investigators. Precondition for reliable efficacy during routine use is an apparatus which is equipped with feed-back techniques and which guarantees the bactericidal and fungicidal activity required for medical use. Decontamination procedures on the basis of gaseous formaldehyde under normal conditions of temperature and pressure must be regarded as unsafe. St. faecalis and the spores of B. stearothermophilus showed the highest formaldehyde resistance within the group of common biological testorganisms. In order to test the efficacy of corresponding procedures testorganisms have to be placed into testdevices with small lumina. The penetration of these devices to formaldehyde and vapour should be similar to that of the longest instruments with the smallest lumina, which are intended to be decontaminated by the testprocedure.

Time concentration relations in virus-disinfection by formaldehyde, benzalkonium-chloride, ethanol and isopropanol are evaluated. The exposure time needed to reduce the number of plaque-forming units (PFU) by 10(-3) (99.9%) at a given disinfectant concentration was determined. Influenzavirus, Coxsackie B viruses, Herpesvirus and Mumpsvirus were used in the experiments. Formaldehyde is effective at very low concentrations, provided that sufficient time is allowed for reaction, but has little use in short-term applications. Alcohols act very rapidly at the optimal concentration, but are almost completely ineffective if the reagent is only slightly diluted. Isopropanol does not neutralize entero-viruses to any considerable extent. The effect of the alcohols on viruses is greatly enhanced by the addition of alkali. An 80% (or higher) ethanol solution containing 0.01 n NaOH is very promising as a potent antiviral disinfectant for skin and surface decontamination. Even closely related virus types may differ greatly in their sensitivity to ethanol. The Herpesvirus hominis has a peculiarly high sensitivity to benzalconiumchloride, a sensitivity which is not shared by the Influenzavirus and enteroviruses.

All of 67 samples of sewage, taken at different points from the sewers of the Bonn University hospitals, contained phenolic substances in concentrations ranging from 0.09 mg/l to 5.05 mg/l. About 0.15 mg/l might be caused by human excretion of phenolics. Six samples contained free formaldehyde (2.72-28.38 mg/l), five samples chlorine (0.1 to 1 mg/l). In the main sewer of the hospitals the substances were diluted, but a measurable concentration reached the communities sewage lines. There were no characteristic diurnal changes of the concentrations. Measurements of biological oxygen demand (BOD) in native and artificially prepared sewages using o Sapromat showed, that pure phenol, o-phenylphenol, chlorine and formaldehyde in concentrations as found do not reduce the biologic decomposition. With the exception of chlorine, the substances seem to be integrated into the aerobic microbial decomposition. 3,4 chlorcresol, instead, is able to retard the begin and reduce the amount of decomposition in concentrations, which were found as maximal concentrations for phenolic substances in the sewage samples. Two of 67 samples with the highest concentrations of disinfectants revealed measurable toxity in form of a BOD reduction. The other samples, instead, showed a faster microbiological decomposition than comparable artificial sewage.

Sewage sludge-garbage composts which are used as soil conditioners usually contain high concentrations of PAH. A risk for human health could arise if the use of such composts leads to high concentrations of PAH in the soil and these are taken up by plants for human consumption. We investigated the fate of PAH introduced into the soil with sewage sludge-garbage compost and the possible association with the microbial flora. Field investigations in wineyards during more than 18 months showed no reduction of PAH in the soil. There was no seasonal variation and no correlation between microbial data and PAH concentrations in the wineyards treated with compost or untreated. From these findings it must be concluded that under natural conditions PAH persist in the soil for a long time and are not taken up by plants to an appreciable extent.

The possible destruction in the soil of PAH present in sewage sludge-garbage composts in considerable amounts has been studied under various conditions. Sandy and loamy soil were mixed with the compost and kept in a climate chamber at 20 degrees C, 25 degrees C and 28 degrees C with 30% and 80% relative moisture. One part of the samples was illuminated the other kept in the dark. Control samples with and without compost were sterilized. PAH determinations, bacterial counts on Moutonagar and counts of the actinomycetes were carried out in regular intervals. No influence of temperature, moisture or light could be demonstrated under the experimental conditions. No difference in the behaviour of PAH concentrations in sterilized and nonsterilized soil samples during the periods of experiment, no increase or decrease of PAH were found. There was no correlation between bacterial counts and PAH concentrations. The laboratory experiments confirmed the results of the field investigations.

