Susceptibility Of H. Influenzae And M. Catarrhalis In Asia And Europe: 2007 Global Surveillance Program

Background: Haemophilus influenzae (HI) and Moraxella catarrhalis (MC) are among the most common etiological agents of community-acquired pneumonia (CAP). Regional differences in susceptibility can occur among these pathogens. The GLOBAL Surveillance initiative provides comprehensive in vitro susceptibility data for respiratory pathogens, particularly focused on widely used oral agents prescribed for the treatment of these pathogens. Methods: During 2007, HI (n = 492) and MC (n = 140) were isolated from patient specimens collected from 4 regions in Asia (AS; Hong Kong [HK], South Korea [SK], China [CH], and Taiwan [TW]). Isolates were centrally tested by broth microdilution (CLSI M7-A7) against levofloxacin (LFX), ampicillin (AMP), amoxicillin-clavulanate (AC), azithromycin (AZI), clarithromycin (CLA), cefuroxime (CFX), and trimethoprim-sulfamethoxazole (SXT). Susceptibility (S) data were interpreted according to CLSI M100-S17 breakpoints (BP) and analyzed according to b-lactamase (BL) status. Results: The current S rates (%) overall among the oral agents for HI were 99.6 for LFX; 69.1 for AMP; and 52.6 for SXT. For HI, the MIC90s (mg/L) were 0.03 for LFX; 2 for AC; 2 for AZI; 2 for CFX; >8 for AMP; and >4 for SXT. LFX-S, AZI-S, and AC-S rates among HI isolates were >97%, regardless of region. SXT-S (35.3% in TW to 61.5% in SK), AMP-S (37.6% in TW to 92.6% in CH), and CLA-S (58.8% in TW to 75.0% in SK) rates among HI varied substantially by region. The rate of HI that were BL positive (+) overall for AS was 30.1%; however, BL+ rates varied considerably by country (6.9% in CH to 61.2% in TW). The BL+ rate for MC was 99.3%. Against MC, all tested agents were highly active (>95% S with the exception of AMP (BP unavailable). MC were 100% S to both LFX and AZI which also had the lowest MIC90s (0.06 mg/L) of the tested agents. Regional variation in activity against MC was most notable for SXT (80.0% in TW to 100% in HK) and ERY (90% in TW to 100% in SK). Conclusions: Susceptibility among HI in AS remained high (≥98%) for many of the commonly used oral agents (LFX, AZI, AC, and CFX), regardless of beta-lactamase production which was found to vary by region. Though BL+ rates among MC have risen above 97% across AS, MC isolates remain >95% to most common CAP agents. Continued regional surveillance to monitor for any change in the susceptibility patterns among these pathogens to agents commonly utilized for empiric therapy is warranted.