A Marchese

Università degli Studi di Genova, Genova, Liguria, Italy

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Publications (91)233.36 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: This study was conducted to evaluate the association between pneumococcal DNA load and parapneumonic pleural effusion (PPE) in children with community-acquired pneumonia. Bacterial load was quantified and related to the presence of PPE with or without empyema in 72 otherwise healthy children aged ≤5 years who were hospitalised because of radiographically confirmed CAP and showed a real-time polymerase chain reaction that was positive for Streptococcus pneumoniae. The proportion of children with a high bacterial load (i.e. ≥265 DNA copies/mL) was larger among the subjects with PPE than those without it. Multivariate analysis showed that a high bacterial load was significantly associated with PPE (OR 8.65; 95 % CI 1.10-67.8 vs a bacterial load of <125 copies/mL). Children with infection due to pneumococcal serotype 19A were at highest risk of developing PPE (OR 7.44; 95 % CI 1.10-50.4 vs all other typeable serotypes). The patients with CAP due to pneumococcal serotypes that are not included in the 13-valent conjugate vaccine (PCV13) were more frequently affected by PPE than those with infections associated with serotypes included in the vaccine, except for serotype 19A. Bacterial loads of ≥265 DNA copies/mL are significantly associated with PPE, and serotype 19A is significantly associated with a high bacterial load and the development of PPE. The mean bacterial load of the patients with empyema was higher than that of patients with simple PPE. Although further studies are required, it seems that serotypes not included in PCV13 can play a major role in causing a higher bacterial load and PPE.
    European Journal of Clinical Microbiology 01/2013; · 3.02 Impact Factor
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    ABSTRACT: Because of increasing antibiotic resistance in Escherichia coli, the main uropathogen of uncomplicated urinary tract infections (UTIs), updated susceptibility data are vital in guiding the selection of first-line treatment agents. interpretation of these data depends on the breakpoints adopted, that may vary among different guidelines.In this study we report the minimum inhibitory concentrations (MICs) of eight antibiotics and compare antimicrobial susceptibility results obtained in 2315 E. coli strains recently collected during the ARESC survey using EUCAST and CLSI breakpoints. We have also evaluated the clinical impact of breakpoint discrepancies on the overall susceptibility patterns.Fosfomycin, nitrofurantoin and mecillinam showed the highest susceptibility rates in all countries (>92%) according to both CLSI and EUCAST criteria. Minor category shifts were observed for ciprofloxacin, amoxicillin-clavulanic acid, ampicillin and trimethoprim/sulfamethoxazole. A large number of strains classified as intermediate resistant to cefuroxime according to CLSI are included by the EUCAST in the susceptible category.In conclusion, fosfomycin, mecillinam, and nitrofurantoin have preserved their in vitro activity in all countries investigated, regardless of the criteria adopted. They continue to represent effective options for the empiric therapy of female patients with uncomplicated cystitis. The use of different interpretative criteria for E. coli responsible for UTIs therefore has no influence on the decision to be taken by the physicians managing the patients.
    Journal of chemotherapy (Florence, Italy) 10/2010; 22(5):345-54. · 0.83 Impact Factor
  • A Marchese, E Coppo, R Barbieri, E Debbia
    Journal of chemotherapy (Florence, Italy) 06/2010; 22(3):212-4. · 0.83 Impact Factor
  • Journal of chemotherapy (Florence, Italy) 03/2009; 21(1):98-100. · 0.83 Impact Factor
  • S Roveta, A Marchese, G C Schito
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    ABSTRACT: The aim of this study was to assess whether the novel lipopeptide daptomycin might be capable of disrupting or inhibiting the synthesis of biofilms produced by staphylococci. Fourteen recently isolated slime-producing methicillin-susceptible (MET-S) and methicillin-resistant (MET-R) strains (three MET-S Staphylococcus aureus, three MET-R S. aureus, three MET-S Staphylococcus epidermidis, three MET-R S. epidermidis and two vancomycin-intermediate S. aureus (VISA)) were tested. Slime formation on polystyrene plates was quantified spectrophotometrically. Daptomycin (2-64 mg/L) inhibited slime synthesis by > or =80% in MET-S strains, by 60-80% in MET-R S. aureus and by 70-95% in MET-R S. epidermidis. At 64 mg/L, biofilm synthesis decreased by 80% in the VISA isolates. Daptomycin also disrupted pre-formed biofilm: >50% breakdown of initial biofilm (5h) was observed in all strains. Disruption of mature biofilms (48 h), in terms of percentage, was more variable depending on the strain, ranging from ca. 20% in a MET-R S. epidermidis strain to almost 70% in two MET-S strains (one S. aureus and one S. epidermidis). Daptomycin at concentrations achievable during therapy promoted a statistically significant inhibition of slime synthesis (preventing biofilm building) and induced slime disruption (disaggregating its structure) both in initial and mature biofilms on a plastic support in all staphylococcal strains studied.
