Biomedical subjects

L Karaivanov

Publications and source records attributed to L Karaivanov.

At least 19 recordsLinked to original sources

PubMed1984

Morphology of Pasteurella multocida bacteriophages.

Twenty-one tailed phages with icosahedral heads belong to the Myoviridae, Siphoviridae, and Podoviridae families and to four morphological types. Type AU, with 10 phages, has a contractile tail and is morphologically identical with coliphage P2. Lysates contain contracted tail sheaths assembled end-to-end and abnormal structures with long tails and multiple tail sheaths. Types C-2 and 32, with one and three phages, respectively, have long, noncontractile tails. Type 22 includes seven phages, has a short tail, and resembles coliphage T7. Our results agree with previous biological data and suggest that types AU, C-2, 32, and 22 correspond to four different phage species.

Bacteriophages↗

PubMed1984

[Phosphatase activity of Pasteurella multocida strains isolated from poultry and mammals].

The qualitative test of Berber et al. was employed to determine the phosphatase activity of Pasteurella multocida strains from birds and mammals (cattle, pigs, and rabbits). Only eight out of a total of 50 Pasteurella strains isolated from birds (34 from cases of acute cholera, 12 - of atypic cholera and 4 - from oedema of the wattles ) proved positive (4 isolated from cases of acute cholera, and 4 isolated from cases of atypic cholera). The remaining 42 strains did not show phosphatase activity. A total of 96 P. multocida strains (37 from cattle, 27 from pigs, and 32 from rabbits) were studied. Positive phosphatase activity were shown to have 32 of the strains isolated from cattle, 26 of those isolated from pigs, and 29 of those from rabbits. In terms of percent 42 (84%) of the investigated strains isolated from birds were negative, and 16% were positive for phosphatase activity. Ninety-six as cited above, were the strains isolated from mammals, of which 90.6% were positive, and 9.4% were negative for phosphatase activity. The phosphatase activity of the Psateurella multocida strains may effectively be used to divide the strains purely biologically - as such isolated from mammals and such isolated from birds. The exceptions observed are likely to be due to migration of Pasteurella organisms from birds to mammals, and vice versa. The phosphatase activity is not shown to correlate with the pathogenicity of the respective strains for albino mice.

Animals↗

PubMed1984

[In vitro action of zinc bacitracin to eliminate drug resistance in Escherichia coli transconjugates].

Investigations in vitro were carried out to overcome the drug resistance of transconjugants of Escherichia coli with resistance to neomycin, kanamycin, chloramphenicol, and tetracycline. Use was made of zinkbacitracin Pharmachim . It was found that in conc. of 32 gammas /cm3 zinkbacitracin the elimination of resistance, on an average, to neomycin is 34.9%, to kanamycin - 27.1%, to chloramphenicol - 42.4%, and to tetracycline - 24.9%. With the transconjugants treated with a higher concentration of 64 gammas /cm3 the figures were 42.8%, 34.5%, 46.2%, and 32.4%, respectively. The conclusion is made that zinkbacitracin Pharmachim is effective in eliminating the resistance of E. coli to the antibiotics in the experiment. The higher the concentration used the higher the percent of resistance climination .

Bacitracin↗

PubMed1984

[Metabolism of free amino acid in strains of Pasteurella multocida and their division into biological types].

A total of 29 Pasteurella multocida strains were isolated in cases of atypical fowl cholera with swelling of the wattles as well as from pigs and calves with pneumonia. All strains were used to study the metabolism of 10 amino acids. Glutaminic acid was found to be metabolized by all investigated strains. Arginine was metabolized by Pasteurella organisms isolated from mammals (calves and pigs), and was metabolized by Pasteurellae isolated from birds. By their positive reaction with proline and their negative one with alanine the Pasteurella strains isolated in cases of acute cholera differed from all other Pasteurella organisms. Asparagine was metabolized only by Pasteurellae isolated in cases of atypical fowl cholera, and serine--only by Pasteurellae isolated from pigs.

Amino Acids↗

PubMed1984

[Biochemical tests for identifying Pasteurella multocida].

Studied was the biochemical activity of a total of 168 strains of Pasteurella--73 isolated from birds (48 from cases of acute fowl cholera, and 25--of chronic cholera), and 95 isolated from mammals (3 from lambs, 24 from pigs, 36 from cattle, and 32 from rabbits) with regard to the tests determining the hemolytic activity, production of indol, reduction of nitrates, breakdown of urea, beta galactosidase activity, production of hydrogen sulfide, ornitin-, arginine-, lysine-decarboxylase-, and phosphatase activity, and the fermentation of substrates such as manite, glucose, galactose, saccharose, manose, levulose, dulcite, lactose, maltose, rafinose, trechalose, salicin, melobiose, icelobiose, arabinose, xylose, and sorbite. To differentiate Pasteurella multocida strains isolated from mamals from those isolated from birds the phosphatase activity test on solid media with sodium phenolphtalein diphosphate had to be employed Pasteurella organisms isolated from mammals showed positive phosphatase activity, while those isolated from birds exhibited a negative one. Arabinose and xylose fermentation tests could simultaneously be used. Pasteurellae isolated in cases of acute fowl cholera showed positive reaction for arabinose and a negative one for xylose, while the strains isolated from mammals showed the reverse activity. The strains isolated in cases of chronic fowl cholera were shown to belong to this group.

Animals↗

PubMed1983

[Passive hemagglutination test with capsular and somatic antigens of Pasteurella multocida strains isolated from birds].

Comparative investigations were carried out with the passive hemagglutination reaction in the serotyping of 14 reference and 34 P. multocida strains isolated from birds with three types of antigens obtained from one and the same bacterial mass: capsular extracts obtained by Carter's method (1), thermostable capsular extracts obtained after Carter and additionally heated at 100 C degrees for one hour (2), thermostable somatic extracts obtained after the additional heading of the depot of bacterial mass, treated after Carter at 100 C degrees for one hour (3). The results obtained with the three extracts correlated fully with each other as established with the passive hemagglutination test. Out of 34 strains 76.47 per cent were typed with the use of two of the capsular extracts, and 97.05 per cent--with the thermostable somatic extracts. Thermostable somatic extracts obtained from reference and field strains of P. multocida showed type specificity according to the classification of Carter. Of the P. multocida strains isolated from birds that succumbed to acute or chronic form of fowl cholera 97.06 per cent were typed as serotype A, and 2.94 per cent--chiefly in the chronic form of the disease--as serotype B. It was found that immunodiffusion conducted with capsular extracts was the most suitable method for the detection of antibodies in the sera of rabbits against P. multocida prior to the animals' hyperimmunization with type cultures.

Animals↗

PubMed1983

[Sensitivity of Pasteurella multocida strains to antibiotics and chemotherapeutic agents].

The disk diffusion method was employed to test the sensitivity of a total of 330 Pasteurella multocida strains to streptomycin and kanamycin, of 309 strains to erythromycin, of 315 strains to chloramphenicol, of 240 strains to tetracycline, of 213 strains to gentamycin, of 211 strains to ampicillin, of 209 strains to neomycin, of 199 strains to novobiocin, of 169 to spectinomycin, of 162 to borgal, and of 67 strains to furazolidon. All tested strains were isolated from birds with cholera and from mammals with pneumonia, showing 100 per cent sensitivity to ampicillin, chloramphenicol, erythromycin, tetracycline, gentamycin, and borgal, 88.2 per cent to spectinomycin, 86.6% to furazolidon, 74.2% to neomycin, 52.7% to kanamycin, 23.7% to streptomycin, 32.7% to novobiocin. 13.9 per cent of the P. multocida strains only were resistant to streptomycin. Strains of intermediate sensitivity were as follows: 67.3%--to novobiocin, 62.4%--to streptomycin, 47.3%--to kanamycin, 25.8%--to neomycin, 13.4%--to furazolidon, and 11.8%--to spectinomycin. Ninety-seven strains (42 from birds, 23 from pigs, and 32 from rabbits) were tested for sensitivity in solid media to lowest inhibiting concentrations of tetracycline--4 micrograms/cm3, gentamycine--6 micrograms/cm3, chloramphenicol--12.5 micrograms/cm3, kanamycin--6 micrograms/cm3, erythromycin--8 micrograms/cm3, ampicillin--8 micrograms/cm3, and imekil--0.8 microgram. All tested strains were sensitive to these concentrations. For the treatment and prophylaxis of birds (fowl cholera) and mammals (pasteurellosis) a wide set of antibiotics and chemotherapeutic agents can be used.

Anti-Bacterial Agents↗

PubMed1982

[Isolation, selection and characteristics of Pasteurella multocida].

