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PubMed1978

Quantitative evaluation of three commercial blood culture media for growth of anaerobic organisms.

The ability of three different commercial blood culture media--brain heart infusion broth (Pfizer), thiol broth (Difco), and PRS-peptone broth (Becton, Dickinson & Co.)--to support the growth of five different anaerobes is described. Inocula of 100 and 1,000 colony-forming units per ml were used to evaluate potential differences in survival, lag time, growth rate, and doubling times of each anaerobe in each medium. In addition, each medium was evaluated for its ability to neutralize the antibacterial effects of whole blood. The results of this study indicate that the PRS-peptone broth is superior to brain heart infusion and thiol broths. Shorter lag times and accelerated generation times and growth rates were noted for more different anaerobes in the PRS-peptone broth. Neither the size of inoculum nor the addition of normal whole blood appeared to alter the survival or growth characteristics of the anaerobes in any medium. However, the addition of normal whole blood did extend the lag time of each anaerobe by approximately 1 to 2 h in each medium.

Anaerobiosis↗
PubMed1979

Factors affecting isolation and identification of Haemophilus vaginalis (Corynebacterium vaginale).

The rate of isolation of organisms resembling Haemophilus vaginalis (Corynebacterium vaginale) from vaginal specimens was not significantly affected by anaerobic versus carbon dioxide incubation atmospheres or whether specimens were inoculated on isolation media immediately after collection or after a delay of 6 h. Forty-one clinically isolated strains were provisionally divided into 30 H. vaginalis strains and 11 H. vaginalis-like (HVL) strains based on morphological and growth characteristics. The H. vaginalis strains were less reactive in API-20A identification test strips, (Analytab Products, Inc.) using Lombard-Dowell broth, than in a modified basal medium that contained proteose peptone no. 3 (Difco). The numbers and kinds of substrates fermented by 30 clinical and 2 reference strains of H. vaginalis varied among conventional, API, Minitek (Baltimore Biological Laboratory), and rapid buffered substrate fermentation systems. A greater number and variety of carbohydrates were fermented by the 11 HVL strains more consistently in all four test systems. Analysis of volatile and nonvolatile fermentation end products by gas-liquid chromatography did not reveal significant differences between the H. vaginalis and HVL strains. However, the latter group grew in peptone-yeast extract-glucose broth, whereas the H. vaginalis strains did not grow without the addition of starch to peptone-yeast extract-glucose. All of the reference and clinical strains were similar in their susceptibilities to a variety of antimicrobial compounds except sulfonamides, which inhibited the HVL strains and bifidobacteria but not the H. vaginalis strains. Sulfonamide susceptibility or resistance corresponded in part to the H. vaginalis and HVL-bifidobacteria strain reactions on selected conventional fermentation substrates. Susceptibility or resistance to sulfonamides and metronidazole in conjunction with fermentation tests is described to aid in the separation of H. vaginalis from other possibly unrecognized biotypes of H. vaginalis or other vaginal bacteria that presumptively resemble the organism. A human blood medium known as V agar was also of considerable value in distinguishing H. vaginalis from HVL strains, because only the H. vaginalis strains produced diffuse beta-hemolysis on V agar.

Bacteriological Techniques↗
PubMed1985

Somatostatin inhibits gastric acid secretion after gastric mucosal prostaglandin synthesis inhibition by indomethacin in man.

The inhibitory effect of indomethacin, 200 + 200 mg administered per os over 24 hours, on the prostaglandin E2 generative capacity of gastric mucosal tissue was determined in healthy male volunteers. The effect of prostaglandin synthesis inhibition on somatostatin induced suppression of food-stimulated acid secretion was tested. Peptone meal stimulated acid secretion was quantified in five healthy volunteers by intragastric titration with and without indomethacin pretreatment. Somatostatin doses of 200, 400, and 800 pmol/kg/h each significantly inhibited the peptone stimulated acid output. Indomethacin treatment, resulting in 90% inhibition of prostaglandin E2 synthesis, did not affect glucose- or peptone-stimulated acid output or modify the inhibitory action of somatostatin. Clinically, acid inhibition by somatostatin has been used to treat bleeding peptic ulcers. Ulcer haemorrhage may be preceded by an excessive use of drugs that inhibit prostaglandin synthesis such as aspirin or other non-steroidal anti-inflammatory agents. Recent observations in the rat indicate that prostaglandins mediate the inhibitory action of somatostatin on gastric acid secretion. The present results suggest that prostaglandins are not required for inhibition of gastric acid secretion by somatostatin in man.