    International Journal of Antimicrobial Agents 04/2008; 31(4):321-8. · 4.42 Impact Factor
  • E A Debbia, E Maioli, S Roveta, A Marchese
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    ABSTRACT: Rifaximin, a poorly absorbed rifamycin derivative, exhibited time-dependent bactericidal activity and at concentrations as low as 1/32 of the minimum inhibitory concentration (MIC) caused morphological alterations in both susceptible and resistant bacterial strains. Spontaneous rifaximin-resistant clones appeared with an incidence of 2.6 x 10(-7). The percentage of Escherichia coli cells cured of various plasmids ranged from: 4.5-70% (Flac), 0-18% (pBP507), 7.7-43.8% (plasmid carrying ESBL genes) and 22.4-41.6% (plasmid encoding toxin from ETEC mex264). 8.4-18.2 and <0.1-18% of Staphylococcus aureus cells were cured (plasmid-mediated penicillinase), 9.5-58.6% of Morganella morganii (ESBL), 10.6-47.1% Citrobacter freundii (ESBL), 2.3-38.7% of Proteus mirabilis (ESBL) and 14.3-66.6% of Klebsiella pneumoniae (ESBL). Rifaximin reduced plasmid transfer from donor to recipient strains by >99%. The MIC of ceftazidime was reduced (2-4 dilutions) in the presence of rifaximin (0.5 x MIC) in ESBL producing strains. Rifaximin lowered the viability and virulence of the bacteria even though they developed resistance to the compound. In conclusion, the present findings add new features to the microbiological characteristics of rifaximin and suggest that if in vivo pathogens are exposed to sub-MICs of the drug, not only are their physiological functions compromised, but gene virulence and antibiotic resistance are not fully expressed.
    Journal of chemotherapy (Florence, Italy) 04/2008; 20(2):186-94. · 0.83 Impact Factor
  • International Journal of Antimicrobial Agents 03/2008; 31(2):185-7. · 4.42 Impact Factor
  • S Roveta, A Marchese, E A Debbia
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    ABSTRACT: In this study (part of the global TEST program), the in vitro activity of tigecycline, a member of a new class of antimicrobial agents, the glycylcyclines, against clinical isolates collected in Italy was evaluated. A total of 200 clinical isolates were collected and identified in our institution during 2005. Minimum inhibitory concentrations (MICs) of the antimicrobial agents were determined by the broth microdilution method recommended by the CLSI in 2005. Globally, 135 Gram-negative and 65 Gram-positive pathogens were evaluated. Tigecycline demonstrated excellent inhibitory activity against Acinetobacter spp., Haemophilus influenzae, Escherichia coli, Enterococcus spp., Staphylococcus aureus, Streptococcus agalactiae and Streptococcus pneumoniae with MIC(90) <or=1 mg/l. Tigecycline exhibited potent in vitro antibacterial activity (comparable to or greater than most commonly employed antimicrobials) against both Gram-positive and Gram-negative clinical pathogens. These data suggest that tigecycline, with an expanded broad-spectrum antimicrobial activity, may be an effective empiric therapeutic option for the treatment of serious infections caused by clinically relevant pathogens.
    Chemotherapy 02/2008; 54(1):43-9. · 2.07 Impact Factor
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    ABSTRACT: Endox((R)) Endodontic System (Endox) is used for endodontic treatment by a high frequency alternating current (HFAC). This device damaged the envelopes of spores and vegetative organisms. If the integrity of the envelope is compromised, the transit of compounds in the two directions is possible. This latter aspect was investigated here. The instrument delivered a 60ms pulse at a frequency 300 kHz, and power 800 KV/m. DNA transfer was verified using Escherichia coli K-12 strain carrying a non conjugative plasmid pBP517 (gyrA(+)) as donor and a rifampicin and nalidixic acid resistant recipient. 0.2 ml of mixture of donor and recipient strains in saline was exposed to HFAC and plated on selective media. Uptake of antimicrobials and a delay in re-growth was assessed exposing the strains to HFAC. Plasmid transfer was detected under different experimental conditions. From 9 to 27 recombinants were found. Representative recombinants cured from plasmid showed the original phenotype. HFAC promoted the uptake of ineffective antibiotics, and induces a 1 h of delay in re-growth on the strains. Endox exhibited an effect on microrganisms which is reminiscent with that occuring in electroporation, but with a mode of action that saved materials and time.
    The Open Microbiology Journal 02/2008; 2:32-7.
  • E Concia, A Novelli, G C Schito, A Marchese
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    ABSTRACT: This article critically evaluates the main in vitro and in vivo studies published which compare generic with the original molecules, both those administered orally and parenterally. The authors indicate that caution should be used in assuming bioequivalence of the generic drug with its clinical efficacy in clinical practice. In fact, mild differences in the content of the active ingredient, less relevant in healthy volunteers, may have an impact in the actual population, which is heterogeneous for age, sex, weight, concomitant risk factors and severity of the underlying disease, as in critically ill patients, with consequences for the patient and ecosystem. Nowadays the requirements for authorization to commercialize a generic antimicrobial agent are focused on demonstration of bioequivalence to the original molecule, with a range variability of +/-20%. However this kind of trial is not sufficient to predict the actual profile in clinical practice, particularly in critically ill patients. Thus while generics can represent an opportunity for physicians, patients and healthcare systems the regulatory procedures do not seem exhaustive, and it is probably necessary to define an ad hoc technical standard of quality before their commercialization and to perform adequate clinical trials regarding efficacy and safety of the "equivalent molecule", especially for drugs used in critically ill patients.
    Journal of chemotherapy (Florence, Italy) 01/2008; 19(6):609-19. · 0.83 Impact Factor
  • A Marchese, G C Schito
    Médecine et Maladies Infectieuses 12/2007; 37 Spec No 1:2-5. · 0.75 Impact Factor
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    ABSTRACT: The aim of this study was to assess whether moxifloxacin is able to inhibit the synthesis of and to disrupt biofilms produced in vitro by bacterial pathogens involved in acute bacterial exacerbations of chronic bronchitis. Three strains each of Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, Staphylococcus aureus and Escherichia coli recently isolated from clinical respiratory specimens and capable of slime production were used. Biofilm formation on polystyrene plates was quantified spectrophotometrically by established methodologies. Moxifloxacin (0.5 mg/L) inhibited slime synthesis by >70% in S. aureus, H. influenzae and S. pneumoniae, 45-70% in E. coli and 35-70% in M. catarrhalis. Disruption of pre-formed structures was also promoted by moxifloxacin both for initial (5h) and mature (48 h) biofilms. Drug concentrations reached during therapy (0.5-4 mg/L) resulted in a breakdown of initial biofilm of 60-80% in H. influenzae and S. pneumoniae, 48-86% in S. aureus, 37-69% in M. catarrhalis and 51-71% in E. coli. Mature biofilms were less susceptible to degradation. Moxifloxacin at concentrations that can be achieved in the bronchial mucosa during therapy therefore promotes a significant inhibition of biofilm synthesis and induces slime disruption, a feature that may be instrumental in reducing the exacerbations so frequently observed in this condition.
    International Journal of Antimicrobial Agents 12/2007; 30(5):415-21. · 4.42 Impact Factor
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    ABSTRACT: Minimum inhibitory concentrations (MICs) and mutant prevention concentrations (MPCs) of prulifloxacin against 30 strains of Escherichia coli isolated from urinary tract infections as well as the 'biological cost' related to acquisition of resistance to the same drug in 10 uropathogenic E. coli were assessed. In terms of MIC(90), prulifloxacin was more potent than ciprofloxacin and levofloxacin. Prulifloxacin produced lower or equal MPC values than the other two fluoroquinolones (93.3% and 73.3% compared with levofloxacin and ciprofloxacin, respectively). Compared with susceptible strains, prulifloxacin-resistant mutants showed a reduced rate of growth (ranging from 20.0% to 98.0% in different culture media and incubation conditions) and a decreased fitness index (ranging from 0.959 to 0.999). They were also impaired in their ability to adhere to uroepithelial cells and urinary catheters (11.7-66.4% and 16.3-78.3% reduction, respectively) and showed a lower surface hydrophobicity (51.2-76.0%). They were more susceptible to ultraviolet irradiation (30.6-93.8% excess mortality), showed increased resistance to colicins and diminished transfer of plasmids (<1-8.5x10(-8) vs. 3.3x10(-7)-2.4x10(-4)). Synthesis of haemolysin and type I fimbriae and production of flagella were also adversely affected. This study demonstrates a strict relationship between acquisition of prulifloxacin resistance and loss of important virulence traits. In this transition, E. coli pays a severe biological cost that entails a general reduction of fitness, thus compromising competition with susceptible wild-type strains in the absence of the drug.
    International Journal of Antimicrobial Agents 07/2007; 29(6):679-87. · 4.42 Impact Factor
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    ABSTRACT: Some new features of the in vitro activity of ceftibuten, an oral third generation cephalosporin, have been studied in reference to respiratory and urinary tract pathogens included in its antibacterial spectrum. At 0.25XMIC (minimum inhibitory concentration) and 0.5XMIC levels, ceftibuten was able to affect the biofilm production in 2/3 of both Escherichia coli and Proteus mirabilis strains, and reduced the number of strains capable of adhering to epithelial cells by about 35% in comparison to the control. Surface hydrophobicity was also influenced by ceftibuten and the other drugs at 0.25-0.5XMIC. In general, no marked variation in the virulence traits of the pathogens studied were found by exposing bacteria to sub-MICs of ceftibuten. Plasmid loss (from 1.8 to 37.2%), and Flac transfer inhibition (about 30-50% reduction in the number of recombinants) were detected under the experimental conditions used. This study confirms the excellent antibacterial properties of ceftibuten by adding new information about the effects of this antibiotic against pathogens often involved in respiratory and urinary tract infections that may be treated with this compound, supporting the appropriate use of this cephalosporin.
