Out-patient operations cause lower costs and they are a method the patients are less burdened with than it is the case with usual operating methods. Avoiding nosocomial infections is regarded as another advantage. The rate of infection can be given by a carefully kept nosocomial infection surveillance. Ambulatory surgery units have difficulties in keeping these statistics because they often do not take over the after-treatment of this patients. Out-patient operations in surgeries must guarantee the same standard of hygiene which can usually be found in hospitals. Hospital epidemiologists, health authorities and professional associations have published corresponding guidelines with organizational/functional and structural requirements. These requirements, however, are only met by few ambulatory practices. Surgery holders justify the non-observance of the guidelines by supposing that the spectrum of germs in their office differs from that in a hospital and that there aren't any pathogens. The standard of hygiene in ambulatory surgery units is not controlled regularly. Therefore the hygienic conditions and the microbial burden of five surgeries that carry out out-patient operations under general anaesthesia were determined within the scope of microbial monitoring of the surroundings. Only two surgeries achieved a standard of hygiene which is comparable with that of a hospital. Up to 42% of the taken samples were sterile. The other three surgeries did not meet the requirements. The microbial burden in these surgeries was distinctly higher. The spectrum of detected microorganisms was very wide and there were pathogens too. Hygienic controls and monitoring of the surroundings should be carried out regularly as a measure to guarantee the production and maintenance of quality. Thus the actually achieved hygienic standard in the surgeries can be controlled and improved if necessary. Ambulatory surgeries should be liable to similar hygienic controls as hospitals.

The effects of various concentrations of sodium chloride solutions (0.1%-3%) and different temperatures (4, 10, 20, 30 and 37 degrees C) on survival of Legionella pneumophila were investigated. It was found that at temperatures between 4 degrees C and 20 degrees C, Legionella organisms survived in salt solutions up to 3% NaCl. Only the combination of high temperatures, i.e. 30 degrees C and 37 degrees C, with NaCl concentrations over 1.5%, reduced cell numbers significantly. It was interesting to note that the addition of small amounts of NaCl (0.1%-0.5%) enhanced survival of Leg. pneumophila, suggesting a protective effect of NaCl. In order to obtain information about conditions encountered in the environment, the survival experiments were repeated in sterile sea water from the Baltic Sea and the North Sea. The marked bacterial die-off, especially at higher temperatures, was not observed in natural sea water. All these results indicate that Leg. pneumophila can survive in the marine environment.

Four media containing 4-methylumbelliferyl-beta-D-glucuronide were evaluated as a non-confirmatory procedure for E. coli detection in recreational water surveillance. The media included ECD-Agar for membrane filtration and laurylsulphate-tryptose, brilliant-green-bile and lactose as broth media in a three tube most probable number procedure. From six representative water sites, samples were collected weekly over a typical summer season (17.05-27.09.1994) and processed as parallels, using each media at two different incubation temperatures (36 degrees/44 degrees C). Results showed that incubation temperature had no impact on E. coli counts. Each media at a given temperature could be regarded as individual enrichment procedure. None of these enrichment procedures showed a constant and predictable higher sensitivity during the sampling period at all sites compared to the others tested. For parallel results, the rate of agreement, based upon EC-guideline (76/160/EWG) staging of recreational water quality, was 85% for membrane filtration and 75% for the MPN-procedure results. Marked differences could be observed in false-positive specificity showing correlation to the selective characteristics of the media. Subsequently lactose-broth at 44 degrees C performed worst with 30% non verifiable results, while ECD-agar and laurysulphate-tryptose-broth, both at 44 degrees C, had a nearly 100% confirmation rate. Thus, combining high specificity with no lack in sensitivity these two MUG-supplemented media seem to be best suited for E. coli detection in routine recreational water surveillance.

Recreational water surveillance is an important tool to prevent health hazards for the population. Therefore distinct guide and imperative values for fecal indicators are listed in the EC directive about water quality control. The detection methods, however, give laboratories some room to choose their own method, which has led to difficulties in the comparability of results. In 1989 an ad-hoc working group of the coastal countries of Germany established detection methods, which by now are obligatory for these countries. Fecal and total coliforms (FC and TC) are detected by a triplicate mpn-procedure using brilliant green-bile-lactose broth supplemented with tryptophane and 4-methylumbelliferyl-beta-D-glucuronide (BGB-MUG) as selective medium. Gas-, fluorescence- and indole-positive cultures are considered fecal coliform-positive. In the last years rises in TC but not in FC counts were observed in fresh waters. A study was carried out to evaluate the official method in another bathing season, to determine bacterial species leading to false-positive TC cultures and to compare BGB-MUG with laurylsulphate-tryptophane-MUG (LSTB-MUG). Water samples of different salinities and nutrient input were collected in weekly intervals from April to October. FC and TC concentrations were determined and all TC-positive cultures were differentiated further. The FC counts obtained by enrichment in BGB-MUG or LSTB-MUG were nearly identical, the rate of fluorescence-positive, indole-negative tubes being approximately 0.6%. Differentiation of FC-negative cultures showed a false-negative rate of 2.87% for BGB-MUG and of 8% for LSTB-MUG. During the summer months TC counts in BGB-MUG exceeded FC counts by far at most of the sampling sites. This effect was much less pronounced in LSTB-MUG; the difference between both enrichment media being significant. Differentiation of presumptive TC from BGB-MUG resulted in a high percentage of Aeromonas spp. in fresh waters. LSTB-MUG was clearly more selective for TC than BGB-MUG, but still with an average of 10% of the test tubes being false TC-positive (BGB-MUG 46%). The sensitivity of BGB-MUG was below 60% (LSTB-MUG 89%). LSTB-MUG should be preferred as enrichment medium in mpn-examination of recreational water, if no further differentiation is carried out. The selectivity for TC is better than in BGB-MUG and the only slight inhibitory effects can be tolerated.

