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Stephen D Weagant – One of the best experts on this subject based on the ideXlab platform.

  • a new chromogenic Agar Medium for detection of potentially virulent yersinia enterocolitica
    Journal of Microbiological Methods, 2008
    Co-Authors: Stephen D Weagant

    Abstract Several outbreaks of foodborne yersiniosis have been documented and this disease continues to be source of infections transmitted through foods. The selective Agars most commonly used to isolate Yersinia enterocolitica in clinical, food and environmental samples, cefsulodin–irgasan–novobiocin (CIN) and MacConkey (MAC) Agars, lack the ability to differentiate potentially virulent Y. enterocolitica from other Yersinia that may be present as well as some other bacterial spp. This study proposes the use of an Agar Medium, Y. enterocolitica chromogenic Medium (YeCM), for isolation of potentially virulent Y. enterocolitica. This Agar contains cellobiose as the fermentable sugar, a chromogenic substrate and selective inhibitors for suppression of colony formation by many competing bacteria. All strains of potentially virulent Yersinia of biotypes 1B, and biotypes 2-5 formed convex, red bulls-eye colonies on YeCM that were very similar to those described for CIN Agar. However, Y. enterocolitica biotype 1A and other related Yersinia formed colonies that were purple/blue on YeCM while they formed typical red bulls-eye colonies on CIN Agar. When a mixture of potentially virulent Y. enterocolitica biotype 1B, Y. enterocolitica biotype 1A and 5 other bacterial species was used to artificially contaminate tofu and then spread-plated on three selective Agars, Y. enterocolitica biotype 1B colonies were easily distinguished from other strains on YeCM. However, Y. enterocolitica biotype 1B colonies were indistinguishable from many other colonies on CIN and only distinguishable from those of C. freundii on MAC. When colonies were picked and identified from these Agars, typical colonies from YeCM were confirmed only as Y. enterocolitica biotype 1B. Typical colonies on CIN and MAC were found to belong to several competing species and biotypes.

Eugene Ngo-lung Lau – One of the best experts on this subject based on the ideXlab platform.

  • Clonal Cultures in vitro for Haemopoietic Cells Using Semisolid Agar Medium
    Cell Biology, 2006
    Co-Authors: Andreas Hüttmann, Eugene Ngo-lung Lau

    Publisher Summary This chapter discusses how to create clonal cultures in vitro for hemopoietic cells using semisolid Agar Medium. The discovery of hemopoietic growth factors was facilitated greatly by the ability to grow hemopoietic cells in vitro. These culture systems enable the undifferentiated hemopoietic precursors to proliferate and differentiate into various hemopoietic cell lineages. Especially valuable has been the development of clonal cultures using semisolid Agar or methylcellulose culture Medium for hemopoietic precursor cells. The fundamental steps in establishing AgarMedium cultures include mixing equal volumes of double-strength Medium and double-strength Agar solution and adding the cells to be cultured and mix. Fetal calf serum (FCS) is used as a source of nutrients in cell cultures. Batches of FCS should be tested extensively prior to purchase, for optimal colony formation in colony number and colony size, in semisolid cultures. Although specific stimuli may be required for many situations, and always for use as a positive control, a variety of conditioned media containing mixtures of hemopoietic growth factors can be prepared.

John D. Perry – One of the best experts on this subject based on the ideXlab platform.

  • development and evaluation of a chromogenic Agar Medium for methicillin resistant staphylococcus aureus
    Journal of Clinical Microbiology, 2004
    Co-Authors: John D. Perry, Andrew L. J. Hopley, Amie Davies, Lynne A Utterworth, A Nicholso, Kate F Gould

    We describe here the development and evaluation of MRSA ID, a new chromogenic Agar Medium for the specific isolation and identification of methicillin-resistant Staphylococcus aureus (MRSA). We used S. aureus ID (bioMerieux, La Balme Les Grottes, France) and supplemented it with various antimicrobials, including cefoxitin, ciprofloxacin, oxacillin, and methicillin. Cefoxitin proved to be superior to the other antimicrobials for the selection of MRSA from other strains of S. aureus. MRSA ID (consisting of S. aureus ID supplemented with 4 mg of cefoxitin/liter) was evaluated by the use of 747 swabs from various clinical sites. All specimens were also cultured on CHROMAgar MRSA and oxacillin resistance screening Agar base (ORSAB) and in selective mannitol broth (SMB). A total of 85 MRSA strains were isolated by a combination of all methods. After 22 to 24 h of incubation, 80% of the MRSA strains were isolated as green colonies on MRSA ID, compared with 59 and 62% of the strains that were isolated as colored colonies on CHROMAgar MRSA and ORSAB, respectively. After 48 h of incubation, 89, 72, and 78% of the MRSA strains were isolated on MRSA ID, CHROMAgar MRSA, and ORSAB, respectively. Sixty-five percent of the strains were isolated by growth in SMB. The specificities of MRSA ID, CHROMAgar MRSA, ORSAB, and SMB were 99.5, 99.3, 97.9, and 92.8%, respectively, after 22 to 24 h of incubation. We conclude that MRSA ID is a sensitive and specific Medium for the isolation and identification of MRSA.

