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Showing papers on "Agar plate published in 1998"


Journal ArticleDOI
TL;DR: Faecal samples from 94 dairy cows and 42 calves in three different herds were examined by a variety of techniques for campylobacters, and enrichment in CAT broth before membrane filtration onto blood agar or CAT agar were the most successful methods of plating.
Abstract: H.I. ATABAY AND J.E.L. CORRY. 1998. Faecal samples from 94 dairy cows and 42 calves in three different herds were examined by a variety of techniques for campylobacters. Cefoperazone amphotericin teicoplanin (CAT) agar, modified cefoperazone charcoal deoxycholate agar (mCCDA), Karmali agar, and membrane filtration onto blood agar, were used with and without enrichment in CAT broth. Seventy-nine percent of cattle in herd A carried campylobacters, compared with 40% and 37·5% of cattle in herds B and C, respectively. Most animals carried only one species of Campylobacter. Campylobacter hyointestinalis was isolated most frequently (32% animals positive) with Camp. fetus subsp. fetus and Camp. jejuni subsp. jejuni detected in 11% and 7% of animals, respectively. In addition, a novel biotype of Camp. sputorum was isolated from 60% of 47 cows tested in herd A. Direct plating detected only two of the total of 40 animals positive for campylobacter. Enrichment in CAT broth before membrane filtration onto blood agar or CAT agar were the most successful methods of plating. Campylobacter sputorum was isolated from CAT agar and blood agar but not from mCCDA or Karmali agar. Karmali agar incubated at 30 °C was especially effective for isolating Camp. fetus subsp. fetus.

104 citations


Journal ArticleDOI
TL;DR: A collection of 381 Listeria monocytogenes strains was examined for strain variations in nisin and pediocin sensitivity at three different concentrations on Tryptic Soya Agar, and it is assumed that there is accordance between the pediOCin and bavaricin sensitivity of the remaining strains.
Abstract: A collection of 381 Listeria monocytogenes strains was examined for strain variations in nisin and pediocin sensitivity at three different concentrations on Tryptic Soya Agar. Two of the strains were able to grow on agar plates containing 500 IU nisin ml−1. These strains were characterized as having an enhanced nisin tolerance. Twenty strains had normal growth on agar plates containing 1600 AU pediocin ml−1 and higher. These strains were characterized as pediocin-resistant. Another 34 strains, characterized as having enhanced tolerance, exhibited inhibited growth at 1600 AU pediocin ml−1. Bavaricin sensitivity, examined for 22 strains of L. monocytogenes, correlated with the pediocin sensitivity of the strains. It is therefore assumed that there is accordance between the pediocin and bavaricin sensitivity of the remaining strains. Cross-resistance between nisin and pediocin/bavaricin was not found.

89 citations


Journal ArticleDOI
TL;DR: The first report of a Hem−E.
Abstract: From two different specimens of a chronic prosthetic hip infection taken at an interval of 2 months a slow-growing gram-negative bacterium was isolated in pure culture. The strain grew with the typical features of a small-colony variant (SCV). 16S rRNA sequencing identified the bacterium as Escherichia coli. Biochemical characterization demonstrated multiple phenotypic alterations of a mutant carrying a defect in the heme biosynthetic pathway (Hem−): (i) catalase and nitrate reductase reactions were both negative, (ii) a negative benzidine reaction demonstrated the lack of heme-containing cytochromes, and (iii) growth stimulation under anaerobic conditions as well as gentamicin resistance indicated defective aerobic respiration. PCR and Southern hybridization demonstrated that the mutation of the SCV of E. coli was localized in the hemB gene and was most likely due to a deletion of the hemB gene. On blood agar plates revertants were recognized growing as normal-sized colonies between the dominant small colonies of the strain. Feeding experiments indicated that the revertants but not the small colonies were permeable for hemin. A strong antibody response against the infecting SCV of E. coli was found. To our knowledge, this is the first report of a Hem− E. coli strain as the etiological agent of a chronic bacterial infection.

76 citations


Journal ArticleDOI
TL;DR: It appears that both direct plating and selective broth amplification techniques are required for the maximum level of identification of colonization with GBS in pregnant women.
Abstract: In 1996, the Centers for Disease Control and Prevention recommended the use of a selective broth culture for the improved detection of genital tract or anorectal carriage of group B streptococci (GBS) in pregnant women. In order to verify this recommendation in our laboratory, we compared the sensitivity of Todd-Hewitt medium with gentamicin and nalidixic acid (SBM) with our current method of direct plating on blood agar medium containing neomycin and nalidixic acid (NNA). Five hundred consecutive cervicovaginal and anorectal specimens submitted for GBS culture were included in the study. Swabs were plated onto NNA and the swabs were immersed in SBM, followed by overnight incubation at 35°C. On the following day, the NNA plates were examined for colonies typical of GBS and the organisms were identified by the CAMP test or by latex agglutination. SBM cultures were subcultured onto blood agar and CNA agar plates, and the plates were reincubated for 24 h. Negative specimens from either medium were incubated for an additional 24 h and were examined again before finalization of the results. GBS were recovered from 78 specimens by both methods; from SBM only for 17 specimens (sensitivity, 86%) and from NNA only for 16 specimens (sensitivity, 85%). A moderate to heavy growth of Enterococcus faecalis was observed on plates containing NNA-positive, SBM-negative specimens. Competitive growth studies suggested that E. faecalis suppressed the growth potential of GBS in SBM. Our study suggests that direct plating on NNA, as a single method, is equivalent in sensitivity to SBM for the recovery of GBS, and the results are often available 24 h sooner. However, it appears that both direct plating and selective broth amplification techniques are required for the maximum level of identification of colonization with GBS in pregnant women.

