Detection of Chlamydia trachomatis DNA in urine and urethral/cervical swab samples: analysis of results from 1 475 outpatients attending sexually transmitted disease clinics / 中华皮肤科杂志

ABSTRACT

Objective:To compare the detection rate of genital Chlamydia trachomatis (CT) DNA between urine and urethral/cervical swab samples. Methods:From December 2018 to December 2019, a total of 1 475 outpatients were collected from sexually transmitted disease clinics in 7 medical institutions, such as Department of Venereology, Guangzhou Institute of Dermatology, including 1 118 males and 357 females. One urethral/cervical swab sample and one urine sample were collected successively from each patient. Real-time fluorescence-based PCR was performed to detect CT DNA in urine and urethral/cervical swab samples, and paired chi-square test was used to compare the positive rate of CT DNA between the 2 kinds of samples. Random- or fixed-effect meta-analysis was conducted for the test of heterogeneity and merging of positive rates of CT DNA in the urine and urethral/cervical swabs among 7 medical institutions.Results:The positive rate of CT DNA in the urine samples was significantly higher than that in the swab samples from 4 medical institutions (all P < 0.05) , while there was no significant difference in the positive rate of CT DNA between the 2 kinds of samples from 3 medical institutions (all P > 0.05) . The heterogeneity ( I2) estimates of the CT-DNA positive rate in urine and swab samples among different medical institutions were 78.6% (95% CI 55.9% - 89.6%) and 73.7% (95% CI 43.7% - 87.7%) , respectively; meta-analysis showed that the total merged positive rate of CT DNA in the urine samples was 10.8% (95% CI 7.2% - 15.9%) , which was significantly higher than that in the swab samples (7.8%, 95% CI 4.9% - 12.1%; χ2 = 39.2, P < 0.05) . Compared with the swab sample-based CT-DNA detection method, the sensitivity, specificity, positive predictive value, negative predictive value and consistency rate of the urine sample-based CT-DNA detection method were 97.0% (128/132) , 96.3% (1 293/1 343) , 71.9% (128/178) , 99.7% (1 293/1 297) , and 96.3% (1 421/1 475) , respectively. The positive rate of CT DNA in the urine samples from 1 118 male patients was 11.0% (95% CI 7.2% - 16.5%) , which was significantly higher than that in the swab samples (7.6%, 95% CI 4.9% - 11.8%; χ2 = 34.3, P < 0.05) . There was no significant difference in the positive rate of CT DNA between the urine (11.9%, 95% CI 7.7% - 17.9%) and cervical swab samples from 357 female patients (10.4%, 95% CI 7.6% - 14.0%; χ2 = 3.2, P > 0.05) . Conclusions:The positive rate of CT DNA in urine samples is higher than or similar to that in urethral/cervical swab samples. The urine sample-based CT-DNA detection method has characteristics of convenience, non-invasiveness, painlessness and low cost, and is worthy of clinical promotion.