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PubMed1983

Identification of pathogenic Neisseria species with the RapID NH system.

The RapID NH system (Innovative Diagnostics Systems, Inc., Decatur, Ga.) is a 4-h test used in the identification of Neisseria and Haemophilus species. The system was evaluated for accuracy and reliability and compared with conventional (cystine proteose peptone agar; Prepared Media Laboratory, Tualatin, Ore.) carbohydrate degradation tests with Neisseria gonorrhoeae and N. meningitidis, as well as a variety of Neisseria, Branhamella, and Moraxella species. The RapID NH system correctly identified all N. gonorrhoeae, N. meningitidis, and N. lactamica isolates, but the level of accuracy varied considerably for the remaining organisms. One strain of N. subflava was misidentified as a pathogenic Neisseria strain. The RapID NH tests were concluded in 4 h, whereas the cystine proteose peptone agar tests required up to 48 h for results to be useful. The RapID NH system is an accurate, reliable, and useful method for the identification of pathogenic Neisseria species. It has been proven that it shortens identification time and specimen turnaround time by at least 24 h.

Humans↗
PubMed1984

Differentiation of Alcaligenes-like bacteria of avian origin and comparison with Alcaligenes spp. reference strains.

Although standard biochemical tests used for the identification of Alcaligenes spp. revealed only minor differences, the oxidative low-peptone technique clearly differentiated between Alcaligenes-like bacteria of avian origin and Alcaligenes spp. reference strains. Based on their colonial morphology, biochemical profiles, and hemagglutination, the Alcaligenes-like bacteria of avian origin were further divided into two subgroups, C1-T1 and C2-T2. Colonies of subgroup C1-T1 were nondescript, round, raised, glistening, translucent, greyish, and about 2 mm in diameter. Colonies of subgroup C2-T2 were off-white, flat, dry and wrinkled, generally round, and resembled tiny lily pads. Biochemical profiles by the oxidative low-peptone method showed the C1-T1 subgroup alkalinizing only three substrates (citrate, acetate, and succinate), whereas the C2-T2 subgroup alkalinized eight substrates (citrate, acetate, butyrate, itaconate, malonate, saccharate, succinate, and M-tartrate). Subgroup C1-T1 agglutinated human, chicken, and turkey erythrocytes, whereas subgroup C2-T2 did not. The recognition of these two subgroups within the Alcaligenes-like bacteria of avian origin is important, since it may explain the differences seen in pathogenicity among isolates.

Alcaligenes↗
PubMed1975

Unusual Enterobacteriaceae: lactose-positive Salmonella typhimurium which is endemic in São Paulo, Brazil.

Since 1971 a lactose-positive (lac+) Salmonella typhimurium variety Copenhagen has been endemic in the city of Sao Paulo. The strain is a strong lactose fermenter and resembles Escherichia coli on primary plating media and in triple sugar iron agar. Although most isolates of the strain have uniform properties, some have slightly different antigens, antibiograms, phage types, or fermentation patterns. Most isolates have come from stools of infants under 1 year of age and are probably hospital acquired; however, other isolates are probably community acquired. Eighteen other lac+ Salmonella isolated in the United States were also studied. Most of these strains resembled E. coli on primary plates and triple sugar iron agar; thus their identification would pose a problem for most clinical laboratories. A simple procedure for detecting lac+ Salmonella mixed with lac+ E. coli consists of touching 12 colonies in succession with a straight wire and then inoculating a peptone iron agar tube. H2S production is apparent from lac+ Salmonella even if 11 E. coli and one Salmonella colony are picked. If a positive peptone iron agar tube is observed, then individual colonies are tested to rule out other strong H2S producers. The true incidence of lac+ Salmonella is unknown because they are not isolated and identified in most laboratories.

Antigens, Bacterial↗
PubMed1984

Effect of D-tryptophan on hemolysin production in Vibrio parahaemolyticus.

Production of the Kanagawa hemolysin by a strain of Vibrio parahaemolyticus isolated from a gastroenteritis patient was found to correlate with the presence in cell lysates of two unidentified compounds, designated X and Y. The two compounds were present in cell lysates of the organism grown in peptone at the optimal pH for hemolysin synthesis but were not present when cell lysates were grown in peptone at a constant pH of 8.0. They were also absent in cells grown in synthetic medium at pH 6.2 without the addition of D-tryptophan, a condition under which hemolysin is not produced. Both X and Y were present intracellularly only from the time that D-tryptophan was added to synthetic medium, a known method of inducing hemolysin synthesis.