71 citations


Journal ArticleDOI
TL;DR: The proposed selective medium gives a clear signal, is easy to prepare, does not contain dyes or any compounds toxic to humans, and can also detect E. amylovora strains deficient in levan synthesis.
Abstract: Erwinia amylovora strains formed yellow colonies on minimal agar medium MM2 containing asparagine and copper sulfate (MM2Cu), in contrast to a white morphology on minimal agar without copper salt. Additionally, the colonies were mucoid to various extents. The yellow color was characteristic for the fire blight pathogen, including strains from raspberry and from other unusual host plants, and was used to establish a novel plating technique for identification of E. amylovora. The new identification method was especially superior to semi-selective media with sucrose when natural levan-deficient strains were assayed. No growth of E. amylovora was observed for the similar medium MM1 containing 2 mM CuSO4, due to its low content of as paragine. Identification by colony morphology on MM2 agar with copper was confirmed by staining the bacterial capsules with FITC-labeled lectin from Abrus precatorious, a compound which has a high affinity for galactose residues, the main sugar in the capsular exopolysaccharide amylovoran of E. amylovora. Other plant-associated bacteria usually did not produce the typical colony morphology of E. amylovora on MM2 agar with copper. Furthermore, those cells were not stained with the Abrus lectin. Capsule staining was also observed for weakly mucoid strains of E. amylovora, but not for strains with mutations affecting amylovoran synthesis. The secretion of fluorescent compounds by Pseudomonas syringae pathovars and even growth of any other bacterial colonies adjacent to E. amylovora could interfere with the formation of typical yellow colonies on MM2Cu, which could be white in case of dense plating. After screening for white colonies on LB agar, E. amylovora was identified in extracts from Cotoneaster leaves and in bark from apple trees with fire blight symptoms by its yellow growth pattern on MM2Cu agar and by capsule staining. The proposed selective medium gives a clear signal, is easy to prepare, does not contain dyes or any compounds toxic to humans, and can also detect E. amylovora strains deficient in levan synthesis.

68 citations


Journal ArticleDOI
TL;DR: The cloned endosymbiotic algae presented here will provide an excellent opportunity to examine the mechanism of symbiont-host interaction and the interaction between the cloned algae and algae-free paramecia.
Abstract: The green parameciumParamecium bursaria has many endosymbiotic algae in its cytoplasm. Here, we cloned and characterized endosymbiotic algae fromP. bursaria and examined in detail the interaction between the cloned algae and algae-free paramecia. Homogenates ofP. bursaria were cultured on agar plates containing various kinds of media to establish clones of the endosymbiotic algae. Many algal colonies were obtained from poorly nutritious medium (CA medium) after one month in culture. Algae were picked up from these colonies and inoculations were repeated 9 times on agar plates containing CA medium. On enriched media including bacto-peptone, glucose, proteose-peptone and/or yeast extract, however, bacteria and mold grew rapidly and no algal colonies were formed. When the cloned algae were cultured in liquid CA medium, they grew faster than on agar plates and the numbers stayed constant at 1 × 107 algae/ml after 7 days in culture. They revealed high infectivity to algae-free paramecia, and an incubation period of 24 h and at least 1 × 103 algae/paramecium were required to achieve successful infection (80–90%). The growth and infection rate did not change through 74 repeated inoculations of algae in liquid CA medium. Optical microscopic observations revealed marked morphological similarity between endosymbiotic algae and free-livingChlorella, but the latter showed no infectivity to algae-free paramecia. The cloned endosymbiotic algae presented here will provide an excellent opportunity to examine the mechanism of symbiont-host interaction.

52 citations


Journal ArticleDOI
TL;DR: The biological implication of this study is that P. intermedia, by virtue of its hemolytic activity, is capable of liberating the hemoglobin from erythrocytes, thereby acquiring an essential nutrient, iron, for its metabolism.
Abstract: Hemolysin production was measured in strains of Prevotella intermedia. Zones of beta-hemolysis were detected on agar plates supplemented with either sheep, rabbit or human erythrocytes. A standard tube assay was performed on cell suspensions of the organism to measure hemolytic activity, which was found to be dose dependent, eliminated by heat treatment, and saturable with increasing concentrations of blood. Growth-phase experiments suggested that hemolysin production was increased during logarithmic growth and was reduced during stationary phase. Cell fractionation, performed on several strains of P. intermedia, localized the activity in the outer membrane and in cell vesicles. The biological implication of this study is that P. intermedia, by virtue of its hemolytic activity, is capable of liberating the hemoglobin from erythrocytes, thereby acquiring an essential nutrient, iron, for its metabolism.

35 citations


Journal Article
TL;DR: Application of a direct inoculation technique for bacterial culture made it possible to isolate more anaerobes than the commonly used technique using transport medium and to delineate the semiquantitative bacteriology of closed odontogenic abscess.
Abstract: Pus samples from twenty-three dentoalveolar abscesses were collected by needle aspiration and examined by direct inoculation technique using 6 different aerobic and anaerobic agar plates. For aerobic culture, sheep blood agar and chocolate agar (Kyokuto Pharmaceutical Co., Tokyo, Japan) were used. For anaerobic culture, four different media, 1) brucella HK agar with hemolyzed rabbit blood and defibrillated sheep blood, 2) paramomycin-vancomycin brucella HK agar with hemolyzed rabbit blood, 3) phenylethyl alcohol brucella HK agar with hemolyzed rabbit blood, 4) bacteroides bile esculin agar (Kyokuto Pharmaceutical Co., Tokyo, Japan) were prepared in an anaerobic jar prior to inoculation. The aerobic agar plates were incubated for 24 h at 37 degrees C, and the anaerobic plates at least 48 h at 37 degrees C in anaerobic jars. From 23 closed odontogenic abscess samples, a total of 112 bacterial strains were isolated; 81 strains (72.3%) were strict anaerobes, and 31 strains (27.7%) were aerobes. The mean number of bacterial strains per positive sample was 4.86. Oral Streptococci, Prevotella, Fusobacterium, Peptostreptococcus and Veillonella were common isolates. The combination of Oral Streptococci and Prevotella was found in 11 patients (47.8%), and that of Prevotella and Peptostreptococcus in 12 patients (52.2%). The present study demonstrated that closed odontogenic abscesses are polymicrobial infections by aerobes and anaerobes. Application of a direct inoculation technique for bacterial culture made it possible to isolate more anaerobes than our commonly used technique using transport medium and to delineate the semiquantitative bacteriology of closed odontogenic abscess.

34 citations


Journal ArticleDOI
TL;DR: A “microbial inhibition assay” for rapid and economical measurement of phenylalanine levels in whole blood is described, which permits mass screening for hyperphenylalaninemia.
Abstract: The article describes a “microbial inhibition assay” for rapid and economical measurement of phenylalanine levels in whole blood. Capillary blood, from a heel prick, is collected from the newborn infant onto Schleicher and Schuell no. 903 filter paper; a disk of the sample is then transferred to an Agar plate containing a heavy inoculum of Bacillus subtilis ATCC 6051; an inhibitor of bacterial growth (β-2-thienylalanine) is counteracted by any significant excess of phenylalanine in the blood sample; and semiquantitative positive tests (hyperphenylalaninemia) are recorded by size of the bacterial growth zone in the Agar around the filter paper disc. The method permits mass screening for hyperphenylalaninemia.

30 citations


Journal ArticleDOI
TL;DR: Pig fat as an economic substrate for lipase production was investigated and revealed 11 aspergilli and 15 penicillium spp.
Abstract: Forty each of aspergilli and penicillia were screened for extracellular lipase production on agar plates and in liquid medium containing olive oil as substrate. Twenty-nine aspergilli and twenty-six penicillia produced lipase. Out of these, 19 aspergilli and 22 penicillia showed activity both on Nile blue sulfate and glycerol tributyrate agar plates while only 10 aspergilli and 4 penicillia showed a positive response to glycerol tributyrate agar alone. The screening revealed 11 Aspergillus spp. and 15 Penicillium spp. as new lipase producers. Pig fat as an economic substrate for lipase production was also investigated.

30 citations


Journal ArticleDOI
TL;DR: It is recommended that TSA-sheep blood agar be used for optochin susceptibility testing of Streptococcus pneumoniae, because 15.3, 0, and 22.2% of S. pneumoniae organisms were misidentified on Columbia agar, Trypticase soy agar (TSA), and Mueller-Hinton agar respectively, each containing sheep blood.
Abstract: To determine the optimal media for optochin susceptibility testing of Streptococcus pneumoniae, we measured inhibition zones for 72 S. pneumoniae and 22 Streptococcus viridans isolates on three blood-containing media. Because 15.3, 0, and 22.2% of S. pneumoniae organisms were misidentified on Columbia agar, Trypticase soy agar (TSA), and Mueller-Hinton agar, respectively, each containing sheep blood, we recommend that TSA-sheep blood agar be used.