Adult↗
PubMed1993

Cholecystokinin in the control of gastric acid secretion in man.

This study was designed to determine the role of cholecystokinin in the control gastric acid secretion in men using loxiglumide, a specific cholecystokinin receptor blocker. Three groups of healthy subjects (A, B, and C) were used; group A--for studies with postprandial gastric secretion, group B--for studies with exogenous gastric secretagogues and group C--for 12 hour intragastric pH-metry. Cephalic phase stimulated by modified sham feeding in group A subjects increased gastric acid secretion to about 50% of pentagastrin maximum and the treatment with loxiglumide in a standard dose (20 mumol/kg iv loading dose plus infusion of 20 mumol/kg/h afterwards) failed to affect this secretion. Gastric acid response to a 5% peptone meal instilled intragastrically greatly enhanced gastric acid secretion and plasma gastrin concentration but the addition of loxiglumide in the standard dose resulted in further increase in both gastric acid and plasma gastrin responses to peptone meal. Infusion of caerulein in gradually increasing doses (15-120 pmol/kg/h) and gastrin releasing peptide (25-200 pmol/kg/h) resulted in a dose dependent stimulation of gastric acid secretion reaching about 35% and 25% of maximum attained with pentagastrin. When loxiglumide was added in a standard dose, the acid responses to caerulein and gastrin releasing peptide were further increased two to three fold attaining the peak reaching, respectively, about 100% and 50% of pentagastrin maximum. In group C subjects, 12 hour pH-metry revealed the usual increase in gastric pH after each meal in tests with placebo. Loxiglumide (1200 mg tablets tid, po) resulted in significantly lower pH after each meal and this was accompanied by significantly higher gastrin responses than in placebo tests. We conclude that cholecystokinin released by peptone meal, ordinary meals or gastrin releasing peptide exerts a potent inhibitory influence on gastric acid secretion and gastrin release in men and this inhibition involves subtype A cholecystokinin receptors.

Adult↗
PubMed1960

Observations on the effect of magnesium on blood coagulation.

Previous observations on the effect of oral magnesium and peptone on thrombin generation time are examined. The smallest amounts of magnesium and peptone regularly producing a significant shift demonstrable after one hour are 0.25 g. magnesium and 15 g. peptone. The oral effect can be reproduced by the intravenous injection of magnesium. The minimum amount required is 50 mg. The effect is transient, and after 30 minutes can no longer be demonstrated. Amounts of magnesium of the same order as those acting on intravenous injection can produce a shift of thrombin generation time in vitro. This action of magnesium in vitro can be antagonized by the addition of calcium.

Blood Coagulation↗
PubMed1987

Effect of rioprostil, a synthetic prostaglandin E1 on meal-stimulated gastric acid secretion and plasma gastrin levels in humans.

The effects of rioprostil (a newly developed synthetic prostaglandin E1 analogue) on meal-stimulated gastric acid secretion was evaluated in 8 healthy human volunteers. Gastric acid output was measured by intragastric titration on 4 different occasions. The following procedure was invariably employed: after a basal period of 45 min, 5 peptone meals (8%, 500 ml each) were given intragastrically in 45-min intervals and gastric acid output was measured continuously. 45 min after the first meal, either placebo or 150, 300 or 600 micrograms of rioprostil were given intragastrically in a randomized order and on different days. 15 min later, the second meal was given and intragastric titration continued. Rioprostil caused a dose-dependent inhibition of the 3-hour integrated gastric acid response to the peptone meals. The percentage of inhibition was 41, 68 and 79%, respectively, for 150, 300 and 600 micrograms of rioprostil. Whereas the inhibition by the two highest doses was statistically significant, this was not the case for the lowest dose of rioprostil. The integrated 3-hour plasma gastrin response to the peptone meals was not significantly changed by any of the doses of rioprostil. No significant adverse effects were observed with rioprostil.

