Improved PCR detection of Chlamydia trachomatis by using an altered method of specimen transport and high-quality endocervical specimens

Abstract

Duplicate endocervical swabs were collected for detection of Chlamydia trachomatis by PCR (Roche Diagnostics). One swab was swirled in Specimen Transport Medium (Roche) for PCR testing and discarded. A saline aliquot from the other specimen, sent as a dry swab to the laboratory, was Papanicolaou stained to determine specimen adequacy, and the remainder was PCR tested. Significantly more (24%) PCR-positive results (118 versus 95; P < 0.001) were obtained with the dry specimens than with the swirled specimens when first tested. In addition, PCR-positive results were obtained with 107 (10.6%) of 1,007 microscopically adequate specimens but with only 3 (0.9%) of 341 inadequate specimens (P < 0.001).

Use of PCR for the detection of genital Chlamydia trachomatis infection on self-obtained mailed vaginal samples

“…It has been earlier demonstrated by others (16) that chlamydial DNA survives postage well in a sample buffer and remains suitable for the PCR analyses after arrival at the laboratory. PCR sensitivity was shown also not to change in samples kept dry before the PCR-testing (20). In the present study we confirmed both statements, extending it to that, that samples still remain suitable for the PCR testing even if they have been sent to the laboratory in a dry tube.…”

Use of Ligase Chain Reaction with Urine versus Cervical Culture for Detection of Chlamydia trachomatis in an Asymptomatic Military Population of Pregnant and Nonpregnant Females Attending Papanicolaou Smear Clinics

“…Additionally, the quality of the endocervical specimen, as measured by the presence of columnar epithelial cells, has been shown to play a significant role in the numbers of positive specimens (19,37). In another study of family-planning clinics in Baltimore, Md., clinicians obtained adequate specimens only 72.3% of the time (37).…”

Influence of endocervical specimen adequacy on PCR and direct fluorescent-antibody staining for detection of Chlamydia trachomatis infections

“…The slides were evaluated for the presence of elementary bodies, columnar epithelial or metaplastic cells, polymorphonuclear cells, vaginal squamous epithelial cells, and erythrocytes. According to criteria set forth by Kellogg et al, a specimen was considered to be adequate on a cellular-component basis if it contained any columnar epithelial or metaplastic cells, with or without the other cells, or if it contained more than 100 erythrocytes per high-power field (18,20,21). Specimens containing this many erythrocytes could not be judged for the presence of columnar cells because the erythrocytes mask the other cells present in a sample (18).…”

“…The presence or absence of these cells has been shown to significantly affect the sensitivity and the specificity of the detection of chlamydia by the Chlamydiazyme assay (Abbott Diagnostics, Abbott Park, Ill.) as well as by direct fluorescent-antibody (DFA) staining (18,21,24). Additionally, the quality of the cervical specimen has been shown to affect the positivity rate of the commercial PCR assay (Roche Molecular Systems) (20). We wanted to ascertain whether specimen adequacy could be determined by performing DFA staining of a single cervical swab specimen, which would then also be used to determine the presence of C. trachomatis by the PCR assay (Roche), and whether the adequacy of the specimen affected the positivity rates of the two assays.…”