Anomalous first rib in a high school wrestler

The aim of the study was to compare the efficacy of pp65 antigenemia assay and the shell-vial culture (SVC; viremia) for the diagnosis of cytomegalovirus (CMV) infection in renal transplant recipients, comparing the results obtained in the first blood sample and the total number of blood samples analyzed in this group of patients. During the study period, 70 renal transplant recipients were studied: 44 (62.8%) with CMV infection. The method of sedimentation in a dextran solution for leukocyte extraction was used in the pp65 antigenemia assay. The MRC-5 shell-vial assay was used for CMV isolation from leukocytes (viremia). Eighty blood samples were examined from 70 renal transplant recipients: Of the 44 positive samples studied, in 77.5% of cases, both the antigenemia assay and the SVC were positive. In 16.2%, only the antigenemia assay was positive, and, in 6.2%, only the SVC was positive. In all blood samples studied, the antigenemia was present in 93.7% of cases, and the SVC was present in 83.7% (P = 0.04). If the results obtained in only the first blood sample taken for the diagnosis are studied, then we observe that the antigenemia assay was positive in 39 patients (88.6%), whereas the SVC was positive in 41 patients (93.1%), although the difference was not statistically significant (P = 0.39). It is concluded that the inoculation of all of the leukocytes extracted from blood samples in the SVC seems to produce a slight increase in the sensitivity of the cell culture and that the SVC becomes positive before the antigenemia for the detection of CMV in peripheral blood, especially in the first blood sample.     

Evaluation of sensitivity of 10 diagnostic assays for Chlamydia trachomatis by use of a simple laboratory procedure

AIMS: To determine the sensitivity of commercially available diagnostic assays for Chlamydia trachomatis using a simple method. METHODS: Nine commercial assays and an "in-house" polymerase chain reaction (PCR) were evaluated using serial dilutions of a laboratory grown H serovar--four of them using a laboratory grown E serovar. Seven of the assays were further tested using dilutions of several cervical samples known to contain chlamydiae. RESULTS: The most sensitive assays were the MicroTrak direct fluorescent antibody (DFA) test (Syva) and the PCR which detected C trachomatis at a 10(-8) dilution of the H serovar, while the two least sensitive, Clearview (Unipath) and TestPack (Abbott), were positive only at 10(-4) and 10(-3) dilutions, respectively. A range of enzyme immunoassays (EIAs) and a nucleic acid hybridisation test were of intermediate sensitivity. The results with serovar E were consistent with these. When clinical samples were examined, the DFA test detected C trachomatis in dilutions at least 10-fold greater than any other assay. CONCLUSIONS: The range of sensitivity of diagnostic assays determined by the laboratory dilution procedure is very wide. Sensitivity assessed in this way, however, reflects the ability of the assays to detect C trachomatis in large scale clinical trials. The dilution procedure, which is simple to undertake, could therefore be applied by any laboratory before a new diagnostic method is considered for routine use.     

Species differences in the metabolic activation of tamoxifen into genotoxic derivatives: risk assessment in women

A prospective study was conducted comparing the sensitivity of the pp65 antigenemia assay (AGA) to that of the shell-vial culture (SVC) inoculated with increasing quantities of polymorphonuclear leukocytes (PMNLs) in the detection of cytomegalovirus (CMV) in peripheral blood. From the cellular suspension, three SVCs were inoculated with 200,000, 400,000, and 800,000 PMNLs, respectively. Of the 201 patients studied, 67 (31.9%) had positive results in one of the two analytic tests (AGA or SVC). In this group, 13 (19.4%) presented a negative AGA assay; 13 (19.4%) an AGA of 1; 13 (19.4%) an AGA of between 2 and 5; and 28 (41.8%) an AGA with a value > 6 PMNL-positive x 100,000 PMNLs. The SVC inoculated with 200,000 PMNLs detected the presence of CMV in 42 cases (62.6%); 55 (82%) with 400,000; and 64 (95.5%) with 800,000. Statistically significant differences were observed between the isolation capacities of the SVC inoculated with 200,000 and 400,000, and the SVC inoculated with 800,000 PMNLs (p = 0.0001). In the comparison of the overall sensitivity of the AGA with that of the SVC with 200,000, the AGA was found to be significantly more sensitive (p = 0.0052). When comparing with the SVC with 400,000 PMNLs, the two techniques were found to be equally sensitive; and in the comparison with the SVC with 800,000, the culture displayed a greater detection sensitivity (p = 0.0023). According to these results, it seems evident that the increase in the absolute number of PMNLs inoculated in the SVC leads to a significant increase in the sensitivity of the SVC in the detection of low-level viremia by CMV.     

