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ABSTRACT: The adherence to eukaryotic cells of Escherichia coli, Neisseria gonorrhoeae, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis and the yeast Candida albicans was studied by light microscopy with an in vitro micromethod involving different cell lines. The method is inexpensive, consumes little time and material, and is reproducible. It was used to show that the gram-positive Cowan I strain of S. aureus, which naturally forms protein A on its surface, adheres in much larger numbers to human lung fibroblasts than the protein A-free Wood 46 strain, the strain of S. epidermidis, and the encapsulated Smith strain. The presence of a capsule on the latter strain apparently prevented its attachment to the fibroblasts. Among the gram-negative species studied, a piliated clinical isolate of N. gonorrhoeae, displaying the opaque colonial phenotype, adhered in larger numbers than another isolate lacking pili and displaying the transparent phenotype. E. coli K12 attached slightly to the cell line, whereas P. aeruginosa adhered to it moderately. One strain of C. albicans tested did not attach in any detectable numbers. No clear correlation between bacterial cell surface hydrophobicity, as evaluated by the hexadecane assay, and adherence to eukaryotic cells could be demonstrated for these microorganisms. With our method, bacterial attachment proceeded best at 37 degrees C and did not require more than 1 h of contact with the cell monolayer. The method described revealed differences in the adherence to eukaryotic cells, not only among species, but also between strains of the same species.
Experimental biology 02/1986; 45(4):323-34.
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ABSTRACT: The purpose of the present study was to compare the auxotypes and the minimal inhibitory concentrations of four antibiotics for 50 isolates from women with gonococcal pelvic inflammatory disease with those of 55 isolates from uncomplicated anogenital gonococcal infections. No significant differences in auxotype patterns and susceptibilities were found between isolates from the two groups.
Antimicrobial Agents and Chemotherapy 01/1984; 24(6):952-4. · 4.84 Impact Factor
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Canadian Journal of Microbiology 05/1983; 29(4):421-4. · 1.36 Impact Factor
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ABSTRACT: In experiments with mixed cultures of Staphylococcus aureus and Candida albicans both in the absence and in the presence of 5-fluorocytosine (5-FC), we have observed that (1) there is an inhibition of S. aureus growth in mixed cultures with C. albicans in media supplemented with 1 microgram/mL of 5-fc and that 5-FC has no effect on staphylococci in pure cultures; (2) this inhibition occurred with clinically isolated and laboratory strains and could be reversed by specific metabolites; (3) Staphylococcus aureus was inhibited by filtrates of C. albicans cultures treated with 5-FC and this seemed to be favored by some C. albicans filterable product which can affect the cell wall and the permeability of the staphylococcal cells since they become sensitive to 5-FC; (4) nine other commonly used antimicrobials showed an increased inhibitory activity against S. aureus in mixed cultures with C. albicans; and (5) there is a decrease in the number of precipitating antigens of S. aureus and of the activity of alpha toxin when this species was grown with both C. albicans and 5-FC. Our results indicate that the susceptibility of some species to antimicrobials could be significantly modified in the presence of other species. One cannot exclude that a similar phenomenon could happen in hosts under treatment with antibiotics against infection.
Canadian Journal of Microbiology 05/1979; 25(4):429-35. · 1.36 Impact Factor
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ABSTRACT: Mice were protected against a lethal dose of Pseudomonas aeruginosa by a previous sublethal infection with Staphylococcus aureus. Under similar conditions, Staphylococcus epidermidis afforded only slight protection. The following characteristics of this increased resistance that we have observed are (1) survival of mice, and decrease of the number of viable units of P. aeruginosa in the peritoneal cavity of the same mice infected with S. aureus coagulase-positive strains, either from our laboratory collection or from hospital cases, when the time interval between the injection with staphylococci and that of P. aeruginosa was between 4 and 96 h; (2) absence of a net inhibitory effect in vitro on P. aeruginosa with serum from mice infected with a sublethal dose of coagulase-positive S. aureus; (3) changes in the appearance of peritoneal exudate cells after infection with a sublethal dose of S. aureus; P. aeruginosa injected afterwards in the peritoneal cavity of mice was eliminated; when P. aeruginosa was injected alone, "activated macrophages" were not observed and bacterial cells were present in large numbers in the exudate. The immunostimulation induced by a previous sublethal injection of S. aureus coagulase-positive strains seemed to be inhibited by the immunosuppressive drug cyclophosphamide, since mice were no longer protected against a lethal dose of P. aeruginosa. Cell immunity may intervene in such infections with opportunistic species and check the invasiveness of a gram-negative bacterium superinfecting a host already exposed to coagulase-positive S. aureus.
Canadian Journal of Microbiology 01/1977; 22(12):1734-42. · 1.36 Impact Factor
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ABSTRACT: In our study of opportunistic pathogens, we have some indication that Staphylococcus aureus can increase resistance in mice against Pseudomonas aeruginosa. Intraperitoneal injections of sublethal doses of S. aureus had a protective effect in mice against lethal doses of P. aeruginosa, more so if living and coagulase-positive S. aureus strains were injected. This protective effect was obtained both with laboratory and freshly isolated hospital strains. The interval between these infections can be extended from 2 h up to 1 week and it is still possible to observe the resistance phenomenon. The increased resistance was accompanied by a decrease in viable units of P. aeruginosa in the peritoneal cavity of mice 6 h after the injection of this species. There was no protection by S. aureus against Candida albicans in similar experimental conditions. These observations indicate that intermicrobial ecology, understood here as the previous presence of another species in a host, may be a significant factor in the resistance to infection with opportunistic pathogens such as P. aeruginosa.
Canadian Journal of Microbiology 08/1976; 22(7):1024-33. · 1.36 Impact Factor