Journal ArticleDOI
TL;DR: Twenty-one strains of Verocytotoxin-producing Escherichia coli that hybridized with DNA probe CVD419 were examined and it was concluded that haemolysins produced by VTEC appear to be quite distinct from E. coli alpha-haemolysin and resemble a form of beta-haEMolysin.
Abstract: Summary: Twenty-one strains of Verocytotoxin-producing Escherichia coli (VTEC) that hybridized with DNA probe CVD419 were examined for the ability to produce haemolysin. With solid media, all strains produced most haemolysin when grown in blood agar tubes and least when grown on blood agar plates incubated in air. Haemolysin production was increased considerably by incubating blood agar plates in an atmosphere comprising 8% carbon dioxide, 40% hydrogen and 52% nitrogen at 37 °C for 16 h, followed by 6 h at 21 °C in air. Haemolysin production was also increased when strains were grown on L-agar containing the iron chelator ethylenediamine-di(o-hydroxyphenylacetic acid) prior to subculture on blood agar. Intracellular haemolysin was detected in five out of the 21 strains of E. coli grown on L-agar in the atmosphere described above, but haemolysin was not detected in L-broth culture supernatants. The haemolysins lysed guinea pig, mouse and ferret erythrocytes, but not human, rabbit, rat, turkey or chicken erythrocytes. Also, the addition of calcium ions to culture media was not required for haemolytic activity. It was concluded that haemolysins produced by VTEC appear to be quite distinct from E. coli α-haemolysin and resemble a form of β-haemolysin.

Journal ArticleDOI
TL;DR: The colony lift immunoassay provided a simple, rapid, and accurate method for confirming the presence of E. coli O157:H7 colonies isolated on filter monitors or spread plates by traditional culture methods.
Abstract: E. coli O157:H7 is a food-borne adulterant that can cause hemorrhagic ulcerative colitis and hemolytic uremic syndrome. Faced with an increasing risk of foods contaminated with E. coli O157:H7, food safety officials are seeking improved methods to detect and isolate E. coli O157:H7 in hazard analysis and critical control point systems in meat- and poultry-processing plants. A colony lift immunoassay was developed to facilitate the positive identification and quantification of E. coli O157:H7 by incorporating a simple colony lift enzyme-linked immunosorbent assay with filter monitors and traditional culture methods. Polyvinylidene difluoride (PVDF) membranes (Millipore, Bedford, Mass.) were prewet with methanol and were used to make replicates of every bacterial colony on agar plates or filter monitor membranes that were then reincubated for 15 to 18 h at 36 ± 1°C, during which the colonies not only remained viable but were reestablished. The membranes were dried, blocked with blocking buffer (Kirkegaard and Perry Laboratories [KPL], Gaithersburg, Md.), and exposed for 7 min to an affinity-purified horseradish peroxidase-labeled goat anti-E. coli O157 antibody (KPL). The membranes were washed, exposed to a 3,3′,5,5′-tetramethylbenzidine membrane substrate (TMB; KPL) or aminoethyl carbazole (AEC; Sigma Chemical Co., St. Louis, Mo.), rinsed in deionized water, and air dried. Colonies of E. coli O157:H7 were identified by either a blue (via TMB) or a red (via AEC) color reaction. The colored spots on the PVDF lift membrane were then matched to their respective parent colonies on the agar plates or filter monitor membranes. The colony lift immunoassay was tested with a wide range of genera in the family Enterobacteriaceae as well as different serotypes within the E. coli genus. The colony lift immunoassay provided a simple, rapid, and accurate method for confirming the presence of E. coli O157:H7 colonies isolated on filter monitors or spread plates by traditional culture methods. An advantage of using the colony lift immunoassay is the ability to test every colony serologically on an agar plate or filter monitor membrane simultaneously for the presence of the E. coli O157 antigen. This colony lift immunoassay has recently been successfully incorporated into a rapid-detection, isolation, and quantification system for E. coli O157:H7, developed in our laboratories for retail meat sampling.

Journal ArticleDOI
TL;DR: Concerning repeatability and reproducibility, Z-agar proved to be superior to cetrimide agar, and a relevant and statistically significant difference was found in the results of sample I in favour of theZ-agar, that could indicate the presence of a low number of bacteria.

Journal ArticleDOI
TL;DR: In this article, a differential medium for the detection of tetrahydrothiophene-1,1-dioxide (sulfolane)-degrading bacteria was developed.

Journal ArticleDOI
TL;DR: The addition of a filter method for routine laboratory isolation of campylobacters should be considered in selected age groups (in children <10 years of age) or in areas where catalase-negative or weakly-positiveCampylobacter strains may be of epidemiological significance.
Abstract: A study was conducted to assess the value of a combination of two culture methods for isolation ofCampylobacter spp. from Spanish children. Seven hundred twenty-nine diarrhoea] stool specimens from 599 patients were examined forCampylobacter spp. by culturing them on charcoal cefoperazone deoxycholate agar and on blood agar with a membrane filter. One hundred sixteenCampylobacter strains were isolated from a total of 108 specimens; 75 (64.6%) wereCampylobacter jejuni, 32 (27.5%) wereCampylobacter coli, 8 (6.8%) were non-typeable, and one (0.9%) wasCampylobacter upsaliensis. Campylobacters were isolated from 99 positive samples using charcoal cefoperazone deoxycholate agar alone. The filtration technique alone yielded only 86 positive samples. Seven specimens yielded differentCampylobacter spp. with different media. The only catalase-negative strain was recovered using the filter method. The combination of the selective medium with the filter method increased the isolation rate ofCampylobacter strains by 14.1%. Isolation rates of campylobacters using the filter method were similar to those reported in European studies, in which a similar frequency ofCampylobacter upsaliensis was observed. The addition of a filter method for routine laboratory isolation of campylobacters should be considered in selected age groups (in children <10 years of age) or in areas where catalase-negative or weakly-positiveCampylobacter strains may be of epidemiological significance.