The data presented have demonstrated the applicability of monitored, automatic bacteriological testing of water from different sources. Information from experiment show a continuous variation in the number of polluting bacteria in water samples obtained from the same water source, thus indicating the necessity of using multiple samples in order to establish a "most probable contamination". When trying to determine the pollution of a certain water source, assay must be performed at different seasons of the year and under various climatic and weather conditions like heavy rain fall, drought and sub-zero temperatures. Working with sea water obtained from the same spot at sea, the degree of pollution in some samples appears to be influenced by changing wind and currents, high and low tide. The advantages of automatic sampling, inoculation and incubation on the spot are obvious. It is visualized that an industrial adapted modification of the prototype machine may serve wide variations of individual requirements pertinent to water assay.

A method for testing a throat antiseptic procedure is described. As indicator bacteria alpha-hemolytic streptococci were chosen. Povidone-Iodine and Chlorhexidindigluconate (0.5% and 0.1%) and aqua dest. as control substance were tested by a mouthwash technique. The best reduction of alpha-hemolytic streptococci could be detected after mouthwashing by 0.5% Chlorhexidindigluconate (1.4 log reduction), whereas by Povidone-Iodine a reduction of 0.85 log steps was achieved.

At the occasion of the usual preparations preceding gynecological operations the average vaginal bacterial release of 42 patients, already anaesthesized, was assessed by a rinsing technique to be 5,04 +/- 0,98 log10 c.f.u. per ml sampling fluid after aerobic and anaerobic culture. The reduction of this bacterial release caused by the measurement itself is relatively small, therefore the technique was found to be suitable for evaluation of the efficacy of germreducing measures like irrigation or disinfection. An irrigation with isotonic saline during 30 s was measured to reduce the vaginal bacterial release by 0,4 +/- 0,5 log-steps. A solution containing 0,08% chlorhexidine gluconate + 0,1% benzalkon gluconate applicated during 5 min caused a reduction of 1,04 +/- 0,76 and a watery solution of povidone-iodine one of 2,29 +/- 1,00 log-units when used for 3 min. When after disinfection the sustained antimicrobial action of the chlorhexidin-containing preparation was not neutralized already during the sampling process by Tween 80 + lecithine + histidine being contained in the sampling fluid, an erroneously optimistic log reduction of 2,35 +/- 0,48 was measured. From the results it was calculated that 17-23 volunteers are necessary in order to detect with sufficient statistical safety an observed mean log reduction to be 0,5 log-units smaller than a hypothetical minimal reduction of 2,00 log-steps as required provisionally on an arbitrary basis.

It is obvious that the surfaces of the boxes of sterile packed disposable instruments and infusion bottles are not sterile. The disposable surgical masks and surgical caps used for sterile clothing are delivered by the producers not sterile, either. To quantify these gaps and to judge their risks in the aseptic region the surfaces of 117 sterile packed disposable instruments and the inner sides of their boxes were examined bacteriologically. The surfaces of these objects proved to be not sterile by 21% and 4% were heavily contaminated with saprophytic germs. 3% of the examined articles showed pathogenic germs like Clostridium perfringens, Staphylococcus aureus, and Acinetobacter spec. 5-15% of the surfaces (glass- respectively plastic and labels) of the 331 infusion bottles proved to be heavily bacteriologically contaminated; 4-6% of them even showing pathogenic germs like Clostridium perfringens, Staphylococcus aureus, and Achromobacter spec. The surfaces of 25% of the examined disposable surgical masks and caps were considerably contaminated with saprophytic germs. Although pathogenic germs could not be detected, it means that these not sterile objects represent a considerable deficiency in surgical asepsis.

The preparation of suspensions of bacterial cells impaired by the action of chlorine require a very accurate standardization of all the procedural detail of controlled experimental impairment by chlorine. All measures suitable to spread the kinetics of reduction of bacterial numbers in time will facilitate the reproducibility of results. The exact amount of hypochlorite--determined experimentally prior to the actual test--is transformed to chloramine at 0 degrees C then a defined quantity of bacteria is added. After different periods of contact samples are taken and stabilized by adding thiosulphate of sodium. When the bactericidal action is not abrupt but sufficiently drawn out a relatively high proportion of bacteria impaired by chlorine but still viable is obtained (50-90%). In suspension the proportion remains relatively stable during storage in the refrigerator (4 degrees -6 degrees C). Resuscitation experiments carried out with suspensions of organisms damaged as explained above showed resuscitation times of 3 h in casein soy broth not to grow as well as those after 24 h of resuscitation. Obviously the process of reparation after impairment by chlorine must be assumed to be relatively slow under these conditions.