Prevalence of herpes simplex virus type 1- and 2- specific antibodies among the acute, recurrent, and provoked types of female genital herpes

Sixty-eight sera from the acute, recurrent, and provoked types of female genital herpes were compared for the seroprevalence of herpes simplex virus (HSV) types 1 and 2 by immunodot assay using HSV glycoprotein G. In the HSV-1-isolated patients, no HSV-2 antibodies were detected, whereas in the HSV-2-isolated patients, HSV-1 seroprevalence was 9% for the acute type, 89% for the provoked type (P < 0.005), and 55% for the recurrent type (P < 0.05). The natural history of female genital herpes and the possible protective role of pre-existing antibodies in preventing the acquisition or clinical manifestation of a subsequent HSV infection are discussed.     

Herpes simplex virus type 1 in brain and risk of Alzheimer's disease

BACKGROUND: The apolipoprotein E epsilon 4 (APOE-epsilon 4) allele is a risk factor for Alzheimer's disease (AD), but it is neither essential nor sufficient for development of the disease. Other factors-genetic or environmental-must therefore have a role. By means of a PCR we have detected herpes simplex virus type 1 (HSV1) in latent form in brains of elderly people with and without AD. We have postulated that limited reactivation of the virus causes more damage in AD patients than in elderly people without AD because of a difference in the hosts. We now report the APOE genotypes of AD patients and non-AD sufferers with and without HSV1 in brain. METHODS: DNA was extracted from 84 samples of brain from 46 AD patients (39 temporal lobe, 39 frontal lobe, three hippocampus) and from 75 samples of brain from 44 non-AD elderly people (33 temporal lobe, 36 frontal lobe, six hippocampus). PCR amplification was used to detect HSV1 thymidine kinase gene and the host APOE gene. FINDINGS: By multiple logistic regression, the APOE-epsilon 4 allele frequency was significantly higher in the patients positive for HSV1 in brain than in the HSV1-negative AD group, the HSV1-positive non-AD group, or the HSV1-negative non-AD group (52.8% vs 10.0%, 3.6%, and 6.3%, respectively). The odds ratio for APOE-epsilon 4 in the HSV1-positive AD group compared with HSV1-negative non-AD group was 16.8 (95% CI 3.61-77.8) and in the HSV1-negative AD group, 1.67 (0.21-13.4). We also compared APOE genotypes of 40 people who had recurrent cold sores and 33 non-sufferers; the APOE-epsilon 4 allele frequencies were 36% and 9%, respectively (p < 0.0001). INTERPRETATION: These findings suggest that the combination of HSV1 in brain and carriage of an APOE-epsilon 4 allele is a strong risk factor for AD, whereas either of these features alone does not increase the risk of AD. The findings in people with cold sores support our hypothesis that APOE-epsilon 4 and HSV1 together are damaging in the nervous system.     

Polymerase chain reaction on cerebrospinal fluid for diagnosis of virus-associated opportunistic diseases of the central nervous system in HIV-infected patients

OBJECTIVE: To assess the diagnostic reliability of polymerase chain reaction (PCR) on cerebrospinal fluid (CSF) for virus-associated opportunistic diseases of the central nervous system (CNS) in HIV-infected patients. DESIGN: CSF samples from 500 patients with HIV infection and CNS symptoms were examined by PCR. In 219 patients the PCR results were compared with CNS histological findings. METHODS: Nested PCR for detection of herpes simplex virus (HSV) type 1 or 2, varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and JC virus (JCV) DNA. Histopathological examination of CNS tissue obtained at autopsy or on brain biopsy. RESULTS: DNA of one or more viruses was found in CSF in 181 out of 500 patients (36%; HSV-1 2%, HSV-2 1%, VZV 3%, CMV 16%, EBV 12%, HHV-6 2%, and JCV 9%). Among the 219 patients with histological CNS examination, HSV-1 or 2 was detected in CSF in all six patients (100%) with HSV infection of the CNS, CMV in 37 out of 45 (82%) with CMV infection of the CNS, EBV in 35 out of 36 (97%) with primary CNS lymphoma, JCV in 28 out of 39 (72%) with progressive multifocal leukoencephalopathy. Furthermore, HSV-1 was found in one, VZV in four, CMV in three, EBV in three, HHV-6 in seven, and JCV in one patient without histological evidence of the corresponding CNS disease. CONCLUSIONS: CSF PCR has great relevance for diagnosis of virus-related opportunistic CNS diseases in HIV-infected patients as demonstrated by its high sensitivity, specificity, and the frequency of positive findings.     

