1,721,106 research outputs found
In-vitro activity of atovaquone, sulphamethoxazole and dapsone alone and combined with inhibitors of dihydrofolate reductase and macrolides against Pneumocystis carinii.
No full textThe anti-Pneumocystis carinii activity of atovaquone, dapsone and sulphamethoxazole alone and combined with dihydrofolate reductase (DHFR) inhibitors and macrolides was investigated against five clinical isolates of P. carinii. The susceptibility tests were performed by inoculation of the organisms on to cell monolayer and parasite count after 72 h incubation at 37 degrees C. Culture plates were added to Dulbecco's modified Eagle's medium containing serial dilutions of atovaquone, dapsone and sulphamethoxazole alone or in combination with diaveridine, pyrimethamine, trimethoprim, azithromycin, clarithromycin and roxithromycin. Atovaquone, dapsone and sulphamethoxazole were found to be effective at levels well below the concentrations that could be achieved clinically, while DHFR inhibitors were shown to combine effectively with dapsone and sulphamethoxazole. No synergy could be demonstrated between atovaquone and DHFR inhibitors or macrolides. A mild synergic effect was noted when macrolides were combined with dapsone and sulphamethoxazole. Pyrimethamine (0.5 mg/L) combined with dapsone and trimethoprim (0.5 mg/L) combined with sulphamethoxazole exerted the strongest inhibitory effect
In-vitro activity of macrolides alone and in combination with artemisin, atovaquone, dapsone, minocycline or pyrimethamine against Cryptosporidium parvum.
No full textThe anticryptosporidial activity of four macrolides alone and in combination with other antimicrobial agents was investigated against ten clinical isolates of Cryptosporidium parvum recovered from stools of AIDS patients. The susceptibility tests were performed by inoculation of the protozoa on to cell monolayers and determining the parasite count after 72 h incubation at 37 degrees C. The culture medium was supplemented with Dulbecco's modified Eagle's medium containing serial dilutions of azithromycin, clarithromycin, roxithromycin, spiramycin, alone or in combination with artemisin, atovaquone, dapsone, minocycline or pyrimethamine. Most of the agents had an inhibitory effect on parasite growth, but only at high concentrations. No agent was able to inhibit parasite growth completely, even at the highest concentrations used. The more effective agents, azithromycin, clarithromycin, roxithromycin, minocycline and pyrimethamine, produced no more than a 13.1-27.8% reduction in oocyst count and no more than a 15.1-35.7% in schizont count. Positive interaction was clearly demonstrated when macrolides were tested in combination with minocycline or pyrimethamine
In vitro anticryptosporidial activity of ranalexin alone and in combination with other peptides and with hydrophobic antibiotics.
No full textThe in vitro activity of ranalexin alone and in combination with other cationic peptides, macrolides, rifampin, and rifabutin was investigated against a clinical isolate of Cryptosporidium parvum. Susceptibility tests were performed by inoculation of the isolate onto cell monolayers and determining the parasite count after 48 h of incubation at 37 degrees C. Antibiotic-free cultures were used as controls in the study. Ranalexin showed low anticryptosporidial activity: it suppressed the growth of parasites by > or = 40% at 50 microM. Ranalexin showed enhanced activity when it was combined with noninhibitory concentrations of other compounds: a 74.4-94.1% reduction in the number of parasites was observed when ranalexin 50 microM was combined with magainin II 50 microM, indolicidin 50 microM, clarithromycin 8 mg/l, azithromycin 8 mg/l, rifampin 8 mg/l, and rifabutin 8 mg/l. The results suggest that ranalexin may be effective in inhibiting Cryptosporidium parvum growth in vitro upon combination with other peptides and hydrophobic antibiotics
In vitro anti-cryptosporidial activity of cationic peptides alone and in combination with inhibitors of ion transport systems.
No full textThe anti-cryptosporidial activity of four cationic peptides alone and in combination with five ion transport system (ITS) inhibitors was investigated for six clinical isolates of Cryptosporidium parvum recovered from stools of AIDS patients. The susceptibility tests were performed by inoculating the protozoa on to cell monolayers and determining the parasite count after 48 h incubation at 37 degrees C. The culture medium was supplemented with serial dilutions of cecropin P1, magainin II, indolicidin and ranalexin alone or in combination with amiloride and its analogues. No agent was able to inhibit parasite growth completely. The peptides had some inhibitory effect on parasite growth: cecropin P1, magainin II, indolicidin and ranalexin at a concentration of 50 microM produced 30.6, 33.2, 38.5 and 42.1% reductions, respectively, in schizont count. Conversely, the ITS inhibitors were scarcely effective. Positive interaction was demonstrated when the peptides were tested in combination with ITS inhibitors
In-vitro activity of lytic peptides alone and in combination with macrolides and inhibitors of dihydrofolate reductase against Pneumocystis carinii.