There are alarming reports about high counts of Legionella and Pseudomonas in the aerosol of inhalation-rooms. We therefore investigated 14 institutions (6 kurhauses, 5 hospitals and 3 sanatoria for children) in Schleswig- Holstein, each of them at least five-fold. For that purpose the inhalant (seawater as a rule) was investigated for the total bacterial number and the number of Legionella. Cfu/m3 air were determined at the aerosol outlet and a qualitative search for Legionella was done in the piping. In addition bacterial numbers in the air at the breathing-levels of patients were measured in order to be able to assess health hazards by germs of other patients. Detected bacterial numbers (10(1) > 10(4)) were basically subject to the handling of the equipment and the type of apparatus used. Predominantly Staphylococci and Bacilli were found and above all when the first row of investigations was carried out large numbers of Pseudomonas, Aeromonas and others ocurred. Legionella could not be detected. As a whole the investigations showed that properly maintained room-inhalators pose no higher risk of infection. These facilities, however, might be contaminated at any time and there is a certain - even though comparatively low - risk of infection due to germs exhaled by other patients. Patients, which are predisposed to infections of the respiratory tract - f. i. patients suffering from mucoviscidosis or patients with lowered resistance - should therefore generally use single inhalators.

Not least because of possible cost reduction ambulatory operations are being performed increasingly in hospitals and in accordingly equipped surgical practices. From the hygienical point of view infection control is just as important as with inpatients, i.e. requirement have to be the same in principle. This applies to constructional requirements, i.e. structure of operation areas including technical equipment and ventilation system, as well as to organizational requirements. On the other hand particularly operations in surgical practices have special features that have to be taken into account. One has to consider several factors like the lower probability of patients to be colonized by hospital specific bacteria, the as a rule relatively low number of operations and the small group of persons involved with operations, so that often staff discipline can be improved more easily than in big hospitals. Problems can arise with the supply of sterile goods, as facilities comparable to those of sterilization centers in hospitals are usually lacking. In these particular cases hygienically perfect solutions that consider all special features of a practice should be sought in cooperation with a hygienist.

In subsurface aquatic environments two groups of micro-organisms are observed: allochthonous bacteria and viruses, which as contaminants are eliminated from water after some time, and autochthonous groundwater micro-organisms, which belong to the natural subsurface environment and may reach very high abundances under favourable conditions-especially in the presence of a high nutrient supply. The migration of micro-organisms is controlled by flow length dependent transport processes (advection-dispersion, adsorption -desorption), and predominantly by filtration. This can be described on the basis of an expanded advection - dispersion concept.The filter effects in a certain porous aquifer can be quantified by the filter efficiency (filter factor) as a measure of the specific decrease of an initial concentration on a certain flow length. Recent laboratory experiments show that for sand the filter factor depends on the respective microbial species and is highly correlated to the effective grain diameter of the porous material, which is routinely determined in hydrogeology.Experiments with columns filled with quartz sand using the bacteria species Escherichia coli ATCC 11229, Pseudomonas cepacia DSM 50181, Streptococcus faecalis ATCC 6569, and polystyrene beads with similar density and diameters show that the filter factor is controlled by the grain size of filter material, the flow velocity, the diameter of the particle and the ionic strength of the water:- The filter factor is specific for each microbial species for the same conditions of the aquatic environment.- The filter factor is decreases one order of magnitude if the flow velocity increases in the same order.- A major control of the filter factor is the grain size. Conventionally the grain size is used as characteristic length instead of the pore size which, although it should be the real reference date, is relatively difficult to measure. For the assessment of the filter factor, the grain size d10, taken from the grain size distribution curve, can be used.- The influence of the particle diameter on the filter factor, which was predicted by the filtration theory, was confirmed. The minimum values of the filter factor were encountered at particle diameters of about 1-mu-m, which is about the size of bacteria.- The filter factor is influenced strongly by the ionic strength in water with low ionic strength, whereas in water of higher ionic strength its influence can be neglected.- These relationships can be formulated into empirical equations, which allow prediction of the filter factor for given hydraulic conditions

A number of germ carriers have been tested quantitatively, in order to select the optimum germ carrier for future quantitative tests of chemical disinfectants, belonging to the class of surface and instrument disinfectants. Quality criteria applied were the storage capacity of the carrier and the germ recovery fraction. For the surface disinfectant, the cotton piece was confirmed to be suited best, while for the instrument disinfection the mineralized soft rubber tube proved to be optimal. The cotton piece, however, stores ten times more germs than the rubber tube which means that with the former, reduction factors of as high as log 6 (-7) can be measured.