Epidemiological survey of bacterial resistance in upper respiratory tract infections in italy.

The vast majority of infections in the upper airways are caused by four bacterial species;, in Italy as elsewhere, antibiotics resistant strains are emerging. Enzymatic resistance to beta-lactams in Haemophilus influenzae is becoming more important and affects 15% of isolates. On the other hand less than 0.3% of H. influenzae strains are fluoroquinolone-resistant. The number of beta-lactamase-producing Moraxella catarrhalis strains in Italy has been thought to be lower than in other countries, but recent studies suggest 90% of strains are positive, a figure similar to figures reported in the international literature. The most recent data estimate high-level resistance to penicillin in pneumococci to be around 5%, but varies greatly in different geographical areas and with the different origins of the isolates. In spite of the low incidence of penicillin-resistant strains, the most recent figures for macrolide-resistance in Streptococcus pneumoniae range from 26.4 to 31.7%. More than 3 years after the dramatic increase in erythromycin-resistant Streptococcus pyogenes, the resistance levels in Italy are still among the highest in the world. Unlike the experience in other countries, resistance is often related not to the active efflux of antibiotic from the bacterial cell but to ribosomal methylation, thus affecting not only 14- and 15-membered macrolides, but also 16-membered compounds and lincosamides.