Lowering the cut off value of an automated chlamydia enzyme immunoassay and confirmation by PCR and direct immunofluorescent antibody test

AIMS: To increase the sensitivity of an automated chlamydia enzyme immunoassay by significantly lowering its cut off value, and to maintain specificity by confirmation with polymerase chain reaction (PCR) and direct immunofluorescent antibody test (DFA). METHODS: Over five months, the cut off value of the enzyme immunoassay used to screen urogenital samples for chlamydia antigen was reduced from 80 to 10. Samples with a test value of 10 or above were further tested with a commercial PCR assay. All samples during the first three months and discrepant samples during the last two months of the study were also tested with the DFA. RESULTS: 3250 urogenital swabs (1246 urethral, 1335 endocervical, 669 pooled urethral/endocervical) from 1246 males and 2004 females were processed. Using the manufacturer's recommended cut off of 80, the enzyme immunoassay identified chlamydia antigen in 134 samples (4.1%). Using the lower cut off value of 10 and either PCR or DFA as the confirmatory test, Chlamydia trachomatis was identified in 178 samples (5.5%). Thus, 45 additional positive samples were identified and the confirmed detection rate was increased by 33.8% (45/133). Excluding equivocal PCR results, the concordance between DFA and PCR was 91.8%. This strategy increased the detection rate by 2.1% in men and 0.9% in women (significant only in men). In female patients, pooled urethral/endocervical swabs as a specimen gave a significantly higher yield than endocervical swabs regardless of whether the lower cut off strategy was used. CONCLUSIONS: This strategy of significantly lowering the cut off test value with confirmation on the same specimen by either PCR or DFA is feasible and cost effective. The use of pooled urethral/ endocervical specimens in females should be considered routinely as detection rate was significantly improved.     

The prevalence of herpes family virus DNA in the conjunctiva of patients positive and negative for human immunodeficiency virus using the polymerase chain reaction

OBJECTIVE: To help understand the pathogenesis of herpes family virus ocular infection among patients positive for HIV, the authors compared the rates of detection of herpes family virus DNA from the conjunctiva of patients who are positive and negative for human immunodeficiency virus (HIV) using the polymerase chain reaction (PCR). DESIGN: Cross-sectional study. PARTICIPANTS: The conjunctival scrapings of 30 patients positive for HIV and 30 patients negative for HIV were examined. INTERVENTION: PCR was used to assay for the presence of herpes simplex virus type 1 (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) DNA (n = 240 samples). MAIN OUTCOME MEASURE: The rate of detection of virus DNA in the two groups, controlling for age, gender, and race, was measured. RESULTS: HSV and VZV DNA were not detected in any of the HIV-positive or HIV-negative samples. CMV DNA was detected in 20% (6 of 30) of patients positive for HIV and was undetected in control subjects negative for HIV (P = 0.01). EBV DNA was detected in 40% (12 of 30) of patients positive for HIV and in 47% (14 of 30) of control subjects negative for HIV (P = 0.58). CONCLUSIONS: There was no difference in the frequency of detection of HSV, VZV, or EBV DNA from the conjunctiva of patients positive or negative for HIV. Only CMV DNA was detected at a significantly higher rate in the conjunctiva of patients positive for HIV compared with control subjects negative for HIV. These different rates of peripheral virus shedding may be one possible explanation for the different rates of clinical infection among the herpes family viruses among patients positive for HIV.     