Chromatography, High Pressure Liquid↗
PubMed1988

Method for in vitro conversion of rough strains of Pseudomonas aeruginosa to smooth strains.

Rough and serologically nontypable strains of Pseudomonas aeruginosa were found to become smooth and typable in vitro when they were maintained in a soft agar containing 0.5% peptone in distilled water and the dried out agar cultures were replenished monthly with a similar peptone solution in distilled water. After about a year, all of the nine rough strains of P. aeruginosa maintained this way became smooth and typable, and their pigmentations also changed significantly. Some melanogenic strains became fluorescine producers, and some weakly chromogenic strains became strong producers of fluorescine and pyocyanin.

Culture Media↗
PubMed2000

Estimation of minimum sterol 14alpha-demethylation-inhibitory concentration of azoles in Candida yeasts using acetate-mediated growth inhibition: potential utility in susceptibility testing.

We have recently shown that 14alpha-demethylation-deficient cells of Candida albicans are subject to growth arrest by 0.24 M acetate in a yeast extract-peptone-glucose medium and that the minimum concentration of an azole antifungal agent required for total inhibition of sterol 14alpha-demethylation (MDIC for minimum demethylation-inhibitory concentration) is practically identical to its MIC determined in the acetate-supplemented medium (O. Shimokawa and H. Nakayama, Antimicrob. Agents Chemother. 43:100-105, 1999). In the present study we estimated the MDICs of three different azoles (fluconazole, ketoconazole, and itraconazole) for strains of various Candida species using this method and compared them with the MICs determined in the corresponding acetate-free medium. The results demonstrated that the test strains were divided into two classes. One class of strains was characterized by tolerance to 14alpha-demethylation deficiency (MIC > MDIC) and consisted of strains of C. albicans, C. guilliermondii, C. kefyr, and C. tropicalis. The other class was intolerant to 14alpha-demethylation deficiency (MIC approximately MDIC) and comprised strains of C. glabrata, C. krusei, and C. parapsilosis. We also showed that replacement of the yeast extract-peptone-glucose medium with RPMI 1640 medium did not affect the results substantially. Furthermore, the 80% inhibitory concentration (IC(80)) in RPMI 1640 medium, recommended as a substitute for the conventional MIC in susceptibility testing, was found to be close to the MDIC.

Acetates↗
PubMed1977

Development of specific tests for rapid detection of Escherichia coli and all species of Proteus in urine.

Proteus mirabilis was distinguishable from Escherichia coli and from several other species that may be associated with urinary tract infections when grown in a nutrient medium supplemented with 0.1 M L-methionine by the formation of large amounts of dimethyl disulfide and methyl mercaptan, which were detected by head-space gas-liquid chromatography (HS-GLC). E. coli could be detected by the same HS-GLC technique by ethanol production from methionine peptone water enriched with 1% either lactose or arabinose but not by any product from 10 amino acids tested. Ethanol from lactose was detected early in the exponential phase of growth. Significant numbers, 10(5) or more per ml, of E. coli in urine could be detected in about 5 h by ethanol production from an unshaken culture of urine in lactose methionine peptone water buffered at pH 7.2 (urine test medium); only a trace of dimethyl disulfide was produced. Significant numbers of P. mirabilis in urine could be detected in 4 h by dimethyl disulfide production and in 5 h by methyl mercaptan production from a shaken culture of urine in urine test medium; no ethanol was produced. Incubation of urine specimens in the test medium followed by examination by HS-GLC is proposed as a rapid method of detecting whether or not the urine contains significant numbers of E. coli or a species of Proteus.

Bacteriological Techniques↗
PubMed1987

Telenzepine is at least 25 times more potent than pirenzepine--a dose response and comparative secretory study in man.

