title: Effect of extended pre-incubation with chlamydia pneumoniae and extended incubation with antimicrobial on the minimum inhibitory concentrations (MICs) of five antimicrobials.
abstract: There is no single standard methodology for in vitro susceptibility testing for Chlamydia pneumoniae, but many investigators pre-incubate this organism with the cell monolayer for 1 h prior to adding antimicrobial and incubating for 72 h. The aim of this study was to determine the effect of extended C. pneumoniae pre-incubation, and extended incubation in the presence of antimicrobial, on the MICs of 5 antimicrobials. MICs were determined for 5 ATCC strains of C. pneumoniae by employing similar methods as those previously described in the literature. MICs were then determined following 1, 4, 6, 20 and 24 h C. pneumoniae pre-incubation. Finally, MICs were determined following 1 and 24 h C. pneumoniae pre-incubation, and 48 and 72 h incubation with antimicrobial and organism. Extending the incubation time in the presence of antimicrobial from 48 to 72 h had little or no effect on MICs. Similarly, pre-incubation periods of less than 20 h had little effect on MICs, but MICs increased significantly with 20 and 24 h pre-incubation.
authors.affiliation: SmithKline Beecham Pharmaceuticals, Collegeville, PA, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Stewart
authors.forename: K
authors.initials: K
authors.lastname: Coleman
authors.forename: J
authors.initials: J
authors.lastname: Mortensen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016993:Chlamydophila pneumoniae / Q000187:drug effects*; D008826:Microbial Sensitivity Tests / Q000379:methods*; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents