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Biomedical subjects

W Witte

Publications and source records attributed to W Witte.

At least 181 records · Page 10Linked to original sources
PubMed1978

Ecology of Staphylococcus aureus: comparative characterization of strains isolated from man, cattle and sheep in Bulgaria and in the GDR.

Staphylococcus aureus strains from man, cattle and sheep have been differentiated by biochemical tests and by phage typing. Strains from pathological material of human origin mostly belong to the host-specific variety hominis, strains from mastitis in cattle mostly belong to the host-specific variety bovis. However, there are also strains from cattle which cannot be allotted to one of the known host-specific varieties and also strains which belong to the host-specific variety hominis. Strains from mastitis in sheep clearly differ from strains of human and bovine origin; these strains are designated as variety ovis. The frequency distribution of the host-specific varieties in man, cattle and sheep is the same in Bulgaria and in the GDR.

Animals↗
PubMed1978

[Characteristics of Staphylococcus aureus strains from pathological processes in swine].

120 Staphylococcus aureus strains from different and sporadic pathological process in swines have been investigated on biochemical properties and phage patterns. 98 strains (82%) exhibit coagulation of human plasma, no coagulation of bovine plasma, crystal-violet-type C, hemolysin-type beta, no formation of fibrinolysine and sensitivity for phages of group I, III and M. Only in few strains we observed reactions with phages of group II. 26 from 66 strains were resistant to antibiotics, and among them 24 showed resistance to oxytetracacline.

Animals↗
PubMed1978

[Transfer of drug resistance plasmids from Staphylococcus epidermidis to Staphylococcus aureus in mixed culture].

A possibility of transfer of chloramphenicol-resistance and penicillin-resistance plasmids from 4 different donor S. epidermidis strains to 2 S. aureus strains was demonstrated. Chloramphenocol-resistance plasmid was found in S. epidermidis 1065/77 which was not expressed in this strain but could be transferred to and was expressed in Staphylococcus aureus strains. Penicillin-resistance and chloramphenicol-resistance plasmids were transferred simultaneously in 40 per cent of the colonies.

Chloramphenicol↗
PubMed1978

[Chemical and immunogenic properties of the capsular antigen of Staphylococcus aureus. III. Protective activity of capsular antigen in experiments on mice].

Experiments were conducted on 1500 albino mice; protective activity of 7 batches of S. aureus capsular antigen isolated from 5 strains was studied. The animals were immunized subcutaneously with different doses of the preparation (from 0.001 to 10000 microgram) once, twice, and thrice, and infected intraperitoneally with 6 encapsulated cultures. Capsular antigen proved to possess weak protective properties. The following regularities were revealed: 1) high antigen doses (over 5 microgram) increased mouse sensitivity to staphylococcus infection; 2) the greatest protective activity was shown by doses within 0.01-1 microgram; 3) there was no distinct "dose-effect" dependence; 4) single immunization was less effective than double and triple; 5) antigenic specificity of the capsular material was not connected with its protective properties.

Animals↗
PubMed1977

Ecology of Staphylococcus aureus: characterization of strains from chicken.

The majority of S. aureus strains isolated from beak-swabs and pathological processes in chicken shows coagulation of human plasma (not of bovine plasma), crystal violet-type A, hemolysine-type A, formation of fibrinolysin, not formation of DNase and reactions with the experimental phage A1591. Because of the absence of DNase-formation and the reaction-specificity for phage A1591 we propose to designate these strains as host-specific variety gallinae of S. aureus. The strains from chicken are compared with strains of human, bovine, and ovine origin. An ecological study in a chicken farm has shown that S. aureus strains from chicken are not found in man and vice versa.

Animals↗
PubMed1977

Surveillance of R-plasmids.

The surveillance of R-plasmids consists of: (1.) Ecological and epidemiological investigations. (1.1.) Prevalence of R-plasmids in pathogenic and apathogenic bacteria occurring in the biotic environment (man, animal); in the abiotic environment (sewage, food, feed); under high selection pressure (hospital, animal production, plant production). (2.) Biological investigations. (2.1.) Genetic properties of R-plasmids: (2.2.) Plasmid induced variations of the properties of the host bacteria (virulence, phage pattern, antigenic pattern, serological properties). The problems resulting from plasmid-mediated drug resistance call for a strict chemotherapeutic drug policy with the regard to ecological processes.

Drug Resistance, Microbial↗
PubMed1977

[Study of the chemical and immunogenic properties of the capsular Staphylococcus aureus antigen. 2. Evaluation of the immunogenic properties of the capsular antigen in experiments in vitro].

Albino mice were immunized with a purified capsular antigen isolated from the S. aureus strain 1193/74. The presence of specific anticapsular antibodies in the sera of animals were determined by two methods: 1) by conversion of diffuse growth of a homologous strain into compact one, and 2) by determination of opsonic index in phagocytosis of homologous staphylococci by human neutrophils. It was revealed that antibodies converting the microbical growth were absent in the sera of normal mice and reached the highest level after the second antigen injection; opsonins were present in the sera of normal mice in widely varying quantities; their maximal level was noted after the 3rd immunization.

