The PROTEKT surveillance study: Antimicrobial susceptibility of Haemophilus influenzae and Moraxella catarrhalis from community-acquired respiratory tract infections

Abstract

This paper presents data relating to Haemophilus influenzae and Moraxella catarrhalis from PROTEKT (1999-2000), a surveillance study that examined the susceptibility of respiratory pathogens to current and new antibacterials. β-Lactamase production is the principal mechanism of resistance to ampicillin and other β-lactam antibacterials in H. influenzae and M. catarrhalis. The PROTEKT study showed that globally, the prevalence of β-lactamase production in H. influenzae varied considerably: of 2948 isolates, 489 (16.6%) were β-lactamase-positive [range: 1.8% (Italy) to 65% (South Korea)]. β-Lactamase-negative, ampicillin-resistant (BLNAR) strains of H. influenzae were uncommon (<0.1%) but their very detection highlights the need for continued vigilance. Overall, few isolates of H. influenzae showed resistance to either macrolides or telithromycin. The emergence of clarithromycin-resistant strains is worrying, however, as such isolates may also show resistance to other macrolides. There was a geographical correlation between β-lactamase production and the prevalence of resistance to chloramphenicol and tetracycline among the H. influenzae isolates. Of 1131 M. catarrhalis isolates, 92% were β-lactamase-positive. Most isolates, however, were fully susceptible to nearly all the antibacterials tested, except ampicillin. The most active were ciprofloxacin and levofloxacin (both having MIC90 values of 0.03 mg/L), moxifloxacin (MIC90 0.06 mg/L), azithromycin (MIC90 0.06 mg/L) and telithromycin (MIC90 0.12 mg/L). Overall, there were no concerns in terms of resistance to fluoroquinolones for both H. influenzae and M. catarrhalis. In summary, the PROTEKT surveillance study confirmed the problem of widespread prevalence of β-lactamase-producing strains of H. influenzae and M. catarrhalis, although these pathogens generally remain susceptible to macrolides, fluoroquinolones and the new ketolide telithromycin.