Showing papers on "Agar plate published in 1976"
TL;DR: A differential agar medium for the identification of Ureaplasma urealyticum in primary cultures of clinical specimens is described and colonies are identified as dark golden-brown or rich deep-brown colonies, in sharp contrast to the light background of the medium, when viewed by direct transmitted illumination under the low power of the microscope.
Abstract: A differential agar medium for the identification of Ureaplasma urealyticum in primary cultures of clinical specimens is described. The differential medium (no. A7) is specific for the identification of U. urealyticum and other members of the genus Ureaplasma. Large-colony, classical Mycoplasma and Acholeplasma species and Proteus L colonies are unreactive on this differential medium. The medium incorporates the biochemical principle of the direct spot test for urease in colonies of Ureaplasma and contains added urea and a sensitive indicator of ammonia, manganous sulfate. Ureaplasma colonies on this medium are identified as dark golden-brown or rich deep-brown colonies, in sharp contrast to the light background of the medium, when viewed by direct transmitted illumination under the low power of the microscope.
213 citations
159 citations
TL;DR: A case of septicemia and meningitis secondary to dog bites by two different dogs on two consecutive days is described, and the unidentified Gram-negative bacillus showed susceptibility to all antimicrobials tested except gentamicin.
Abstract: This report describes a case of septicemia and meningitis secondary to dog bites by two different dogs on two consecutive days. The case is noteworthy because of the unusual characteristics of the etiologic agent and the inability to place the etiologic agent into any currently defined genus or to identify it by the existing systems of classification. The organism is a small, thin, Gram-negative bacillus after 24 hours of incubation on blood agar; after prolonged incubation, it becomes filamentous. The organism is catalase- and oxidase-positive, hydrolyzes esculin, and forms acid in glucose, xylose, and maltose after 21 days' incubation. The organism does not manifest lysis on sheep blood agar, and does not grow on MacConkey, Salmonella-Shigella, Centrimide, nutrient, or Kligler iron agars. The tests for urea, nitrate reduction, and indol are negative. The unidentified Gram-negative bacillus showed susceptibility to all antimicrobials tested except gentamicin.
155 citations
TL;DR: An unidentified halophile isolated from plates of a complex agar medium containing 4.25 M NaCl showed optimum growth in broths containing 0.5-1.0 M Na Cl but exhibited a wide range of growth from 0.045-4.5 M.
Abstract: An unidentified halophile isolated from plates of a complex agar medium containing 425 M NaCl showed optimum growth in broths containing 05–10 M NaCl but exhibited a wide range of growth from 0
82 citations
TL;DR: Time in pure culture before water storage did not affect viability of any fungal species following water storage, and four fungi retained their original growth rates and root-infecting abilities on pine seedlings after 3 years storage.
Abstract: Mycelial cultures of 64 isolates of 14 species of ectomycorrhizal fungi and 27 isolates of 15 species of plant pathogenic fungi were grown on agar medium in Petri dishes. Mycelial discs, 8 mm in di...
75 citations
TL;DR: It was possible to increase the percentage of plantlet-producing anthers in Nicotiana considerably by the use of a liquid medium and the formation of androgenic embryos was inhibited during a fairly long period of culture.
66 citations
TL;DR: CT agar compares favorably with, or in some cases is an improvement over, other selective media which have been recommended for isolating Serratia and could be quite useful in ecological surveys, especially those related to hospital-acquired infections.
Abstract: A defined agar medium (hereinafter designated caprylate-thallous [CT5 agar) containing 0.01% yeast extract, 0.1% caprylic (n-octanoic) acid, and 0.025% thallous sulfate is highly selective for all Serratia species and effectively discriminates against most non-Serratia strains likely to be in the same habitats. The selectivity of CT agar is demonstrated by the very high efficiency of colony formation (mean, 80.7% of that on a nonselective complex medium) on CT agar by known Serratia strains and the very low efficiency of colony formation (close to zero) on CT agar by bacterial strains known not to be Serratia. The utility of this medium in actual clinical laboratory practice is demonstrated by the more rapid and higher recovery of Serratia on this selective medium as compared to conventional procedures of in-tandem runs of 513 consecutive urine, feces, and sputum specimens. Pigmented and nonpigmented Serratia strains deliberately added to fecal specimens can be selectively and quantitatively recovered on CT agar. CT agar compares favorably with, or in some cases is an improvement over, other selective media which have been recommended for isolating Serratia. This selective CT agar medium could be quite useful in ecological surveys, especially those related to hospital-acquired infections.