No full textThe in-vitro activity of cecropin P1, magainin II, indolicidin and ranalexin alone and in combination with macrolides and dihydrofolate reductase inhibitors (DHFRs) was investigated against six clinical isolates of Pneumocystis carinii. The susceptibility tests were performed by inoculation of the isolates on to cell monolayers and determining the parasite count after 72 h incubation at 37 degrees C. The culture medium was supplemented with serial dilutions of each agent. The four peptides suppressed the growth of cysts and trophozoites by > or = 50% at 20 microM and 2 microM, respectively, with the exception of indolicidin (cysts: IC50, 20 microM; trophozoites: IC50, 20 microM). The IC90 values of all peptides for either cysts or trophozoites were observed at a concentration of 20 microM. Our data showed that the activity of lytic peptides remained virtually unchanged when they were tested either alone or in combination with macrolides and DHFRs, with the exception of ranalexin: a cysts/trophozoites reduction in the range 77.3-85.1% was observed when ranalexin 2 microM was combined with 4 mg/L of macrolides. Our study suggests that lytic peptides may be effective in inhibiting the growth of P. carinii in vitro. In addition some of these compounds seem to have an effective interaction with hydrophobic antibiotics
In-vitro activity of lytic peptides, inhibitors of ion transport systems and ionophorous antibiotics against Pneumocystis carinii.
No full textThe in-vitro activity of two vertebrate lytic peptides, two ion transport system inhibitors and two polyether ionophores was investigated against four clinical isolates of Pneumocystis carinii recovered from bronchoalveolar lavages of AIDS patients. The susceptibility tests were performed by inoculating the isolates on to cell monolayers and determining the parasite count after 72 h incubation at 37 degrees C. The culture medium was supplemented with Dulbecco's modified Eagle's medium containing serial dilutions of cecropin P1, magainin II, benzamil, 5-(Nmethyl-Nisobutyl)amiloride (MIBA), lasalocid and nigericin. The two vertebrate lytic peptides showed high activity against trophozoites and cysts. At a concentration of 66.77 mg/L, cecropin P1 produced a 93.3% and 98.1% reduction in cyst and trophozoite counts, respectively, while magainin II at a concentration of 49.33 mg/L produced a 90.6% and 98.7% reduction in cyst and trophozoite counts, respectively. The IC50s of benzamil and MIBA were observed at the highest concentrations tested, 35.62 and 29.98 mg/L, respectively. However, 90% inhibition was not achieved. Lasalocid and nigericin at 0.05 mg/L gave inhibition comparable to that observed with the highest tested concentrations of cecropin P1 and magainin II, but significant injury to the cell monolayer was also observed when nigericin was tested at this concentration. Lasalocid 0.05 mg/L produced a reduction of 91.3% and 92.0% in cyst and trophozoite counts, respectively. Our results suggest that lytic peptides and lasalocid may be effective in inhibiting P. carinii growth at concentrations which are not toxic for the cell monolayer
Imipenem and meropenem induced resistance to beta-lactam antibiotics in Pseudomonas aeruginosa.
No full textThe ability of imipenem and meropenem in subinhibitory concentrations to influence the results of disk diffusion susceptibility tests was assessed. Selection of stably derepressed mutants resistant to beta-lactam antibiotics other than carbapenems was also investigated. Beta-lactams were shown to be subject to carbapenem-mediated antagonism in the disk diffusion test. On the other hand in vitro selection of stably derepressed mutants resistant to other beta-lactams could not be demonstrated
In-vitro activity of polycationic peptides against Cryptosporidium parvum, Pneumocystis carinii and yeast clinical isolates.
No full textThe in-vitro activity of magainin II, indolicidin and ranalexin against 14 clinical isolates of eukaryotic microorganisms was evaluated. Antifungal susceptibility testing was performed by broth microdilution, and activity against Pneumocystis carinii and Cryptosporidium parvum was determined by inoculation on to cell monolayers. For yeasts, peptide MICs and MFCs ranged from 6.25 to > 50 mg/L. Ranalexin showed the highest activity against Candida spp., while magainin II demonstrated greatest anticryptococcal activity. The peptides suppressed the growth of P. carinii by > or = 50% and > or = 90% at 5 and 50 microM, respectively, with the exception of indolicidin. Ranalexin, the most effective compound against C. parvum, suppressed its growth by > or = 40% at 50 microM
In vitro and in vivo activity of aurintricarboxylic acid preparations against Cryptosporidium parvum.
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