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Background and Objectives: More information is needed on the natural history of Chlamydia trachomatis urethral infections in men. Newer assays for detecting antigens in male first void urine and urethral swabs identify patients for control programs. A new microparticle enzyme immunoassay from Abbott Laboratories called IMX Select Chlamydia was evaluated and compared with culture and an expanded gold standard for sensitivity and specificity. Study Design: Paired samples of first void urine and two urethral swabs were tested from 230 men, 73% of whom had symptoms of urethritis. Both specimen types were tested with IMX Select, the other swab was cultured, and a part of the first void urine was tested by Chlamydiazyme enzyme immunoassay. Performance calculations were made against urethral culture and an expanded gold standard that included direct fluorescent staining of discordant specimens by Microtrak. Results: Compared with urethral swab culture, the IMX Select test performed on urethral swabs and first void urine had sensitivities of 93.8% and 81.3%, and specificities of 95.2% and 95.7%, respectively. Calculations of sensitivity and specificity based on the expanded gold standard were: IMX Select on urethral swabs, 88.5% and 99.4%; IMX Select on first void urine, 80.8% and 100%; Chlamydiazyme after blocking confirmation on first void urine, 73.1% and 100%; culture on urethral swabs, 61.5% and 100%. Conclusion: This IMX Select Chlamydia enzyme immunoassay, which generates laboratory results within 2 hours, performed better than culture and an established enzyme immunoassay on male urethral swabs. The experimental first void urine protocol showed promise for noninvasive mate testing., A new test appears effective in detecting chlamydia infection of the male urethra in urine samples and urethral swabs. Two urethral swabs and a urine specimen were collected from 203 men attending a sexually transmitted disease clinic. One swab was cultured, the best currently known method of diagnosis, and the other underwent the IMX Select Chlamydia immunoassay. The urine specimen underwent the IMX Select assay as well as other assays for comparison purposes. Using urethral swabs, the IMX Select assay correctly identified 93.8% of infected men compared with swab culture results. Testing the urine sample, the IMX assay correctly identified 81.3% of infected men compared with swab culture results. The IMX Select assay has the advantages of providing results within two hours, and it shows promise of being the first noninvasive diagnostic test for chlamydia infections in men.

Background and Objectives: Chlamydia trachomatis antigen testing of clinical specimens is replacing culture as the test of choice. Because of a potential for false positive results in low prevalence populations, there is an apparent need for confirming specimens positive by enzyme immunoassay (EIA). Goal of this Study: To examine specimens falsely positive in the Chlamydiazyme EIA assay according to gender and specimen type. Study Design: Testing of genitourinary specimens from men and women consecutively enrolled from five health care delivery sources in an urban Canadian population. All specimens were initially tested in the Chlamydiazyme test and all positives repeated in a confirmatory blocking assay provided by the manufacturer. Additional confirmatory testing was performed using immunofluorescence (IF) staining for C. trachomatis elementary bodies (EB's) and polymerase chain reaction (PCR). Results: From Jan. 1, 1990 to June 1, 1991, multiple specimens from 656 men and 5,628 women of varying population prevalences were screened. EIA-positive specimens from women had a repeat negative rate of 22% to 27% from cervical swabs and 29% from urethral swabs. Male urethral swabs had a high repeat negative rate of 22% when EIA was the only positive test, but 2.4% when the specimen was positive by EIA and culture. EIA-positive first void urine (FVU) specimens from men had a repeat negative rate of 8.7% as opposed to 17% to 32% from women. Only 1.7% (2/115) of male FVU did not block compared to rates of 47% (22/47) to 80% (4/5) in FVU from women. Analysis of EIA optical densities (OD's) and EB counts showed an association between the absorbance range 0.1 to 1.4 OD and 0-85 EB's. The greatest number of EB's and highest OD's were seen with cervical specimens, followed by urine and urethral specimens in women infected at all three specimens. All 55 specimens that did not confirm in the blocking test had no EB's and a convenience sample of seven were negative by PCR. All of a subset of 50 blocked specimens contained EB's or were positive by PCR. Conclusions: Although a variable proportion of specimens may not repeat positive in the EIA, use of the blocking reagent to confirm the repeat positives is highly recommended and the rate of blocking may be heavily influenced by gender and specimen type., Gender and specimen type may affect the prevalence of false-positive test results on the Chlamydiazyme enzyme immunoassay (EIA). The Chlamydiazyme EIA is a laboratory test used to diagnose infections of the urogenital tract caused by Chlamydia trachomatis. Researchers used different methods to test multiple specimens from 6,284 individuals who were initially tested for chlamydial infection using the Chlamydiazyme EIA. Twenty-two percent to 27% of the specimens taken from women by cervical swabs had false-positive results on the Chlamydiazyme EIA. Twenty-nine percent of the specimens taken from women by urethral swabs had false-positive results. In men, 22% of specimens taken from urethral swabs had false-positive results on the Chlamydiazyme EIA. False-positive test results were more prevalent among urine specimens taken from men than among those from women.

Background and Objectives: The detection of asymptomatic urethritis using a leukocyte esterase (LE) strip may have a role in primary care screening to select men who need diagnostic testing for Chlamydia trachomatis and Neisseria gonorrhoeae. Study Design: Eight-hundred and eighty-two men, 16 to 35 years of age were studied when they attended their family physician or university health clinic for nongenitourinary complaints. First void urine (FVU) was tested by an LE strip (Chemstrip 2 LN, Boehringer Mannheim Corp., Indianapolis, IN), Chlamydiazyme (Abbott Laboratories, N. Chicago, IL) enzyme immunoassay with confirmatory blocking and polymerase chain reaction (PCR) with chlamydial plasmid primers. Results: Forty-five men (5.1%) were positive (> trace) by LE strip. Of the LE-positive urines, 9 (20.0%) were positive by EIA or PCR, and none of the LE-negatives were positive by EIA or PCR. Twenty-three LE positives (5 EIA/PCR-positive; 1 PCR-positive; 17 EIA/PCR-negative) were able to be followed with a second urine and 2 urethral swabs. All of the 6 chlamydia-positives who had follow-up tests were positive by both immunoassay and PCR on urine. Based on the FVU results, the prevalence of asymptomatic chlamydial infection was 1.0% (9/882) (95 % CI, 0.5 to 1.9) for which the LE urine strip was 100% (9/9) sensitive and 95.9% (837/873) specific. Analyses based on screening 1,000 men, 16 to 25 years of age, showed that the cost per case detected was $192.00 using the LE strip (> 1 +) to select urine specimens for EIA testing, compared to $1,326.00 using the EIA to test all urine specimens. Conclusion: In this low prevalence, primary care setting, the LE urine strip was an accurate screening test, which if used to preselect urine specimens for subsequent chlamydial testing, would be less costly per case detected than assaying each specimen for chlamydia., A cost-effective and efficient means of screening asymptomatic men for Chlamydia trachomatis or Neisseria gonorrhoeae infection is to test a urine specimen with a leukocyte esterase (LE) strip. The leukocyte esterase (LE) strips screen for elevated white blood cell counts which could indicate infections. Men with positive LE results can then be referred for further enzyme immunoassay testing and treatment. Results of LE analysis of urine samples of 882 sexually active men on routine visits to their doctors varied according to which cutoff value was used. The lower the cutoff value, the greater the accuracy in predicting that chlamydia would be diagnosed by the more sensitive enzyme immunoassay method. One percent of the men screened with LE strips tested positive. The cost of one screening by LE strip was estimated at 1.70 Canadian dollars and the enzyme screening was estimated at 15.51 Canadian dollars.

Traditionally, evaluations of nonculture assays for Chlamydia trachomatis are based on a comparison with urethral culture in men and cervical culture in women as the standard for positivity of infection, but it is known that culture may be less than 100% sensitive. A chemiluminometric immunoassay, Magic Lite (Ciba Corning, Medfield, MA) that detects C. trachomatis antigens was performed on centrifuged first void urine samples and urethral swabs collected from men attending a sexually transmitted disease (STD) clinic. Immunoassay performance was compared to urethral culture and also to a broader gold standard: an infected patient with positive culture results or a confirmed positive Chlamydiazyme enzyme immunoassay (Abbott, Chicago) result. Two studies were performed on a retrospective group of stored first void urine samples from 200 men and a prospective group of urethral swabs and first void urine samples from 199 men. Expanding the gold standard showed that a urethral swab assayed by culture had a sensitivity between 70.3% and 87.5%, with the following effects on immunoassay performance in the prospective study: the sensitivity of urethral swabbing was reduced from 96.2% to 78.4% (specificity increased from 96.0% to 98.1%) and first void urine sensitivity increased from 92.3% to 94.6% (specificity went from 87.9% to 93.8%). In the retrospective study, sensitivity of first void urine testing went from 91.4% to 92.5%, with a corresponding increase in specificity from 93.9% to 96.9%. This maneuver had relatively little impact on the negative predictive values, but dramatically increased the positive predictive values, for both samples. Expansion of the gold standard provides a clearer understanding of the performance characteristics of each assay and the contribution to diagnosis of each specimen type.

* Background.--Since chlamydial cervicitis is not associated with specific complaints, screening asymptomatic women is an important initiative to prevent pelvic inflammatory disease and its sequelae. Compared with universal screening, selective screening is less costly but less effective so the cost savings vs the consequences of missing infected women need to be weighed carefully. Methods.--In two family planning clinics, 1002 women were surveyed for chlamydial infection (prevalence, 7%) and its predictors to determine whether universal or selective screening is the most efficient strategy. Two rules for the selection of patients were determined by logistic regression modeling and their relative efficiencies were compared by incremental cost-effectiveness and sensitivity analysis. The validity of the screening rules was tested in 191 students attending a university health clinic. Results.--If those with cervical friability, suspicious discharge, urinary frequency, or intermenstrual bleeding had been tested, 55.3% of all women would have been screened and 83.3% of all cases would have been detected. If those reporting a new sex partner in the preceding year had also been tested, 75.4% would have been screened, identifying 93.3% of all cases. The predictive power and practicality of the selection rules were validated in the university health clinic sample. Sensitivity analyses showed selective screening using cervical enzyme immunoassay with blocking confirmation was efficient if the prevalence of chlamydial infection was 16% or less, 11 % or less, or 5 % or less depending on whether base analyses, overestimated costs, or worst performance scenarios, respectively, were used. Conclusions.--Selective screening based on four or five predictors and confirmed cervical enzyme immunoassay is an effective and efficient strategy in low prevalence settings. (Arch Intern Med. 1992;152:1837-1844)

Chlamydia trachomatis is a bacteria-like organism that causes pelvic infections, which may result in infertility. Although testing for C. trachomatis infection is cost-effective, the most appropriate testing methods and sites of sampling have not been clarified. Infection with C. trachomatis may be detected by obtaining a sample of tissue from the cervix, the urethra, or the day's first voided urine (FVU). The samples are tested for the growth of C. trachomatis in culture, a laboratory procedure in which the growth of the organism is enhanced. In addition, infection can also be determined by using enzyme immunoassay (EIA) methods to identify the presence of antigens, or elements of the organism that can trigger an immune response. The effectiveness of sampling the cervix, urethra, and FVU was assessed in 937 women by using culture and EIA techniques. According to culture results or EIA, C. trachomatis was detected at either the cervix or urethra in 67 cases, the cervix in 64 cases, and the urethra in 40 cases. Of the 67 infections, C. trachomatis was confirmed in both cervical and urethral tissue in 37 specimens; from only urethral tissue in 3 specimens and in only the FVU in none. Of the 67 women who tested positive for C. trachomatis infection, only 25 had positive tests using the FVU sample. The combined use of cervical culture and EIA detected C. trachomatis infection in 95.5 percent of cases, compared with 76.1 percent of infections detected by culture and 79.1 percent by EIA of cervical tissue. (Consumer Summary produced by Reliance Medical Information, Inc.)