Epidemiology of antibiotic resistance in respiratory tract infections

An evolving problem: Antibiotic resistance currently concerns H. influenzae , S. species which are particularly susceptible to beta-lactamines, fluoroq uinolones and macrolides. Incidence of resistance has reached high levels i n many countries, including France in certain instances. beta-lactamine resistance: Penicillin-resistant pneumococci (partial and to tal resistance) are unequally distributed over the globe. In France the fre quency is high, particularly in children. S, pyogenes strains remain sensit ive to peni-G. Amino-penicillin resistance of H. influenzae and M. catarrha lis results from enzymatic processes (penicillinase production) and concern s 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 th is bacterial species can adapt to new antibiotics used for the treatment of respiratory tract infections. Resistance is acquired by modifying the anti biotic target, DNA gyrase and/or topo-isomerases, enzyme implicated in bact erial 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 t he presence of erm genes causing a modification in the bacterial ribosome b y methylation or by the presence of mel genes coding for efflux proteins. I ncidence of macrolide resistance and the distribution of these different me chanisms vary greatly from one country to another I Empirical treatment of respiratory tract infections: Epidemiological data and the locoregional bac terial ecology must be considered when prescribing an empirical treatment f or respiratory tract infections.