    Journal of chemotherapy (Florence, Italy) 05/2007; 19(2):152-60. · 0.83 Impact Factor
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    ABSTRACT: The activity of amphotericin B, fluconazole, flucytosine, itraconazole and voriconazole was tested in vitro against 618 clinical Candida spp. isolates, using the broth microdilution or the disk diffusion method (voriconazole). Amphotericin B and voriconazole were the most potent antifungal agents assayed (100% of susceptible strains). Resistance to fluconazole and itraconazole was detected in three (0.7%) and 11 (2.7%) isolates of Candida albicans and in four (3.7%) isolates of Candida glabrata. Flucytosine intermediate, resistant strains, or both, were observed in C. albicans (0.3% and 0.7%), C. glabrata (2.8% intermediate) and C. tropicalis (15.2% and 15.2%). C. krusei was the least susceptible species to azoles. No statistically significant differences in the rates of resistant isolates depending on site of infection and age of the patient were observed, with the exception of C. albicans and itraconazole (higher percentage of resistance in children). At present, acquired antifungal resistance represents an uncommon finding in most Candida spp. circulating in Northern Italy.
    International Journal of Antimicrobial Agents 03/2007; 29(2):179-84. · 4.42 Impact Factor
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    ABSTRACT: The most frequent agents of severe bacterial infections and their antibiotic susceptibility patterns were determined in patients admitted to 45 Italian hospitals over the years 2002-2003. The most common diagnoses were: sepsis (33.8%), pneumonia (9.4%), intravascular catheter-associated infections (9.3%) and ventilator-associated pneumonia (8.1%). Overall, 5115 bacterial isolates were identified from 4228 patients. Three bacterial species, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, accounted for more than 50% of the isolates. Other prevalent bacterial isolates were Staphylococcus epidermidis and Enterococcus faecalis, while Acinetobacter baumanii ranked third among all Intensive Care Unit (ICU) isolates. 7% of S. aureus had intermediate resistance to vancomycin. Although E. faecalis displayed no vancomycin resistance, 34% of vancomycin-resistant isolates were found among Enterococcus faecium, one of the highest rates found to date, emphasizing the difference between these two enterococcal species. All the Gram-positive pathogens were susceptible to linezolid, with the exception of approximately 2% of the enterococcal isolates that were intermediate with a minimum inhibitory concentration (MIC)=4 microg/ml. Almost 10% of Escherichia coli, 14% of Klebsiella pneumoniae, 22% of Serratia marcescens and 50% of Enterobacter cloacae were non-susceptible to cefotaxime. Amikacin was the most active antibiotic against P. aeruginosa that showed lack of susceptibility to ceftazidime, gentamicin, piperacillin and ciprofloxacin ranging from 20 to 35%. Finally, Acinetobacter baumanii showed a high level of resistance to all the antibiotics tested including imipenem (58%). The results obtained in this study, the first of its kind in Italy, offer indications for guiding empirical therapy and implementing specific interventions to fight antibiotic-resistant bacterial infections and their transmission in the hospital setting in Italy.
    Journal of chemotherapy (Florence, Italy) 01/2007; 18(6):589-602. · 0.83 Impact Factor
  • International Journal of Antimicrobial Agents - INT J ANTIMICROBIAL AGENTS. 01/2007; 29.
  • S. Roveta, A. Marchese, E. Debbia
    International Journal of Antimicrobial Agents - INT J ANTIMICROBIAL AGENTS. 01/2007; 29.
  • International Journal of Antimicrobial Agents - INT J ANTIMICROBIAL AGENTS. 01/2007; 29.
  • S. Roveta, A. Marchese, G. Schito
    International Journal of Antimicrobial Agents - INT J ANTIMICROBIAL AGENTS. 01/2007; 29.

Publication Stats

2k Citations
233.36 Total Impact Points


  • 1993–2013
    • Università degli Studi di Genova
      • Sezione di Microbiologia
      Genova, Liguria, Italy
  • 2008
    • University of Verona
      Verona, Veneto, Italy
  • 1991–2000
    • University of Toronto
      • Department of Pharmacology and Toxicology
      Toronto, Ontario, Canada
  • 1998
    • The Rockefeller University
      New York City, New York, United States