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S M Gubash

Publications and source records attributed to S M Gubash.

14 recordsLinked to original sources
PubMed1997

Comparison of a new, bismuth-iron-sulfite-cycloserine agar for isolation of Clostridium perfringens with the tryptose-sulfite-cycloserine and blood agars.

A new differential and selective, bismuth-iron-sulfite-cycloserine (BISC) medium, for isolation and enumeration of Clostridium perfringens from food and feces, was developed. The medium was compared with the widely-used tryptose-sulfite-cycloserine (TSC) medium and blood agar (BA) in recovering actively growing cells, cold- (refrigerated and frozen) stressed, and heat-stressed C. perfringens cells, and heat-activated spores from human feces. Both selective media were satisfactory in recovering actively growing cells and heat-activated spores of C. perfringens. Both were inferior to non-inhibitory blood agar in recovering heat or cold-stressed cells. The advantages of the new BISC medium over the TSC medium were: elimination of the need to prepare pour- or overlay-agar plates, which simplified inoculation of specimens on the medium and simplified the subcultures of colonies for confirmatory identification. All colonies of C. perfringens developed on BISC were black or dark gray. This was contrary to TSC medium, which gave, on average, 39.6% of white colonies when inoculated with the pure cultures of C. perfringens.

Bacteriological Techniques↗
PubMed1997

Evaluation of the synergistic haemolysis (CAMP-like) test in the identification of motile, mesophilic Aeromonas species.

Usefulness of the synergistic haemolysis (CAMP-like) test in the identification of Aeromonas hydrophila, Aeromonas sobria, and Aeromonas caviae was evaluated, using beta-toxin producing Staphylococcus aureus ATCC 25923 and alpha-toxin producing Clostridium perfringens ATCC 13124 as sphingomyelinase producing indicator strains. The tests were done on Columbia Blood Agar Base supplemented with 5% sheep blood (CBA; Difco Laboratories, Detroit, MI, USA). When cultured aerobically, 77% of A. hydrophila isolates, 75% of A. sobria isolates, and 23% of A. caviae isolates elicited synergistic haemolysis of sheep erythrocytes with the beta-toxin producing strain of S. aureus. Anaerobically, using the same indicator strain, synergistic haemolysis was given by 91%, 51% and 82% of A. hydrophila, A. sobria, and A. caviae, respectively. When alpha-toxin producing C. perfringens was used in the test instead of beta-toxin producing S. aureus, 100%, 86%, and 93% of A. hydrophila, A. sobria, and A. caviae isolates, respectively, showed synergistic haemolysis of sheep erythrocytes. Due to the high number of the tested isolates of A. hydrophila, A. sobria, and A. caviae giving a positive synergistic haemolysis reaction in both atmospheric conditions of culture, this test cannot be used to identify any of the three Aeromonas spp. The use of alpha-toxin producing C. perfringens did not improve discriminatory power of the test. Because the nature of the product of Aeromonas spp. responsible for the lytic phenomenon is not known, the use of Aeromonas factor and synergistic haemolysis terms was proposed rather than CAMP (reaction, test) or CAMP (-like) factor.

Aeromonas↗
PubMed1993

Detection of bacterial nitrate reductase activity by the use of a powdered reagent and rapid swab methods as compared to the conventional test.

A rapid swab method using either a dry or moist swab soaked with potassium nitrate/benzalkonium chloride solution, and a method employing a single powdered reagent were assessed as possible alternatives to the conventional test for the detection of bacterial nitrate reductase activity. Results obtained by the use of the powdered reagent agreed 100% with those obtained by the conventional method. The moist swab method had a sensitivity and predictive value of the negative test of 80% and 73%, respectively. The dry swab method was least sensitive (72%) and had the lowest predictive value of the negative test (66%). The use of the single powdered reagent, which has a long shelf life, is a reliable alternative to the use of conventional reagents A and B. Results obtained by the rapid swab methods were inferior to those obtained by the conventional method.

1-Naphthylamine↗
PubMed1991

Improved egg-yolk agar plate medium for the detection of clostridial phospholipase C activity.

A new modification of the egg-yolk agar plate medium, an egg-yolk triple-salt medium, is described. The medium incorporates a tryptic soy agar base, yeast extract, D-glucose CaCl2, MgCl2 and ZnSO4. Only in egg-yolk triple-salt medium did all tested phospholipase-C-producing clostridia form a lecitho-vitellin precipitate after overnight incubation; 95.5% formed a high-density precipitate in the new medium as opposed to 6.1%, 6.6%, 10.6% and 20.2% of the isolates not forming a visible precipitate in liver-veal, Lombard-Dowell, McClung and Toabe modified, and "viande-levure" egg-yolk media, respectively, after the same incubation time.

Agar↗
PubMed1988

Inhibition of Escherichia coli serotype O157:H7 by bromthymol blue.

Bromthymol blue, at a concentration of 0.1% in tryptose-glucose broth, inhibited growth of 98.4% of Escherichia coli serotype O157:H7 isolates but only 0.8% of E. coli non-O157:H7 isolates after an overnight incubation at 44.5 degrees C, but not 35 degrees C. The inhibition was dependent on temperature, density of inoculum, bromthymol blue concentration, time of incubation, and composition of the medium. Compared with serologic typing, the inhibition had sensitivity, specificity, predictive values of the positive and negative tests, and overall agreement between the two tests of 98.4, 99.2, 98.4, 99.2, and 98.9%, respectively. The inhibition could be useful as a presumptive test to identify E. coli isolates of serotype O157:H7, especially in laboratories that do not have serotyping capabilities.

