Ruolo attuale dei macrolidi nella terapia delle infezioni comunitarie trattate al domicilio o in ospedale

none2Schito G.C.; Marchese A.Marchese, Anna; Marchese, A

Activity of moxifloxacin on biofilms produced in vitro by bacterial pathogens involved in acute exacerbations of chronic bronchitis

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

The oxazolidinones as a new family of antimicrobial agent

The oxazolidinones are a new chemical class of synthetic antimicrobials characterized by a unique mechanism of protein synthesis inhibition. Linezolid is the first compound of this class and has recently received approval for the treatment of community- and hospital-acquired pneumonia and skin and skin structure infections. In vitro tests demonstrate that linezolid possesses a significant activity against Gram-positive pathogens including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), vancomycin-intermediate strains (VISA) and penicillin-resistant pneumococci (PRPN). Combined with other drugs linezolid interacts favourably against many important pathogens and it is able to affect some bacterial virulence factors as well as produce a postantibiotic effect.Results from experimental models of infection reveal linezolid to be highly active in vivo against infections due to Gram-positive pathogens.Linezolid may be administered either intravenously or orally with oral bioavailability of approximately 100% and limited adverse effects. The clinical efficacy of linezolid has been investigated in several phase II and III trials. Linezolid has been proved to be useful in severe infections sustained by multiresistant Gram-positive micro-organisms. Synthesis of the second-generation oxazolidinones with improved potency against Gram-positive and negative bacteria is currently under way