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

A novel transposon mutagenesis system has been developed for Shigella. We have used it to isolate specific mutants of Shigella sonnei and Shigella dysenteriae 1 that fail to produce lipopolysaccharide 'O' side chains. The virulence of the mutants was evaluated in the Sereny test and in a HeLa cell invasion assay. All HO'-minus mutants failed to provoke a positive Sereny reaction but retained the ability to invade HeLa cells. This demonstrates that 'O' side chains are virulence factors of S. sonnei and S. dysenteriae 1. 'O'-minus mutants of S. sonnei which still contained the Form I plasmid were capable of invading HeLa cells whilst plasmid-minus mutants were not, demonstrating that this plasmid encodes properties other than 'O'-antigen production that are involved in virulence.

The sporocidal properties of peracetic acid (PAA) at defined concentrations were characterized by determination of decrease in PAA after addition of D-glucose, human albumin and suspensions of spores; concentration of PAA, which inactivates 10(6)-10(7) spores of Bacillus cereus, B. subtilis, B. megaterium and B. licheniformis within 10-30 min; inactivation constant k, decimal reduction time D and the sporocidal index (mg PAA X min X ml-1) at that concentration. In contrast to albumin, the spore suspension caused relatively little reduction of PAA concentration (less than 5% at the concentrations used). B. cereus, B. subtilis and B. megaterium had similar inactivation rates with k-values in the range of 0.368 and 0.541 min-1, D-values between 4.26 min and 6.26 min at 0.2 mg/ml PAA. B. lichenformis was much more resistant showing a k = 0.345 min-1 and D = 6.66 min at 3.0 mg/ml PAA. The sporocidal index of B. lichenformis was 180 mg X min X ml-1 while the three other species had sporocidal index-values of 7 mg X min X ml-1.

Bioindicators serve to test the efficacy of disinfection and sterilization procedures. Such indicators mostly consist of a support (filter paper, as a rule) to which micro-organisms have been fixed by drying. The authors have used a thread as support and a special apparatus for semi-automatic preparation of the bioindicators. The components of the device are either commercially available or may be prepared from commercially available material without difficulty. The principle of the method is as follows: The thread serving as the support is drawn slowly, at constant speed, through the suspension of test organisms and dried in an air stream immediately afterwards. The apparatus consists of a cylindrical glass tube of a few centimeters in diameter, an electric motor slowly rotating the cylinder, a fan, a magnetic stirrer, and an ice-water bath. A small vial containing the germ suspension is immersed in the ice-water bath. The vial is sealed by a screw cap with two glass tubes of about 3 mm inner diameter passing through it. One of the glass tubes being bent in its upper part reaches far down into the vial to leave just enough play for free rotation of a magnetic stirring rod. This tube serves to introduce the thread into the germ suspension. The second straight tube does not reach as far down as the first one. Its lower opening should not be immersed in the germ suspension. This tube serves as a guide for the returning thread. Preparation begins by winding the thread to be soaked with the suspension around the cylinder.(ABSTRACT TRUNCATED AT 250 WORDS)

The infestation by the larva of Echinococcus multilocularis, also known as alveolar echinococcosis, is the most dangerous parasitic disease of man in Middle Europe. This is due to the location in the liver but still more so because of the proliferative and infiltrating growth of the larval tissue. The basic infective cycle of the parasite is a zoonosis between foxes as final hosts and small rodents such as common voles as intermediate hosts. Man can be a false intermediate host and thus a carrier of the larval stage. The infection arises from oral ingestion of the tapeworm eggs either on wild berries or in dust. Dogs and cats are a further important source of infection. They can be facultative carriers of adult E. multilocularis and are thus able to excrete eggs or proglottids of the tapeworm. In west Germany, in particular the "Schwäbische Alb" must be regarded as an endemic region for E. multilocularis. According to the examinations of Zeyhle, the infection rate of foxes here is more than 15% on an average, in some local areas as for example in the district of Reutlingen it is over 25%. In order to estimate the danger of infection for man in hyperendemic areas the population of two villages of this district and also specially endangered occupational groups (hunters, foresters) of the whole "Schwäbische Alb" have been examined for echinococcosis by serological means. A stepless ELISA was used as screening test. Thus circa 2200 persons liable to E. multilocularis could be examined. Among the population of the district of Reutlingen nine highly suspective sera could be detected. Computer tomography of these nine persons showed only one case of Echinococcus which could be identified as E. multilocularis after operation. Presumably serological positive cases come up as a consequence of a real contact with E. multilocularis. But in most cases the larval cestode tissue might soon degenerate because man is a relatively poor intermediate host. It cannot be excluded, however, that the Echinococcus-larva could not yet be identified clinically because of its early stage. According to most cautious estimation the prevalence of E. multilocularis in this endemic area might be one per thousand, the contact frequency, however, up to one per cent.

