SCI scientific publications 1989
Purification and characterization of two Listeria ivanovii cytolysins, a sphingomyelinase C and a thiol-activated toxin (ivanolysin O)
Infection And Immunity 57(12):3928-35.
The strong bizonal hemolysis on blood agar and the positive CAMP reaction with Rhodococcus equi denotes the production of two different cytolytic factors by Listeria ivanovii. One was characterized as a thiol-activated (SH) cytolysin of 61 kilodaltons and was termed ivanolysin O (ILO) since data suggested that it is different from listeriolysin O, the SH-cytolysin produced by Listeria monocytogenes. The other is a 27-kilodalton hemolytic sphingomyelinase C that was found to be the cytolytic factor responsible for the halo of incomplete hemolysis synergistically enhanced by R. equi exosubstances. When thiol-disulfide exchange affinity chromatography and gel filtration were applied to the purification of ILO from concentrated L. ivanovii cult… Leer más
Vazquez-Boland JA., Dominguez L., Rodriguez-Ferri E. and Suarez G.
Preliminary evidence that different domains are involved in cytolytic activity and receptor (cholesterol) binding in listeriolysin O, the Listeria monocytogenes thiol-activated toxin
FEMS Microbiology Letters 53(1-2):95-9.
The inactive truncated 52 Kilodaltons (kDa) Listeriolysin O (LLO) produced by a transposon Tn1545-induced Listeria monocytogenes non-hemolytic/avirulent mutant previously described (Gaillard et al. (1986) Infect. Immun. 52, 50-55), that lacks a 48 aminoacid fragment at the C-terminal end including the single cysteine residue essential for activity (Mengaud et al. (1988) Infect. Immun. 56, 766-772), bound to the SH-cytolysin membrane receptor cholesterol, as did the active 60 kDa toxin. These results indicate that the missing fragment is a functionally important region needed in the 60 kDa LLO to cause membrane-disruption but not to bind to cholesterol, which strongly suggests that in LLO (and presumably in the other SH-cytolysins, in accord… Leer más
Vazquez-Boland JA., Dominguez L., Rodriguez-Ferri E., Fernandez-Garayzabal JF. and Suarez G.
A technique for the direct identification of haemolytic pathogenic listeria on selective plating media
Letters In Applied Microbiology 9:125-128.
A technique based on the addition of a red cells top layer to a selective plating medium after listeria growth is proposed in order to detect directly the haemolytic activity of pathogenic listeria colonies. It was applied to different selective plating media (modified McBride agar, lithium chloride-phenylethanol-moxalactam, listeria selective medium–Oxford formulation, polymyxin-acriflavine-lithium chloride-ceftazidime-aesculin-mannitol and LSAMM). The haemolytic activity of listeria colonies was more easily detected with the top layer than when red cells were incorporated in the selective plating medium. The LSAMM was the best medium for the recovery and identification of Listeria monocytogenes colonies by this technique (three Listeria m… Leer más
Blanco JL., Blanco MM., Fernandez-Garayzabal JF., Dominguez L., Briones V., Vazquez-Boland JA., Garcia JA. and Suarez G.
Growth of Staphylococcus aureus and synthesis of enterotoxins in home-made yoghurt
Zeitschrift Für Lebensmittel-Untersuchung Und -Forschung 189(1):16-20.
Staphylococcus aureus strains FRI-100, S6, FRI-137 and FRI 472 were inoculated into milk to study growth and enterotoxin production in home-made yogurts. The yogurt used as starter was progressively weakened by successive inoculations (up to four) in milk to prepare other yogurts in order to study the ability of yogurt microflora to inhibit staphylococci. After elaboration, yogurts were stored at 4 degrees C, 22 degrees C, and 37 degrees C for a maximum of 21 days. Periodically, staphylococcal counts, pH and the production of enterotoxins A, B, C, and D were determined. Enterotoxins were only detected in the last batch. It was concluded that the inhibitory effect of the starter culture is not only due to the decrease of pH, but also to othe… Leer más
Orden JA., Goyache J., Blanco JL., Hernandez FJ., Domenech A., Suarez G. and Gomez-Lucia E.
Production of enterotoxin A by supposedly nonenterotoxigenic Staphylococcus aureus strains
Applied And Environmental Microbiology 55(6):1447-51.
The production of staphylococcal enterotoxins A (SEA) and B (SEB) was studied by inoculating six well-defined staphylococcal collection strains into cows, goats, or sheeps milk (individually or as a 50% mixture of cows + goats or cows + sheeps), into brain heart infusion, and into a medium generally used to enhance the synthesis of enterotoxins (3+3 medium). Four of the strains used are considered to be SEB producers, another is considered an SEA producer, and the remaining strain is nonenterotoxigenic but produces large quantities of staphylococcal protein A. Staphylococcal protein A masked the results in most cases. Only one strain secreted exclusively SEB, while the other three SEB producers synthesized SEA in different amounts. We concl… Leer más
Gomez-Lucia E., Goyache J., Orden JA., Blanco JL., Ruiz JA., Dominguez L. and Suarez G.
Direct isolation (without enrichment) of Listeria monocytogenes in milk
Acta Microbiologica Hungarica 36(2-3):297-301.
In the present work we have developed a direct method (without enrichment) for the isolation of listeriae in milk, using the combinated action of SDS (sodium dodecyl sulphate), centrifugation and selective media. It is possible to identify even 0.5 listeriae/ml amongst 7.2 x 10(7) c.f.u. contaminants/ml… Leer más
Dominguez L., Briones V., Blanco MM., Fernandez-Garayzabal JF., Blanco JL., Vazquez-Boland JA. and Suarez G.
Serological diagnosis of listeriosis in man, sheep and rabbit by immunoperoxidase technique
Acta Microbiologica Hungarica 36(2-3):315-9.
Due to the already demonstrated specificity and usefulness of Listeria intracellular antigen in paraffin-embedded tissues for the direct diagnosis, we have used an indirect immunoperoxidase technique for the serological diagnosis of listeriosis in man, sheep and rabbit. This technique has been compared with other immunoperoxidase techniques (PAP) using the same antigen, and with other serlogical techniques--ELISA and microplate agglutination test--using two kinds of Listeria antigens, live formalinized and heat at 100 degrees C for one hour whole cells… Leer más
Briones V., Dominguez L., Domingo M., Marco A., Ramos JA., Garcia JA. and Suarez G.