Imaging herpes virus thymidine kinase gene transfer and expression by positron emission tomography

We report a series of studies that assess the feasibility and sensitivity of imaging of herpes virus type one thymidine kinase (HSV1-tk) gene transfer and expression with [124I]-5-iodo-2'-fluoro-1-beta-D-arabinofuranosyluracil ([124I]-FIAU) and positron emission tomography (PET) and the ability of [124I]-FIAU-PET imaging to discriminate different levels of HSV1-tk gene expression. Studies were performed in rats bearing multiple s.c. tumors derived from W256 rat carcinoma and RG2 rat glioma cells. In the first set, we tested the sensitivity of [124I]-FIAU-PET imaging to detect low levels of HSV1-tk gene expression after retroviral-mediated gene transfer. HSV1-tk gene transduction of one of preestablished wild-type W256 tumor in each animal was accomplished by direct intratumoral injection of retroviral vector-producer cells (W256-->W256TK* tumors). Tumors produced from W256 and W256TK+ cells served as the negative and positive control in each animal. Highly specific images of [124I]-FIAU-derived radioactivity were obtained in W256TK* tumors (that were transduced in vivo) and in W256TK+ tumors but not in nontransduced wild-type W256 tumors. The level of "specific" incorporated radioactivity in transduced portions of both W256TK* and W256TK+ tumors was relatively constant between 4 and 50 h. In the second set, we tested whether [124I]-FIAU and PET imaging can measure and discriminate between different levels of HSV1-tk gene expression. Multiple s.c. tumors were produced from wild-type RG2 cells and stably transduced RG2TK cell lines that express different levels of HSV1-tk. A highly significant relationship between the level of [124I]-FIAU accumulation [% injected dose/g and incorporation constant (Ki)] and an independent measure of HSV1-tk expression (sensitivity of the transduced tumor cells to ganciclovir, IC50) was demonstrated, and the slope of this relationship was defined as a sensitivity index. We have demonstrated for the first time that highly specific noninvasive images of HSV1-tk expression in experimental animal tumors can be obtained using radiolabeled 2'-fluoro-nucleoside [124I]-FIAU and a clinical PET system. The ability to image the location (distribution) of gene expression and the level of expression over time provides new and useful information for monitoring clinical gene therapy protocols in the future.     

Rapid detection and typing of herpes simplex virus DNA in clinical specimens by the hybrid capture II signal amplification probe test

A second-generation signal amplification, nucleic acid-based test for the rapid detection and typing of herpes simplex virus (HSV) DNA was developed and evaluated with artificial and clinical specimens. The analytical sensitivity of the Hybrid Capture II (HC II) HSV DNA assay was determined by testing either cloned HSV DNA or total genomic HSV DNA titrations and resulted in detection thresholds of between 5 x 10(3) and 1 x 10(4) copies per assay. Specificity was assessed by testing a panel of bacteria and viruses commonly found in the female genital tract. Sensitivity was assessed by testing 112 ulcerative genital lesions by the HC II assay and comparing the results to those obtained by routine cell culture. Discrepant results were resolved by PCR testing. After resolution of the discrepant results, the sensitivity of the HC II assay compared to the consensus result (the results of two of three tests, the HC II assay, culture, and PCR, were in agreement) was 93.2% (41 of 44 specimens), and the specificity was 100% (60 of 60 specimens). Culture gave a sensitivity of 84.1% (37 of 44 specimens) and a specificity of 100% (60 of 60 specimens) compared to the consensus result. The results of HSV typing by the HC II assay and culture agreed in all cases. The HC II assay is a rapid and accurate assay for detecting and typing HSV types 1 and 2, with a sensitivity comparable to that of culture and greater ease of use than culture.     

Detection of viral DNA in neonatal herpes encephalitis autopsy tissues by solution-phase PCR: comparison with pathology and immunohistochemistry

To detect DNA sequences of herpes simplex virus (HSV) in neural and non-neural tissue sections in disseminated human neonatal HSV infection, a solution polymerase chain reaction (PCR) protocol was developed which amplified HSV thymidine kinase and host genomic DNA sequences that were hybridized with sequence-specific probes in Southern blots. Serial sections of formalin-fixed, paraffin embedded autopsy tissues were tested by PCR and compared to histology and HSV antigen detection. The sensitivity, specificity and reproducibility of this PCR protocol were determined on uninfected and HSV-infected mouse tissues and on HSV DNA from infected tissue culture cells. Samples estimated to contain as few as 60 copies of preserved HSV DNA target sequence gave a positive PCR result. In nine neonates that died during acute HSV infection, all non-neural tissues and a minority of neural tissues with histological lesions had HSV antigen; when DNA could be amplified, HSV DNA sequences were detected by PCR. Together, these findings indicate a direct role for virus in the pathogenesis of these lesions. In the same cases, some or all brain samples were negative for HSV antigen, but nevertheless had HSV DNA sequences detected by PCR. The possible explanations for this finding are discussed. In one neonate dying seven weeks after birth, HSV sequences were found in brain lesions in the absence of HSV antigen; neither HSV DNA nor antigen were found in non-neural tissues, suggesting a latent HSV infection in brain. It is practical to apply PCR methods to detect minute quantities of viral DNA in formalin-fixed, paraffin embedded autopsy tissues.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of two nonculture antigen tests and three serotests for detection of anti-chlamydial antibodies in the diagnosis of ocular chlamydial infections

