Laboratory Diagnosis

_ diagnosis of C. tmclwimtis can be achieved by cytology, Xjilture, direct detection of antigen or nudeic add, and serologic testing.

Specimen Collection and Transport. The organism can be recovered from or detected in infected cells of the urethra, cervix, conjunctiva, nasopharynx, and rectum and from material aspirated from the fallopian tubes and epididymis. For collecting specimens from the endo-cervix (preferred anatomic site to collect screening specimens from women), the specimen for C. trachomatis culture should be obtained after all other specimens (e.g., those for Gram-stained smear, Neisseria gonorrhoeae culture, or Papanicolaou [Pap] smear). A large swab should first be used to remove all secretions from the cervix. The appropriate swab (for nonculture tests, use the swab supplied or specified by the manufacturer) or endocervical brush is inserted 1 to 2 cm into the endo-cervical canal, rotated against the wall for 10 to 30 seconds, withdrawn without touching any vaginal surfaces, and then placed in the appropriate transport medium or swabbed onto a slide prepared for direct fluorescent antibody (DFA) testing.3

Urethral specimens should not be collected until 2 hours after the patient has voided. A urogenital swab (or one provided or specified by the manufacturer) is gently inserted into the urethra (females, 1 to 2 cm; males, 2 to 4 cm), rotated at least once for 5 seconds; and then withdrawn. Again, swabs should be placed into the appropriate transport medium or onto a slide prepared for DFA testing. Because chlamydiae are relatively labile, viability can be maintained by keeping specimens cold and minimizing transport time to the laboratory. For successful culture, specimens should be submitted in a chlamydial transport medium such as 2SP (0.2 M sucrose-phosphate transport medium with antibiotics); a number of commerdal transport media are commercially available. Specimens should be refri

Inculation Centrifugation

Inculation Centrifugation

Iodine

Figure 46-2 Processing of specimens for the cultivation of G trachomatis. (From Smith TF: Role of the diagnostic virology laboratory in clinical microbiology: tests for Chlamydia trachomatis and enteric toxins in cell culture. In de la Maza LM, Peterson EM, editors: Medical virology, vol 1, New York, 1982, Elsevier Biomedical.)

Iodine

Fluorescence

Figure 46-2 Processing of specimens for the cultivation of G trachomatis. (From Smith TF: Role of the diagnostic virology laboratory in clinical microbiology: tests for Chlamydia trachomatis and enteric toxins in cell culture. In de la Maza LM, Peterson EM, editors: Medical virology, vol 1, New York, 1982, Elsevier Biomedical.)

gerated upon receipt, and if they cannot be processed for culture within 24 hours, they should be frozen at -70' G.

Cultivation. Cultivation of C, trachomatis is discussed before methods for direct detection and serodiagnosis because all nonculture methods for the diagnosis of C. trachomatis are Compared with culture.

Several different cell lines have been used to isolate C. trachomatis in cell culture, indnding McCoy, Hela, and monkey kidney cells; cydoheximide-treated McCoy cells are commonly used. After shaking the clinical specimens with 5-mm glass beads, centrifugation of the specimen onto the cell monolayer (usually growing on a coverslip in the bottom of a vial, the "shell vial") presumably facilitates adherence of elementary bodies. After 48 to 72 hours of incubation, monolayers are stained with an immunofluorescent stain and examined microscopically for indusions; less specific indusion-detection methods such as using iodine staining are not recommended.3 Figure 46-2 is an overview of the basic steps in processing of specimens for chlamydial culture. Procedure 46-1 describes a method for isolation of chlamydiae. Although its specifidty approaches 100%, the sensitivity of culture has been estimated at between 70% and 90% in experienced laboratories. Limitations of Chlamydia culture that contribute to this lack of sensitivity indude prerequisites to maintain viability of patient specimens by either rapid or frozen transport and to ensure the quality of the sped-men submitted for testing (i.e., endocervical specimens devoid of mucus and containing endocervical epithelial or metaplastic cells and/or urethral epithelial cells).22 hi addition to these issues is the requirement for a sensitive

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Bacterial Vaginosis Facts

Bacterial Vaginosis Facts

This fact sheet is designed to provide you with information on Bacterial Vaginosis. Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina.

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