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Biomedical subjects

G Slavchev

Publications and source records attributed to G Slavchev.

18 recordsLinked to original sources
PubMed1987

[Susceptibility of Yersinia bacteria to antibiotics and disinfectant agents].

Studied was the susceptibility of Yersinia bacteria to antibiotics and disinfection means. Results showed that the reference strains of the Yersinia enterocolitica, Y. pseudotuberculosis, Y. fredericksenii, and Y. intermedia species manifested high sensitivity to gentamycin, nalidixic acid, chloramphenicol, and streptomycin. Serovariety 03 of Y. enterocolitica strains, isolated from milk and sewage water, were most sensitive to gentamycin (100 per cent), chloramphenicol (100 per cent), nalidixic acid (100 per cent), kanamycin (95.8 per cent), and streptomycin (92.8 per cent). The disinfection preparations Dezinfect B (4 per cent solution) and Reiniger Combi (0.5 per cent solution) destroyed V. enterocolitica, Y. fredericksenii, and Y. intermedia for 30 sec., and Y. pseudotuberculosis for 5 minutes. Under productional conditions the same effect was produced for 10 to 15 minutes.

Anti-Bacterial Agents↗
PubMed1986

[Development and survival of Yersinia enterocolitica in pasteurized milk and ice cream].

Studied were the laboratory development and survival of Yersinia enterocolitica organisms in pasteurized milk and ice-cream that had been contaminated with varying amounts of microbial cells. The milk was kept at 4 degrees, 9 degrees, and 21 degrees C for 120 days, and the ice-cream--at--18 degrees and --23 degrees C for 8 months. Yersinia development and survival were found to be dependent on temperature as well as on the numbers and activity of microflora. When milk was kept at temperatures below 10 degrees C the organisms retained viability for more than 120 days, while at room temperature (20 degrees--22 degrees C) they remained active for up to 30-60 days. The presence of coliform bacteria inhibited the development of Yersinia, its replication and survival rates being reduced. These were dependent in ice-cream on the amount of viable cells in the initial raw material. When contamination was at 10-15 cells per cu. cm Yersinia organisms remained viable up to the 45th day, and at 100 cells per cu. cm--up to the 90th day. At 1000 cells/cu. cm and more viable cells could be found up to the eighth month, their count over a 6-month period being reduced from 84.2 up to 98.5 per cent.

Animals↗
PubMed1985

[Bactericidal effect of the preparation trozin].

Tested was the bactericidal action of the combined cleansing and disinfecting preparation trozin under laboratory and production conditions. It was found that trozin meets the requirements in terms of rapid disinfection, killing the asporogenous test organisms. The presence of at least 2 per cent milk protein lowers the bactericidal action of the detergent. The cleansing and disinfection of milking units supplied with a milk-can, resp., with a central milk pipeline leads to 97.00, resp., 98.00 per cent reduction, on an average, of microflora. The bacterial count of the udder is likewise reduced by about 96.00 per cent.

Animals↗
PubMed1984

[Improved method for isolating Yersinia enterocolitica].

Investigations were carried out to restore and isolate Yersinia enterocolitica from both pure and mixed cultures as well as from sewage waters through enriching and alkaline treatment, employing the method of Aulisio and coll. It was found that the peptone used for the purpose (containing sorbitol, 10.0, yeast extract, 5.0, sodium taurocholate, 2.0, bacto-peptone, 2.0, bacto-tryptone, 2.0, bromthymol blue, 0.007, and 1/15 phosphate buffer, 1000 cm3 at pH = 7) made it possible for Y. enterocolitica to replicate at 4 degrees C in 8 to 10 days and inhibited the development of many other organisms. Enriching the medium at 4 degrees C with the alkaline treatment that followed enabled the isolation of Y. enterocolitica from mixed cultures and sewage waters from milk-processing enterprises in a very high percent of the cases as against enriching at 22 degrees C. Such enriching broth could be used not only for the enriching of Y. enterocolitica at 4 degrees C, but also for the differentiation of pure cultures in culturing at the same temperature.

Bacteriological Techniques↗
PubMed1984

[Cold resistance of S. aureus and staphylococcal enterotoxins A and C2 in ice cream].

