Comparison of the effectiveness of polymerase chain reaction and enzyme immunoassay in detecting Chlamydia trachomatis in different female genitourinary specimens.
BACKGROUND
In high-volume laboratories, enzyme immunoassay (EIA) is the most commonly used method of detecting Chlamydia trachomatis. The optimal specimen for detecting C trachomatis is a combined urethral and cervical swab.


OBJECTIVE
To compare EIA with the combined urethral and cervical swab with polymerase chain reaction (PCR) on urine alone and urine mixed with cervical cells.


METHODS
Phase 1 of the study included 752 sets of specimens used for comparison. In phase 2, another 212 samples of urine and urine plus cervical cells were added to the study for comparison of the 2 specimen types using PCR.


RESULTS
In phase 1, 648 samples were negative and 76 were positive by all 3 methods and specimen combinations. Enzyme immunoassay was able to detect 81 positive samples (10.8%), whereas PCR on urine alone detected 97 positive samples (12.9%) and PCR on urine plus cervical cells detected 102 positive samples (13.6%), giving a sensitivity of 75%, 93.3%, and 98. 1% respectively. In phase 2, PCR on urine alone detected 119 positive samples (12.3%) and PCR on urine plus cervical cells detected 127 positive samples (13.1%), with a sensitivity of 92.2% and 98.5%, respectively.


CONCLUSIONS
Polymerase chain reaction on urine alone or urine plus cervical cells is superior to EIA on combined cervical and urethral swabs. There is a slight advantage of adding cervical cells to the urine compared with the urine specimen alone when PCR is used as the assay for detection. The total inhibition rate in our female population is only 3.1% when PCR is used.
Chan
E L
EL
Department of Clinical Microbiology, Provincial Laboratory, Saskatchewan, Regina, Canada. echan@health.gov.sk.ca
Brandt
K
K
Stoneham
H
H
Antonishyn
N
N
Horsman
G B
GB
D002584:Cervix Uteri / Q000382:microbiology* / Q000473:pathology; D002690:Chlamydia Infections / Q000175:diagnosis*; D002692:Chlamydia trachomatis / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D016133:Polymerase Chain Reaction / Q000379:methods*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012749:Sexually Transmitted Diseases / Q000382:microbiology; D014521:Urethra / Q000382:microbiology* / Q000473:pathology; D014552:Urinary Tract Infections / Q000175:diagnosis*; D014556:Urine / Q000382:microbiology; D002577:Uterine Cervical Diseases / Q000175:diagnosis*; D014626:Vaginal Smears