Adolescent↗
PubMed1992

pH-dependent secretion of gastrin in duodenal ulcer disease: effect of suppressing Helicobacter pylori.

Patients with duodenal ulcers and Helicobacter pylori infection have elevated plasma gastrin concentrations which fall after suppression of the organism. This may be due to H. pylori elevating the pH of the antral mucous layer, therefore preventing luminal acid from inhibiting gastrin release. To test this idea, we measured the plasma gastrin concentrations under basal conditions and in response to 4% peptone when the gastric lumen was maintained at pH 2.5 and at pH 5.5 by gastric perfusion. We studied 11 duodenal ulcer patients before and after suppression of H. pylori. Gastrin concentrations were significantly higher before suppression of H. pylori than after treatment in all three states; basal gastrin (pmol/l) fell from 9.2 (3.7-23, median and range) to 5.1 (1.7-15) after treatment; from 11.3 (3.8-29) to 5.9 (5.7-6.1) at pH 2.5 and from 15.2 (3.9-32) to 7.15 (6.1-14) at pH 5.5. The ratio of peptone-stimulated gastrin at pH 2.5/pH 5.5 was similar before (0.8; 0.5-1.7) and after (0.8; 0.5-1.1) suppression of H. pylori. These results indicate that infection with H. pylori increases basal and peptone-stimulated plasma gastrin concentrations, and that this response is independent of luminal pH.

Amoxicillin↗
PubMed2006

Effects of the principal nutrients on lovastatin production by Monascus pilosus.

Lovastatin production is dependent on the substrates provided. We investigated how several carbon and nitrogen sources in the medium affect lovastatin production by Monascus pilosus. M. pilosus required a suitable concentration of organic nitrogen peptone for high lovastatin production. As sole carbon source with peptone, although glucose strongly repressed lovastatin production, maltose was responsible for high production. Interestingly, glycerol combined with maltose enhanced lovastatin production, up to 444 mg/l in the most effective case. Moreover, an isolated mutant, in which glucose repression might be relieved, easily produced the highest level of lovastatin, 725 mg/l on glucose-glycerol-peptone medium. These observations indicate that lovastatin production by M. pilosus is regulated by strict glucose repression and that an appropriate release from this repression by optimizing medium composition and/or by a mutation(s) is required for high lovastatin production.

Carbon↗
PubMedDate not supplied

Protease and virulence of the extracellular products produced by Vibrio carchariae after growth on various media.

Protease and virulence of the extracellular products (ECP) of Vibrio carchariae strain EmI82KL, a causative agent of gastroenteritis in Epinephelus coioides, cultured on different media were studied. The bacteria grown on peptone agar, nutrient agar or brain heart infusion agar produced higher protease activities than that grown on tryptic soy agar (TSA) in terms of protein content. The addition of ethylenediamine di(o-hydroxyphenylacetic acid) or horse serum in TSA enhanced the ECP protease production while the addition of grouper serum apparently reduced the enzyme activity indicating the presence of protease inhibitor(s) in the fish serum. Furthermore, the use of grouper meat or peptone as a single nutrient source remarkably enhanced the production of ECP protease. Adding proteinaceous materials from animal sources (horse serum, grouper meat or peptone) on agar manifested higher ECP protease activity than that from plant source (TSA), indicating the intestine of carnivorous groupers might favour the existence, survival or infection of the bacterium. The protease was a metal-chelator-sensitive serine protease since it was inhibited by 3,4-dichloroisocoumarin and phenylmethanesulfonyl fluoride while about 80% of its activity inhibited by chelating agents (ethylene-diaminetetraacetic acid and ethylene glycol-bis(beta-amino-ethylether) N,N,N',N'-tetraacetic acid). The ECP obtained from each medium was not lethal to the groupers suggesting that the bacterium is low virulent. As grouper is carnivorous, therefore, the role of the protease played in the fish intestine probably is competing for nutrients and/or associated with the cause of edema leading to gastroenteritis.

