Prospective Comparison of Cell Cultures and Nucleic Acid Amplification Tests for Laboratory Diagnosis of Chlamydia trachomatis Infections

Abstract

Specimens submitted in M5 medium for cell culture detection of Chlamydia trachomatis were tested by nucleic acid amplification testing (NAAT) and in cell cultures. Of 35 (genital) and 26 (nongenital) specimens positive for C. trachomatis, 21 and 14 specimens, respectively, were detected exclusively by NAAT. NAAT is significantly (P < 0.0001) more sensitive than cell culture and should be considered the new "gold standard" for the laboratory diagnosis of C. trachomatis infections.Chlamydia trachomatis is the most common cause of reportable cases of sexually transmitted infections (7, 16). Sensitive, Food and Drug Administration (FDA)-approved nucleic acid amplification testing (NAAT) has replaced poorly standardized cell culture methods for the laboratory diagnosis of these infections (5,13,15,17).Specimens submitted to our laboratory with a specific request for C. trachomatis culture in M5 medium (Remel, Lenexa, KS) were inoculated into cell cultures and simultaneously processed by NAAT for both C. trachomatis and Neisseria gonorrhoeae (BDProbeTec ET). The goal of our study was to assess the performance characteristics of NAAT as a possible exclusive replacement for cell cultures for the testing of all specimens submitted for the laboratory diagnosis of C. trachomatis infections.Shell vials containing cycloheximide-treated McCoy cells (Diagnostic Hybrids Inc., Athens, OH) on coverslips were inoculated with 0.1 ml of the specimen extract in M5 transport medium and centrifuged at 700 ϫ g for 60 min. Cell cultures were incubated at 35°C for 48 h, stained with fluoresceinconjugated monoclonal antibody specific for C. trachomatis (Trinity Biotech Co., Wicklow, Ireland), and examined at 200 ϫ for the detection of C. trachomatis-infected cells (18).For NAAT, specimens (200 l) in M5 medium were placed into BD diluent, lysed by heating at 114°C for 30 min, and assayed by the BDProbeTec ET system using the BD Viper (BD Biosciences, Sparks, MD) for sample processing and detection of C. trachomatis and N. gonorrhoeae following the manufacturer's instructions.Of 383 genital specimens (cervix, 179; vagina, 166; urethra, 38) submitted to Mayo Clinic for cell culture diagnosis of C. trachomatis infections processed also by NAAT, 14 (3.7%) were positive for the organism by both methods (Table 1). Two specimens (cervix) were toxic in cell culture, and diagnostic results were not available by that method. In addition, 21 specimens were exclusively positive for C. trachomatis by NAAT (150% increase in the rate of detection compared with that of cell cultures). These 21 discrepant results were confirmed as positive by direct fluorescent antibody to specifically detect the elementary bodies of C. trachomatis (Tables 1 and 2). Importantly, there were no specimens that were detected by culture that were not detected by NAAT (100% specificity) ( Table 1). Of the 35 (14 plus 21) NAAT-positive C. trachomatis specimens, 5 (cervix, 4; vagina, 1) (14.3%) were also positive for both C. trachomatis and N. gonorrhoeae (Table 2). In addition,...

GenitalChlamydia trachomatisandNeisseria gonorrhoeaeinfections among women in sub-Saharan Africa: A structured review

“…This may be explained by logistic and operational challenges in culturing N. gonorrhoeae, the bacterial frailty and the known higher sensitivity of molecular assays. [143][144][145] This observation has implications for STI control programmes in these settings. Given lower performance of culture compared to molecular techniques, studies and health policies using culture are likely to underestimate the burden of STIs.…”

DNA Sequencing Validation ofChlamydia trachomatisandNeisseria gonorrhoeaeNucleic Acid Tests

“…However, it is now recognized that variation in the sensitivity and specificity of the comparator NAA tests themselves may significantly influence the performance estimates of the other test. [13][14][15] The problem is further complicated when this approach is applied to evaluate the NAA tests for N gonorrhoeae DNA detection because there is frequent horizontal genetic exchange occurring within the Neisseria genus, leading to commensal Neisseria species acquiring N gonorrhoeae genes. 16 Some N gonorrhoeae subtypes may even lack the specific DNA sequences targeted by a particular NAA test on the market.…”

Chlamydial Infection Prevalence in Human Immunodeficiency Virus Patients

“…1 Nowadays, polymerase chain reaction (PCR) method has been approved by the Food and Drug Administration (FDA) as the new gold standard for the diagnosis of chlamydial infection. 4 In comparison with culture, the PCR method has higher sensitivity in detecting chlamydial infection (90.4% vs 70.8%) which makes it the best method for screening. 5 Acquired immunodeficiency syndrome (AIDS) caused by human immunodeficiency virus (HIV) has become a great public health concern.…”