70 research outputs found
The post-antibiotic effects of rokitamycin (a 16-membered ring macrolide) on susceptible and erythromycin-resistant strains of Streptococcus pyogenes
No full textThe post-antibiotic effects (PAEs) on susceptible and erythromycin-resistant strains of Streptococcus pyogenes (M phenotype and inducibly resistant) of rokitamycin and erythromycin were investigated in vitro using microbiological impedance measurement. Exposure of susceptible S. pyogenes strains to 1/4, 1/2, 1 and 2 MIC erythromycin and rokitamycin resulted in PAEs of rokitamycin in the same order of magnitude as those of erythromycin and that were dose dependent. The duration of rokitamycin PAEs in erythromycin-resistant S. pyogenes strains (M phenotype and those with inducible resistance) were comparable with those observed in susceptible strains. This was not the case for erythromycin. The investigation showed that a 16-membered ring macrolide such as rokitamycin has different PAEs from those of a 14-membered ring macrolide such as erythromycin. They also indicated that, as the PAEs of rokitamycin on the M phenotype and inducible resistant strains were comparable with those on susceptible strains, no re-evaluation of therapeutic dosing regimens was required
Visual evaluation of binding to mucosal cells of a medical device against the common cold
No full textThe objective of this study was to investigate the possibility of visualizing the ability of hydroxypropylmethylcellulose (HPMC) and a nasal spray (First Defense), in which the bioadhesive is HPMC, to bind to human mucosal cells using inorganic (black carbon particles and Congo red dye) and organic markers (Escherichia coli). A significant reduction in the bacterial adhesiveness has been observed. Our findings indicate the possibility of counteracting the lock-and-key mechanism of microorganism adhesion using the bioadhesive properties of polymers, such as HPMC, in First Defense to prevent a possible contact between adhesins and complementary receptors
Flow cytometric assessment of susceptibilities of Streptococcus pyogenes to erythromycin and rokitamycin
No full textThe effects of erythromycin (a 14-membered ring macrolide) and rokitamycin (a 16-membered ring macrolide) on the viability of the Streptococcus pyogenes M phenotype were studied by means of flow cytometry and fluorescence microscopy by using a combination of two fluorochromes (syto 9 and propidium iodide) that stains live bacteria green and dead bacteria red. In order to apply the flow cytometry, a bacterial sonication procedure was expressly set up to separate single cells from the long, intralaced S. pyogenes chains of up to 30 to 40 cells that have previously prevented the application of flow cytometry to this type of bacteria. The association of flow cytometry using an appropriate sonication procedure, together with a combination of fluorescent probes, offered the possibility of very quickly investigating the different microbiological effects of rokitamycin at 2 microg/ml, which was active on the S. pyogenes M phenotype, and of erythromycin at doses of up to 32 microg/ml, which was not
Cinetica delle alterazioni morfostrutturali indotte dal timolo sulla Candida albicans. Studio in microscopia elettronica a scansione
No full textMorphostructural damage and the inhibition of bacterial adhesiveness of Staphylococcus aureus and Moraxella catarrhalis induced by moxifloxacin
No full textThe aim of this study was to investigate the ability of moxifloxacin to interfere with the mechanism of bacterial adhesion and disrupt the morphological and structural integrity of bacteria. Three Staphylococcus aureus and three Moraxella catarrhalis strains were grown in the presence of 1/2-1/128 minimum inhibitory concentration (MIC) serial dilutions and incubated with human epithelial cells. A significant decrease in adhesion was observed from 1/ 2 MIC to 1/64 MIC for S. aureus, and from 1/2 MIC to 1/16 MIC for M. catarrhalis. The use of atomic force microscopy, a new technique capable of revealing surface structures in three-dimensional detail and at very high resolution, showed the rapid onset and time course of the sequence of disruptive morphostructural events following the incubation of both S. aureus and M. catarrhalis with sub-MICs of moxifloxacin. Our findings suggest that less than conventional MIC moxifloxacin concentrations may be effective in reducing bacterial adhesiveness and structural integrity on which the maintenance of bacterial activity depends
Morphostructural Damage and the Inhibition of Bacterial Adhesiveness of Staphylococcus aureus and Moraxella catarrhalis Induced by Moxifloxacin
No full textThe aim of this study was to investigate the ability of moxifloxacin to interfere with the mechanism of bacterial adhesion and disrupt the morphological and structural integrity of bacteria. Three Staphylococcus aureus and three Moraxella catarrhalis strains were grown in the presence of 1/2-1/128 minimum inhibitory concentration (MIC) serial dilutions and incubated with human epithelial cells. A significant decrease in adhesion was observed from 1/ 2 MIC to 1/64 MIC for S. aureus, and from 1/2 MIC to 1/16 MIC for M. catarrhalis. The use of atomic force microscopy, a new technique capable of revealing surface structures in three-dimensional detail and at very high resolution, showed the rapid onset and time course of the sequence of disruptive morphostructural events following the incubation of both S. aureus and M. catarrhalis with sub-MICs of moxifloxacin. Our findings suggest that less than conventional MIC moxifloxacin concentrations may be effective in reducing bacterial adhesiveness and structural integrity on which the maintenance of bacterial activity depends
Cinetica della riduzione indotta dal timolo sul biofilm maturo della candida albicans : studio in microscopia elettronica a scansione
No full textMorphological alterations of Candida albicans induced by thymol. A scanning electron microscopy study
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