Molecular techniques for the detection of Chlamydia trachomatis

Abstract

San Diego, Calif.) was compared with a culture reference method for the detection of Chlamydia trachomatis. Using stock isolates of each of the 15 serovars (A to K, Ba, Lt, L2, and L3) of C. trachomatis, the lower limit of sensitivity for the DNA probe ranged between 1,086 inclusion-forming units (IFU) for serovar E (Bour) to 2,930 IFU for serovar Lt (440), with the only exception being serovar C (TW-3), with which 99 IFU was detected. There was no cross-reactivity with Chlamydia psittaci (Texas turkey) and Chlamydia pneumoniae (TWAR-183). Bacterial and fungal isolates representing 14 species of normal vaginal fora as well as Neisseria gonorrhoeae gave negative results with the DNA probe when tested at a level of 1.5 x 107 CFU/mI. In addition, the DNA probe, a direct fluorescent-antibody stain (DFA) (MicroTrak; Syva Corp., Palo Alto, Calif.), and an enzyme-linked immunosorbent assay (Chlamydiazyme; Abbott Laboratories, North Chicago, 111.) were compared with culture for the detection of C. trachomatis, using 196 clinical cervical samples. Of the 196 samples, 20 (10%) were culture positive. Of the 176 culture-negative samples, 1 was not evaluated by DNA probe and 4, because of a lack of cellular material, were not evaluated by DFA. The sensitivities of the DNA probe, DFA, and enzyme-linked immunosorbent assay were 60, 75, and 85%, respectively, and specificities were 95, 99, and 97%, respectively. Of the false-positive direct results, there was only one specimen with which more than one direct method was positive, and with this specimen all three direct methods were positive. The majority of false-negative results by the direct methods were from specimens which by the culture method gave <100 IFU per culture.

Infection with a plasmid-free variant Chlamydia related to Chlamydia trachomatis identified by using multiple assays for nucleic acid detection

“…In addition, a potential advantage of nucleic acid detection as a method of diagnosing infections is the ability to detect nonculturable microorganisms. Nucleic acid hybridization and PCR assays have frequently been reported to detect the presence of C. trachomatis in culture-negative specimens (5,15,19,24). These results are usually attributed to either the presence of nonviable organisms or, in some cases of PCR, a false-positive reaction.…”

Performance of a commercial polymerase chain reaction test for endocervical Chlamydia trachomatis infection in a university hospital population

“…10,11 These serovars are poor antigens, so serodiagnosis has not been helpful. Identification of the organism by more affordable tests such as enzyme immunoassay, 12 direct fluorescent antibody staining, 13 Pap test, 14 and DNA probes 15 is relatively insensitive. Culture of the organism is slow, labor intensive, and expensive but has traditionally been taken as the gold standard for laboratory diagnosis of genital chlamydial infection.…”

Reproducibility problems with the AMPLICOR PCR Chlamydia trachomatis test

“…Swabs and transport media for PCR were provided with the AMPLICOR assay kit. Culture was performed within 24 h of sample collection as described previously (13). Briefly, 24-to 48-h-old monolayers of McCoy cells contained in glass vials (15 by 45 mm) were inoculated with 0.2 ml of specimen and centrifuged at 1,000 ϫ g at 30ЊC for 1 h. Afterward, 1 ml of Eagle's minimum essential medium containing fetal bovine sera (10%), gentamicin (50 g/ml), and cycloheximide (1.0 g/ml) was added.…”