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, 16.2%; amoxicillin-clavulanate, 12.2%; cefuroxime, 28.1%; ceftriaxone, 3.6%; trimethoprim-sulfamethoxazole, 30.3%; azithromycin, 21.4%; levofloxacin, 0.6%; and moxifloxacin, 0.1%. Compared to the previous 1997-1998 study (Jones et al., Antimicrob. Agents Chemother. 44:2645-2652, 2000), increases were noted for resistance to penicillin (3.7%; P < 0.001), amoxicillin-clavulanate (3.9%; P < 0.001), cefuroxime (5.7%; P < 0.001), azithromycin (2.4%; P = 0.014), trimethoprim-sulfamethoxazole (15.4%; P < 0.001), and levofloxacin (0.3%; P = 0.017). Resistance to ceftriaxone (0.1%; P = 0.809) and moxifloxacin (0.03%; P = 0.570) decreased. Concurrently, multidrug resistance increased (P < 0.001) from 6.3% to 11.3%.