The mutagenic activities of different nitrothiazole derivatives were examined by the Ames-test. Such nitrothiazoles which display pronounced antibacterial properties against aerobic as well as anaerobic bacteria exert strong mutagenic activities. Thereby, both base pair substitution and frame-shift mutation occur. Reduction of the nitro-group of the nitrothiazoles by bacterial nitroreductases is a prerequisite for these mutagenic activities. In contrast, nitrothiazole derivatives which are unable to inhibit bacterial multiplication are also not mutagenic.

The authors obtained a total of 136 mite specimens from dust samples collected from the pavement of Prague in monthly intervals for a period of one year. Of utmost importance was the finding of Dermatophagoides farinae Hughes, 1961 and Euroglyphus maynei (Cooreman, 1950), both of the family Pyroglyphidae, allergogenic mites. Apart from a few exceptions, all other species were common mites of food stores.

At the end of the year 1983 and at the beginning of 1984, groundwater contamination with tetrachloroethylene was discovered south of Graz. Many wells showed an elevated concentration of tetrachloroethylene. 1210 persons living in this area were examined. As tetrachloroethylene may cause liver damage, screening tests were carried out in order to detect pathological liver function tests (LFT), such as gamma-GT elevation. In most cases, initially elevated LFT could be attributed to alcohol abuse. After thorough medical examinations, two cases remained unclear; later on, however, the initially elevated LFT could no longer be detected. This is a certain indication that there was some type of stress on the liver shortly before the blood sample was taken. In all other cases of liver disease, the causes could be determined. The pollution of drinking water was not the cause of pathological LFT. Nevertheless, the inhabitants of this region will receive drinking water from the public water supply for safety reasons. However, one thing that needs to be stated very clearly is that these findings which fortunately show no detrimental effect due to the pollution of drinking water, do not allow any conclusions concerning the possibility of injury to health, i.e. they do not preclude possible impairment of health as a consequence of prolonged consumption of the polluted drinking water.

Refuse from medical consulting rooms, a mixture of those refuse with municipal refuse (1:10), and municipal refuse were disposed aerobically and roughly anaerobically for over six months in a model landfill. Survival, proliferation, and transportation of microorganisms were estimated at different periods of time. Concentrations of aerobic bacteria and hyphomycetes decreased during the first weeks of deposition but remained later almost unchanged. Concentrations of nonsporeforming indicator bacteria (Escherichia coli, feacal streptococci) decreased more strongly, and E. coli could not be found at latest after 23 weeks. In municipal refuse alone and mixed with refuse from medical consulting rooms, Pseudomonas aeruginosa proliferated temporarily. Leaching of microorganisms from the model landfill was observed in the whole course of the disposal period.

Fresh and stored liquid manure from the pig could be deodorized by addition of 2% (w/v) Ammonperoxodisulfate (= APS). This effect was accompanied by a rapid increase of the redox potential up to +400 mV, fluctuating oxygen contents of maximal 0.8 mg/l, a significant decrease of pH below 7.0, a complete decomposition of organic nitrogen compounds and a considerable increase of total nitrogen caused by APS-addition. After 20 days, odour production could be noted again in the fresh slurry sample. It is assumed, that this effect is due to a population of yeasts, vigorously grown up towards the end of the test. The stored slurry sample was shown to be stable with respect to deodorization effect and yeasts could be found in portions lesser than 1%. In the fresh as well as in the stored slurry samples, organisms of the genus Bifidobacterium dominated towards the end of manure handling. In spite of an oxidised substrate it is assumed, that these anaerobic to aerotolerant microorganisms found a microbiotope with a reduced environment inside the flocks, built up by APS-addition. The facultatively anaerobic microorganisms, for the most part of the genus Bacillus, which mainly belong to producers of odorous compounds almost could be eliminated within 20 days at the latest by APS-treatment. It should be focused to prevent a secondary odour production by H2S-forming yeasts. This may be managed in future by an odour-reducing minimal APS-addition under a 2%-application. In addition, the costs of APS-treatment of liquid piggery waste could be reduced considerably.