Journal ArticleDOI
TL;DR: Cell counts revealed that cultures stored in glycerol or fetal bovine serum had a significantly lower loss in viability when compared with cultures stored without cryopreservatives.
Abstract: This study investigated the growth of Helicobacter (H.) pylori in Brucella broth supplemented with either IsoVitaleX (1% vol/vol), hemin (.01% wt.vol), agar (0.3% wt/vol), or blood agar blocks (1.5% wt/vol agar). IsoVitaleX was found to significantly shorten the lag phase, while hemin inhibited the growth within the first 24 hours but later acted as a growth stimulant. There was a tendency toward stronger growth when blood agar blocks were added to the medium. Subsequent electron microscopic evaluation revealed that cells of H. pylori were attached to blood agar block surfaces. In contrast, the supplementation of Brucella broth with agar did not significantly increase the cell density. When H. pylori was grown in the presence of IsoVitaleX, strongly stainable electron-dense bodies (140-200 nm) were seen in the cytoplasms. Incubation of cultures on rotary shakers at 10 rpm significantly enhanced growth. The addition of glycerol (15% vol/vol) or fetal bovine serum (15% vol/vol) showed good ultrastructural preservation of bacteria with undamaged cell walls and cytoplasmic membranes, and cytoplasms were ribosome-dense. Cell counts revealed that cultures stored in glycerol or fetal bovine serum had a significantly lower loss in viability when compared with cultures stored without cryopreservatives. Unprotected cells of H. pylori showed on electron micrographs, clumping, cell lysis, and flagellar damage. Finally, the survival rates of H. pylori after multiple thawing from storage at -80 degrees C were best in Brucella broth/glycerol, Brucella broth/fetal bovine serum, and Brucella broth without cryopreservative (in descending order).

Journal ArticleDOI
TL;DR: The results show that the ability of microorganisms to colonize aquatic ecosystems in the fixed state (i.e. as biofilms) must be considered in studies evaluating cell survival in these environments.

Journal ArticleDOI
TL;DR: In soil from three different locations in The Netherlands from which brown rot-infected potatoes were harvested, the pathogen was not detected by IFC, nor by bioassay in tomato plants, but was not detectable at 4 or 20°C after 50–92 days.
Abstract: Survival of Ralstonia solanacearum (race 3) in different soil types in The Netherlands is currently under investigation to determine its significance in the epidemiology of brown rot. For detection of the brown-rot pathogen, immunofluorescence colony staining (IFC) and selective enrichment in liquid media were optimized and evaluated. In IFC, pour-plating of extracts from a clay soil and a loamy sand in the semi-selective SMSA medium resulted in relatively low recoveries. Using non-selective trypticase soy agar (10% TSA) medium, colonies of target bacteria added to extracts, particularly the sandy loam, remained very small and were weakly stained. Increased colony size and improved staining quality were found after addition of sucrose and crystal violet to 10% TSA. IFC detected 103-104 cfug-1 of dry soil. Detection of R. solanacearum by dilution plating on selective SMSA agar was complicated by the growth of many saprophytic bacteria which was confused with that of R. solanacearum. For detection of populations lower than 103 cfu g-1 of dry soil, selective enrichment in SMSA broth containing the same nutrients as SMSA agar medium was evaluated. After enrichment, R. solanacearum was detected by serial dilution of the sample and immunofluorescence cell staining. EFC was less suitable here, due to the high densities of non-target bacteria in the samples. In clay soil, initial populations of 1–10 cfu g-1 of dry soil were enlarged within 48h to higher than 108 cfu g-1. In sandy soil, enrichment occurred only when initial populations exceeded 100 cfu g -1 of dry soil. IFC was used to study the survival of R. solanacearum in sandy soil from the north-east of The Netherlands (Drenthe). The pathogen survived at 15°C in soil for at least 92 days, but was not detectable at 4 or 20°C after 50–92 days. When the soil was frozen for 24 h at -8°C, the pathogen could not be detected by IFC. In soil from three different locations in The Netherlands from which brown rot-infected potatoes were harvested, the pathogen was not detected by IFC, nor by bioassay in tomato plants. Cross-reacting bacteria were detected in IFC preparations at a low frequency. They were weakly stained and could be distinguished from target bacteria in control preparations. Reisolated bacteria from these weakly stained colonies did not grow on SMSA and were negative in PCR amplifications, based on primers OLI-1 and Y-2.

Journal Article
TL;DR: It was shown that in comparison to other methods the agar slab technique, although less sensitive than others, gave most consistent and reproducible results.
Abstract: A comparison was made of three methods: paper disc, double layer and a newly proposed agar slab techniques for testing antibacterial activity of Lactobacillus strains. Strains of indicator bacteria were selected from important pathogens of the human alimentary and genitourinary tract. The agar slab method, which is based on applying of slabs of MRS agar with overnight growth of the antagonistic bacteria to the surface of appropriate agar plates seeded with indicator bacteria, appeared to be the only method suitable for testing of aerobic and anaerobic fastidious bacteria. After testing of 27 Lactobacillus strains against 3 selected indicator bacteria: E. coli, Salmonella enteritidis and Staphylococcus aureus, calculating mean values and standard deviations for diameters of inhibitory zones and making variance analysis it was shown that in comparison to other methods the agar slab technique, although less sensitive than others, gave most consistent and reproducible results.

Journal ArticleDOI
TL;DR: CA has the number of advantages over SAO when considering practical use, however, SAO is indispensable for qualitative analysis, the elucidation of the mode of action and relationship between structure and activity.
Abstract: An assay system was described for studying the mechanism for the lysis of cyanobacteria, which consists of (1) the improved soft-agar overlayer (SAO) method, and (2) the chlorophyll absorbance (CA) method. In the SAO, the activity was observed on a following double-layer agar plate; the agar was covered with a soft agar containing precultured Microcystis aeruginosa in a schale. Lytic plaques on the agar plate were observed using the disk method and/or cup method. In the CA, the cultured cyanobacterium was centrifuged and an aliquot of the concentrated suspension was poured into each well of a 96-well microplate. Subsequently, sample solution was added to the well and the plate was settled. The plates were daily measured for observing any increase or decrease in the OD665. CA has the number of advantages over SAO when considering practical use, however, SAO is indispensable for qualitative analysis, the elucidation of the mode of action and relationship between structure and activity. This method was applied to screen lytic compounds in a lake and two amino acids were found to have lytic activity.

Journal ArticleDOI
TL;DR: Challenge of the selective medium with reference and clinical strains showed that CBU agar was inhibitory for gram-negative bacteria and reduced the gram-positive flora, allowing the growth of C. urealyticum strains.
Abstract: A new selective medium (CBU agar) was compared with blood agar (BA) medium for primary isolation of Corynebacterium urealyticum from urine and skin samples of hospitalised patients. Overall, the CBU agar detected C. urealyticum in 14 (4.6%) of 302 urine samples and the BA medium detected the organism in four (1.3%), but most cultures which were positive only on CBU agar had < 10(4) cfu/ml. Six strains of C. urealyticum were isolated from 60 skin samples with CBU agar, whereas none was detected with BA. Although most skin samples had heavy inocula, the selective agar facilitated the recognition of low colony counts (< or = 10 cfu/plate) of C. urealyticum by reducing the growth of competing flora. Challenge of the selective medium with reference and clinical strains showed that CBU agar was inhibitory for gram-negative bacteria and reduced the gram-positive flora, allowing the growth of C. urealyticum strains. The new selective medium appears to be a useful epidemiological tool to study urinary and skin colonisation by C. urealyticum.

Journal ArticleDOI
TL;DR: The characteristic E test inhibition ellipse was clearer on TEY agar than on standard blood agar and gave results comparable to those of the agar dilution test.
Abstract: Metronidazole and tetracycline E tests were compared to an agar dilution method for the antimicrobial susceptibility testing of Helicobacter pylori. Sixteen strains were tested by using tetrazolium egg yolk (TEY) agar. The characteristic E test inhibition ellipse was clearer on TEY agar than on standard blood agar and gave results comparable to those of the agar dilution test. The use of TEY medium is preferable to that of blood agar medium in E test MIC determinations for H. pylori.

Journal ArticleDOI
01 Dec 1998-Botany
TL;DR: The position of the antheridium on the oogonium of Phytophthora boehmeriae was greatly affected by culture media, and the effect of culture media on antheridial configuration was found to be due to nutrient concentration.
Abstract: The position of the antheridium on the oogonium of Phytophthora boehmeriae was greatly affected by culture media. Agar medium containing lecithin and basal salts and corn grain agar favored the production of paragynous antheridia, while corn meal agar, lima bean agar, vegetable juice agar, and tomato agar were conducive to formation of amphigynous antheridia. The effect of culture media on antheridial configuration was found to be due to nutrient concentration. A high concentration of nutrients in the media was favored the formation of amphigynous antheridia, and a low concentration of nutrients favored paragynous antheridia.Key words: antheridial configuration, oogonium, nutrients, Phytophthora boehmeriae.

