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Biomedical subjects

G Manicardi

Publications and source records attributed to G Manicardi.

At least 37 records · Page 2Linked to original sources
PubMed1987

Production of bacteriocin-like substances by human oral streptococci.

A sample of human streptococci (mainly Streptococcus mutans species) from dental plaques was examined in order to evaluate the production frequency and activity spectrum of bacteriocin-like substances (mutacins). 89% of the 55 Streptococcus mutans strains produced substances with a wide spectrum of antibacterial activity. The bacteriocins produced showed a marked inhibitory activity against Gram-positive bacteria. Among the Gram-negative species tested, only Neisseria sicca was inhibited by 25% of Streptococcus mutans strains. Also, 16 strains belonging to oral streptococci other than Streptococcus mutans, were examined for their inhibitory capacity against the same indicator. The authors stress the importance of mutacins production in oral ecology and Streptococcus mutans pathogenicity.

Bacteriocins↗
PubMed1984

Plasmids in Streptococcus faecalis subsp. zymogenes: transferability and molecular properties.

Seven strains of Streptococcus faecalis subsp. zymogenes were studied. Plasmids originally harboured by these bacteria, codifing for drug resistance, hemolysin and gelatinase activity, were transferred to a recipient strain ( JH2 -2) by conjugation. Studies on bacteria in mating showed the formation of protoplasmatic bridges between donors and recipients; these bridges should provide for the passage of genetic material. Kinetics of acquisition of the transferable resistance were carried out in liquid medium. Plasmids harboured in donor and transconjugant strains, responsable for antibiotic-resistance, for hemolysin and gelatinase activity, were analyzed later by agarose gel electrophoresis. These analysis permitted us to demonstrate the presence of many plasmids, some conjugative with a high molecular weight and others small and non-conjugative.

Conjugation, Genetic↗
PubMed1984

Conjugal plasmids in group D streptococci.

159 strains of group D streptococci isolated from clinical specimens were examinated for plasmids content. Our objective was to study some characters carried by plasmids: drug-resistance, hemolysins and bacteriocin activity. 73,6% of the strains were antibiotic resistant and in 69% of these, the drug-resistance was transferable by conjugation. In mating of S. faecalis subsp. zymogenes strains we could also isolate three different types of transconjugants in hemolytic activity. The interpretation of this observation was facilitated by the research of bacteriocin activity. We also classified the bacteriocins found in our strains into different types.

Bacteriocin Plasmids↗
PubMed1982

R factors in group D streptococci: classification by compatibility.

Antibiotic transferable resistance determined by R-factors is largely distributed among the enterococci. Over a two year period, 106 strains of D streptococci have been tested. Transferable resistance has been detected in 45 strain (57.7% of the resistant strains). The compatibility group of 24 plasmids has been determined: 12 belong to the group I; 4 belong to the group II; only one to the group III; one belongs to compatibility group IV; k R-factors have attributed to a new group V and the other two are not classifiable in any of the described groups.

Anti-Bacterial Agents↗
PubMed1979

[The incidence and variation of transferable antibiotic-resistance in Salmonella strains isolated in Modena in the years 1975-1977 (author's transl)].

The antibiotic-resistance of 450 strains of Salmonella isolated by the Microbiology Unit of the hospital of Modena during the years 1975-1977 was examined. During the study, the following antibiotics were assayed: ampicillin, kanamycine, tetracycline, chloramphenicol, streptomycin, sulfonamides, trimethoprim, tobramycin, gentamicin and nalidixic acid. The transfer capacity of antibiotic-resistance was measured by the double conjugation of E. coli K-12. During the period studied, a remarkable reduction was noted in those strains with multiple resistance (3 or more elements) decreasing from 72.9% in 1975 to 23.5% in 1977. These phenomena are due to the decrease of the serum-type wien during the years under study. Antibiotic-resistance demonstrated itself most frequently to streptomycin and tetracycline; and chloramphenicol-resistance showed the highest transfer capacity (97.2%).

Anti-Bacterial Agents↗