Comparative recoveries of chlamydia from urethral specimens using glass vials and plastic microtiter plates

Urethral specimens known to contain Chlamydia were stored at -70 C in transport medium (2SP). For the test, circular glass coverslips were placed in the bottom of each culture vessel (glass shell vials and plastic microtiters plates [5 by 15 cm]) and seeded with McCoy's cells in medium containing 5-iodo-2-deoxyuridine. After 72 hours, cultures were inoculated with the specimens, and after 72 additional hours the monolayers on the coverslips were stained with iodine. Of 43 specimens, Chlamydia was recovered from 29 in glass vials but only from three in plastic plates (P less than .001). Chlamydia isolates could be passed serially only by vial-to-vial transfer; losses of 1,800 inclusion-forming units occurred after one subpassage from plates to either vials or plates. The extents of inactivation at 36 C of Chlamydia suspended in medium and placed in plastic plates and in glass vials were similar after seven hours. A substance toxic for Chlamydia could not be demonstrated in the plastic plates. Any new system for isolating Chlamydia from clinical specimens should be evaluated by comparison with culturing in glass vials.