Telenzepine is an analogue of pirenzepine with a higher potency and similar selectivity for M1-receptors in animals. In this placebo controlled, double blind, randomised study mean peptone stimulated gastric acid secretion (mean +/- SEM) of 10 male healthy subjects (58 +/- 6 mmol H+/3 h for placebo) was significantly and dose dependently inhibited by oral telenzepine (2 mg: 31 +/- 5, 3 mg: 23 +/- 5, 5 mg: 21 +/- 4 mmol H+/3 h). Telenzepine 3 and 5 mg were significantly stronger than pirenzepine 50 mg orally (37 +/- 8 mmol H+/3 h). Mean percentage acid inhibition was 37% for pirenzepine, and 48, 61, and 64% for 2, 3, and 5 mg telenzepine, respectively. Basal and peptone stimulated gastrin release was unaffected. Mean salivary output per three hours declined moderately from 156 +/- 45 g (placebo) to 136 +/- 45 g with pirenzepine and significantly to 88 +/- 28 g, 95 +/- 39 g and 39 +/- 13 g with telenzepine 2, 3, and 5 mg, respectively. There was a parallel effect on Na+, K+, Ca++ and amylase output in saliva. Near point vision was not altered by either drug. Pulse rates were lowered by both substances. Complaints of dry mouth were more frequent with telenzepine 5 mg. On a molar basis telenzepine proved to be a 25 and 50 times more potent inhibitor of gastric and salivary secretion, respectively.

Adult↗
PubMed1997

Relation between cholecystokinin and antral innervation in the control of gastric emptying in the rat.

BACKGROUND: Antral motility and the hormone cholecystokinin (CCK) are major determinants of the rate of gastric emptying. The relation between CCK and antral neurons in regulating gastric emptying is uncertain. Benzalkonium chloride (BAC) causes selective lesions in gut myenteric neurons after serosal application. AIM: To develop a model of antral denervation using BAC to enable the study of the relation between CCK and antral neurons in regulating gastric emptying. METHODS: BAC, vehicle or the afferent neurotoxin capsaicin were applied to the serosal surface of the rat antrum or corpus; neurochemical markers of intrinsic and afferent neurons were detected by using immunohistochemistry and radioimmunoassay. Gastric retention of solids was determined after fasting, and emptying of liquids was measured in rats with gastric fistulae. RESULTS: In BAC treated rats radioimmunoassay of tissue extracts revealed a dose related specific loss of gastrin releasing peptide, substance P, and vasoactive intestinal polypeptide immunoreactivities from the treated region, and immunohistochemistry revealed loss of the neuronal marker PGP 9.5 and the afferent neuropeptide calcitonin gene related peptide (CGRP). Adjacent untreated regions were unaffected by BAC, with the exception that CGRP was depleted in both corpus and antrum after antral treatment. After antral BAC treatment fasted rats retained solids for over 48 hours. Moreover, in antrally denervated rats with gastric fistulae, the emptying of saline, acid and peptone was delayed substantially. The CCK dependent inhibition of gastric emptying of peptone was preserved after antral treatment with BAC. CONCLUSIONS: Serosal BAC causes lesions in the innervation of the treated region of the stomach. The innervation of the antrum is essential for normal emptying of both liquids and solids, but the inhibition of gastric emptying produced by CCK is not dependent on antral neurons.

Animals↗
PubMed1978

[Denitrification by Bacillus licheniformis].

The denitrifying capacity of 15 strains of Bacillus licheniformis was evaluated. In general, N2 production by the cultures on complex media containing NO3- is irregular and quite slow and three of the strains never produce gas. Bacillus licheniformis grows rapidly in anaerobiosis on peptone medium containing NO3- which is reduced to NO2-. None of the strains grow in peptone medium with NO2- or N2O as the respiratory substrate, nor do they grow under an atmosphere of 10% NO-90% N2. Denitrification was studied in cell suspensions using gas chromatography. N2O production from NO3- or NO2- is always weak at best; nitric oxide is reduced to N2O at an appreciable rate. All the strains synthesize nitrate reductase A in anaerobiosis when NO3- is present. In cell extracts, nitrite reductase activity is always negligible or nil with tetramethyl-p-phenylenediamine as an electron donor.

Anaerobiosis↗
PubMed1978

A taxonomic study of the Spirillum lipoferum group, with descriptions of a new genus, Azospirillum gen. nov. and two species, Azospirillum lipoferum (Beijerinck) comb. nov. and Azospirillum brasilense sp. nov.