Journal ArticleDOI
TL;DR: A case of necrotizing lymphadenit is from which the authors isolated Mycobacreriunr tuberculosis on blood agar within 13 days during the diagnostic process for cat scratch disease, which found the isolate was susceptible to all antituberculous drugs tested.
Abstract: We here present a case of necrotizing lymphadenit is from which we isolated Mycobacreriunr tuberculosis on blood agar within 13 days during the diagnostic process for cat scratch disease. A 82-year-old woman was admitted with a 4-month history of enlarged right supraclavicular lymph nodes. Ultrasonography revealed three enlarged, partially suppurated nodes. An incision biopsy was performed and yielded pus which remained sterile in rout ine microbiological workup. Cultures for mycobacteria were not performed at this time. Histological examinat ion revealed a granulomatous necrotizing inf lammation with giant cells. Acid-fast bacilli were not detected, and the findings were found suggestive of either tuberculosis or cat scratch disease. Chest roentgenogram and computed tomogram of the thorax did not reveal any signs of tuberculosis, but thickening of both apices and a large left pleural effusion. The intracutaneous tuberculin skin test was positiv at t_ TU. After 4 weeks, a fistula had developed at the incision area so that a second operat ion was performed and the node extirpated. Biopsy specimens were sent to our laboratory to be examined for Bartonetla henselae and to a second laboratory for the detection of mycobacteria. We received the lymph node biopsy material in saline a few hours after extirpation. The specimen was minced and homogenised in 2 ml saline, 0.2 ml ahquots were plated onto solid media. including trypticase soy agar (BBL Microbiology Systems, Cockevsville, MD, USA), supplemented with 5% sheep erythrocytes tb lood agar), chocolate and Columbia agar (Unipath LTD, Basingstone. UK), both supplemented with 5"/0 human erythrocytcs, and incubated at 37~ in a 7% CO 2 atmosphere for up to 6 weeks. One aliquot was subjected to PCR for B. henselae [1] with negative results. After 13 days, approximately 50 small, non-pigmented, rough colonies grew on blood agar. At this time, growth was not observed on Columbia and chocolate agars; however, after further 12-14 days of incubation, several minute colonies grew also on the latter media. The bacteria were not properly labelled bv Gramstain, while Ziehl-Neelsen stain revealed slender, granulated, acidfast bacilli. The isolate was identified as M. tuberculosis bv means of RNA-amplification (AMPLIFIED, Gen-Probe. San Diego, CA. USA), DNA-RNA-hybridisation (ACCU-Probe, Gen-Probe. San Diego. CA, USA), and biochemical tests. Subcultures grew within 10 days with a typical colony morphology on solid Middlebrook and Loewenstein-Jensen media: the isolate was susceptible to all antituberculous drugs tested. Upon further subcultivation on blood agar, the isolate grew even more rapidly, i.e., within 6--7 days. Recently, a rapid growing M. tuberculosis strain has been described in the USA [2], and we tested whether our isolate might belong to this group of mycobacteria, However, when inoculated in comparable numbers, the M. tttberculosis reference strata H37 Rv [3], which serves as a control strain in susceptibility testing [4] and has been serially passaged on Loewenstein-,lensen agar for over 20 )'ears in our laboratory, also grew on blood agar within a similiar period of time. Hence, the patient's isolate did not possess any special properties with respect to its nutritional requirements or growth kinetics. Our report documents the isolation of M. tuberctdosts from a clinical specimen under conditions used for the culture of B. hense&e [5 7]. As both M. tuherculosis and B. henselae are common agents of chronic lymphadenitis, microbiologists should be aware of the possibility to culture M. tuberculosis during the diagnostic process for cat scratch disease. M, Arvand, M. E. A. Mielke. T. Weinke, 7~ Regnath, H. Hahn

Journal ArticleDOI
TL;DR: Carbon agar (CA) significantly increased the final germination percentage of teliospores, AUGPC, and SAUGPC when compared with water agar for all taxa under study and reduced significantly the incubation period whenCompared with WA for teliOSPores of T. bromi, T. controversa, and T. fusca.
Abstract: The effect of activated charcoal as an amendment to water agar medium on teliospore germination was analyzed for two species of wheat-infecting bunts, Tilletia controversa and T. tritici, and two related wild-grass infecting species, T. bromi and T. fusca. Final percentages of teliospore germination, area under the germination progress curves (AUGPC), and a standardized AUGPC (SAUGPC) on carbon agar and water agar were compared among strains. Carbon agar (CA) significantly increased the final germination percentage of teliospores, AUGPC, and SAUGPC when compared with water agar (WA) for all taxa under study. Additionally, CA reduced significantly the incubation (i.e., lag) period when compared with WA for teliospores of T. bromi, T. controversa, and T. fusca. Bovine serum albumin and polyvinyl pyrrolidone were used as alternative chemical adsorbent amendments to WA to establish the role of activated charcoal in the medium. Only media amended with bovine serum albumin and activated charcoal improv...

Journal ArticleDOI
TL;DR: Monolayer plates are acceptable for use in analyses of meat and poultry for antibiotics residues, with savings in laboratory resources and time.
Abstract: Standard curves of 5 antibiotics were determined in an antibiotic assay using bilayer and monolayer agar plates and AOAC-specified test organisms and agar media. Micrococcus luteus ATCC 9341a and antibiotic medium No. 2 were used to prepare the penicillin G standard curve. The same organism and antibiotic medium No. 11 were used to prepare the erythromycin standard curve. Standard curves for streptomycin, tetracycline, and gentamicin were prepared, respectively, with antibiotic medium No. 5 and Bacillus subtilis ATCC 6633, antibiotic medium No. 8 and B. cereus ATCC 11778, and antibiotic medium No. 11 and Staphylococcus epidermidis ATCC 12228. Assays of inhibition by meat fortified with penicillin, streptomycin, gentamicin, tetracycline, erythromycin also were performed on monolayer and bilayer plates. Differences in standard curves and inhibitory responses obtained with monolayer and bilayer plates were < 10%. Thus, monolayer plates are acceptable for use in analyses of meat and poultry for antibiotics residues, with savings in laboratory resources and time.