Bacteriophages of 2 and AV signature were isolated from lysogenic P. multocida strains. spontaneous mutation of bacteriophage 32 of various indicator Pasteurella strains led to the isolation of 6 new bacteriophages with signature of the indicator strain 10, 55, 168, 895, 994. Bacteriophages 3,4, and 115 served to isolate bacteriophages with signature 3/10, 4/10, and 115/10 of a phage-resistant 3/10 strain. Phages TH and VL were selected from AV phage, and phage 1 was selected from phage 10. A total of 14 new P. multocida bacteriophages were obtained in all, which were reproduced on one and the same indicator strain No 10. The newly isolated phages 1, 2, 10, 895, 3/10, 4/10, 115/10, AY, VL, and TH were neutralized by antisera 2, 10, 4/10, AY, and TH in 99 to 100 per cent, and belong to a common serologic group (IVth group). Bacteriophages 55, 168, 994, and 995 were not neutralized by these sera. By the effect of chemicals and sodium citrate the AY and VL phages were found to be stable to inactivation, while tetracycline inactivated 50 per cent of them. Bacteriophages 10, and 3/10 survived at pH 9 and 11. By these indices the mentioned 10 bacteriophages were referred to the new P. multocida IVth group phages. Spontaneous mutations in the P. multocida phage populations are likely to occur. Such mutations could belong to various phage types. The genetic changes in the phage populations appear as a base in the production of P. multocida bacteriophages of various types which could be used in the phage typing of the P. multocida species.

Bacteriophage Typing↗

PubMed1981

[Antibiotic relationship of streptomycin-dependent and streptomycin-resistant Escherichia coli mutants pathogenic for poultry].

Studied was the reaction streptomycin-dependent and streptomycin-resistant mutants and their revertants of the Escherichia coli strains 078:K80, 02:K1, and 0111:K58 to the following, practically important antibiotics: rifampicin, novobiocin, chloramphenicol, and penicillin. The study made use of mutants of both smooth (S) and rough (R) form obtained through induced mutagenesis effected by means of nitrosoguanidine and nitrous acid. The method of serial dilution of antibiotics and that of dynamic recording of their action through automatic biophotometry were employed. Negligible differences were established in the behaviour of the various groups of organisms. The streptomycin - dependent mutants retained unchanged the reaction of the initial strains to the antibiotics. The revertants showed high level of of resistance to streptomycin and by their behaviour they were closer to the streptomycin - resistant mutants than to the initial strains. In connection with this the probability is discussed of the "suppressor" origin of the streptomycin-dependent mutants.

Animals↗

PubMed1981

[Nitrous acid induction of Escherichia coli mutants pathogenic for poultry].

Three strains of Escherichia coli - 0 78:K 80, 0 2:K 1, and 0 111: K 58, the first two pathogenic for birds - were used to test the mutagenic action of nitrous acid. Survival curves were drawn, and the optimal conditions were determined for the action of nitrous acid as a mutagenic factor. A scheme was suggested for the isolation of streptomycin-resistant and streptomycin-dependent mutants. The capacity of nitrous acid to induce mutations was demonstrated with regard to the streptomycin-dependence phenomenon and the rough (R) form of colonies. Discussed is the optimization of the streptomycin concentrations needed for the growth of the streptomycin-dependent mutants. Tested have been some biochemical activities of the mutants in comparison with the initial forms. It has likewise been demonstrated that the streptomycin-dependent mutants in R form change their reaction to some carbohydrate sources, either assimilating them at a delayed rate (as in most cases) or losing the capacity to assimilate them.

Animals↗

PubMed1981

[Streptomycin-dependent mutants of a Pasteurella multocida strain isolated from poultry].

A culture of strain Pasteurella multocida 115, isolated from a hen affected with fowl cholera, was treated with 50 mcg/cm3 streptomycin and subjected to selection at an additional treatment with 200 mcg/cm3 of the same antibiotic. A total of 16 streptomycin-resistant mutant strains were obtained. All of them were shown to be avirulent in testing their pathogenicity for mice, however, two of the mutants were of lowered virulence in tests with birds. Fourteen days post vaccination birds that survived were challenged with 1000 LD of the initial wild strain 115. Two of the mutants only did not induce immunity. In cross immunologic testing of the birds with Pasteurella strains X73, 1059, 1662, and 3940 best immunologic properties showed mutants 115.2 and 115.3. In agglutination of sera from the vaccinated birds with HCl--and formalin-treated antigen of strain 115 the titers were low, ranging from 1:10 to 1:40.

Animals↗

PubMed1981

[Determination of the nucleotide composition of Pasteurella multocida strains].

Studied was spectrophotometrically the nucleotide composition of DNA of Pasteurella multocida strains along with studies on the nucleotide base ratio, the molar relations between nucleotide bases, the guanine/cytosine ratio in percent, and the specificity index adenine-tinin/guanine cytosine. The strains used were isolated from birds with various forms of fowl cholera (acute, atypic, and swelling of the wattles), and from calves with bronchopneumonia. Used were also mutants that were streptomycin dependent, obtained through induction with nitrosoguanidine. Close values were established of the nucleotide bases both with the individual groups of Pasteurella strains and with the mutants and their initial strains. The molar relations showed values around a unit, the guanine/cytosine ratio in percent varied from 40.14 to 43,54 and the specificity index varied from 1.25 to 1.49. Data showed that all studied strains and mutants belonged to one species - Pasteurella multocida, on the one hand, and their grouping could not be made on the basis of their nucleotide composition, on the other - contrary to some other indexes, such as biochemical activity, virulence, and behaviour to specific phages.