62 citations
TL;DR: The ability of Streptococcus mutans to grow on mitis-salivarius (MS) agar, MC Agar, mitis -sucrose-bacitracin (MSB), BCY agar), and MM10 sucrose agar was studied.
Abstract: The ability of Streptococcus mutans to grow on mitis-salivarius (MS) agar, MC agar, mitis-sucrose-bacitracin (MSB), BCY agar, and MM10 sucrose agar was studied. Batch cultures of S. mutans serotype a demonstrated no growth on MSB agar. Certain serotype d and g strains did not grow on MC agar. The yield for most strains of other serotypes on these selective media was lower compared with that on MS agar. The number of total colony-forming units on BCY and MM10 sucrose agar was similar to the blood agar results. Similar data were obtained when fermenter-grown strains, harvested in the middle or the end of the logarithmic growth phase, were used for inoculation of the various media. Enumeration of S. mutans from plaque samples plated on MC and MSB agar yielded about 75% of the counts obtained on MS or the nonselective medium. When the proportions of S. mutans were expressed as a percentage of the total cultivable flora, the selective media (MC and MSB agar) showed approximately 10% lower values than the MS, BCY, and MM10 sucrose agar.
51 citations
TL;DR: Routine use of SBM is supported for the most accurate identification of women vaginally colonized with group B Streptococcus.
Abstract: Three bacteriological techniques for the isolation of group B streptococci in vaginal cultures were compared. A selective broth medium (SBM) containing gentamicin and nalidixic acid was more sensitive for the detection of vaginal isolates (28/76, 36.8%) from 76 women enrolled in a venereal disease clinic than was an identical selective plate medium (SPM) (17/76, 25%). Similarly, SBM allowed identification of positive cultures from college women (82/459, 17.9%) significantly more often than direct inoculation of swabs onto nonselective blood agar medium (43/460, 9.4%; chi2 = 42.2, P = less than 0.001). Failure to isolate group B streptococci detected in SBM occurred in 32.1% cultures by SPM and 49.4% of cultures by nonselective agar medium. Multiple serotypes were detected in a single vaginal culture from approximately 5% of the patients studied. These data support the routine use of SBM for the most accurate identification of women vaginally colonized with group B Streptococcus.
49 citations
TL;DR: By effective flushing of the cultures with CO2 -free air it is possible to demonstrate that carbon dioxide is essential to the initiation of the growth in suspension culture or on agar plates of cultured sycamore cells and attempts to replace the carbon dioxide requirement by non-toxic levels of organic or amino acids have not been successful.
Abstract: Carbon dioxide (optimum concentration c. 1.0%) is essential to the initiation of the growth in suspension culture or on agar plates of cultured sycamore cells. By effective flushing of the cultures with CO2 -free air it is possible to demonstrate this requirement with initial cell densities up to 50 × 103 cells ml-1 . This growth-promoting activity of carbon dioxide is not related to any effect it may have on the pH of the culture medium. The cells fix applied carbon dioxide into organic and amino acids but attempts to replace the carbon dioxide requirement by non-toxic levels of organic or amino acids have not been successful.
42 citations
TL;DR: Extracellular cyclic-AMP phosphodiesterase and the inhibitor of this enzyme is tested in agar plate cultures of two Dictyostelium discoideum wild-type strains and in a mutant which lacks the inhibitor.
TL;DR: A distinct deoxyribonucleic acid homology group, formerly classified as B. thetaiotaomicron, did not produce abscesses in any of the mice tested, and was initiated by infection of pure cultures grown in semisolid agar medium.
Abstract: The development of a pure Bacteroides fragilis infection in mice is described. The infection produces large subcutaneous abscesses at the site of injection which can be observed grossly within 7 days after injection. The infection was initiated by infection of pure cultures grown in semisolid agar medium. Similar infections were also produced with pure cultures of B. distasonis, B. ovatus, B. thetaiotaomicron, and B. vulgatus. However, a distinct deoxyribonucleic acid homology group, formerly classified as B. thetaiotaomicron, did not produce abscesses in any of the mice tested.
TL;DR: The anaerobic glove box and techniques described by Moodie and Woods (1973 b) were used to isolate 30 obligate anaerobes from human faecal samples, which were maintained under anaerobia conditions and tested routinely for aerobic growth.
Abstract: METHODS Bacteria. The anaerobic glove box and techniques described by Moodie and Woods (1973 b) were used to isolate 30 obligate anaerobic bacteria from human faecal samples. The anaerobes were isolated on blood agar media containing either kanamycin plus vancomycin or rifamycin plus vancomycin, which are selective for Bacteroides and Fusobacterium species, respectively (Finegold, Sugihara & Sutter, I 97 I). All were Gram-negative, non-sporeforming rods, and their ability to grow in media containing desoxycholate (0.1 %, w/v) and bile (20 %, w/v) or desoxycholate alone was determined (Shimada, Sutter & Finegold, I 970). The following abbreviations are used for genetic markers : amp (ampicillin), kan (kanamycin, nal (nalidixic acid), riJ'(rifamycin), tet (tetracycline) and van (vancomycin). Anaerobes that were kanr rifS vanr and were able to grow in medium containing desoxycholate and bile were regarded as Bacteroides fragilis (strains I to 10) and those that were inhibited by desoxycholate, with or without bile, as Bacteroides spp. (strains I to 4). Anaerobes that were kanS rifr vanr and grew in medium containing desoxycholate in the presence or absence of bile were regarded as Fusobacterium spp. (strains I to 7) (Moore & Holdeman, 1972). A fourth group included obligate anaerobes selected on antibiotic media but which could not be grouped in the above scheme (anaerobic strains I to 9). The obligate anaerobes were maintained under anaerobic conditions and tested routinely for aerobic growth. Two facultative E. coli strains were isolated from human faecal specimens : an R factor-containing strain A, (ampr) and a recipient strain B (nalr, rifi') (Moodie & Woods, 1g73a). Media. (Note : all percentage compositions are w/v unless otherwise stated.) All media contained 0.4 % Na,CO, and 0.05 % cysteine-HCl. The liquid medium (BHI-S) and agar medium (BHIA-S) contained brain-heart infusion broth (Difco), supplemented with 0.005 haemin, 0.002 % menadione and 0.5 % yeast extract. Antibiotics were incorporated anaerobically in the agar medium at the following concentrations (pg ml-l): ampicillin, 25; kanamycin, 1000; nalidixic acid, 30; rifamycin, 50; tetracycline, 50; vancomycin, 7-5. Incubation was at 37 "C. 26-3
TL;DR: The hypothesis that the response to α-factor by cells of mating-type a is essential for mating is supported, as well as the ability to mate at low frequency and to sporulate.
Abstract: Mutants that are resistant to α-factor have been isolated from a mating-type haploid strains of yeast by direct selection on agar medium containing partially purified α-factor. All resistant mutants isolated were found to be sterile. They were characterized and compared with mutants previously isolated as nonmating. Among 93 able to mate at low frequency and to sporulate, none showed linkage to the mating-type locus. The results support the hypothesis that the response to α-factor by cells of mating-type a is essential for mating.
TL;DR: It was thought that the reason for the reduction of acidogenic and aciduric oral flora in the X-group was partly due to the fact that xylitol is generally not metabolized by these microorganisms.
Abstract: The possible qualitative and/or quantitative alterations in the proportions of cultivable groups of oral microorganisms were analysed during a clinical trial involving the consumption of fructose (F) or xylitol (X) in comparison to sucrose (S). Supragingival plaque samples and paraffin-stimulated saliva were collected from 115 subjects. The samples were dispersed by sonication, diluted stepwise, plated on blood agar, Mac Leod agar, MacConcey agar, Rogosa S.L. agar, and Sabouraud agar plates and incubated anaerobically and/or aerobically. The number of the total colony forming units (CFU) on blood agar plates in anaerobic incubation was about 1–3 × 109/ml saliva and 1–4 × 108/mg plaque and in aerobic respectively 5–18 × 108/ml saliva and 108/mg plaque. The total CFU on Mac Leod agar was of a similar order of magnitude. The variation between subjects and consecutive determinations was relatively large. The arithmetic mean of the total CFU on MacConcey agar was about 1–5 × 105/ml saliva, on Rogosa S.L. agar ...
TL;DR: The detection of group A beta-hemolytic streptococci by bacitracin susceptibility was examined, with the presumptive identification on primary blood agar plates compared with that on pure subcultured plates.
TL;DR: Tests for production of coagulase and thermostable nuclease should be used in the classification of these intermediate strains in diagnostic bacteriology.
Abstract: Twenty-seven coagulase-negative and deoxyribonuclease-positive staphylococci were isolated from more than 3000 specimens from human infections. The strains were tested by conventional biochemical tests and by simple agar plate assays for production of different extracellular enzymes and toxins. Three strains were lysed byS. epidermidis phages and 7 strains byS. aureus phages. All strains produced thermolabile nuclease but only 21 strains produced thermostable nuclease.
TL;DR: Observations suggest that assays based on measurements of colony diameter made on only one occasion are unsuitable for determining the fungitoxicity of phaseollin and may also be misleading in tests with other phytoalexins.
Abstract: The onset of mycelial growth of Colletotrichum lindemuthianum was delayed on agar which contained the phytoalexin phaseollin. The length of this delay varied considerably depending upon the concentration of phaseollin and the age of the inoculum. Subsequent growth took place at a rate similar to that on agar medium alone. These observations suggest that assays based on measurements of colony diameter made on only one occasion are unsuitable for determining the fungitoxicity of phaseollin and may also be misleading in tests with other phytoalexins.
TL;DR: In cord leukocyte cultures exposed to EBV, cells capable of growing in semisolid agar medium appeared early and increased rapidly, though the total numbers of leukocytes and control cultures decreased during the first several days.
Abstract: The semisolid agar method for the selective growth of transformed cells was applied to investigations of Epstein-Barr virus (EBV) transformation. When 1 X 10(5) HUMAn umbilical-cord blood leukocytes were seeded in agar medium immediately after EBV exposure, about 100 colonies developed in each dish. The occurrence of colonies correlated well with dilutions of EBV inoculum. These colonies were composed of lymphoblasts, were positive for EBV-determined nuclear antigen immunofluorescence, and consistently resulted in the establishment of cell lines. In cord leukocyte cultures exposed to EBV, cells capable of growing in semisolid agar medium appeared early and increased rapidly, though the total numbers of leukocytes and control cultures decreased during the first several days.
TL;DR: The data suggest that freshness of the plates may be as important as using rich media in the growth of anaerobic bacteria, and nonenriched brain heart infusion was found to be a better basal medium than Trypticase soy agar (TSA) medium.
Abstract: By measuring the colony size of a variety of anaerobic bacteria isolated from clinical specimens, an evaluation was made of the benefits derived from the addition of several enrichments to blood agar medium commonly used for the growth of anaerobes. Similar methods were used to study the effects of various storage conditions and age of the medium. The results were compared with those obtained on freshly prepared and enriched blood agar plates as well as commercially available blood agar plates. Freshly prepared and enriched blood agar was found to give substantially larger colonies than could be grown on commercially obtained blood agar plates when both were inoculated and incubated under identical conditions. Storage of plating media under CO2 for periods of up to 72 h had only a minor effect on the growth of the anaerobic bacteria studied, but longer periods of storage under CO2 resulted in a less efficient plating medium. Nonenriched brain heart infusion (BHI) was found to be a better basal medium than Trypticase soy agar (TSA) medium. Colony size on fully enriched BHI blood agar plates was greater than nonenriched BHI greater than nonenriched TSA greater than commercially prepared nonenriched TSA plates. The data suggest that freshness of the plates may be as important as using rich media.
TL;DR: Fifty-eight human isolates of Bacteroides melaninogenicus, 42 from a variety of clinical infections and the rest from normal flora, were studied for pigment production and ultraviolet light fluorescence and by forty biochemical tests, including end-product analysis by gas-liquid chromatography.
Abstract: Fifty-eight human isolates of Bacteroides melaninogenicus, 42 from a variety of clinical infections and the rest from normal flora, were studied for pigment production and ultraviolet light fluorescence and by forty biochemical and other tests, including end-product analysis by gas-liquid chromatography. In a number of instances, tests were repeated several times and the results were reproducible. Agar plate dilution susceptibility tests were also performed to 12 antimicrobial agents. These 58 strains could be reliably placed into three groups, corresponding to the three subspecies described, based on seven characteristics. These included acid production in peptone-yeast-glucose medium, production of n-butyric acid from peptone-yeast-glucose medium, esculin hydrolysis, starch hydrolysis, indole production, effect on milk, and lipase production. Production of hydrogen gas in peptone-yeast-fructose medium may be another distinguishing characteristic. In general there was not much difference in the susceptibility of the three groups to the various antimicrobial agents tested. Two strains had a minimal inhibitory concentration of penicillin G of 16 and 32 U/ml, respectively. Three strains did not produce a black pigment in spite of prolonged incubation on blood-containing media.
TL;DR: Several pure cultures of methane-utilizing bacteria, including types I and II membrane representatives, were found to be capable of fixing nitrogen, apparently common in methane-oxidizing bacteria.
Abstract: Several pure cultures of methane-utilizing bacteria, including types I and II membrane representatives, were found to be capable of fixing nitrogen. One nitrogen-fixing isolate grew in liquid medium, but not on a solid agar medium. Apparently, the ability to fix nitrogen is common in methane-oxidizing bacteria.
TL;DR: Yeast mutants unable to degrade certain nitrogen compounds produce characteristic small red colonies on an agar medium containing the red dye phloxine B, galactose, the test nitrogen compound, and a small amount of ammonium chloride.
Abstract: Yeast mutants unable to degrade certain nitrogen compounds produce characteristic small red colonies on an agar medium containing the red dye phloxine B, galactose, the test nitrogen compound, and a small amount of ammonium chloride.
TL;DR: A selective agar medium (pork plasma medium for S. aureus (PPSA) enables the direct enumeration of coagulase-positive staphylococci) and has the advantage over egg yolk containing media such as Baird-Parker agar that fewer suspect colonies have to be confirmed.
Abstract: A selective agar medium (pork plasma medium for S. aureus (PPSA)) enables the direct enumeration of coagulase-positive staphylococci. This medium is based on the Baird-Parker agar without egg yolk ...
01 Oct 1976
TL;DR: A mutant (uvr-1) of Bacillus subtilis that is deficient in excision of ultraviolet (UV)-induced pyrimidine dimers from deoxyribonucleic acid (DNA) shows a marked increase in ability to survive UV irradiation when plated on amino acid-supplemented agar medium, the effect is considered to be one of growth-dependent lethality.
Abstract: A mutant (uvr-1) of Bacillus subtilis that is deficient in excision of ultraviolet (uv)-induced pyrimidine dimers from deoxyribonucleic acid (DNA) shows a marked increase in ability to survive uv irradiation when plated on amino acid-supplemented agar medium compared with its survival ability when plated on nutrient agar. Since the extent of killing depends on the richness of the plating medium, the effect is considered to be one of growth-dependent lethality. Irradiated stationary phase uvr-1 cells, incubated in liquid medium lacking amino acids required for growth, recover from this sensitivity to rich medium within 3 to 4 h after irradiation. Recovery is greatly reduced in the absence of glucose or in the presence of NaCN, athough it is not completely eliminated. Exponentially growing cells have a limited ability to recover from sensitivity to rich medium. Growth-dependent lethality can also occur in liquid medium. In nutrient broth the ability of irradiated stationary-phase uvr-1 cells to form colonies on defined agar medium decreases during postirradiation incubation, but treatment with chloramphenicol inhibits the loss of colony-forming ability. Recovery from sensitivity to rich media is inhibited by caffeine but not by 6-(p-hydroxyphenylazo)-uracil, an inhibitor of DNA replication. Alkaline sucrose gradient profiles show that conditions allowingmore » recovery also favor maintaining intact DNA strands, whereas DNA strand breakage or degradation is associated with loss of viability.« less
TL;DR: The potassium salt of carrageenan was found to be an adequate replacement for agar in solid bacteriological media and common microbial genetic techniques carried out sucessfully with a number of mutant strains of Escherichia coli.
Abstract: The potassium salt of carrageenan was found to be an adequate replacement for agar in solid bacteriological media. The common microbial genetic techniques, such as purifying colonies by streaking, replication tests, and titration of cultures, were carried out sucessfully with a number of mutant strains of Escherichia coli.
