A comparative in vitro surveillance study of gemifloxacin activities against 2,632 recent Streptococcus pneumoniae isolates from across Europe, NorthAmerica, and South America

From 1997 to 1999, 94 study centers in 15 European, 3 North American, and 2 South American countries contributed 2,632 isolates of Streptococcus pneum oniae to an international antimicrobial susceptibility testing study. Only 62.0% of isolates were susceptible to penicillin, while 22.3% were penicill in intermediate and 15.6% were penicillin resistant. Resistance to trimetho prim-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 gemifl oxacin, levofloxacin, ofloxacin, clarithromycin, and azithromycin were 0.03 , 1, 2, >16, and >64 mug/ml, respectively. Similarly, for isolates resistan t to both azithromycin and clarithromycin (n = 649), gemifloxacin, levoflox acin, ofloxacin, and penicillin MIC(90)s were 0.03, 1, 2, and 4 mug/ml, res pectively. Overall rates of resistance to trovafloxacin (0.3%), levofloxaci n (0.3%), grepafloxacin (0.6%), and ofloxacin (0.7%) were low. For ofloxaci n-intermediate and -resistant isolates (n = 142), gemifloxacin had the lowe st MIC90 (0.12 mug/ml) compared to the MIC(90)s of trovafloxacin (0.5 mug/m l), grepafloxacin (1 mug/ml), and levofloxacin (2 mug/ml). For all S. pneum oniae isolates tested, gemifloxacin MICs were less than or equal to0.5 mug/ ml, suggesting that gemifloxacin has the potential to be used as a treatmen t for pneumococcal infections, including those arising from isolates resist ant to beta -lactams and macrolides.