Molecular Epidemiology Of Genitourinary Tract Chlamydia Trachomatis Infection And Laboratory Diagnosis

Chlamydia trachomatis urogenital infections often run a mild course, but the major medical concern of such infections is the late complications, such as ectopic pregnancy and tubal infertility. Thus a rapid, sensitive diagnostic laboratory technique is very crucial for the early diagnosis and treatment of chlamydial infections. Although serotyping is a useful typing method for C. trachomatis, it is expensive and time-consuming. Modem molecular biotechniques provide powerful tools for rapid and sensitive typing of C. trachomatis and studing on the variation of chlamydial pathogenic genes. Using cell culture, polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) and gene cloning, etc, we undertook a series studies on the detection and genotyping of C. trachomatis in urogenital infections.1. In order to facilitate the detection of high volume of spcimens, a microculture technique was developed.Compared with conventional vial culture, this method is more sensitive, rapid, convenient and cost-effective. A total of 966 urogenital specimens, collected from 683 patients attending our sexually transmitted disease (STD) clinic, 107 nongonococcal urethritis and 176 prostitutes, were tested by microculture. The total prevalence of C. trachomatis in this three group people was 7.9%(?) 24.3% and 21.6%, respectively. Clinical analysis was also made on 26 Chlamydia-positive patients.2. A simple sample preparation precedure was developed for the PCR assay, which involved only addition of dilute alkali, pelleting cell debris in a microfuge, resuspending in a dilute alkali and heating 10 miniteSat 88℃ .This processing procedure has the effciency similar to that of detergent-proteinase K procedure. A total of 576 urogenital specimens from 176 prostitutes and 400 STD clinic patients were test for C. trachomatis by plasmid-based PCR and by cell culture. If a specimen produced a positive plasmid PCR result and a negative culture result, the PCR against major outer membrane protein gene (ompl) was taken into consideration. If the ompl PCR was postive, then the specimen was considered truly positive. The sensitivity of PCR and cell culture was 97.0% ~ 100% and 86.4% -87.9%, respectively. The specificity of PCR was 98.5% -99.7%. PCR had a positive predictive value (PPV) of 95.7% -96.9%, and a negative predictive value (NPV) of 99.7% -100%. A total of 100 STD clinic male patients were tested by the PCR in first void urine (FVU) and by cell culture in the urethra. The results show that the sensitivity of PCR and cell culture were 92.3% and 84.6%, respectively, the specificity were 98.9% and 100%, respectively. PCR had a PPV of 92.6% and a NPV of 98.9%. This study indicates that PCR is more sensitive than cell culture in detection of C. trachomatis in urogenital samples and male urine from patientsat high risk for STD, and may be a good alternative to culture in detecton of C. trachomatis.