Comparison of two commercially available isolation systems for Chlamydia trachomatis

In a comparison of two commercially available chlamydial isolation systems in which cycloheximide-treated McCoy cell monolayers are used, the system from Bartels Immunodiagnostic Supplies, Inc., Bellevue, Wash., was found to be superior to that from M. A. Bioproducts, Walkersville, Md. for the detection of Chlamydia trachomatis by iodine staining. Of 288 clinical specimens run in parallel, 47 (16.3%) were positive, with 16 of 47 positive results detected in the Bartels system only and 1 of 47 positive results detected in the M. A. Bioproducts system only (P less than 0.001). A comparison of the number of inclusion-forming units per cover slip from clinical specimens and passaged isolates also showed that the Bartels cell system demonstrated higher inclusion counts than the M. A. Bioproducts system. In routine clinical use, overall isolation rates were higher (P less than 0.001) and contamination rates were lower (P less than 0.001) with the Bartels system as compared with results obtained in a previous time period in which the M. A. Bioproducts system was used.