Sixty-one strains of the root-associated nitrogen fixer Spirillum lipoferum exhibited a similar morphology in peptone--succinate salts medium: vibrioid cells having a diameter of 1.0 micrometer. When grown in broth the cells had a single polar flagellum, but when grown on agar at 30 degrees C lateral flagella of shorter wavelength were also formed. The DNA base composition was 69--71 mol% guanine + cytosine when determined by thermal denaturation. DNA homology experiments indicated the occurrence of two distinct but related homology groups: 46 strains were in group I and 15 strains were in group II. Group II strains were distinguished by their ability to use glucose as a sole carbon source for growth in nitrogen-free medium, by their production of an acidic reaction in a peptone-based glucose medium, by their requirement for biotin, and by their formation of wider, longer, S-shaped or helical cells in semisolid nitrogen-free malate medium. The results indicate that two species exist, and on the basis of their characteristics it is proposed that they be assigned to a new genus, Azospirillum. Strians belonging to group II are named A. lipoferum (Beijerinck) comb. nov., while those belonging to group I are named A. brasilense sp. nov. Strain Sp 59b (ATCC29707) is proposed as the neotype strain for A. lipoferum, and strain Sp 7 (ATCC 29145) is proposed as the type strain for A. brasilense.

Culture Media↗
PubMed1985

Growth of Vibrio costicola and other moderate halophiles in a chemically defined minimal medium.

A simple chemically defined minimal medium consisting of sodium glutamate, glucose, vitamins, and salts was devised to support growth of the moderate halophile, Vibrio costicola, over as wide a range of NaCl concentrations as the complex medium, proteose peptone + tryptone. The lag period at higher NaCl concentrations was longer in the chemically defined minimal medium than in proteose peptone + tryptone. Chemically defined minimal medium also supported the growth of an unidentified moderate halophile, HX, and of Vibrio alginolyticus and Vibrio cholerae. The Mg2+ concentration required for good growth changed with the growth temperature for both V. costicola and HX.

Culture Media↗
PubMed2005

Lactobacillus reuteri beta-galactosidase activity and low milk acidification ability.

Beta-galactosidase activity was studied as a possible cause of the low milk acidification ability observed in Lactobacillus reuteri NRRL 14171. Enzymatic activity was determined in MRS broth supplemented with either glucose or lactose and milk at the middle and final stage of the exponential phase, as well as at the stationary phase. Results were compared with beta-galactosidase activity in Lactobacillus casei NRRL-B1922, a strain that shows the milk acidification ability. The effects of the types of carbon and nitrogen sources were established by comparison of growth parameters (higher maximum cell concentration and specific growth rate) in broth culture and skim milk supplemented with 2% glucose or 1% casein peptone. In milk, L. reuteri showed higher beta-galactosidase activity in all growth phases compared with L. casei. Greater cell concentration maxima, specific growth rates, and acidification abilities were observed in L. reuteri when it was cultured in milk supplemented with 1% casein peptone compared with non-supplemented milk cultures. Results suggest that the poor milk acidification ability observed in L. reuteri may be more related to a weak proteolytic system than to deficient beta-galactosidase activity.

Animals↗
PubMed1982

Somatostatin-14 and -28: clearance and potency on gastric function in dogs.

To examine the significance of somatostatin-14 (S-14) and somatostatin-28 (S-28) in gastric physiology, we compared their relative potencies on acid secretion in the dog. On a molar infusion basis, S-14 and S-28 appeared to be equipotent, causing 50% inhibition of peptone meal-stimulated acid secretion at a dose of 400 pmol . kg-1 . h-1. However, comparison of the plasma half lives (t 1/2) of the two peptides revealed that S-28 disappeared at a much slower rate (t 1/2 = 2.84 +/- 0.15 min, mean +/- SE, n = 7) than S-14 (t 1/2 = 0.57 +/- 0.06 min). When acid-inhibitory effect was compared against increment in plasma concentrations produced by peptide infusion, S-14 was roughly 10-fold more potent than S-28. No alteration of gastrin response to peptone was observed at a dose of S-14 or S-28 that completely abolished acid secretion, suggesting that regulation of acid secretion is not mediated by gastrin inhibition. Thus, S-14 is a potent and possibly important physiological inhibitor of gastric acid secretion. Although circulating S-28 may have importance in regulation of some biological functions, it appears to play a less prominent role in regulation of gastric secretion.

Animals↗
PubMed1988

CNS regulation of gastric and autonomic functions in dogs by gastrin-releasing peptide.