BACKGROUND: Diagnosis of chlamydial conjuctivitis is difficult in chronic diseases because chlamydial elementary bodies are mostly undetectable in conjunctival scrapings by cell culture. We therefore compared two nonculture antigen tests and three different serotests for anti-chlamydial antibodies with McCoy cell culture, the "gold standard" of chlamydial diagnosis. Conjunctival scrapings and serum samples of 93 patients attending the outpatient eye clinic in Graz because of chronic follicular conjunctivitis were tested. METHODS: A total of 558 conjunctival scrapings and 93 serum samples were investigated. Chlamydial antigen detection was done by McCoy cell culture, polymerase chain reaction (PCR; Amplicor, Roche), and direct immunofluorescence assay (DFA; Microtrak, Syva). Antichlamydial IgA and IgG antibodies in the sera were detected by an immunoperoxidase assay (IPAzyme, Savyon) and two different enzyme-linked immunosorbent assays (SeroELISA, Savyon and rELISA, medac). RESULTS: Cell culture and PCR yielded identical results. The positivity rate for chlamydial conjunctivitis was 8.6% (8 of 93 patients). PCR proved most sensitive and most specific. IPAzyme was 75% sensitive for IgA and 100% for IgG; SeroELISA and rELISA were less sensitive. IPAzyme was 81% specific for IgA and 47.3% for IgG. SeroELISA and rELISA were less specific for IgA, but more specific for IgG. Post-test likelihood of disease was greatest in IPAzyme. CONCLUSIONS: PCR proved to be a good alternative to cell culture; DFA is useful for quick diagnosis. Genus-specific serotests cannot compete with chlamydial antigen detection. They differ in sensitivity and specificity because of the antigen type they present. They are still of only supportive value in cases where chlamydial antigen detection is not possible. Recently introduced species-specific antibody tests should be of greater value.     

Detection of Chlamydia trachomatis in first-void urine from men and women as an alternative to swabs

BACKGROUND: Ideally, an effective preventive strategy for the control of Chlamydia trachomatis infection should take into account the following attributes: rapid and simple specimen collection, low cost and noninvasive test processing. Therefore, we compared the performance profile of urine-based detection of C. trachomatis antigen in first-void urine with that of testing urethral and endocervical samples in men and women. MATERIAL AND METHODS: Urethral and endocervical samples and first-void urine from 285 men and 192 women attending the Sexually Transmitted Diseases Outpatient Clinic at the Medical University in Plovdiv, Bulgaria were tested using direct immunofluorescence assay (DFA) (MicroTrak, Syva, Palo Alto, CA, USA). RESULTS: Seventy (25%) of all men tested were positive for C. trachomatis antigen in either urethral or urine samples. 65 men (93%) had both a positive urethral and urine sample, three men (4%) had only a positive urethral sample and two (3%) had only a positive urine sample. Thirty-five women (18%) had C. trachomatis infection. Twenty-six women (74%) had both a positive endocervical and urethral sample, 6 (17%) had only a positive endocervical sample and 3 (8%) had only a positive urethral sample. All women with positive urethral samples tested positive on their urine samples. Two of the women with a negative urethral sample and a positive endocervical sample had a positive urine sample. CONCLUSIONS: These results show that using direct immunofluorescence assay on first-void urine samples is a reliable noninvasive method which can replace urethral swabs in the diagnosis of C. trachomatis infection in symptomatic men. Urine-based strategies are also an acceptable alternative for the diagnosis of C. trachomatis infection in symptomatic women when it is not possible to obtain an urogenital sample.     

Structure and variation of mood in individuals with Parkinson's disease: A dynamic factor analysis.

