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C Genigeorgis

Publications and source records attributed to C Genigeorgis.

At least 19 recordsLinked to original sources
PubMed2003

Factors associated with the serological prevalence of Salmonella enterica in Greek finishing swineherds.

Blood samples were taken from 50 finishing pigs at 90-105 kg in each of 59 randomly selected farrow-to-finish herds. The sera were tested for antibodies to Salmonella enterica by the Danish mix-ELISA. Samples with an optical density of > 10% were considered to be positive. Associations between the odds of seropositivity of pigs and possible risk factors were evaluated in multivariable logistic regression models. The results of the analysis indicated that pigs fed non-pelleted dry or wet ration had 11 (P = 0.0004) or 9 (P = 0.02) times, respectively, lower odds of seropositivity than those fed pelleted ration. The risk of seropositivity was 4 (P = 0.0006) times higher in pigs fed a combination of chlortetracycline, procaine penicillin and sulphamethazine during fattening than in those fed an approved growth promotor or a probiotic.

Animal Feed↗
PubMed2001

Seroprevalence and antibiotic sensitivity of serotypes of Salmonella enterica in Greek pig herds.

Blood samples were taken from 50 pigs in each of 59 farrow-to-finish production herds and from 40 pigs in each of four of five registered multiplying herds. Samples of feed and faeces were also collected from 17 of the production herds and from the four multiplying herds. The sera were tested for antibodies to Salmonella enterica by the Danish mix-ELISA, and the organisms were isolated, serotyped and sensitivity tested by standard techniques. The average within-herd seroprevalence was 3.4 per cent and at least one pig tested seropositive in 21 of the 59 herds. In the multiplying herds, only a single seroreactor was detected. Salmonellae were isolated from only five of 95 feed samples, from two of the 17 herds sampled, Salmonella tennessee in four of five samples from one herd and an untypable strain in one of five samples from another. Four infected faecal samples were detected in four herds; they harboured Salmonella typhimurium, Salmonella bredeney or Salmonella london. No salmonellae were isolated from the samples of feed and faeces taken from the multiplying herds. The S london and S typhimurium had a low sensitivity to streptomycin, kanamycin and neomycin, and the S typhimurium also had low sensitivity to amoxycillin, ticarcillin, piperacillin, amoxycillin + clavulanic acid, cefalotin and cefoperazone. The other isolates were sensitive to all the antimicrobial agents tested.

Animal Feed↗
PubMed1998

Prediction of Listeria spp. growth as affected by various levels of chemicals, pH, temperature and storage time in a model broth.

The effects of concentration of NaCl (0.5 to 12.5%), methyl paraben (0.0 to 0.2%), sodium propionate (0.3%), sodium benzoate (0.1%), potassium sorbate (0.3%), pH (> 5.9) temperature (4 to 30 degrees C), storage time (up to 58 d) and inoculum (> 10(5) to > 10(-2) per ml) on the log10 probability percentage of one cell of Listeria spp. to initiate growth in a broth system were evaluated in a factorial design study. At pH 5.96 and temperature ranging from 4 to 30 degrees C the concentrations of sodium propionate, potassium sorbate, and sodium benzoate examined allowed growth of L. monocytogenes with lag phases at 4 degrees C of 18, 27 and 21 days, respectively. For 0.1 and 0.2% methyl paraben growth of all Listeria spp. was initiated at 8 degrees C and 30 degrees C, respectively. At pH 6, concentration of 12% NaCl supported the growth of L. monocytogenes at 8 to 30 degrees C, whereas 12.5% inhibited all Listeria species. Four regression equations were derived relating probability of growth initiation to temperature, concentrations of NaCl and preservatives storage time, and Listeria species specific effects. From these equations, the number of cells needed for growth initiation can be calculated. The impact of this type of quantitative study and its possible application on the development of microbial standards for foods is discussed.

Benzoates↗
PubMed1997

Temperature distribution and prevalence of Listeria spp. in domestic, retail and industrial refrigerators in Greece.

The present paper examined the presence of Listeria spp. in the environment of domestic, retail and industrial refrigerators. From 136 household refrigerators, 136 surface samples were taken from the walls or shelves, and 125 from cheese compartments. Only two refrigerators harboured L. monocytogenes. From 228 food store refrigerators, 335 samples were taken. Of these, 118 were in in contact with cheeses, 69 with sausages, 21 with cheese and sausages, 20 with miscellaneous products and 107 from refrigerator handles. Listeria spp. and L. monocytogenes were found in 3.1% and 1.7%, of the samples respectively. Listeria spp. was not detected in any of the nine dairy plant refrigerators examined. Listeria monocytogenes and L. innocua were found in 4.5 and 36.4%, respectively, of the 22 refrigerators inside meat processing plants, with only one of 22 refrigerators handles being positive for L. monocytogenes. Temperature distribution in the refrigerators was also investigated. Fifty five per cent of the 136 domestic and 32% of the 228 retail store refrigerators had temperatures of greater than or equal to 9 degrees C. The range of refrigeration temperatures of the industrial refrigerators was 0-2 degrees C for meat plants and 2-7 degrees C for dairy plants. No correlation of any kind could be established between the prevalence of Listeria spp. and the temperature of the various refrigerators due to the low number of positive samples.

Food Microbiology↗
PubMed1995

Potential growth and control of Escherichia coli O157:H7 in soft hispanic type cheese.

This study examined growth and control of two enterohemorrhagic Escherichia coli serotype O157:H7 strains in a soft Hispanic type cheese (Queso Fresco). Cheese was made in the laboratory using a commercial procedure and after inoculation it was stored under vacuum at temperatures ranging from 8 to 30 degrees C. The minimum temperature that allowed growth of E. coli in the unmodified normal cheese (pH 6.6) was 10 degrees C. No growth of either strains was observed during a 2 month storage period at 8 degrees C. Accumulated data from the growth studies were used for development of models relating square root of 1/LT (LT = lag time) and specific growth rate, to temperature. The effect of selected antimicrobials (potassium sorbate, sodium benzoate, and sodium lactate) added to milk or cheese on the growth and survival of these pathogens at various storage temperatures was also evaluated. Addition of sodium benzoate (0.3%) to cheese (pH 6.6) or addition of potassium sorbate (0.3%) to cheese (pH 6) made from milk acidified to pH 5.9 with propionic acid, had a significant impact on delaying or preventing growth of the pathogens.

Animals↗
PubMed1994

Potential growth and control of Salmonella in Hispanic type soft cheese.

This study evaluated the growth and control of Salmonella serotypes in a soft Hispanic type cheese (Queso Fresco). Cheese was made in the laboratory using a commercial procedure and after inoculation it was stored under vacuum at temperatures ranging from 6 to 30 degrees C. The minimum temperature that allowed growth of Salmonella was 8 degrees C. Accumulated data from the growth studies were used for the development of models relating the square root of 1/LT (LT = lag time) and specific growth rate to temperature. The effect of selected antimicrobials (potassium sorbate, sodium benzoate and sodium lactate) on the growth and survival of Salmonella in milk and in cheese at various storage temperatures was also examined. Addition of sodium benzoate (0.3%) to cheese (pH 6.6) or addition of potassium sorbate (0.3%) to cheese (pH 6.0) made from milk, which was acidified to pH 5.9 with propionic acid, had a significant impact on delaying or preventing growth of the pathogen.

Acetates↗
PubMed1992

Disease determinants of sporadic salmonellosis in four northern California counties. A case-control study of older children and adults.

A population-based, case-control study of sporadic salmonellosis was conducted in 1988 and 1989 in four northern California counties. The study included 120 patients and 265 control subjects. Conditional logistic regression analysis (adjusted for age) revealed that patients were more likely to consume undercooked chicken prior to the onset of disease (odds ratio [OR], 23.57; 95% confidence interval [CI], 2.89 to 192.30). Elevated associations were also found with recent travel to foreign countries (OR, 9.69; 95% CI, 3.18 to 29.56), diabetes (OR, 6.29; 95% CI, 1.56 to 25.34), hormonal replacement therapy (principally conjugated estrogen) in older women (OR, 4.20; 95% CI, 1.82 to 9.71), and antibiotic therapy prior to illness (OR, 1.96; 95% CI, 0.86 to 4.37). The problems of studying self-selected cases that may lead to alternative explanations for these findings are also discussed.

