Determining antimicrobial resistance to Chlamydia trachomatis and applying present findings in daily practice

Chlamydia trachomatis (C. trachomatis) is the most common bacterial causative agent of sexually transmitted diseases today. Treatment outcome will depend on the choice of antimicrobial drug. Therefore, it is very important to know antimicrobial sensitivity of this pathogen. Cultivation in cell culture is a method of choice for diagnosis of C. trachomatis infection, in terms of medico-legal investigations and follow-up after completed therapy, but also serves for determining the antimicrobial sensitivity of C. trachomatis. Tetracyclines, macrolides and kinolones are commonly used in the treatment of the C. trachomatis infection. Resistance to these antibiotics was described for strains isolated from unsuccessfully treated patients. All described resistant clinical strains demonstrated in vitro heterotypic resistance. To date no homotypic resistance was described for human isolates. An evaluation of antimicrobial resistance and treatment outcome in C. trachomatis infection is complicated by the lack of standardized tests, as well as by the fact that in vitro resistance does not correlate with clinical outcome. In case of any suspicion of unsuccessful treatment of genitourinary infection caused by C. trachomatis isolation should be attempted and isolated strains forwarded to a specialized laboratory.