Animals↗
PubMed2002

Mechanisms involved in milk endogenous proteolysis induced by a lipopolysaccharide experimental mastitis.

Experimental mastitis has been induced by the lipopolysaccharide (LPS) of Escherichia coli on six dairy cows in order to study the mechanisms involved in milk endogenous proteolysis during the inflammatory process. Variations in somatic cell count (SCC), plasmin activity, and total casein (CN) content were measured, and proteose-peptone content and the percentage of pH 4.6 insoluble peptides including gamma-CN have been considered as indicators of endogenous proteolysis. Furthermore, polymorphonuclear neutrophils (PMN) maturity has been evaluated by optical microscopy, and proteolysis by PMN proteinases has been studied at neutral and acidic pH in order to establish a link between caseinolysis, proteinase class, and PMN maturation. Two peaks of proteose-peptones content have been noticed for the six cows. First peak could be explained by both plasmin activity and SCC, while second peak was concomitant with a low plasmin activity but a SCC remaining high. The second peak of proteose-peptones content confirmed the role of cellular proteases in milk caseinolysis. Casein breakdown by cellular proteases was confirmed by SDS-PAGE electrophoresis, and a link between neutral proteinases activity and immature PMN recruitment was shown. Acidic proteinases activity was effective with mature PMN and during the recovery phase.

Animals↗
PubMed1986

Effects of different skim milk fractions on activity of cow milk purified lipoprotein lipase.

Hydrolysis of a long-chain triglyceride substrate by purified cow milk lipoprotein lipase, in the absence of blood serum, was changed by adding heated skim milks. Preincubation of the substrate with small amounts of several skim milks increased (+50 to 300%) lipoprotein lipase activity. By contrast, greater amounts of skim milk increased further or decreased lipoprotein lipase activity (+ 300 to -90%). The inhibitory effect was due to substrate surface protection. Results obtained after removal of casein (by isoelectric precipitation or by ultracentrifugation) and of whey proteins (by heat treatment) showed that the effect of skim milk was due to the proteose-peptone fraction. Fractionation of the proteose-peptone fraction into component 5-enriched fraction and component 3-enriched fractions suggested that the activating effect was due partially to proteose-peptone component 5, and the inhibitory effect resulted from component 3. These effects were overcome by blood serum.

Animals↗
PubMed1999

Contamination of intact apples after immersion in an aqueous environment containing Escherichia coli O157:H7.

The extent and location of Escherichia coli O157:H7 contamination after intact apples were immersed in cold (2 degrees C) 1% peptone water containing approximately 3x10(7) CFU/ml was assessed using four apple varieties, Golden Delicious, McIntosh, Red Delicious, and Braeburn. Room temperature and refrigerated apples were used to determine the effect of temperature differential on E. coli infiltration. The highest levels of E. coli were associated with the outer core region of the apple, followed by the skin. Apples were subsequently treated by immersing them for 1 min in 2,000 mg/liter sodium hypochlorite, followed by a 1-min tapwater rinse. This treatment reduced pathogen levels by 1- to 3-log cycles but did not eliminate the microorganism, particularly from the outer core region. While E. coli was not detected in the inner core of most apples, warm fruit immersed in cold peptone water occasionally internalized the pathogen. The frequency and extent of internalization of the pathogen was less when cold apples were immersed in cold peptone water. Subsequent dye uptake studies with Golden Delicious apples indicated that approximately 6% of warm apples immersed into a cold dye solution accumulated dye via open channels leading from the blossom end into the core region. However, dye uptake did not occur when the dye solution was warmer than the apple.

Coloring Agents↗
PubMed1999

Antibacterial effect of lactoferricin B on Escherichia coli O157:H7 in ground beef.

