[Value of agglutination tests for the rapid identification of isolated streptococci in medical microbiology]. / Intérêt des tests d'agglutination pour l'identification rapide des streptocoques isolés en microbiologie médicale.

The clinical need for rapidly and correctly differentiating pathogenic streptococci into Lancefield groups prompted the development of rapid agglutination techniques by the direct colony method. Pastorex Streptogroupe (Diagnostics Pasteur, France) and Streptex (Wellcome Diagnostics, USA) were tested on 90 streptococcal isolates and compared with the identification obtained by conventional procedures. No cross-reactions were observed with any of the 33 strains of enterococci and of the seven strains representative of other genus among Gram-positive bacteria. When combined with colonial morphology and hemolytic reaction, both Pastorex and Streptex were specific tests for identifying beta-hemolytic streptococci, with Pastorex being slightly faster.

An anti-Cryptococcus neoformans monoclonal antibody directed against galactoxylomannan.

Six monoclonal antibodies (mAb) were produced by immunizing mice with a Cryptococcus neoformans serotype A spheroplast lysate (CNSL). Two mAb were of the IgG1 isotype; the others were IgM. The results obtained with one IgM mAb (CN6) are reported herein. This mAb recognized the four serotypes of C. neoformans and no cross-reactions were observed with extracts from Cryptococcus melibiosum, Candida albicans, Saccharomyces cerevisiae, Torulopsis glabrata or Trichosporon beigelii. Fractionation of the CNSL by gel filtration revealed that mAb CN6 recognized high molecular weight substances as well as a range of smaller molecules. Indirect ELISA inhibition studies showed that this mAb recognized substances in a cryptococcal culture filtrate. Inhibition studies and agglutination tests using latex beads sensitized with purified CN6 showed that CN6 strongly reacted with the C. neoformans serotype A cell envelope galactoxylomannan-mannoprotein complex (GAlXM-MP) and only weakly with the glucuronoxylomannan (GXM) component. These tests also showed that purified galactoxylomannan (GalXM) from C. neoformans serotype A was more reactive than purified mannoprotein (MP). An anti-GalXM mAb might be a useful tool for monitoring the clinical course of cryptococcal infections.

[Gas-liquid chromatography in microbiological diagnosis]. / Apport de la chromatographie gaz-liquide au diagnostic microbiologique.

With gas-liquid chromatography, it is possible to detect chemical compounds which are specific of micro-organisms: either metabolic products, or structural components. This technique permits to simplify the diagnosis: it is the case for anaerobic bacteria, where the analysis of the fermentation acids produced in a 48 hours liquid culture enables to rapidly establish the diagnosis, at least as far as the genus is concerned. It may also increase the accuracy of the diagnosis by searching such or such metabolite or structural component which are specific of a species or a sub-species. Some authors have already determined automatic systems of bacterial identification; these systems are based on a computer analysis of the chromatographic profile of cellular fatty acids. Finally it is important to emphasize that liquid-gas chromatography may markedly shorten the delay of identification by allowing, in some cases, a direct diagnosis in pathological samples.