title: Postantibiotic effect of amikacin and rifapentine against Mycobacterium avium complex.
abstract: Postantibiotic effect (PAE) has received little attention in the therapy of chronic intracellular infections, such as those caused by mycobacteria. Amikacin is active therapeutically against Mycobacterium avium complex, even though serum levels exceed the MIC for only a few hours. To determine the PAE of amikacin and rifapentine for M. avium, bacteria were exposed to concentrations of 1x, 4x, and 10x the MIC of each drug for up to 120 min. Regrowth of M. avium was compared with similarly diluted untreated cultures. No PAE was observed on an inoculum of 10(4) bacteria when rifapentine was used at 5x MIC, although a slight inhibition of growth was obtained at 10x MIC for 2 h. For amikacin, PAE was observed up to 48 h at concentrations of 4x and 8x MIC and exposure times of 30-120 min. A PAE of 22 h was seen with 10(7) cfu of M. avium during incubation for 30 min with amikacin at 4x MIC. These results show that amikacin, unlike rifapentine, has a long PAE against M. avium.
authors.affiliation: Kuzell Institute for Arthritis and Infectious Diseases, Medical Research Institute of San Francisco, California Pacific Medical Center.
authors.forename: L E
authors.initials: LE
authors.lastname: Bermudez
authors.forename: M
authors.initials: M
authors.lastname: Wu
authors.forename: L S
authors.initials: LS
authors.lastname: Young
authors.forename: C B
authors.initials: CB
authors.lastname: Inderlied
mesh_terms: D000583:Amikacin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007917:Leprostatic Agents / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D015269:Mycobacterium avium Complex / Q000187:drug effects* / Q000254:growth & development; D012293:Rifampin / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors
chemical_list: D007917:Leprostatic Agents; D000583:Amikacin; D012293:Rifampin; C018421:rifapentine