In vitro activity of novel rifamycins against gram-positive clinical isolates.

We describe novel rifamycins that have improved activity, compared with rifampin, against clinical isolates of staphylococci and streptococci, with MIC(90)s of 0.008 and 0.0005 microg/ml, respectively.

Phenotypic and genotypic analysis of levofloxacin-resistant clinical isolates of Streptococcus pneumoniae collected in 13 countries during 1999-2000.

During 1999-2000, 5015 isolates were collected from 13 countries and tested against levofloxacin. Overall, levofloxacin resistance minimum inhibitory concentration (MIC>or =8 mg/l) was found in 40 isolates (0.8%).

Longitudinal assessment of antipneumococcal susceptibility in the United States.

The prevalence of antimicrobial resistance among 4,940 U.S. pneumococcal isolates collected during 1999 was as follows: penicillin, 16.

Antimicrobial surveillance of Haemophilus influenzae in the United States during 2000-2001 leads to detection of clonal dissemination of a beta-lactamase-negative and ampicillin-resistant strain.

A 2000-2001 U.S. Haemophilus influenzae surveillance study (n = 1,434) detected nine (0.