Biomedical subjects

L Karaivanov

Publications and source records attributed to L Karaivanov.

8 recordsLinked to original sources

PubMed1979

[Decarboxylase activity study of Pasteurella multocida].

Ornithine-, lysine- and arginine-decarboxylase activity of 218 P. multocida strains, isolated from birds of varying disease symptoms in Bulgaria and CSSR, and from pigs, rabbits and birds in Cuba, USSR and CSSR, was studied after the method of Moller. Positive ornithine decarboxylase activity was established in 211 strains, low -- in 2, and negative -- in 5 strains. Low arginine decarboxylase activity was observed in 12 Pasteurella strains, while in 14 -- low lysine decarboxylase activity. The presence of ornithine decarboxylase activity can be used, along with the cultural and biochemical properties and with lyzation by a specific bacteriophage, as a taxonomic character for the species. All Pasteurella strains pathogenic for white mice, produce ornithine-decarboxylase. Lines of the strain X 73 obtained following gamma-irradiation having lost their ornithine-decarboxylase are pathogenic for white mice.

Animals↗

PubMed1979

[Atypical course of cholera in poultry].

Atypically developing chicken septicemia was studied at 3 farms in Bulgaria. In one of the observed centers of chicken septicemia infection no pathologic anatomical changes were evident while in the other two centers of infection serofibrinose and serofibrinose vitelline peritonitis, as well as pleurisy were present. In the bacteriological investigation carried out on 2969 samples 233 strains of chicken septicemia were isolated. Identification of 84 of them by the aid of the specific bacteriophage P. multocida 115 and of sugar and alcohol fermantation revealed that they can be classified as P. multocida. They are lyzated by a phage but do not reproduce it. Chicken septicemia cultures are virulent for white mice. In intramuscular injections of pullets these cultures prove not virulent, but their intravenous application kills the pullets in 5--10 days and the initial strain is isolated from all inner organs. The biological test on pullets is suitable for determining chicken septicemia culture virulence.

Animals↗

PubMed1977

[Pasteurella multocida bacteriophage adsorption].

Studied was the adsorption of 8 strains of Pasteurella multocida bacteriophages presenting three groups of phages isolated in Bulgaria. With the bacteriophages of groups I and II the adsorption in broth in the first 10 minutes amounted to 50-65%, and at the 80 the minute reached its maximum value--98-99%. With the bacteriophages of group III adsorption started with a lower percent and by the 140th minute reached 96-97%. It was by 60 min slower as compared with the adsorption with group I and II phages. In a veronal-medinal buffer the adsorption of all investigated phages of the three groups set in with a prolonged time of 60 min as compared with the time elapsed using broth. At the cross testing of adsorption the phages of group I were adsorbed by the hosts of the other two groups to a maximum level, however, the phages of groups II and III were adsorbed to a negligible extent on the other hosts (except for the adsorption on their homologous one). The difference established in the adsorption for a 60 minutes time so far as the phages of group III were concerned was sufficiently persuasive to consider this group as an individual one by this feature too. Adsorption appeared as a subsidiary taxonomic characteristic in the classification of Pasteurella multocida bacteriophages.

Adsorption↗

PubMed1977

[Lysogeny in Escherichia coli isolated from birds and the spectrum of the lytic action of isolated phage].

Studies was the lysogenicity in a total of 70 strains of Escherichia coli isolated from birds. As many as 19 lysogeneic strains were isolated, yielding 19 phages that had the signature of lysogenic strains. Two serologic groups of phages were established by means of the neutralization reaction. It was found that phages 30 and 229, representing the two serologic groups of bacteriophages could lyse up to 44 per cent of the E. coli strains isolated from birds, 7 per cent of those isolated from calves, and 4 per cent of those from pigs. Out of 74 Salmonella strains, belonging to ten species, the same phages lysed two strains of Salmonella newport and 1 strain of Salmonella anatum. It is believed that phage lysis could be used to establish the source of infection and to evaluate the effectiveness of the prophylactic measures applied, incl. disinfection.

Animals↗

PubMed1977

[Electron microscopic studies of Pasteurella multocida bacteriophages].

Studied was the morphology of four Pasteurella multocida phages, Nos. 115, 32, 967, and 1075, with the use of an electron microscope. The bacterial phages had hexagonal heads of a 55 x 55 nm diameter, and were of an isometric polygonal form themselves. The tail of the phages was 120 nm long and was non-contractile. By these characters the P. multocida phages are to be referred to the morphologic group of phages of noncontractile tails--group B after Bradley and group IV after Tihonenko.

Bacteriophages↗

PubMed1976

[Antagonistic action of Pseudomonas aeruginosa in relation to Pasteurella multocida strains].

Studied was the antagonistic action of 4 strains of Pseudomonas aeruginosa toward 48 strains of Pasteurella multocida. Use was made of the method of the delayed antagonism after Fredericq. Ps. aeruginosa organisms were found to manifest a strongly expressed antagonistic activity as regards P. multocida. All Pasteurella strains proved highly sensitive, and showed a zone of inhibited growth sizing from 20 to 70 mm. The antibiotic substance produced by Pseudomonas aeruginosa organisms was yielded better on solid nutrient media than in liquid ones. All Pseudomonas aeruginosa strains manifested bactericidal and not bacteriostatic action upon the studied strains of Pasteurella multocida.

Antibiosis↗

PubMed1976

[Effect of physical and chemical factors on Pasteurella multocida bacteriophages].

Studied was the effect of some physical factors (temperature, pH of various values) and some chemical ones (urea, sodium citrate, sarcolysin, methylene blue, acridine orange, pyronin, crystal violet, potassium permanganate, fuchsin, tetracycline and tetraolean) on phages specifically lysing Pasteurella multocida strains, having the following signature: 3, 4, 6, 22, 32, 115, 967, 1075, and C-2. All investigated phages showed signs of inactivation at 48 degrees C with a further linear dependence, and at 65 degrees C up to 99.99 per cent of them were inactivated. With phages of group III inactivation discontinued between 50 and 60 degrees C, at 65 degrees C it being equal to that observed with I and II group phages. It was found that a broth medium of pH 7.5 was the optimum one for P. multocida phages. With altered pH values lowest percentage of survived phage particles showed I group phages, while those of II and III group proved more stable. So far as the chemical factors were concerned it was established that with the exception of pyronin and potassium permanganate which inactivated the P. multocida phages from 90 to 100 per cent, all other agents produced full inactivation (100 per cent). However urea did not inactivate I group phages, both it and sodium citrate inactivated partially II and III group phages. The variations established with the phages in terms of their physical and chemical behaviour may serve as subsidiary signs bearing upon their classification.

Acridines↗

PubMed1976

[Lysogeny in Pasteurella multocida].

Studied was the possibility of lysis-producing factors (the phenomenon of lysogeny) with 59 strains of Pastuerella multocida isolated in Bulgaria, Cuba, and Czechoslovakia. It was found that eleven of them were lysogenic in terms that a total of 12 bacteriophage strains were isolated from them; one of them yielded 2 phages. Established were three different indicator strains of Pasteurella multocida-97, SHD, and R-II--by means of which 3 different groups of P. multocida phages were isolated. The latter were stabilized and allowed to multiply up to 10(11) phage particles per 1 cc through continuous passaging, and they could be be stored at + 4 degrees C. In accordance with the host strain for multiplying the isolated P. multocida phages were divided into three different groups: phages 3, 4, 5, 6, 22, and Sl fell into group II, and phages 1075 and S-2--to group III.

Animals↗