Mood structure was examined among individuals diagnosed with Parkinson's disease. Twelve individuals completed a measure of positive and negative affect for 70 consecutive days. Mood structure was determined by using dynamic factor analysis (DFA) models that account for both concurrent and lagged relationships in repeated measurements. Five individuals had sufficient variability in positive and negative affect to conduct DFA on both sets of variables. Results showed the presence of 2 2-factor 1-lag models, 2 1-factor 1-lag models, and a P-technique model. There was sufficient variability in positive affect to conduct DFA on positive affect for the entire sample. Two individuals displayed 2-factor 1-lag models, 6 individuals had 1-factor 1-lag models, and 4 individuals showed P-technique models. Implications of lagged relationships are discussed from substantive and methodological perspectives. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Exchangeability of Qsr1p, a large ribosomal subunit protein required for subunit joining, suggests a novel translational regulatory mechanism

The incidence of herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) in herpes simplex encephalitis (HSE) was investigated using cerebrospinal fluid (CSF) samples from sixty-four cases of HSE. A polymerase chain reaction (PCR) employing primers flanking a region of the HSV thymidine kinase gene common to both HSV-1 and HSV-2 was used to detect HSV in the CSF. HSV-1 and HSV-2 were differentiated by digestion with restriction enzymes. Two enzymes were employed; Aval which cleaved only the HSV-2 gene product and Avall which cleaved only the HSV-1 gene product. Sixty-three cases of HSE were found to be due to HSV-1; one case due to HSV-2. These data confirm previous observations that HSV-2 is a rare cause of post-neonatal herpes encephalitis but indicates that a PCR procedure capable of detection of both viruses is essential for efficient diagnosis of HSE.     

Cytotoxic T lymphocyte activity after intravitreal inoculation of herpes simplex virus type I in mice

After inoculating mice with herpes simplex virus (HSV) by a corneal or intravitreal route, cytotoxic T lymphocyte (CTL) activity in the cervical lymph nodes and spleen was assayed. The spleen and cervical lymph nodes were removed at various points till 2 weeks after inoculation, and CTL activity was assayed in a groups: (A) mice intravitreally inoculated with HSV, and (B) mice with topical application of HSV. The reactivity of delayed type sensitivity was determined by the thickness of the mouse ear pinna on the 6th day in both groups. CTL activity in the spleen was at the same level in both groups. Up to 10 days after inoculation CTL activity in the cervical lymph nodes in group (A) was lower than in group (B). The reactivity of delayed type sensitivity in group (A) was lower than in group (B). These results indicate that an anterior chamber associated immune deviation (ACAID)-like phenomenon occurred after HSV inoculation into the vitreous cavity.     

Evaluation of the Biostar Chlamydia OIA assay with specimens from women attending a sexually transmitted disease clinic

Chlamydia trachomatis infections are the most prevalent sexually transmitted diseases (STDs) in the United States. In acute-care settings such as clinics and emergency rooms, a desirable chlamydia screening assay should exhibit good sensitivity and good specificity and should provide test results while the patient is still present. The Biostar Chlamydia OIA (Biostar, Inc., Boulder, Colo.) is an optical immunoassay (OIA) that provides test results in less than 30 min and that uses a test format that allows office-based testing. This assay is performed entirely at room temperature without the need for rotators or other specialized equipment. The goal of this study was to compare the performance of the Biostar Chlamydia OIA for the detection of C. trachomatis with the performance of cell culture, direct fluorescent-antibody (DFA) assay (Syva MicroTrak; Syva Co., Palo Alto, Calif.), and PCR (Roche Amplicor Chlamydia trachomatis; Roche, Branchburg, N.J.) for the detection of C. trachomatis infections in women attending an urban STD clinic. For calculations of relative test performance (sensitivity, specificity, and positive and negative predictive values), patient specimens that yielded positive results by two or more of the four assays (cell culture, DFA assay, PCR, and OIA) were classified as "true infections." By these criteria, 42 of 306 total specimens were classified as positive for C. trachomatis (positive prevalence, 13.7%), 11 (3.6%; 10 by PCR and 1 by DFA assay) were positive by a single assay, and 253 (82.7%) were negative by all four tests. All culture-positive specimens were also positive by at least one other assay. Among the culture-negative specimens, 14(5%) specimens were positive by two of the three non-culture-based assays used. By using the criterion that positivity by at least two of the tests indicated a true infection,the relative sensitivities were as follows: culture and PCR, 92.9% each; Biostar Chlamydia OIA, 73.8%; and DFA assay, 59.5%.