  • Evaluation of S. aureus ID, a New Chromogenic Agar Medium for Detection of Staphylococcus aureus
    Journal of clinical microbiology, 2003
    Co-Authors: John D. Perry, Claire Rennison, L. A. Butterworth, Andrew L. J. Hopley, F. Kate Gould

    S. aureus ID (bioMerieux, La Balme Les Grottes, France) is a new chromogenic Agar Medium designed to enable the isolation of staphylococci and the specific identification of Staphylococcus aureus. S. aureus produces green colonies on this Medium due to production of α-glucosidase. To evaluate this Medium, a total of 350 wound swabs were cultured onto S. aureus ID, CHROMAgar Staph. aureus, and conventional media routinely used in our laboratory. After 18 to 20 h of incubation, 96.8% of strains formed green colonies on S. aureus ID compared with 91.1% of strains forming mauve colonies on CHROMAgar Staph. aureus. A total of 94.3% of strains were recovered within 18 to 20 h with conventional media. The sensitivity was increased after 48 h of incubation to 98.7, 96.2, and 95.6% with S. aureus ID, CHROMAgar Staph. aureus, and conventional media, respectively. A total of 97.4% of green colonies on S. aureus ID were confirmed as S. aureus compared with 94.4% of mauve colonies on CHROMAgar Staph. aureus. We conclude that S. aureus ID is a highly sensitive and specific Medium for the isolation and identification of S. aureus from wound swabs.

William Michael Dunne – One of the best experts on this subject based on the ideXlab platform.

  • A new chromogenic Agar Medium, chromID VRE, to screen for vancomycin-resistant Enterococcus faecium and Enterococcus faecalis.
    Diagnostic microbiology and infectious disease, 2007
    Co-Authors: Nathan A. Ledeboer, Robert J. Tibbetts, William Michael Dunne

    We compared the performance of a chromogenic Agar Medium chromID VRE (bioMerieux, Marcy-l’Etoile, France) designed to recover and identify vancomycin-resistant enterococci (VRE) from clinical specimens with bile esculin azide vancomycin (BEAV) Agar. For this study, 120 stool specimens were plated on chromID VRE and BEAV and examined after 24 and 48 h. At 24 h, the sensitivity and specificity were as follows: BEAV, 90.2% and 73%, respectively; chromID VRE, 86.3% and 100.0%, respectively. Furthermore, we determined that the sensitivity and specificity of chromID VRE for Enterococcus faecium were 85.4% and 100%, respectively, and for Enterococcus faecalis, 90% and 100%, respectively. We conclude that chromID VRE provides an equivalent sensitivity for the recovery of VRE from stool specimens, with improved specificity, and the added advantage of providing differentiation between vancomycin-resistant E. faecium and E. faecalis.

Sara Cohen – One of the best experts on this subject based on the ideXlab platform.

  • Development of an Improved Selective Agar Medium for Isolation of Yersinia pestis
    Applied and environmental microbiology, 2003
    Co-Authors: Raphael Ber, Emanuelle Mamroud, Moshe Aftalion, Avital Tidhar, David Gur, Yehuda Flashner, Sara Cohen

    Existing media designed for selective isolation of clinically important members of the genus Yersinia were found to be unsatisfactory for the growth and isolation of Yersinia pestis. We report the development of a new selective Agar Medium (termed BIN) that supports the growth of Y. pestis. The development of the formulation of this Medium was based on a fluorescence screening system designed for monitoring bacterial growth on semisolid media, using a green fluorescent protein-expressing strain. High-throughput combinatorial experiments can be conducted for the quantitative evaluation of the effect of different Medium components on growth. Generation of fluorescence plots in this system, using microplates, allowed the quantitative evaluation of the growth rate of Y. pestis EV76 cultures in different Agar compositions. The final BIN formulation is based on brain heart infusion Agar, to which the selective agents irgasan, cholate salts, crystal violet, and nystatin were introduced. It was found that BIN Agar is more efficient in supporting colony formation and recovery of Y. pestis than are the conventional semisolid media MacConkey Agar and Yersinia-selective Agar (cefsulodin-irgasan-novobiocin Agar). The advantage of BIN over other media has been also demonstrated in recovering virulent Y. pestis from the mixed bacterial populations found in decaying carcasses of infected mice. The BIN Medium is suggested as a selective Medium for isolation and recovery of Y. pestis from various backgrounds.