Journal ArticleDOI
TL;DR: It is concluded that some Pg isolates have variable hemolytic and/ or leukotoxic properties and that this variability (presence and/or degree) of these 2 properties may affect the relative pathogenicity of Pg in susceptible cattle.
Abstract: Pasteurella granulomatis (Pg) is a recently identified bacterium associated with proliferative fibrogranulomatous panniculitis (also called "lechiguana") in Brazilian cattle. Recent attempts to experimentally reproduce this disease have only been partially successful. We hypothesized that Pg may produce hemolysin(s) and/or cytotoxin(s) which could contribute to its pathogenicity in susceptible cattle. The objective of this study was to determine the presence and degree of hemolytic and leukotoxic activity of selected isolates of Pg. Either ovine or bovine blood agar plates were streaked with 1 of 7 Pg isolates, incubated at 37 degrees C +/- 1 C for 48 hours, and examined for hemolysis. Two of seven isolates showed hemolytic activity on bovine plates, while all seven showed hemolytic activity on ovine plates. By use of the CAMP reaction, involving simultaneous intersecting cultures of Staphylococcus aureus and Pg, all seven Pg isolates showed enhanced (positive CAMP) hemolysis within 24 hours on bovine blood agar plates. Preliminary results using tetrazolium (MTT) dye reductions with bovine neutrophils showed leukotoxicity in 13 of 16 Pg cultures. Alamar blue tests indicate leukotoxic activity for all 7 Pg isolates. We conclude that some Pg isolates have variable hemolytic and/or leukotoxic properties and that this variability (presence and/or degree) of these 2 properties may affect the relative pathogenicity of Pg in susceptible cattle.

Journal Article
TL;DR: The success rate for culture of H. pylori from gastric biopsy increased when two biopsies were taken and inoculated on chocolate blood agar media with and without antibiotics.
Abstract: Factors influencing the successful isolation of Helicobacter pylori from human gastric biopsies were studied. Within 24 h, each of the gastric biopsies was inoculated onto chocolate blood agar media and incubated for up to 2 weeks. Among 63 (70%) culture positive cases in 90 patients, 58 (64%) cases were culture positive for both specimens, while five (6%) cases were culture positive in only one biopsy. Of the 63 positive cultures, 51 H. pylori strains (81%) grew on both media with and without antibiotics. Eight strains (13%) grew only on medium without antibiotics, while four isolates (6%) were obtained only from medium with antibiotics. These results support the previous histological observation of patchy colonization of H. pylori in the stomach. The success rate for culture of H. pylori from gastric biopsies increased when two biopsies were taken and inoculated on chocolate blood agar media with and without antibiotics.

Journal Article
TL;DR: The high carrier frequency of potentially pathogenic bacteria in healthy children in Greenland may be related to the high frequency of URTI's and episodes of OM among children in Iceland.
Abstract: We have systematically studied the aerobic nasopharyngeal bacteria isolated from swabs by unselective subculturing on 5% horse blood agar and chocolate agar in 70 healthy children aged 0-1, 3-5 and 8 years in Nuuk and Sisimiut, Greenland. The purpose was to provide a basis for a better understanding of the infectious pathology and blind antibiotic treatment against potential pathogens thereby improving standard antimicrobial treatment of upper respiratory tract infections (URTI) and otitis media (OM) among children in Greenland. The study serves also as a baseline for future microbiological and immunological research projects. The children were clinically examined for any infectious diseases and a medical history was obtained which allowed for selection of children without a history of severe clinical infection. Nasopharyngeal swabs obtained via the oral route were instantly spread on 5% blood agar and chocolate agar culture plates and incubated aerobically. Subsequently, potentially pathogenic as well as non-pathogenic bacteria were identified by conventional methods. Healthy children in Greenland carry grossly the same aerobic bacterial flora as children in other parts of the world but potentially pathogenic bacteria were found in very high frequency (94%). Staphylococcus aureus, Streptococcus pneumoniae and Moraxella catarrhalis were found in higher frequencies in the youngest children. Haemophilus influenzae non-b was found in high frequencies in all age groups (67-76%). H. influenzae type b was carried by 11.4%. Group A streptococci were found more frequently in older children and in children from Sisimiut. Of M. catarrhalis strains 88% produced beta-lactamase. Neisseria meningitidis, Mycoplasma pneumoniae and chlamydiae were not detected at all. The high carrier frequency of potentially pathogenic bacteria in healthy children in Greenland may be related to the high frequency of URTI's and episodes of OM among children in Greenland.