Potential for antimicrobial resistance in Chlamydia pneumoniae.

Antimicrobial resistance has not yet been described in wild type Chlamydia pneumoniae isolates, nor has selective emergence of resistance in the laboratory after exposure to subinhibitory concentrations of antibiotic. However, few clinical isolates have been tested for resistance, especially strains with resistance phenotypes (i.e., those associated with clinical failure or persistence). More widespread testing of such strains is needed. Further understanding of antimicrobial resistance in chlamydiae would benefit from the development of standardized methods. Further, more physiologic testing methodologies that more closely mimic the chronic intracellular infection usually being treated in vivo would be of value. Animal models demonstrate persistence of C. pneumoniae after antimicrobial therapy and could be used to better define the clinical correlates of in vitro testing.