The antibacterial activity of lactoferricin B on enterohemorrhagic Escherichia coli O157:H7 in 1% peptone medium and ground beef was studied at 4 and 10 degrees C. In 1% peptone medium, 50 and 100 microg of lactoferricin B per ml reduced E. coli O157:H7 populations by approximately 0.7 and 2.0 log CFU/ml, respectively. Studies comparing the antibacterial effect of lactoferricin B on E. coli O157:H7 in 1% peptone at pH 5.5 and 7.2 did not reveal any significant difference (P > 0.5) at the two pH values. Lactoferricin B (100 microg/g) reduced E. coli O157:H7 population in ground beef by about 0.8 log CFU/g (P < 0.05). No significant difference (P > 0.5) was observed in the total plate count between treatment and control ground beef samples stored at 4 and 10 degrees C. The antibacterial effect of lactoferricin B on E. coli O157:H7 observed in this study is not of sufficient magnitude to merit its use in ground beef for controlling the pathogen.

Animals↗
PubMed2002

Optimizing sporulation of Clostridium perfringens.

Many sporulation media have been developed for Clostridium perfringens, but none stimulates sporulation for all strains. The aim of our experiments was to develop a sporulation method using Duncan and Strong (DS) medium, which supports sporulation of a wide variety of strains. Different inoculation levels were tested, and the effects of sporulation-promoting substances and acid shock were evaluated. Furthermore, DS medium was compared with other sporulation media. Highest spore numbers in DS medium were obtained with a 10% 24-h fluid thioglycollate broth inoculum (5.0 x 10(5)/ml). Addition of theophylline and replacement of starch by raffinose increased spore yields for some strains, but most strains were not affected (average increases in log N/ml of 0.2 and 0.3, respectively). One strain was enhanced by the addition of bile, but other strains were strongly inhibited (average decrease in log N/ml of 2.5); agar did not influence sporulation. Neither short-time acid exposure nor addition of culture supernatant fluids of well-sporulating strains resulted in higher spore numbers in DS medium. None of the tested methods enhanced sporulation in general; only strain-dependent effects were obtained. Peptone bile theophylline medium was the most promising sporulation medium tested; peptone bile theophylline starch medium yielded highest spore numbers (2.5 x 10(5)/ml), but some strains failed to sporulate. In conclusion, adding theophylline to DS medium may optimize sporulation of C. perfringens, but peptone bile theophylline medium with or without starch is most suitable.

Clostridium perfringens↗
PubMed1999

Simultaneous removal of phenol, ortho- and para-cresol by mixed anaerobic consortia.

Two different anerobic consortia, one removing phenol and ortho (o-) cresol and other removing para(p-) cresol, were cultivated in serum bottles using whey as cosubstrate substitute for proteose peptone. Phenol and p-cresol removal with the phenol-removing consortium were the same with 0.0125% (w/v) whey as with 0.05% proteose peptone. For the other consortium, 8 days were required to decrease the p-cresol concentration from 35 to 2 mg/L with 0.025% whey, while 35 days were required to achieve a similar removal with 0.5% proteose peptone. The two consortia were mixed and cultivated with 0.025% whey. Phenolic compound removal with the mixed consortia was as good as that achieved by each of the two initial consortia against their respective substrates. This removal activity was maintained after several transfers. In a continuous upflow fixed-film reactor, the mixed consortia removed over 98% of 150 mg/L of phenol and 35 mg/L of each o- and p-cresol in the influent at 29 degrees C, with 0.025% whey as cosubstrate. The hydraulic retention time (HRT) was 0.25 day, corresponding to a phenolic compound volumic loading rate of 880 mg/(L of reactor x day). Once the continuous flow reactor achieved constant phenolic compound removal, no intermediates were found in the effluent, while in serum bottles, m-toluic acid, an o-cresol intermediate, accumulated. Measurements of the specific activity for the uptake of different substrates demonstrated the presence of all trophic groups involved in methanogenic fermentation. These activities were, in mg of substrate/(g of volatile suspended solids x day), as follows: 849 +/- 25 for the acidogens; 554 +/- 15 for the acetogens; 934 +/- 37 for the aceticlastic methanogens; and 135 +/- 15 for the hydrogenophilic methanogens. Electron micrographs of the mixed consortia showed seven different morphological bacterial types, including Methanotrix-like bacteria.

