Journal of hygiene, epidemiology, microbiology, and immunology最新文献

A complex toxicological study was carried out in relation to the hygienic standardization of the fungicide preparation Ridomil, whose forthcoming production in this country will be under the name Metalaxyl. The study was performed on sexually mature white rats of both sexes, at oral, dermal and inhalation exposure, acute, subacute and chronic experiments, according to the Bulgarian State Standard. Besides the routine toxicological studies were carried also studies for establishing the long-term effects of the preparation (gonadotropic, embryotoxic and teratogenic, cardiovascular). The results from the study permitted the Agromet preparation to be put in III class--moderately toxic according to limiting index LD50 oral. On the basis of data from the authors study on the general toxicity and long-term effects of Metalaxyl a temporary MAC 4 mg/m3 was proposed.

The in vitro antimicrobial efficacy of different extracts of seeds of Centratherum anthelminticum was studied by the filter paper disk method against several human pathogenic bacteria and fungi. Some of the extracts showed significant effect over tested bacteria and fungi.

We compared the "in vitro" activity of imipenem with 14 beta-lactams, both alone and in combination with clavulanic acid, and sulbactam against 110 beta-lactamase-producing strains of Bacteroides fragilis. The following antibiotics were tested: amoxycillin, penicillin, mezlocillin, piperacillin, cephalothin, cephazolin, cefamandole, cefmetazole, cefonicid, cefoxitin, cefotaxime, ceftazidime, ceftizoxime, and ceftriaxone. In all cases, except those of cefoxitin and cefmetazole, these combinations showed a statistically significant increase in beta-lactam activity, which was, however, never higher than that of imipenem, the antibiotic which performed best against Bacteroides fragilis.

From May 1985 to June 1986, 21 water supply sources in 3 districts and 6 sub districts of Kaffa Administrative region, south west Ethiopia were surveyed. All together Eighty water samples were collected and bacteriological examinations were done in a public health laboratory in the region. The field survey have shown that the so called protected springs are in un desirable sanitary conditions. Bacteriological quality of the water was also found in unacceptable level (More than 50 coliform organisms per 100 ml. of samples). The poor quality of water may be responsible for the predominance of water born and related diseases observed in the region. Therefore a prior consideration should be given to improve the quality of water, and sewage disposal system. To obtain and maintain good quality water an integrated plan and work system between the various governmental agencies is crucial.

Using suitable immunomodulators (Corynebacterium parvum vaccine, Zymosan or muramyl dipeptide), lipopolysaccharides (LPS) from various members of the family Enterobacteriaceae (Escherichia, Salmonella, Serratia, Shigella) were tested on rabbits in relation to the production of tumor necrosis factor (TNF). TNF was determined by means of the serum titration of L-929 cell cultures in the presence of Actinomycin D, this with resulting titres of 3.2 x 10(3) to 5.1 x 10(4) IU TNF/ml. Analogous titres were noted after the action of denatured LPS (ie LPS subjected to alkaline hydrolysis or H2O2).

Some differential growth characteristics for Vibrio cholerae and Vibrio metschnikovii were examined in a liquid medium with reference to pH and ionic strength, as well as temperature and length of incubation. The purpose was to discover the combination of the above conditions which would enable selective replication of V. cholerae accompanied by suppressed growth of V. metschnikovii. Preliminary routine verification of one combination of conditions which involves a lengthening of incubation to 22 h at a heightened temperature of 41 degrees C in sewage water samples pointed to the possibility of rapid and simple quantitative demonstration of V. cholerae.

As a part of multipurpose health survey of the population in Vietnam the antibodies against S. typhi were determined by the micromethod using haemagglutination test (O-antigen 9, 12) and agglutination test using standard H-diagnostic antigen (d). Totally 292 sera were examined, 139 from Duyen Thai village and 154 from Mai Chau. The data on vaccination against typhoid fever are recorded only in 102 persons. The positivity on Vi antibodies is very high--70% in Duyen Thai and 47% in Mai Chau. This finding is significant according to the high titres in the carriers of S. typhi. The titres of all antibodies are lower in Mai Chau area situated in mountains then in crowded lowlands of Duen Thai. The level of antibodies is decreasing with age. The frequency distribution of antibodies by age proves endemicity of the disease in area, where a large part of population is infected already before reaching 20 years of age. The effectivities of vaccination is discussed.

The effects of oestrogen and progesterone on the re-excretion of IB virus strain G in chickens infected at day-old was evaluated in this study. Following infection of the chickens at day-old, the birds were swabbed regularly from the trachea and cloaca until no more virus was isolated from either site. Between 10 and 14 weeks of age oestrogen and progesterone were administered by intramuscular injection to infected or control chickens. An infected but non-hormone injected group was maintained. All the birds were monitored for virus re-excretion and/or increase in serum neutralising (SN) antibody levels during this period of treatment. Similar parameters, and the egg production of these birds were evaluated when they reached their natural sexual maturity. At the end of the experiment, the birds were sacrificed and their internal organs especially the reproductive organs were examined for any pathological lesions. The acute phase of the disease following infection at day-old was typical of IB virus infection in terms of clinical signs and virus excretions from trachea and cloaca [1]. The injected hormones failed to induce virus re-excretion as no virus was isolated during this period. There was no change in the level of antibody during this period either. However, when the hens attained their natural sexual maturity, IB virus was re-excreted by all the birds. Isolations was also more frequent from the cloaca than from the trachea. The SN antibody levels of individual showed no definite pattern to correspond with periods of re-excretion in the birds up to the end of the experiment. The control birds remained normal throughout the period of the study.

Clinical and laboratory findings among 123 paediatric patients infected by intestinal protozoa were analysed. Dientamoeba fragilis (D. f) was found in 102 cases. The other patients proved to be carriers of Giardia lamblia or of mixed infections with several protozoa. Acute and recurrent diarrhoea have been found to be the most common symptoms, whereas abdominal pain was most common in children with chronic infections. Peripheral blood eosinophilia was seen in a third of the children with dientamoebiasis. Metronidazole, oxytetracycline, doxycycline, and erythromycin were effective drugs in the treatment of D. f. infections. The therapy coincidentally led to the elimination of protozoal infections as well as the abdominal complaints. These results underline the pathogenic role of D. f. in children with gastrointestinal symptoms.

The biodegradation of T-2 toxin was studied by strains of micromycetes which were isolated from the environment. The 26 tested strains were divided into three groups. Group contains strains which degraded T-2 toxin very fast. This toxin could not be chromatographically determined in the medium even after 48 hours of incubation and the antifungal activity of residua against Kluyveromyces fragilis CCY-51-1-2 was low or zero. There were strains of Alternaria sp., Ulocladium sp., Aspergillus candidus, Cladosporium cladosporioides, Rhodotorula sp., Aspergillus flavus and Cladosporium macrocarpum. Group II contains with a low activity and in group III the results were variable and non stable.