Zentralblatt fur Bakteriologie. 1. Abt. Originale B, Hygiene, Krankenhaushygiene, Betriebshygiene, praventive Medizin最新文献

Both the microflora and some physical parameters of the air in three underground railway (metro) stations were analysed. The air samples taken in the first two stations contained considerably more microbes, namely three times as many, than the sample from station No. 3. In the samples from the first two stations both the pathogenic and anthropogenic germs occured more frequently than in the samples from the third station. The normal flora consisted of gram-positive cocci/Streptococci, Micrococci, Sarcina. Roughly 10 per cent of the microbes proved to be spore-formers. Selective investigations led to the detection of Staph. aureus, Enterococci, Haemophilus influenzae, Escherichiae, Klebsiella and Proteus bacteria. The reason why the stations of line 2 were found to be contaminated to a greater degree is probably because of the higher passenger traffic, the smaller space, as well as the stronger airflow due to the artificial ventilation and the piston effect of the trains. The effect of the artificial environmental conditions on the staff of the metro company still needs further investigation. The effect on the passengers is considered to be less pronounced.

The quantity of bacteria taken from 8 watersamples and 46 slimesamples in the sphere of drinking water were examined using 15 different solid media. These media showed variations in total colony count and more or less selectivity against several bacterial groups. For the recording of as much bacteria as possible and as much different species as possible low nutrient containing media are necessary.

Bearing in mind the insufficiency of commercialized starters for the manufacture of french dried sausage, a starter (Micrococci and Lactobacilli) named Lyoflore was perfected and tested during ten months in three factories. The results obtained show the value of this additif: acceleration in maturity, rapid acidification, inhibition of undesirable bacteria, very good colouring and excellent organoleptic qualities of the finished product.

The factors influencing the concentration of air-borne bacteria during operations have been analysed. It was found that the concentration of air-borne bacteria depended primarily on the number of persons present in the operating theater, the air exchange rate per hour and the room volume. Persons with sterile dress were found to have much less influence than did persons with unsterile dress. A formula describing the relationship between the average concentration of air-borne germs in operating theaters, the number of persons in sterile and unsterile dress, the air exchange rate and the room volume was derived. In a total of 142 operations, the formula has been found to give reliable estimates of the concentration of air-borne germs. This equation can be used for testing whether or not the concentration of air-borne bacteria in an operating theater is within acceptable limits which have been defined.

We analyzed the effect of two samples of city smog extracts and their fractions from Duisburg on the rate of DNA synthesis of mammalian cell cultures. - We employed tissue cultures of kidney and embryonic cells from the Syrian golden hamster (Cricetus aureatus) and kidney cells from the African green monkey (Cercopithecus aethiops). The DNA synthesis was determined autoradiographically after incubation with 3H-thymidine. We found that both city smog extracts exerted a dose-dependent suppression of cellular DNA synthesis. Monkey kidney cells were more sensitive than rodent cells. Analysis of single fractions indicate that the inhibition of DNA synthesis is the result of combined effects of all fractions. At present time it is not possible to correlate the toxic effect of the complete extract special to a single fraction or compound group.

The kinetics of inactivation and the resistance to gamma radiation of microorganisms usually to be found in raw sludge were examined with five viruses, three bacteria and a fungus serving as prototypes in comparative studies. All these infectious agents could reliably be inactivated by gamma rays in raw sewage sludge but they were clearly more resistant to gamma rays compared to irradiation in a liquid suspension. The reduction of the virus content required a much higher radiation dose compared to bacteria and the fungus used, excluding Streptococcus faecalis which was exceptionally resistant. Considering the content of pathogenic viruses and other agents in raw sewage sludge, the required radiation dose necessary to comply with average to strict demands for the hygienisation of sewage sludge is discussed. The radiation dose of 500 to 1,000 krad seems therefore to be sufficient.

Suppression by lead of resistance to bacterial or viral infections has been reported by several authors. We have studied, if a decrease of resistance to bacterial infection could be evaluated at blood lead concentrations (PbB), which correspond to the upper levels of environmental or occupational lead exposure regarded as tolerable (PbB = 35 resp. 60 microgram/100 ml). NMRI mice were chronically exposed to lead by feeding with lead acetate containing diets and given a challenge with Salmonella typhimurium. No increase of susceptibility to bacterial infection could be demonstrated at PbB < 90 microgram/100 g. At PbB > 100 microgram/100 g, however, an increase of lethality and a decrease of 50% survival times could be observed after bacterial infection.

In order to identify sources and routes of the contamination of bread by moulds, the microbial germ content of the air and machine surfaces was investigated in 25 large bakeries of different geographical position and size. On its way from the baking oven to the delivery station, the bread passes through production areas likely to be loaded with more than 90,000 mould spores/cbm air. With a germ content of the air in the bread storage rooms from 85 to 5,000 mould spores per cbm, bread contamination by 10 to 400 mould spores per 100 sq.cm must be expected to take place in the course of one hour. The germ content of the air in bread factories depends, among other factors, on the dust content of the air, the producton processes, the time and type of cleaning as well as on the fresh-air supply system for the production and storage areas. Especially in the bread slicing and packaging areas, a number of production-related sources of microbial spread exist which should be eliminated. The "knife oils" used for the slicing tools are occasionally found to be heavily contaminated with mould and yeast already at their arrival at the bakery. The continuous use of these oils leads to a considerable enrichment with microbial germs.

445 strains of Staphylococcus aureus were isolated from poultry and further 345 strains were isolated from the personnel of a poultry processing plant. The strains were typed with the International Basic Set and a set of poultry phages according to Gibbs et al. (1978b). In total, it was possible to type 38% more of the staphlococci with the poultry set than with the human set, of which the most frequent phage reaction occurred in phage groups III (human set) and B1 (poultry set). 83% of all the strains which were not typable, using the International Basic Set, were however typable with the poultry set. - Poultry specific staphylococci, classified according to biochemical characteristics, in general did not react with the human set. They did, however, show the most frequent reaction in phage groups A and A/B2 of the poultry set. - The human specific strains were almost all typable with the International Basic Set. They also reacted frequently with the phage group B1 of the poultry set, mainly in combinations of B1/III and B1/NT. - In contrast to the International Basic Set, the poultry phage set exhibited a lower specifiy, in that a greater number of strains were typable with the poultry set which were classified by biochemical characteristics as human specific. - It was also possible to type about 70% of the human staphylococci with both sets. A clear classification into the poultry biotype appeared to be possible only with strains reacting with phages of group A of the poultry set.