title: Implications of antimicrobial resistance in the empirical treatment of community-acquired respiratory tract infections: the case of macrolides.
abstract: Macrolide resistance among pneumococci is increasing worldwide and is associated with increasing macrolide use. Recent studies show that use of macrolides and azalides increases nasopharyngeal carriage of both macrolide-resistant and penicillin-resistant pneumococci. Carriage of a resistant pneumococcus may foster dissemination. The clinical relevance of in vitro resistance has been debated. However, recent data from a matched case-control study showed that 18 (24%) of 76 patients had breakthrough bacteraemia with an erythromycin-resistant pneumococcus while taking a macrolide, whereas none of the 136 matched controls with an erythromycin-susceptible pneumococcal bacteraemia was taking a macrolide (P = 0.0000001). Moreover, five (24%) of 21 patients bacteraemic with the low-level resistant M phenotype and none of the 40 matched controls were taking a macrolide (P = 0.00157). These data indicate that macrolide resistance due to both the efflux and the methylase mechanisms is clinically relevant. Furthermore, they favour guidelines for the empirical treatment of outpatients with community-acquired pneumonia that recommend high-dose oral amoxicillin and reserve coverage of atypical pathogens for selected high-risk populations.
authors.affiliation: Brown Medical School and the Miriam Hospital, Providence, RI, USA. John_Lonks@brown.edu
authors.forename: J R
authors.initials: JR
authors.lastname: Lonks
authors.forename: J
authors.initials: J
authors.lastname: Garau
authors.forename: A A
authors.initials: AA
authors.lastname: Medeiros
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D002353:Carrier State / Q000188:drug therapy / Q000382:microbiology; D017714:Community-Acquired Infections / Q000188:drug therapy* / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial / Q000502:physiology*; D006801:Humans; D018942:Macrolides; D009302:Nasopharyngeal Diseases / Q000188:drug therapy / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides