Susceptibility of Streptococcus pneumoniae and Haemophilus influenzae Collected Across Europe and Asia to Levofloxacin and Other Respiratory Agents; Results from GLOBAL Surveillance (1997-2007)
C. M. Pillar, PhD
C. Thornsberry, PhD
D. F. Sahm, PhD
Chantilly, Virginia, USA
The GLOBAL (Global Landscape On the Bactericidal Activity of Levofloxacin) Surveillance Program is a worldwide initiative intended to detect changes in resistance among common respiratory tract pathogens. In the 2007 study period, a total of 2,395 isolates of Streptococcus pneumoniae (S. pneumoniae ) and 2,287 Haemophilus influenzae (H. influenzae ) were collected from 12 countries in Asia and Europe and tested for susceptibility to commonly used antimicrobial agents. Among the evaluated pneumococci, penicillin and azithromycin resistance were more predominant in Asia. Penicillin susceptibility was 42.1% in Asia compared with 75.5% in Europe. Azithromycin susceptibility was only 21.5% in Asia compared with 67.3% in Europe—a 5% decrease in azithromycin susceptibility was seen in both Asia and Europe in 2005 compared with 1997-1999. Multidrug resistance was also more prevalent among pneumococci in Asia. One-third of all pneumococcal isolates from Asia exhibited resistance to four antimicrobials tested (penicillin, azithromycin, cefuroxime, and trimethoprim/sulfamethoxazole) compared with only 6.6% of isolates from Europe. Multidrug resistance rates also varied greatly among specific countries in each region. In contrast to other agents, levofloxacin remained highly active against the evaluated pneumococci regardless of resistance phenotype, including multidrug-resistance, and maintained a consistent MIC50 and MIC90 of 1 μg/ml over time. H. influenzae remained largely susceptible to the evaluated oral agents, excluding trimethoprim/sulfamethoxazole where resistance ranged from 30 to 60%, primarily among the evaluated Asian countries. β-lacatamase varied by country but again was high in parts of Asia (40-60% in Taiwan and South Korea). As with pneumococci, H. influenzae remained >99.9% susceptible to levofloxacin regardless of resistance phenotype.