Bromthymol Blue↗
PubMed1988

Serologic confirmation of Neisseria gonorrhoeae by monoclonal antibody-based coagglutination procedures.

Two commercially available monoclonal antibody coagglutination tests, Phadebact Monoclonal GC OMNI Test (PMGOT; Pharmacia Diagnostics AB, Uppsala, Sweden) and GonoGen (GG; New Horizons Diagnostics, Columbia, Md.), for the confirmation of Neisseria gonorrhoeae were evaluated. The sensitivities of PMGOT and GG were 99.2 and 98.7% and the specificities were 91.5 and 100.0%, respectively. False-positive reactions were observed with Neisseria lactamica and Neisseria meningitidis in PMGOT. A modification of the procedure recommended by the manufacturer for PMGOT was done by substituting Todd-Hewitt broth for 0.9% saline to prepare the suspension of the test organism. This eliminated technical difficulties with the test and resulted in a sensitivity and a specificity of 99.3 and 100.0%, respectively. Advantages offered by the modified PMGOT over GG were the better predictive value of the negative test, the lower cost, the ease of reading of the test, and the lack of noninterpretable results.

Agglutination Tests↗
PubMed1986

Evaluation of the GO Slide (Roche) growth transport system for isolation of Neisseria gonorrhoeae from clinical specimens.

A new growth transport system for the isolation of Neisseria gonorrhoeae from clinical specimens was evaluated. The system, GO Slide (Roche) of F. Hoffmann-La Roche & Co., Basel, Switzerland, showed 88% sensitivity for male urethral specimens and 59% sensitivity for endocervical specimens compared with transport in the Amies transport medium combined with culturing on modified Thayer-Martin medium. The media used appear not to support growth of certain strains of N. gonorrhoeae. recovery and growth-supporting capabilities of this system need to be improved before the system can be used routinely.

Bacteriological Techniques↗
PubMed1980

Synergistic haemolysis test for presumptive identification and differentiation of Clostridium perfringens, C. bifermentans, C. sordellii, and C. paraperfringens.

A new test for the presumptive identification of Clostridium perfringens, C. bifermentans, C. sordellii, and C. paraperfringens is described. The test is based on the synergistic haemolysis shown by the clostridia and group B streptococci on sheep and human and CaCl2-supplemented human blood agar. C. perfringens gave crescent-shaped synergistic lytic zones (7 to over 20 mm in length), and C. paraperfringens usually small-sized (3 mm), bullet-shaped reactions on all three types of media. C. bifermentans showed a horseshoe-shaped synergistic reaction only on human blood containing media, and C. sordellii only on CaCl2-supplemented human blood agar. C. perfringens type A antiserum inhibited synergistic lytic activities of the four species. The test provided a reliable method for presumptive identification and differentiation of the four clostridial species and may obviate the need for the Nagler test.

Agar↗
PubMed1978

Synergistic hemolysis phenomenon shown by an alpha-toxin-producing Clostridium perfingens and streptococcal CAMP factor in presumptive streptococcal grouping.

A new phenomenon of synergistic hemolysis by Clostridium perfringens alpha-toxin and the streptococcal CAMP factor on human and guinea pig erythrocytes is described. A possible mode of action of the CAMP factors is suggested. On human blood agar all of the tested isolates of group B streptococci gave an arrowhead-shaped zone of hemolysis; 74% of group A gave a crescent-shaped lytic zone, whereas all isolates of groups C and G and the remaining 26% of group A streptococci gave a bullet-shaped lytic zone. By comparison, in the CAMP test incubated aerobically and anaerobically, 70 and 91%, respectively, of streptococci other than group B gave positive, arrowhead-shaped lytic zones. If all intermediate positive reactions in the CAMP tests were read as negative after aerobic incubation, only 89% of group B streptococci would be properly identified. The synergistic hemolysis phenomenon, using an alpha-toxin-producing C. perfringens and human blood agar, provided a reliable test for presumptive identification of group B streptococci, with promising potential to differentiate in the same test group A streptococci from other groups.

Animals↗
PubMed1975

California encephalitis virus development in mosquitoes as revealed by transmission studies, immunoperoxidase staining, and electron microscopy.

Isolates of the snowshoe hare subtype of California encephalitis (CE) virus from Yukon mosquitoes during 1972 and 1973 were transmitted by bites of Aedes aegypti mosquitoes after 4 to 5 weeks of extrinsic incubation at 55 degrees F after intrathoracic injection, and the 1973 strain was transmitted after mosquitoes were fed virus and held for 3 to 4 weeks at 75 degrees F. Antigen of a 1971 isolate of CE virus (Marsh Lake 23) was detected in salivary glands of infected mosquitoes by the immunoperoxidase technique, using highly purified antiserum before and after conjugation with horseradish peroxidase, plus the use of orthotolidine as a substitute for benzidine. enveloped virions 45 nm in diameter were observed in thin sections of salivary glands of Culiseta inornata mosquitoes 59 days after intrathoracic injection with the 1971 isolate, afterincubation at 55 degrees F.

Aedes↗