In vitro susceptibility of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis: a European multicenter study during 2000–2001

ObjectivesTo assess the current (2001) activity of respiratory fluoroquinolones and comparator agents against respiratory pathogens isolated in European countries.MethodsDuring 2000–2001, we prospectively collected 1995 isolates of Haemophilus influenzae, 1870 isolates of Streptococcus pneumoniae and 649 isolates of Moraxella catarrhalis from hospital laboratories in France, Germany, Greece, Italy, Spain and the UK. National Committee for Clinical Laboratory Standards (NCCLS)-approved broth microdilution antimicrobial susceptibility testing methods and interpretive criteria were used throughout.ResultsOf the S. pneumoniae isolates, 99.6% were susceptible to moxifloxacin, gatifloxacin and levofloxacin; the corresponding figure for H. influenzae was 100%. All M. catarrhalis isolates had moxifloxacin MICs ≤0.12 mg/L. For all three pathogens, fluoroquinolone susceptibility remained unchanged from the previous 1997–98 study. The incidence of penicillin non-susceptibility in the S. pneumoniae isolates tested remained similar to or higher than that recorded in previous studies: France, 165/291 (56.7%); Germany, 46/506 (9.1%); Greece, 20/55 (36.4%); Italy, 45/364 (12.4%); Spain, 146/268 (54.5%); and the UK, 26/386 (6.7%). Significant levels of resistance to oral compounds (cefuroxime, cefaclor, cefdinir, clarithromycin, azithromycin, tetracycline, and trimethoprim–sulfamethoxazole) were detected among S. pneumoniae isolates. β-Lactamase production among H. influenzae isolates ranged from 6.2% to 33.1% per country, and ampicillin, clarithromycin or trimethoprim–sulfamethoxazole resistance were the most common phenotypes detected. β-Lactamase production among M. catarrhalis isolates ranged from 94.1% to 100% per country.ConclusionsWith the exception of a few localized reports, resistance to moxifloxacin and other new fluoroquinolones in common respiratory pathogens is a rare occurrence, despite significant resistance to other compound classes. Surveillance will play a key role in tracking changes in fluoroquinolone susceptibility in European countries