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Biomedical subjects

L Drago

Publications and source records attributed to L Drago.

At least 19 recordsLinked to original sources
PubMed2005

In vitro synergy and selection of resistance by fluoroquinolones plus amikacin or beta-lactams against extended-spectrum beta-lactamase-producing Escherichia coli.

This study compared the potential synergy of levofloxacin and ciprofloxacin in combination with cefepime, ceftazidime, imipenem, piperacillin/tazobactam or amikacin, against extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli by using checkerboard and time kill studies. Moreover, selection of resistance was determined by frequency of mutations and by calculating the increase in minimum inhibitory concentrations (MICs) after five serial subcultures on antibiotic-containing plates. Synergy occurred more often with levofloxacin combined with imipenem (7/10 strains) and with levofloxacin or ciprofloxacin with amikacin (10/10) than for the other combinations. Time kill studies showed synergy for levofloxacin combined with amikacin, ceftazidime, imipenem or piperacillin/tazobactam, and for ciprofloxacin combined with amikacin, cefepime or imipenem. Antibiotic combinations selected for resistance less frequently than antibiotics alone. Mutation frequency was <10(-12) for all combinations. In conclusion, the combination of a fluoroquinolone with a beta-lactam or amikacin may provide improved antimicrobial activity and help limit the occurrence of resistance in ESBL-producing E. coli strains.

Amikacin↗
PubMed2005

In vitro selection of resistance to clarithromycin in Streptococcus pneumoniae clinical isolates.

In this study the effects of exposure to serum, lung and breakpoint concentrations on Streptococcus pneumoniae susceptibility to clarithromycin, azithromycin, amoxicillin/clavulanate, levofloxacin and moxifloxacin were evaluated. Development of resistance was determined by multi-step and single-step methodologies. In the first experimental set, minimum inhibitory concentrations (MICs) were determined after 10 passages on antibiotic-gradient plates and 10 passages on antibiotic-free plates. Acquisition of resistance was defined as an increase of > or = 4-fold from the starting MIC. In single-step studies, the rate of spontaneous mutations was calculated after a passage on antibiotic-containing agar plates. Azithromycin and levofloxacin gave the highest number of strains with MIC increased of at least 4 times the starting value, followed by moxifloxacin and by clarithromycin which only at the lowest concentration tested selected for resistance in 5 strains. Amoxicillin/clavulanate never displayed > or = 4-fold MIC increase. Frequencies of mutation were lower for clarithromycin and moxifloxacin than for the comparators. At lung concentrations clarithromycin had limited potential to select for resistance.

Amoxicillin↗
PubMed2004

Effect of moxifloxacin on bacterial pathogenicity factors in comparison with amoxicillin, clarithromycin and ceftriaxone.

Moxifloxacin is a recent fluoroquinolone with an antibacterial spectrum encompassing both aerobic Gram-negative and Gram-positive strains, as well as anaerobic bacteria. In this study the activity of moxifloxacin against Streptococcus pneumoniae, Staphylococcus aureus, Moraxella catarrhalis, Haemophilus influenzae, Escherichia coli, Proteus mirabilis and Pseudomonas aeruginosa, and effects of subinhibitory concentrations on bacterial morphology and adhesion properties were compared with those of amoxicillin, clarithromycin and ceftriaxone. The in vitro activity of moxifloxacin against Gram-positive and Gram-negative pathogens was equal to or better than that of comparators. Subinhibitory concentrations of moxifloxacin significantly affected bacterial morphology of S. pneumoniae, M. catarrhalis, H. influenzae and P. aeruginosa, leading to formation of spherical forms and filaments. Moreover, bacterial adhesion to buccal cells and fibroblasts was reduced after treatment with 1/4 and 1/8 X MIC of moxifloxacin. In conclusion, subinhibitory concentrations of moxifloxacin remarkably interfere with some bacterial pathogenic factors, thereby contributing to its antimicrobial activity.

Amoxicillin↗
PubMed2004

Microbiological evaluation of commercial probiotic products available in Italy.

Scientific evidence of the prevention and therapy of some intestinal diseases is accumulating in regard to probiotic products. However, sufficient information on the use of probiotics in specific therapies is not yet available and, above all, there is no clear legislation about these products in Europe. In this study, we evaluated five different probiotic products commercially available in Italy for their qualitative and quantitative microbial content after about 12 and 22 months of storage. We also evaluated the stability of lactobacilli to 0.3% bile salts and to pH of 3.58 and 7.98. There were discrepancies between the declared content and our results found after storage for 4 of the tested products. Bile salts and basic pH did not affect the growth of the lactobacilli tested, while for 2 tested products 6 hours at acid pH produced a complete inhibition of bacterial growth. Our results suggest the need for clear legislation and adequate control of the manufacturing of probiotic products.

