Antimicrobial susceptibilities of clinical isolates of Haemophilus influenzae and Moraxella catarrhalis collected during 1999-2000 from 13 countries.

OBJECTIVE: To determine antimicrobial activity against Haemophilus influenzae and Moraxella catarrhalis. METHODS: A central laboratory performed NCCLS susceptibility testing for all isolates and beta-lactamase and capsular serotype determinations for H. influenzae. RESULTS: A total of 2712 H. influenzae and 1079 M. catarrhalis were collected. H. influenzae susceptibilities were >90% for amoxicillin/clavulanate, cefaclor, loracarbef, cefprozil, cefuroxime, ciprofloxacin, azithromycin and clarithromycin and were <80% for trimethoprim/sulfamethoxazole and ampicillin. 19.3% were beta-lactamase positive. The most common serotype was type-b (5.6%); 86.1% were nontypeable. M. catarrhalis had MIC90 within therapeutic range for all antimicrobials except ampicillin. CONCLUSION: The conclusion of the study is that antimicrobials, except ampicillin and trimethoprim/sulfamethoxazole, remain good empiric choices against H. influenzae and M. catarrhalis.

A comparative In vitro surveillance study of gemifloxacin activities against 2,632 recent Streptococcus pneumoniae isolates from across Europe, North America, and South America. The Gemifloxacin Surveillance Study Research Group.

From 1997 to 1999, 94 study centers in 15 European, 3 North American, and 2 South American countries contributed 2,632 isolates of Streptococcus pneumoniae to an international antimicrobial susceptibility testing study. Only 62.0% of isolates were susceptible to penicillin, while 22.3% were penicillin intermediate and 15.6% were penicillin resistant. Resistance to trimethoprim-sulfamethoxazole (24.4%), azithromycin (26.0%), and clarithromycin (27.1%) was also highly prevalent. For the penicillin-resistant isolates (n = 411), the MICs at which 90% of isolates are inhibited (MIC(90)s) for gemifloxacin, levofloxacin, ofloxacin, clarithromycin, and azithromycin were 0.03, 1, 2, >16, and >64 microgram/ml, respectively. Similarly, for isolates resistant to both azithromycin and clarithromycin (n = 649), gemifloxacin, levofloxacin, ofloxacin, and penicillin MIC(90)s were 0.03, 1, 2, and 4 microgram/ml, respectively. Overall rates of resistance to trovafloxacin (0.3%), levofloxacin (0.3%), grepafloxacin (0.6%), and ofloxacin (0.7%) were low. For ofloxacin-intermediate and -resistant isolates (n = 142), gemifloxacin had the lowest MIC(90) (0.12 microgram/ml) compared to the MIC(90)s of trovafloxacin (0.5 microgram/ml), grepafloxacin (1 microgram/ml), and levofloxacin (2 microgram/ml). For all S. pneumoniae isolates tested, gemifloxacin MICs were

Levofloxacin in vitro activity: results from an international comparative study with ofloxacin and ciprofloxacin.

Levofloxacin, the S-(-)-isomer of ofloxacin, was compared to ofloxacin and ciprofloxacin against > 6000 recent clinical isolates of Gram-positive and Gram-negative bacteria from six different countries. This international multicenter study demonstrated a high level of antibacterial activity of levofloxacin against all the members of Enterobacteriaceae [minimum inhibitory concentration (MIC)50s, < or = 0.03 to 0.12 mg/L] except Providencia rettgeri (MIC50, 2 mg/L), and Providencia stuartii (MIC50, 1 mg/L). Oxacillin-susceptible staphylococci (MIC50s, 0.12 to 0.25 mg/L), enterococci (MIC50s, 0.5 to 2 mg/L), and streptococci (MIC50s, 0.5 mg/L) were also susceptible to levofloxacin, but most isolates of oxacillin-resistant staphylococci had MICs of > or = 4 mg/L. Levofloxacin was also active against non-enteric Gram-negative bacilli, including Acinetobacter species (MIC50s, < or = 0.03 to 1 mg/L), Pseudomonas species (MIC50s, 0.5 to 1 mg/L) and Xanthomonas maltophilia (MIC50, 0.5 mg/L). Overall, levofloxacin inhibited 50% and 90% of all the tested strains at the concentrations of 0.12 and 4 mg/L, respectively. The activity of levofloxacin was generally two-fold greater than ofloxacin and equal to or slightly less potent than ciprofloxacin.