TL;DR: Conidia of Aspergillus parasiticus harvested from an agar medium, centrifuged, and resuspended in 0.05% Tween-80 showed signs of injury and continued storage of injured conidia in media of reduced aw eventually resulted in a loss of colony-forming ability.
Abstract: Conidia of Aspergillus parasiticus (an aflatoxin producer) were harvested from an agar medium, centrifuged, and resuspended in 0.05% Tween-80. The suspension was subjected to a thermal stress of 51°C for up to 4 hr. Viability and thermal injury were evaluatd by the use of two plating media, yeast extract agar and yeast extract agar + 10% NaCl. Evidence of injury was demonstrated by the difference in colony counts on the two media. The number of injured cells increased as the heating time continued Colonies from injured conidia developed more slowly than colonies from unheated conidia. The effect of a reduced water activity (aw) was evaluated by comparing the ability of unheated and heated conidia to grow in media of differing water activities. A most probable number technique was used to measure growth. Media of reduced aw limited the ability of injured conidia to outgrow as compared to unheated conidia. Continued storage of injured conidia in media of reduced aw eventually resulted in a loss of colony-forming ability. Solutes used to lower aw were sodium chloride, glycerol, and sucrose.
TL;DR: Ampicillin resistance (minimal inhibitory concentration ≥10 μg/ml) in the absence of beta-lactamase activity by Haemophilus influenzae was noted in tests performed with Mueller-Hinton agar containing one lot of supplement C.
Abstract: Ampicillin resistance (minimal inhibitory concentration >/=10 mug/ml) in the absence of beta-lactamase activity by Haemophilus influenzae was noted in tests performed with Mueller-Hinton agar containing one lot of supplement C. All strains, except five with known resistance due to beta-lactamase activity, were inhibited by 0.6 mug or less of ampicillin per ml of chocolatized blood agar.
TL;DR: The physical and nutritional requirements of the antibiotic-producing slime mold Physarum gyrosum were examined and a liquid medium for this myxomycete was developed to expedite a useful scale of production of antibiotic materials for ease of isolation and structure study.
Abstract: The physical and nutritional requirements of the antibiotic-producing slime mold Physarum gyrosum were examined to develop a liquid medium for this myxomycete. Liquid culture is desired to expedite a useful scale of production of antibiotic materials for ease of isolation and structure study. Culture conditions were selected to favor antibiotic production rather than maximum growth. The medium devised consisted of 0.010 M potassium phosphate buffer (pH 6.0), 2% bakers' yeast, and 0.2% glucose and was supplemented with either 10(-7) M hemoglobin (preferred) or 2.0 ml of live Escherichia coli per 100 ml of culture medium grown to a steady-state population in nutrient broth. The slime mold, which contained some E. coli carried along with the inoculum, was allowed to grow as a surface plasmodium at 20 degrees C in the dark with weekly subculturing for stocks or for 10 days for antibiotic production. P. gyrosum produced the same antibiotic materials when grown in liquid medium as it did when grown on agar plates. A seeded plate disk assay against Bacillus cereus was employed to follow antibiotic activity.
Journal Article•
TL;DR: Observations strongly suggest that these colonies of blastoid cells generated when stimulated in vitro by phytohemagglutinin are made of T-lymphocytes, a subset of PHA sensitive cells.
Abstract: Normal peripheral human white blood cels (WBC) plated in agar culture generate colonies of blastoid cells when stimulated in vitro by phytohemagglutinin (PHA). Aggregates of PHA transformed cells are first visible by day 3-4. By day 7, the morphology of colonies becomes typical as clear discoid raspberry-like aggregates of 50-200 cells or more growing at or near the surface of the agar plate. Their dense arrangement and the coexistence within individual colonies of large and smaller cells are two main characterisitcs of these colonies. Wright-Giemsa stained preparations from cytocentrifuged colonies show cells at different stages of "lymphocyte transformation". These cells are PAS and peroxidase negative. They do not bear surface immunoglobulins but most of them form rosettes with sheep red blood cells. These observations strongly suggest that these colonies are made of T-lymphocytes. However, in view of the number of isolated transformed cells which do not form colonies, the possibility is raised that the cells which generate these colonies may represent a subset of PHA sensitive cells.