Adolescent↗
PubMed1990

Growth and toxigenesis of C. botulinum type E in fishes packaged under modified atmospheres.

Modified atmosphere packaging of fresh fish is used to market high quality products in some European countries. The potential risk of C. botulinum growth in these extended shelf-life foods is still a concern; especially since toxigenesis may precede organoleptic spoilage. This paper will present toxigenic data from rockfish, salmon and sole muscle tissues which were inoculated with a pool of non-proteolytic C. botulinum type E at seven levels (10(-2)-10(4) spores/sample), and stored under vacuum and 100% CO2, at incubation temperatures between 30 and 4 degrees C, for up to 60 days. Factorial experimental design allowed predictive formulae to be developed able to describe the lag time prior to C. botulinum toxigenesis and the probability of one spore to initiate toxigenesis based upon the storage conditions. Accurate characterization of the microbial ecology of C. botulinum in modified atmosphere-packaged fish, will support safe exploitation of these packaging systems in the market place, and identify critical control points for potential product or process abuses.

Animals↗
PubMed1983

Use of enzyme linked immunosorbent assay (ELISA) in the quantitation of Clostridium perfringens type A enterotoxin and antienterotoxin antibodies.

ELISA procedure for quantitation of enterotoxin of Clostridium perfringens type A was worked out. It was possible to detect as little as 0.0022 microgramme of enterotoxin. When applied to quantitate the enterotoxin in laboratory contaminated faeces and cooked minced beef, ELISA detected as little as 0.024 microgramme of enterotoxin. ELISA procedure for determination of titre of antibodies to enterotoxin was also developed using hyperimmunised rabbit and sheep sera. It was possible to use this procedure in sero-survey.

Animals↗
PubMed1981

Production of italian dry salami: effect of starter culture and chemical acidulation on staphylococcal growth in salami under commercial manufacturing conditions.

The effect of starter culture and chemical acidulation on the growth and enterotoxigenesis of Staphylococcus aureus strain S-6 in Italian dry salami under commercial manufacturing conditions was studied. The experimental design included two levels of S. aureus (10 and 10/g), three levels of starter culture (0, 10, and 10/g), three levels of initial pH (pH(0)) (6.1, 5.5, and 4.8), two manufacturing plants, and three replications. S. aureus growth in the salami was affected significantly (P < 0.005) by pH(0), initial levels of S. aureus (staph(0)) and lactic acid bacteria (LAB(0)), day of fermentation, and by the interactions of pH(0) x day, pH(0) x LAB(0), LAB(0) x staph(0), pH(0) x staph(0), and pH(0) x location of fermentation. In general, the lower the pH(0) and the higher the LAB(0), the greater the inhibition of S. aureus. The LAB levels during the fermentation were affected significantly (P < 0.005) by pH(0), LAB(0), day of fermentation, location, LAB(0) x pH(0), and LAB(0) x day. Derived regression equations related level of S. aureus and LAB at any day of fermentation to a number of microbiological and chemical variables. Close similarity of observed and predicted levels of S. aureus and LAB growth demonstrated the usefulness of the experimental approach in evaluating the safety of a process. No detectable enterotoxin or thermonuclease was found at any stage of processing even when S. aureus reached levels of 10/g of salami.

Journal Article↗
PubMed1979

Tandem coagulase/thermonuclease agar method for the detection of Staphylococcus aureus.