Animals↗
PubMed1977

Transfer of drug-resistance-plasmids in mixed cultures of Staphylococci.

Transfer of pen- and chl-plasmids does not only occur between strains of Staph, aureus but also betwen strains of Staph, aureus and Staph, epidermidis. In Staph, aureus, the frequency of transfer of a tet-plasmid is less frequent than the transfer of pen- and chl-plasmids. Lysogenization of the donor strain by a sero-group-B-phage has no influence on the frequency of transfer. The transfer is not inhibited by gamma-globulin. gamma-globulin inhibits unspecifically phage adsorption and also the transduction by phage 80. The transfer is also possible when an encapsulated recipient strain is used. Phages are inhibited by the capsular material (SCHEER and KOFT, 1975); a transduction to an encapsulated strain is impossible. These results speak against a phage-mediated transfer in mixed cultures. A dilution of the incubation mixture leads to an unproportional decrease of the frequency of transfer. A prerequisite to the transfer is probably a close cell-to-cell contact.

Adsorption↗
PubMed1977

[Chemical and immunogenic properties of the capsular antigen of Staphylococcus aureus. I. purification and chemical characteristics of the capsular antigen].

Crude capsular material isolated from S. aureus strain 1193/74 was characterized chemically and subjected to purification by 4 different methods. The best results were obtained by the method including deproteinization of the material with a mixture of chloroform and butanol, fractional precipitation with ethanol and separation on SE-Sephadex. Galactose, uronic acids, and a small amount of protein served as components characteristic of the purified capsular material. Galacturonic and glucuronic acids were identified amoung the uronic acids. Besides, there were revealed other acids with a carbohydrate base, whose nature is still obscure.

Antigens, Bacterial↗
PubMed1976

Mutagenesis in bacteriophage T7. II. UV induced mutagenesis.

UV induced mutagenesis of bacteriophage T7 was investigated by using a forward mutation system (host range system) and a back mutation system (amber system). The results indicate a dependence of mutation of T7 after UV irradiation only on the rec gene controlled functions of the bacterial host. The functions controlled by pol and uvr genes have no influence. Among other types of mutations UV irradiation leads to transitions from AT to GC.

Caffeine↗
PubMed1976

[Restriction and modification in Staphylococcus aureus: properties of resistance plasmids and prophages].

Experiments on elimination and transfer of resistance-plasmids in S. aureus (controlling resistance to penicillin, chloramphenicol and oxytetracycline) show that these plasmids have no restricting influence on phages used for typing of staphylococci. Prophages in lysogenic strains control a mechanism of restriction and modification which is active on phages and on chromosomal markers. The resistance-plasmids used in these experiments are insensitive to prophage controlled restriction.

Chloramphenicol↗
PubMed1976

[Studies of enterotoxin production by strains of Staphylococcus aureus of different origins (author's transl)].

376 Staphylococcus aureus strains of clinical and epidemiological origin were tested for their ability to produce the enterotoxins, A, B and C1. For these investigations, microagargel precipitation against specific antisera has been used. Additionally these strains were studied by phagetyping, biochemical typing and for their antibiogram. The strains tested came from human pathological processes, mouth throat swabs of healthy people, persons working in hospitals, outbreaks of food poisoning from cows suffering from mastritis and some from milk samples. Most of the strains isolated from food poisonings were associated with enterotoxin-A-production. Among the group of strains from autopsy material, the enterotoxin-B-producing strains were predominant. The strains from human pathological processes which were found to be enterotoxin producing, were mostly belonging to phage group III. With regard to the antibiogram, the enterotoxin-producing strains were somewhat more resistent than the enterotoxin-negative strains. Correlations between the production of enterotoxin B and methicillin resistance did not become evident in our material. The strains were differentiated, too, as to their classification as var. hominis or var. bovis. With one exception, all enterotoxin-producing strains which could be classified in this way, were belonging to var. hominis. From five enterotoxin-producing strains isolated from cattle, only one strain belonged to var. bovis, the other to var. hominis. Obviously the ability to produce the enterotoxins, A, B and C1 is very rare in the group of var. bovis strains.

Animals↗
PubMed1975

[Capsule formation in Staphylococcus aureus as a reason for nontypability by phages (author's transl)].

In Staph. aureus strains isolated from human pathological material the frequency of strains which did not react with typing phages (NT-strains) was found to be about 30%. In one half of the NT strains the reaction with typing phages is prevented by a capsule. The capacity for capsule-formation is lost after propagation of the cells in a liquid glycerol-minimal-medium; thus the cells become typable by phages. The capacity for capsule-formation can be restored after intraperitoneal injection into mice. A new propagation in glycerol-minimal-medium leads again to a loss of the capsule.

Animals↗