[Epidemiology of resistance to antibiotics in respiratory tract infections].
AN EVOLVING PROBLEM: Antibiotic resistance currently concerns H. influenzae, S. pneumoniae, S. pyogenes, M. catarrhalis, all species which are particularly susceptible to beta-lactamines, fluoroquinolones and macrolides. Incidence of resistance has reached high levels in many countries, including France in certain instances. BETA-LACTAMINE RESISTANCE: Penicillin-resistant pneumococci (partial and total resistance) are unequally distributed over the globe. In France the frequency is high, particularly in children. S. pyogenes strains remain sensitive to peni-G. Amino-penicillin resistance of H. influenzae and M. catarrhalis results from enzymatic processes (penicillinase production) and concerns an important proportion of the strains, particularly for M. catarrhalis. FLUOROQUINOLONE-RESISTANCE: Fluoroquinolone resistance is now described for H. influenzae. Though rare, this is a serious problem as it proves that this bacterial species can adapt to new antibiotics used for the treatment of respiratory tract infections. Resistance is acquired by modifying the antibiotic target, DNA gyrase and/or topo-isomerases, enzyme implicated in bacterial DNA. The presence of multiple mutations in the genes coding for these enzymes raises the MIC for fluoroquinolones, including those for the most recent compounds. Streptococci resistance to fluoroquinolones is increasing but no new mechanisms of resistance have been described. MACROLIDE-RESISTANT STREPTOCOCCI: Acquired resistance results either from the presence of erm genes causing a modification in the bacterial ribosome by methylation or by the presence of mef genes coding for efflux proteins. Incidence of macrolide resistance and the distribution of these different mechanisms vary greatly from one country to another. EMPIRICAL TREATMENT OF RESPIRATORY TRACT INFECTIONS: Epidemiological data and the locoregional bacterial ecology must be considered when prescribing an empirical treatment for respiratory tract infections.