In optimizing previously reported coagulase agar media to obtain a rapid, reliable, and inexpensive coagulase test agar, variations in plasmas, pH, buffer system, fibrinogen, and fibrinolytic inhibitor were investigated. The agar with the following composition was determined best for the demonstration of coagulase production by Staphylococcus aureus: 25 ml of 15% bovine fibrinogen (fraction I, type I, citrated, Sigma Chemical Co.), 25 ml of rehydrated rabbit plasma (coagulase plasma ethylenediaminetetraacetic acid, Difco), 10.0 mg of soybean trypsin inhibitor (Schwarz/Mann), and 450 ml of brain heart infusion agar (Difco). In additional studies involving 7 different temperatures and 11 heating times, the thermal destruction of microbial nucleases on plate count agar and coagulase test agar was investigated. Heating the plates for 2.5 h at 65 degrees C destroyed all heatlabile nucleases, but not thermonucleases of S. aureus. A tandem agar plate method for the identification of S. aureus was developed. Coagulase and thermonuclease activity of 50 colonies can be detected on a single agar plate. Suspect S. aureus colonies isolated on various selective media are transferred to coagulase test agar, the plates are incubated at 37 degrees C for 18 h, and the coagulase reaction is recorded. The plates are then heated at 65 degrees C for 2.5 h, overlaid with toluidine blue-metachromatic diffusion agar, and reincubated at 37 degrees C for 3 h, and the thermonuclease reaction is recorded. Studies based on 88 enterotoxigenic S. aureus strains and 133 and 48 suspect S. aureus strains isolated from fresh salami mixtures on mannitol salt and tellurite-polymyxin-egg yolk agars, respectively, demonstrated 100% agreement between the tandem agar plate method and standard coagulase and thermonuclease tests. Overall, the tandem agar plate method is a rapid and convenient approach contributing to the identification of S. aureus from foods.

Bacteriological Techniques↗
PubMed1976

Recovery of staphylococcal enterotoxin from foods by affinity chromatography.

Extraction, concentration, and serological detection of staphylococcal enterotoxins from foods are laborious and time consuming. By exposing food extracts to an insoluble matrix tagged with specific anti-enterotoxin B, we have been able to recover the toxin from foods in a sensitive and rapid way. After mixing the reagents for 2 h at room temperature, immunoglobulin G antibodies were attached to CNBr-activated Sepharose 4B at pH 8.5 (0.1 M carbonate buffer with 0.5 M NaCl). Sepharose-antibody complex (1 ml) specifically recovered 0.1 to 30 mug of enterotoxin B from 400 ml of food extract (100 g of food) after mixing for 2 h at 4 C. The Sepharose-antibody-toxin complex was washed with 0.02 M phosphate-buffered saline at pH 7.2, and the toxin was dissociated by 2 to 4 ml of 0.2 M HCl-glycine plus 0.5 M NaCl buffer at pH 2.8. The recovered enterotoxin was free of interfering food components and could be detected serologically. Work to couple antibodies A, B, C, D, and E to Sepharose to recover all five toxins in one step is under study.

Antigen-Antibody Complex↗
PubMed1975

Effect of pH and sodium chloride on growth of Bacillus cereus in laboratory media and certain foods.

The effects of NaCl concentration, pH, and water activity (aw) on the ability of vegetative cells of Bacillus cereus to initiate aerobic growth in brain heart infusion broth at 30 C were studied in a factorial design experiment. By using multiple regression techniques, equations were derived which related the decimal reduction of the bacterial population to the concentration of NaCl and pH of broth to which the population was exposed. From these equations, the percentage of inoculated cells capable of initiating growth could be calculated. The reliability of these equations in foods was tested in laboratory-processed meat and rice media. The foods were less inhibitory than the broths, so that accurate prediction of growth initiation in foods was not possible by using the developed formulas. The impact of this type of quantitative study on the development of specific microbial standards for foods is discussed. When the NaCl concentration is increased, the aw is decreased and, with increased deviation of pH from optimum, more concentrated inoculum of B. cereus cells is needed to assure initiation of growth in culture media and foods.

Aerobiosis↗
PubMed1973

Assay methods for Clostridium perfringens type A enterotoxin.

Enterotoxin produced by a sporulating culture of Clostridium perfringens type A NCTC 8798 was purified to a level of 3,500 mouse mean lethal doses per mg of nitrogen. High-titer sera were obtained from rabbits injected with enterotoxin and used to compare the sensitivity of serological tests and bioassays for C. perfringens enterotoxin. Reversed passive hemagglutination was by far the most sensitive test, followed by microslide diffusion, single gel diffusion and electroimmunodiffusion, guinea pig skin test, mouse test, and rabbit ileal loop test.

Animals↗