Evaluation of Calcium Alginate-tipped Aluminum Swabs Transported in Culturettes® Containing Ampules of 2-Sucrose Phosphate Medium for Recovery of Chlamydia trachomatis
Two calcium alginate-tipped wire swab specimens were obtained from 94 men and 106 women attending a sexually transmitted disease clinic. One swab was extracted thoroughly in 2-sucrose phosphate (2SP) immediately after obtaining the specimen. The second swab was returned to the Culturette® cylinder (Marion Scientific, Kansas City, MO), and the ampule containing 2SP was crushed to moisten the swab during transport to the laboratory. After receipt in the laboratory, the swab was removed from the Culturette and extracted into 2 mL of 2SP. Both specimens then were cultured for the presence of Chlamydia trachomatis in McCoy’s cells. C. trachomatis was recovered from 22 of 94 men (23.4%); 16 isolates came from both the Culturette swabs and vials. Six isolates were recovered exclusively from vials. Of 106 women, 13 (12.3%) were positive for C. trachomatis. In five instances, both vials and swabs yielded C. trachomatis; the organism was recovered eight times from vials but not swabs. The 2SP transport system for the 200 specimens was superior to the Culturettes for the recovery of C. trachomatis (P < 0.01). Based on our results, swab specimens taken for laboratory diagnosis of C. trachomatis should be extracted immediately after collection in a vial containing 2SP. In addition, experiments comparing swab fibers indicated that there was a trend indicating higher inclusion counts with rayon-tipped swabs, compared with those containing calcium alginate. Because of possible toxicity of substances in calcium alginate fibers for several organisms causing sexually transmitted disease, rayontipped swabs or swabs of other composition should be used.