Studied was the cold resistance of enterotoxinogenic strains of Staphylococcus aureus and of A and C2 staphylococcus enterotoxins in milk and cream icecream kept under refrigerator conditions for 7 months at -18 degrees C. The S. aureus strains were shown to have high resistance in icecream. The survival rate of the organisms depended both on the specific peculiarities of the individual strains and on the composition of the icecream mixture. Staphylococci were found to survive longer in milk icecream. A and C2 enterotoxin retained fully their activity in the two types of icecream over the entire period of storing. The data obtained is important for the elucidation of the epidemiology of alimentary staphylococcus intoxications.

Cold Temperature↗
PubMed1984

[Enterotoxic staphylococci in the milk of cows and sheep with mastitis].

Studied were the occurrence and the biochemical and phage characteristic of enterotoxic staphylococci in cow and sheep milk from animals with mastitis. Milk samples taken from 150 cows and 120 ewes were investigated for the presence of Staphylococcus aureus. This organism was found in 88 per cent of the cow milk samples and in 89.2 per cent of the sheep milk ones. The count of bacteria was within the 10(1) to 10(5)/cm3 range. A total of 239 strains of Staphylococcus aureus were isolated from both kinds of milk. They were tested for enterotoxigenicity after Ouchterlony. It was shown that 28.8 per cent of those isolated from mastitis cow milk and 7.5 per cent of those isolated from mastitis ewe milk produced an enterotoxin. Those from the cow milk samples produced enterotoxin A in 65.8 per cent of the cases, enterotoxin B in 13.1 per cent, and enterotoxin C in 5.3 per cent. Simultaneous production of A and D toxin was found in 15.8 per cent of the strains. Those isolated from the ewe milk samples produced enterotoxin C in 75 per cent of the cases, and enterotoxins A and C in 25 per cent. The enterotoxigenic Staphylococcus strains were distinguished by high biochemical and enzyme activity, however, none of the methods tested proved specific for enterotoxic Staphylococci only. The enterotoxic staphylococci of cow milk were typed by II and IV phages and by a mixed group of phages (II/M, III/M, IV/M, II/IV). Most spread were the 116 and 116/118 phage types.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

[Yersinia enterocolitica survival in Bulgarian yogurt and Vita yogurt (experimental studies)].

Laboratory studies were carried out on the development and survival of Y. enterocolitica in Bulgarian sour milk and sour milk 'Vita'. The raw cow milk was contaminated with various amounts of Y. enterocolitica cells. Results showed that the development and survival of the organism in the sour milk was dependent on its count in the raw milk and the running of the process of lactic acid fermentation. Under refrigerator conditions (Bulgarian sour milk contaminated at the rate of 10(4) microbial cells per cm3) Y. enterocolitica retained its viability up to the 24 th hour. When contamination reached 10(5) and 10(5) cells per cm3 the viability of the organism lasted up to 72 hours. Sour milk 'Vita' with a starter of strain of Lb. bulgaricus, producing D (-) lactic acid, possessed stronger inhibitory action on Y. enterocolitica compared with milk with a starter of strain of Lb. bulgaricus, producing L (+) actic acid.

Animals↗
PubMed1982

[Sensitivity of agents of mastitis to various antibiotics].

Studied was the sensitivity to antibiotics of a total of 328 strains of mastitis-causative agents, employing the agar-diffusion method. Staphylococcus aureus proved most sensitive to cephacetril (100%), gentamycin (85.3%), and erythromycin (75.2%). Of the pathogenic streptococci Str. agalactiae was most sensitive to cephacetril (100%), chloramphenicol (100%), and tetracycline (92,8%), while Str. uberis and Str. dysgalactiae ranked second - cephacetril (88,2%), tetracycline (77.4%), and gentamycin (74.5%). Coliform bacteria were found to be most sensitive to streptomycin (75-77%), gentamycin (69-74%), and chloramphenicol (66-73%), and completely resistant to penicillin and ampicillin. Corynebacteria were sensitive to most of the antibiotics - cephacetril (100%), chloramphenicol (83.8%), erythromycin (78.3%), gentamycin (75.6%), and ampicillin (72.9%). Usually, the mastitis causative agents showed polyresistance at one and the same time mostly to three (36.3%) and four (19%) antibiotics.

Animals↗
PubMed1981

[Etiological study of mastitis in cows].

The rapid mastitis test was employed to study a total of 13 880 cows on 40 farms. Positive for mastitis proved 2384 udder quarters. Clinically manifested mastitis was established in 3.23 per cent of the cases, subclinical mastitis - in 58.14 per cent, carrier status - in 12.55 per cent, secretion disturbances - in 22.58 per cent, and normal proved 3.84 per cent. In the mastitis-positive cases pathogenic streptococci were isolated in 57.14 per cent of the quarters, staphylococci - in 20.77 per cent, Corynebacteria - in 9.09 per cent, and other bacteria - in 5.19 per cent. In the cases with subclinical mastitis staphylococci accounted for 40.93 per cent, streptococci - for 38.7 per cent, Corynebacteria - for 14.22 per cent, and other organisms - for 6.0 per cent. Most frequently encountered were the carriers of staphylococci - 46.8 per cent, followed by those of Corynebacteria - 26.4 per cent, and of streptococci - 20.73 per cent.

Animals↗
PubMed1981

[Effect of the sanitary state of the udder on the pyruvate content in the milk].

Studied was the pyruvate content of a total of 302 samples of "aseptic" milk as dependent on the clinical status of the mammary gland. The normal gland indices showed fluctuations from 0.48 up to 1.55 ppm at the respective cell element count, which ranged from 90000 to 480000 per cu. cm. It was found that when the secretory function of the gland was impaired the pyruvate level in the milk varied from 0.68 to 4.07 ppm at the respective cell count of 520000 to 4740000 per cm3. With milk from cows affected with subclinical mastitis the pyruvate value ranged from 0.87 to 6.13 ppm, and the cell count -- from 540,000 to 7,000,000. It is stated that the pyruvate test could not be used alone as a method in the evaluation of the clinical state of the udder, but could be referred to as an adjunct in the complex study of mammary gland.

Animals↗
PubMed1980

[Psychrotrophic microorganisms in raw and pasteurized milk].

The studied were carried out in 360 samples of unboiled milk and 1080 samples of pasteurized milk taken from three processing and distributing dairies having a different capacity and equipment. It was proved that the content of psychrotrophic microorganisms in unboiled milk from the three dairies varied from 120000 up to 200000 in 1 cm3 and was in close connection with the seasons of the year. The conditions applied for pasteurization in the three dairies killed (with the exception of those forming spores) nearly all psychrotrophic bacteria. The secondary seeding of the pasteurized milk by means of psychotrophics was carried out after the pasteurization along the whole technological route till its packing. The pasteurized milk packed in bottles showed a contamination with psychrotrophic microorganisms 4-6 times higher than that of milk packed in plastic bags. In the unboiled and in the pasteurized milk we found the psychrotrophic microorganisms of the species: Pseudomonas--respectively 64% and 53.8%, Micrococcus--8.2% and 30.7%, Enterobacter--9.8% and 2.6%, Bacillus--6.6% and 2.6%, Flavobacter--1.6% and 1.3% and Torula--2.6%. A comparatively high percentage (37.7%) of the isolated strains the psychrotrophic bacteria were lipolytic in the unboiled milk, 24.6%--proteolytic and 9.8% were simultaneously proteolytic and lipolytic. In the pasteurized milk 11.5% of the strains were lipolytic and 5.13% were proteolytic.

Animals↗
PubMed1980

[Psychrotrophic and coliform microflora of the udder in cows].

A study of the psychrotrophic and coliform microflora over the udders of cows was carried out. It was proved that the way and means of cleaning them exercise a great influence on the composition of the psychrotrophic and coliform microflora. The psychrotrophic flora over the udders consisted of 46.9% of specimens of p. Micrococcus, 8.7%-p. Streptococcus, 8.2% Staphylococcus, 7.4%-Corynebacterium, 2.8%-Saccharomyces, 10%-coliform bacteria, 12.5%-psychrophils, mainly of p. Pseudomonas and p. Flavobacterium. The coliform microflora over the udders consisted of 55.4% of p. Escherichia, 20.8%-p. Citrobacter, 16.8%-Klebsiella and 6.9%-p. Enterobacter.

Animals↗
PubMed1979

[Finding of the staphyloccoi and streptococci of mastitis on the udder after various ways and means of cleaning].

The presence of mastitis staphylococci and streptococci on the udder's surface of 400 cows was studied following application of various ways and means of cleaning. The presence of agents causing mastitis was determined before and after cleaning the udder. On uncleaned udder surfaces presence of mastitis staphylococci was observed in 52.5% and of mastitis streptococci--39.5% of udders studied. After washing with water mastitis staphylococci--on 12-20% of the udders. Following udder cleaning with solutions of antigerm 50 (0.04%) or yozan CCT (4%), mastitis staphylococci were found on 4% and 6% of the udders, respectively, while mastitis staphylococci--on 2% and 6%, respectively. Udder surface staphylococci belong in 2.2% to II phagous group, in 46.6%--to the III group, and in 37.7% -- to mixed groups. The most frequently encountered phagous types were 6 and 42D.

Animals↗
PubMed1979

[Use of the pyruvate test for determining the bacterial activity in milk].

Comparative studies were carried out on the pyruvate and reductase tests applied in milk of varying hygienic properties. It was established that: just after milking the pyruvate and reductase tests have a low correlation with bacterial infestation of milk; in milk cooled at 3--5 degrees C for a longer period (72 h) the pyruvate test has a good correlation with bacterial infestation of milk; following storage of milk at temperature above 10 degrees C the reductase test with methylene blue is better correlated with bacterial infestation of milk; the pyruvate-test is appropriate for evaluation of bacterial activity in milk cooled at low temperature and transported every second day; the reductase test is appropriate evaluation of bacterial activity in not well cooled milk which is transported one a day.

Animals↗
PubMed1976

[Coliform microflora of commercial Caucasian cheese].

Studied was in the course of several years the extent of coliform bacterial contamination and the peculiarities the bacteria present in ripened cow's and ewe's white brine cheese offered for consumption. It was demonstrated that these kinds of cheese released in the commercial system contain up to 3.1 per cent coliform bacteria. Certain correlation was established between the coliform count in the cheese and the degree of ripening, the consistence, and the aspect of the cross section surface. If hygiene measures were not observed cheese could be contaminated additionally with coliforms during handling in the shops. Coliform microflora was presented mainly by strains characteristic of fresh fecal contamination (E. coli) and urease-positive organisms of the Citrobacter and Enterobacter genera. To guarantee the consumption of qualitative (in terms of hygiene) white brine cheese it is necessary to include into the respective standards the index "coli titer" of a unit value.

Animals↗
PubMed1976

[Inhibitory action of the residues of some new disinfecting agents on the microflora of Bulgarian milk].

Studied were the amounts of residues of disinfection solutions such as antigerm 0.3 per cent, bradophen 0.2 per cent, abosanit 0.35 per cent, trosilin 0.5 per cent, and oxania 2 per cent which could produce inhibitory effects of the microflora of the Bulgarian sour milk. It was established that the presence of more than 25 ml/1 of a given disinfection solution in the milk of the above-mentioned ones at the concentrations cited (with the exception of trosilin) exert a strong inhibitory action on milk microflora and the enzyme processes. As a result no curdling sets in. The use of Bac. stearothermophilus as a test organism can detect but the presence of 150 mg/1 antigerm in the milk.

Animals↗
PubMed1975

[Influence of some factors on the quality of Bulgarian sour milk].

The results obtained with three feeding experiments revealed that combined forages containing biovit-40 are effective in that the antibiotic is not excreted with cow's milk and it does not inhibit the development of lactic acid fermentation. The season of the year associated with the passage of a given type of feed on to another type was found to influence the course of the lactic acid fermentation as follows: --in feeding green mass in the summer period there is a stimulation of the development of Lactobacillus bulgaricum and Str. thermophilus in the milk; -- in feeding greater amounts of succulent forages in the winter, spring, and autumn periods there is a retardation in the development of the same organisms in the milk.

Animal Feed↗