Laboratory methods for detection of Chlamydia trachomatis: survey of laboratories in Washington State

The last decade has witnessed the development of a wide variety of diagnostic tests for Chlamydia trachomatis. In order to determine what laboratory methods are being used to detect C. trachomatis infections in Washington State and to identify factors influencing test selection, between April 1995 and October 1995 we conducted a mailed questionnaire survey of all 112 laboratories certified to do chlamydia testing. Of these, 20 had discontinued testing for C. trachomatis, and responses were obtained from 89 (97%) of the remaining 92 laboratories. Surprisingly, 38 (43%) of the 89 laboratories used rapid tests such as Clearview and Surecell, making such tests the most commonly used laboratory tests. Laboratories which used rapid tests had lower test volumes, less experience performing tests for C. trachomatis, less frequent attendance at professional meetings, and greater reliance on manufacturers for information compared with laboratories which used other methods. Confirmation of non-culture-positive results was provided by 28 (34%) of the 82 laboratories doing non-culture-based tests. Forty-one (47%) of 88 laboratories reported having compared their method with another method. Test volume was the strongest predictor of laboratories which confirmed positive non-culture-based test results and which had performed a laboratory comparison of methods. We conclude that rapid tests for C. trachomatis are often being used inappropriately and that efforts are needed to improve effective implementation and quality assurance of laboratory testing for C. trachomatis.