In vitro activity of linezolid against Gram-positive uropathogens of hospitalized patients with complicated urinary tract infections

The antimicrobial activity of linezolid, a recently developed antibiotic ag ent active against Gram-positive bacteria, was tested against pathogens fro m three different collections. (1) Uropathogens from hospitalized urologica l patients (1990/1991) with complicated and/or hospital-acquired UTls, Urol ogic Clinic, Hospital St. Elisabeth, Straubing. (2) Uropathogens from a mul ti-centre study (1995/1996) comprising 37 urological centres throughout Ger many. (3) MRSA isolates of patients and staff (1999/2000) within the Hospit al St. Elisabeth, Straubing. Genotyping of the latter isolates was performe d by pulsed-field-electrophoresis. The minimal inhibitory concentrations (M IC) of linezolid determined by an agar (Isosensitest) dilution method using a multipoint inoculator and an inoculum of 10(4) cfu per point ranged for methicillin susceptible Staphylococcus aureus (MSSA) (n = 27) between 2 and 4 mg/l, for methicillin resistant S. aureus (MRSA) (n = 35) between I and 2 mg/l, for methicillin susceptible coagulase-negative staphylococci (CNS) (MSSE) (n = 67) between 0.5 and 4 mg/l, for methicillin resistant CNS (MRSE ) (n = 19) between 0.25 and 2 mg/l, for Enterococcus. faecalis (n = 184) be tween 0.5 and 4 mg/l, for E. faecium (it = 3) 2 mg/l and for Streptococcus spp. (n = 4) between 0.25 and I mg/l, indicating that all strains were susc eptible. According to the in vitro activity, linezolid may be considered a promising antibacterial agent for the treatment of complicated UTI caused b y Gram-positive uropathogens. Thus, linezolid should be evaluated in a clin ical study. (C) 2001 Elsevier Science BN. and International Society of Chem otherapy. All rights reserved.