Colony Count, Microbial↗
PubMed2003

Comparative bactericidal activity of fluoroquinolones against clinical isolates resistant to fluoroquinolones.

The bactericidal activity of levofloxacin, ciprofloxacin, moxifloxacin and norfloxacin against clinical isolates conventionally classified as resistant to fluoroquinolones were compared at their maximum concentrations in serum, urine (except moxifloxacin) and bronchial mucosa (except norfloxacin). Time killing curves against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus epidermidis, and Streptococcus pneumoniae were performed. Serum concentrations of the tested drugs were not able to produce a bactericidal effect on fluoroquinolone-resistant strains. In the urine series, levofloxacin was always bactericidal (decrease > or = 3 logs CFU/ml), while norfloxacin and ciprofloxacin were bactericidal on E. coli (both), P. mirabilis (norfloxacin) and P. aeruginosa (ciprofloxacin). In the bronchial mucosa series, S. pneumoniae was rapidly killed by levofloxacin and moxifloxacin, and K. pneumoniae by levofloxacin after 12 hours. In conclusion, the maximum levofloxacin concentrations achievable at certain body sites allowed killing even of strains defined as resistant by conventional breakpoints.

Anti-Infective Agents↗
PubMed2003

Antimicrobial activity and interference of tobramycin and chloramphenicol on bacterial adhesion to intraocular lenses.

The antimicrobial activities of tobramycin and chloramphenicol were evaluated by determining minimum inhibitory and bactericidal concentrations against Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, group A, group B and group G streptococci, Klebsiella spp., Stenotrophomonas maltophilia and ciprofloxacin-resistant and -susceptible Pseudomonas aeruginosa, as well as by evaluating interference on adhesion of slime producer strains of S. aureus and P. aeruginosa to intraocular lens from tobramycin and chloramphenicol pharmaceutical products by scanning electron microscopy. Chloramphenicol was more active against Gram-positive bacteria than was tobramycin, which instead showed higher activity against ciprofloxacin-susceptible P. aeruginosa. Treatment of lenses with the antimicrobial products eradicated the bacterial biofilm, which was already notably reduced after 5 min. This activity was more pronounced for chloramphenicol against S. aureus and for tobramycin against P. aeruginosa. Bacterial adhesion was also significantly reduced when lenses colonized by P. aeruginosa were treated with chloramphenicol, even if they were resistant to this drug. In conclusion, the tested drugs showed marked antibacterial activity, particularly by interfering with bacterial biofilms. The data obtained in this study suggest a specific use of chloramphenicol in topical prophylaxis aimed at avoiding bacterial contaminations. However, further specific in vivo studies are needed to confirm these data.

Anti-Bacterial Agents↗
PubMed2001

Antimicrobial activity of thiamphenicol-glycinate-acetylcysteinate and other drugs against Chlamydia pneumoniae.

Chlamydia pneumoniae is responsible for respiratory tract infections of both upper and lower respiratory tract. Although this bacterium is one of the most wide-spread pathogens of man, there are limited data on the antibiotic treatment of C. pneumoniae infections. The aim of this study has been to evaluate the in vitro activity of thiamphenicol glycinate acetylcysteinate (TGA, CAS 20192-91-0) in comparison with molecules with established activity against C. pneumoniae, as well as macrolides and quinolones. The results have shown that TGA and clarithromycin (CAS 81103-11-9) are the most active drugs tested, but it is important to underline that the minimal inhibitory concentration (MIC) ranges of TGA are very much lower than the breakpoint of thlamphenicol for the respiratory pathogens. In conclusion, the good antimicrobial in vitro activity of TGA against C. pneumoniae together with its in vivo characteristics, in particular the high concentration reached in lung and the combination with the mucolytic agent N-acetylcysteine (NAC, CAS 616-91-1), can make a valid choice in the treatment of respiratory tract infections caused by C. pneumoniae. These findings need further evaluation by clinical studies.

Acetylcysteine↗
PubMed2001

Comparative in vitro activity of thiamphenicol-glycinate and thiamphenicol-glycinate-acetylcysteinate and other antimicrobials against respiratory pathogens.

Thiamphenicol-glycinate-acetylcysteinate (TGA; CAS 20192-91-0) is widely used for the treatment of infections of varied aetiology. The aim of this study was to compare the antibacterial activity of thiamphenicol-glycinate (TG; CAS 15318-45-3), TGA, amoxicillin (CAS 61336-70-7) plus clavulanic acid (CAS 58001-44-8), azithromycin (CAS 83905-01-5) and ceftriaxone (CAS 104376-79-6). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined against Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pyogenes, Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae according to the National Committee for Clinical Laboratory Standards (NCCLS) methods. The effects of changes in assay conditions were also examined. The activity of TG and TGA was similar to that of amoxicillin plus clavulanic acid, with the exception of methicillin resistant S. aureus. Azithromycin and ceftriaxone were characterised by a limited activity against gram-positive cocci and methicillin resistant and cefinase-positive S. aureus, respectively. TG and TGA are characterized by a wide spectrum of activity, comparable to that of recent commercialized antibiotics for treatment of respiratory tract infections.

Acetylcysteine↗
PubMed2001

Activity of levofloxacin and ciprofloxacin against urinary pathogens.

This study compares the antibacterial activities of levofloxacin and ciprofloxacin against recently isolated urinary tract pathogens, by evaluating their MICs and MBCs in accordance with NCCLS susceptibility tests, time-kill curves and interference with bacterial adhesion to uroepithelial cells. A total of 200 clinical isolates was tested, including the species Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus and Staphylococcus epidermidis. All E. coli isolates were susceptible to levofloxacin and only one was resistant to ciprofloxacin, and there were no differences between beta-lactamase-positive and -negative strains. K. pneumoniae strains resistant to ciprofloxacin were also resistant to levofloxacin. Methicillin-resistant S. aureus seemed to be less susceptible than methicillin-susceptible strains to these quinolones. S. epidermidis strains were susceptible to levofloxacin and ciprofloxacin, with the exception of two isolates. Incubation of S. aureus and E. coli with subinhibitory antimicrobial concentrations reduced their capacity to adhere to uroepithelial cells; this was statistically significant at 0.25 x MIC with respect to controls (P < 0.05). Inhibition of adhesion ranged from 36 to 43% when bacteria were incubated in the presence of 0.25 x MIC of levofloxacin and ciprofloxacin, and from 10 to 27% at 0.125 x MIC. These findings suggest that levofloxacin is an effective alternative to ciprofloxacin in the treatment of urinary tract infections and that sub-inhibitory concentrations may contribute to efficacy.

Anti-Infective Agents↗
PubMed2000

Candida albicans cellular internalization: a new pathogenic factor?

The preliminary results of a study to show the possibility that Candida albicans can internalize into epithelial cells are reported. The study was performed on buccal, vaginal and HeLa cells. Buccal and vaginal cells, at a concentration of 5 x 10(4) cells/ml and HeLa monolayers were incubated for 2, 3 and 4 h with 10(5) colony forming units of a Candida albicans isolate. After incubation, non-internalised yeasts were eliminated and samples were processed for examination by Scanning Electron Microscopy. Results suggest that receptor-mediated endocytosis could be involved in the pathogenesis of recurrent oral and vaginal infections. This phenomenon could represent an interesting experimental model to testing drug interference in the development of therapeutic strategies against C. albicans infections.

Candida albicans↗
PubMed2000

Serum and lung levels of thiamphenicol after administration of its glycinate N-acetylcysteinate ester in experimentally infected guinea pigs.

Thiamphenicol is an analogue of chloramphenicol and is characterised by a broad spectrum of action. In this study, serum and lung levels of thiamphenicol (TAP) were studied in infected guinea pigs after the administration of thiamphenicol glycinate N-acetylcysteinate (TGA). Animals received a single dose of TGA (15 mg/kg, subcutaneously) immediately after intra-tracheal infection with Haemophilus influenzae (about 10(7) CFU/animal). Serum and lung concentrations of TAP were determined at 0, 1, 3, 6, 12 and 24 h after drug administration by means of HPLC. TAP serum levels were elevated at 1 h and remained detectable for 24 h after drug administration. Tissue lung levels were comparable to peak serum concentrations but remained higher and decreased more slowly than serum concentrations.

Acetylcysteine↗
PubMed2000

Evaluation of the abbott LCx HIV-1 RNA quantitative, a new assay for quantitative determination of human immunodeficiency virus type 1 RNA.

A new quantitative reverse transcription (RT)-PCR assay for human immunodeficiency virus type 1 (HIV-1) RNA (Abbott LCx HIV RNA Quantitative assay) has been compared with the Organon NucliSens assay on 521 retrospective samples obtained from HIV-1-positive patients monitored during highly active antiretroviral therapy, 79 of whom were assayed also by the Chiron Quantiplex 3.0 system and on characterized panels. The LCx system showed a moderate correlation (r = 0.795) and gave higher results than the NucliSens system on 245 of 327 concordant positive samples, with similar sensitivity. Correlation with Quantiplex system results was higher (r = 0.943). LCx reproducibility was very good; the procedure was simple, well controlled, and rapid (up to 48 results in 7 h). The HIV RNA quantitative assay on the LCx system is suitable for routine use.

Antiretroviral Therapy, Highly Active↗