Animals↗

PubMed1980

[Drug-resistance markers from Salmonellae in Pasteurella multocida].

A transfer of resistance was effected of S. haidelberge strain, having 7 medicinal resistance markers, onto 2 Pasteurella multocida strains No. 10 and Vladislavovo. In strain No. 10 were found 20% of recombinations, whereas in Vladislavovo their number was 10%, hence the different pasteurella strains can be recipients at a higher or lower degree. The recombinations obtained are not stable and during their short conservation in bouillon they spontaneously get rid of the markers of resistance acquired.

Drug Resistance, Microbial↗

PubMed1980

[Elimination of multidrug resistance in E. coli in calves in vivo with rimactan].

An experiment was carried out for eliminating the multimedicinal resistance markers of E. coli, populating the intestinal tract of calves, in vivo with rimactan introduced per os, and rationed 10 mg/kg of live weight, once during a period of 8 days. The highest percentage and the longest elimination were observed for the neomycin, the novobiocin and the chlornitromycin resistance markers. The elimination was weaker for the erythromycin, the streptomycin and the kanamycin markers and the weakest was for the penicillin and tetracycline markers. There appeared a difference in the elimination of the resistance markers with the different calves, especially for the markers with a low degree of elimination, depending on the individual peculiarities of the calves. Riphamycin proved to be an eliminating means for the resistance markers of E coli in vivo of calves suffering from enteritis. Alongside with the elimination of the resistance markers, due to the treatment of calves with rimactan, an almost complete recovery was achieved. Rimactan is a reliable means for fighting enteric illnesses with calves, caused by enteropathogenic E. coli.

Animals↗

PubMed1980

[Attempt at eliminating the multiple drug resistance of E. coli in pigs with enteritis using Rimactin].

The eliminating effect of rimactan was studied in vivo on resistance markers of E. coli, isolated from 18 new-born pigs with a clinic of enteritis. Rimactan is given per os in 15 mg/kg, liver weight, once a day in the course of 6 days. The sensitivity of the strains eliminated was checked in vitro in respect of 16 medicinal preparations (Pe, Sm, Km, Neo, Chl, Novo, Te, Er, Ty, Sp, Le, Am, Ox, Oxte, Ge-penicillin, streptomycin, kanamycin, neomycin, chlornitromycin, novobiocin, tetracycline, erythromycin, tylan, spectam, lentamycin, ampicillin, oxacillin, oxytetracycline, gentamicin and borgal). To 11 of them E. coli were resistant. After a treatment with rimactan an elimination of resistance markers was observed right on the first day, namely, with regard to Sm, Chl, Novo, Te, Er, Sp, Oxte. On the second day was eliminated the Pe-marker, on the third--the Ty-marker, and it was not until on the fifth day that Am and Ox-markers were eliminated. The elimination frequency was the highest between the third and the fifth days. The experiments studied also the sensitivity of the investigated coli strains with regard to different rimactan concentrations (2-256 mg/cm3) in vitro. It was most pronounced for a concentration of 16-32 mg/cm3. It was proved that rimactan can be used as a preparation for eliminating resistance markers (R-factors) of E. coli in pigs suffering from enteritis.

Animals↗

PubMed1980

[Amino acid metabolism in Pasteurella multocida studied using thin-layer chromatography].

Amino asid metabolism was studied by thin layer chromatography in 25 Pasteurella multocida strains isolated from various manifestations of the disease chicken septicemia. Six amino acids were used: DL-ornithin, L-cystein, L-asparagin, DL-serin, L-arginin and Acidum glutaminicum. The Pasteurella strains studied include in their metabolism the amino acid asparagin, but serin and cystein are excluded. The strains isolated from birds suffering from acute and atypical septicemia do not metabolize ornithin, while these isolated from birds having wattles oedema or from calves suffering from arthritis metabolize it. The reaction of Pasteurellae to arginin and glutamic acid varies and no regularity in this respect is observed. Strains isolated from calves suffering from bronchopneumonia do not include in their metabolism any one of the named amino acids. As a result of the test applied a correlation between the Pasteurella multocida biotypes assessed by the authors and the amino acid metabolism was established. This is one proof more that the isolated pasteurellae can be groupped in two big biotypes by the tests for virulence in birds and including in their metabolism the amino acid ornithin.

Amino Acids↗

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↗