The central nervous system effects of canine gastrin-releasing peptide (GRP) were studied on gastric acid secretion, emptying, blood flow, and the autonomic nervous system in conscious dogs. GRP injected into the third cerebral ventricle significantly (P less than 0.01) increased plasma epinephrine but not norepinephrine concentrations. GRP (0.1-1.0 nmol/kg) significantly decreased gastric acid secretion stimulated by an 8% peptone meal, delayed gastric emptying of the liquid peptone meal, and increased left gastric artery flow. Ganglionic blockade, truncal vagotomy, or adrenalectomy did not abolish the inhibitory effect of GRP on gastric acid secretion. However, ganglionic blockade or vagotomy abolished the GRP-induced inhibition of gastric emptying, and ganglionic blockade or adrenalectomy abolished the GRP-induced increases in left gastric artery flow and plasma epinephrine concentrations. An intravenous infusion of epinephrine that produced similar plasma concentrations of epinephrine that were observed after cerebroventricular injection of GRP mimicked the increase in left gastric artery flow induced by GRP. It is concluded that 1) GRP acts within the central nervous system to activate the sympathoadrenal axis, 2) GRP inhibits gastric emptying of a liquid meal by a vagally dependent mechanism and enhances left gastric artery flow by the release of epinephrine from the adrenal medulla, and 3) the pathway(s) that mediate the GRP-induced inhibition of gastric acid in the dog remain unknown.

Adrenalectomy↗
PubMed1997

Candidate canine enterogastrones: acid inhibition before and after vagotomy.

The relative contributions of several gut-derived peptides as enterogastrones known to be released in response to a fatty meal and to inhibit acid secretion have not previously been compared directly. We determined the acid-inhibitory activities of increasing intravenous doses of several peptides before and after highly selective vagotomy (HSV) during intragastric titration of a peptone meal in dogs. Before HSV, threshold inhibitory doses of peptide YY (PYY), cholecystokinin (CCK), and secretin were 5, 7, and 10 pmol.kg-1.h-1, respectively, whereas neurotensin, glucagon-like peptide-1 (GLP-1), and oxyntomodulin failed to inhibit acid secretion at doses up to 1,000 pmol.kg-1.h-1. The calculated dose producing 50% acid inhibition (ID50) of secretin (62 pmol.kg-1.h-1) was one-half that of PYY (128 pmol.kg-1.h-1). Maximal (90%) acid inhibition was produced by 100 pmol.kg-1.h-1 secretin and 500 pmol.kg-1.h-1 PYY. The highest dose of CCK that did not cause vomiting (100 pmol.kg-1.h-1) inhibited peptone-stimulated acid output by only 60%. After HSV, 500 pmol.kg-1.h-1. PYY and 200 pmol.kg-1.h-1 CCK failed to inhibit acid output by more than 50%. Threshold doses for inhibition by PYY and CCK were 200 and 100 pmol.kg-1.h-1, respectively. Secretin remained a potent inhibitor after HSV, with an ID50 of 80 pmol.kg-1.h-1 and a threshold dose of 10 pmol.kg-1.h-1. HSV also failed to affect inhibition caused by somatostatin. This study has shown that PYY and secretin are somewhat more potent and efficacious inhibitors of acid secretion than CCK but that all three peptides are far more active than GLP-1, neurotensin, and oxyntomodulin. PYY and CCK inhibit acid secretion in large part through vagal innervation of the gastric fundus, but the inhibitory effects of secretin are independent of fundic vagal innervation.

Animal Feed↗
PubMed1998

Duodenal nutrient exposure elicits nutrient-specific gut motility and vagal afferent signals in rat.

Volume and chemical characteristics of meals in the gut have been proposed to generate vagal afferent signals that mediate the negative feedback control of ingestion and gastric emptying. Furthermore, duodenal nutrients elicit changes in gastrointestinal motility that may stimulate mechanosensitive vagal afferents. The degree to which the activity of an individual vagal afferent fiber can be modified by moth mechanical and nutrient properties in the gut remains unclear. The present studies evaluated the relationships between distal antral and proximal duodenal load-sensitive vagal afferent activity and gastroduodenal motility in response to duodenal nutrient exposure in ketamine-xylazine-anesthetized rats. Duodenal carbohydrate (glucose) and amino acid (peptone) infusions (0.2 ml/min, 0.2-0.5 kcal/ml) stimulated concentration-dependent increases in 1) antroduodenal contractions and 2) antral and duodenal vagal afferent activity beyond those attributable to osmolarity alone. In addition, duodenal peptone was more effective than equicaloric glucose in eliciting this vagal activity. These data demonstrate that the proximal duodenum can discriminate its nutrient chemical contents and that gastroduodenal load-sensitive vagal afferents indirectly transduce nutrient chemical information.

Animals↗