Anaerobiosis↗
PubMedDate not supplied

The effect of media composition on the thermal resistance of Bacillus stearothermophilus.

Spores of Bacillus stearothermophilus ATCC 7953 were developed at 62 degrees C on 32 media composed of various amounts of 11 components: D-glucose, L-glutamic acid, yeast extract, peptone, sodium chloride, magnesium sulfate, ammonium phosphate, potassium phosphate, calcium chloride, ferrous sulfate and manganese sulfate. Statistical models were used and demonstrated a strong interaction of yeast/peptone/ammonium phosphate, contributing positively to the best sporulation yield (6-7 log10 spores). The most influential medium components on the thermal resistance (at 121 degrees C) of spores in suspension (calcium acetate, pH 9.7) were yeast extract (positively) and potassium phosphate (negatively), both creating the positive interaction, for spores from a 6-day incubation period. However, the strong negative effect of sodium chloride decreased the D-value from 1.81 min to 0.57 min upon increasing the incubation period (62 degrees C) from 3 days to 6 days. The D-glucose and peptone exhibited greater effects than the yeast extract and potassium phosphate interaction on D-values for 3-day spores on strip, just as the highly joint-positive peptone/sodium chloride effect maintained the thermal resistance of 6-day spores on strips. The spores on strip system showed less stability than the spores in suspension. The most stable spore system confirmed D-values at 121 degrees C at a range between 1.5 min and 1.9 min, which were obtained by keeping sodium chloride and potassium phosphate at minimum concentrations and yeast extract and peptone at maximum concentrations, regardless of the 3- to 6-day sporulation.

Culture Media↗
PubMed2001

[Culture medium optimization and primary kinetics analysis for nisin production].

Response surface methodology was used to optimize a medium for nisin production of Lactococcus lactis. In the first optimization step the influence of sucrose, soybean peptone, yeast extract, potassium dihydrogen phosphate, sodium chloride, and magnesium sulfur on nisin production was evaluated using a fractional factorial design. Potassium dihydrogen phosphate influenced nisin production positively while soybean peptone affected nisin production negatively. The other components had no significant effect on nisin production. The path of steepest ascent was used to approach the optimal region of the medium composition. In the third step the optimal concentrations of KH2PO4 and soybean peptone were determined by a central composite design and response surface analysis. The optimized medium allowed nisin production to be increased from 1074 IU/mL to 2150 IU/mL. The kinetic analysis showed that nisin production fashion at optimized and non-optimized media was not changed and maintained partially growth-associated. But the specific growth rates and the specific nisin production rates for the strain at the optimized medium were bigger than the ones at the non-optimized medium after the cells entered the middle of exponential phase.

Anti-Bacterial Agents↗
PubMedDate not supplied

Indigenous rapid diagnostic method for Escherichia coli O157:H7.

Rapid methods for detection of Escherichia coli O157: H7 diarrhoea are preferred to limit differential diagnostic evaluation including invasive procedures. Fifty stool samples from children and adult patients having diarrhoea and ten control samples from volunteers without diarrhoea were collected. Each sample was inoculated into two tubes containing peptone water and one containing MacConkey broth. They were incubated for 5 hours or longer till growth occurred. The first tube of peptone water with growth was tested for production of indole. All samples were tested for enzyme beta-glucuronidase in the pellet of the second peptone water growth. The MacConkey broth growth was tested with latex beads sensitized separately with antisera to E. coli O157 and E. coli H7. All indole positive and beta glucuronidase negative samples with positive agglutination with E. coli O157 and H7 coated latex beads were taken as E. coli O157: H7 positive samples. Three out of 50 diarrhoeic samples were found to be positive for E. coli O157:H7. Confirmation of the results of our rapid assay was done by parallel conventional culture of faecal specimens on sorbitol MacConkey agar. Our rapid assay required only 7-10 hours compared to the conventional technique where the report is available only on the third day. It can therefore be used routinely for initial screening of faecal specimens for E. coli O157: H7.

Adult↗