In vitro activity of daptomycin versus linezolid and vancomycin against gram-positive uropathogens and ampicillin against enterococci, causing complicated urinary tract infections

Objectives: The existing therapeutic options for complicated urinary tract infections ( UTI) caused by gram-positive uropathogens are not always optimal. Therefore, newer antimicrobials have to be assessed. Methods: The antimicrobial activity of daptomycin was tested versus linezolid, vancomycin, and ampicillin ( enterococci only), against pathogens from three different collections: ( 1) Uropathogens from hospitalized urological patients with complicated and/or hospital-acquired UTIs of the Urologic Clinic, Hospital St. Elisabeth, Straubing. ( 2) Uropathogens from a multicenter study comprising 37 urological centers throughout Germany. ( 3) Meth icillinresistant Staphylococcus aureus (MRSA) isolates of patients and staff within the Hospital St. Elisabeth, Straubing. Genotyping of the latter isolates was performed by pulsed-field gel electrophoresis. The minimal inhibitory concentrations ( MIC) of daptomycin, linezolid, vancomycin, and ampicillin ( only tested against enterococci) were determined by an agar dilution method using a multipointer with an inoculum of 10(4) CFU per point. Results: For all methicillin-susceptible Staphylococcus aureus ( n = 25), MRSA ( n = 49), methicillin-susceptible coagulase-negative staphylococci ( n = 129), methicillin-resistant coagulase-negative staphylococci ( n = 33), for Enterococcus faecalis ( n = 289), and for Enterococcus faecium ( n = 4) the MICs ranged up to 2 mg/l (daptomycin, linezolid), up to 4 mg/l ( vancomycin), and up to 8 mg/l ( ampicillin, enterococci only) indicating that all strains were susceptible to the antibiotics tested. Conclusions: According to the in vitro activity daptomycin may be considered a promising antibacterial agent for the treatment of complicated UTI caused by gram-positive uropathogens. Thus, daptomycin should be evaluated in a clinical study Copyright (C) 2005 S. Karger AG, Basel.