title: Effect of pH on the in vitro potency of clarithromycin against Mycobacterium avium complex.
abstract: Employing 7H11 agar medium at pH 6.6, the MICs of clarithromycin for 50% (MIC50) and 90% (MIC90) of 19 strains of Mycobacterium avium complex were 8 and 16 micrograms/ml, respectively. However, the MICs were 2 to 3 log2 dilutions lower in the 7H11 medium adjusted to pH 7.4, and the MICs on 10% OADC (oleic acid-albumin-dextrose-catalase)-enriched Mueller-Hinton agar at pH 7.3 were also 2 log2 dilutions lower than those measured on 7H11 agar at pH 6.6. Therefore, clarithromycin is more active at a physiologic than at an acidic pH.
authors.affiliation: Faculté de Médecine Pitié-Salpetrière, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Truffot-Pernot
authors.forename: B
authors.initials: B
authors.lastname: Ji
authors.forename: J
authors.initials: J
authors.lastname: Grosset
mesh_terms: D017291:Clarithromycin; D004917:Erythromycin / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D015269:Mycobacterium avium Complex / Q000187:drug effects*
chemical_list: D004917:Erythromycin; D017291:Clarithromycin