Effects of age, race, sex, and smoking on prothrombin fragment 1.2 in a healthy population.

Prothrombin fragment 1.2 (F1.2) is a biomarker of thrombin generation during blood coagulation and has diagnostic potential for assessing thrombotic risk and monitoring anticoagulation therapy. We used a monoclonal antibody-based immunoassay for plasma F1.2 to establish a well-defined reference interval and to evaluate the effects of age, race, sex, and smoking status on F1.2 concentrations in a healthy population. Plasma samples and demographic information were obtained from 357 healthy individuals. F1.2 concentrations more closely followed a lognormal than a gaussian frequency distribution. In a multiple linear-regression model in which the logarithms of F1.2 concentrations were regressed on age, race, sex, and smoking status, the significant explanatory variables were age and, to a lesser extent, sex and smoking. A segmented "hockey stick" regression model indicated that F1.2 concentrations and age were unrelated for individuals < 44 years old but were positively correlated above that age threshold. The estimated 95% tolerance interval (P = 0.95) for F1.2 in healthy individuals < 44 years old (n = 268) was 0.21-2.78 nmol/L. We conclude that age-matched F1.2 reference intervals may be important for studies evaluating the diagnostic utility of F1.2 measurements, and that the clinical relevance of increased thrombin generation during aging warrants further investigation.

Test of cure for genital Chlamydia trachomatis infection in women.

Convenient, reliable tests of cure for genital chlamydial infections have not been evaluated. Cervical appearance, endocervical Gram stain, enzyme immunoassay, and culture for Chlamydia trachomatis were evaluated during a pretreatment visit and at two subsequent randomized test-of-cure visits for 64 nongravid women with endocervical C trachomatis of 3544 patients screened. There were no useful correlations between C trachomatis resolution and cervical appearance. Endocervical Gram stain was determined to be unreliable for test-of-cure use. Both C trachomatis culture and enzyme-linked immunosorbent assay (ELISA) were shown to be effective for test-of-cure evaluation. The ELISA test became reliably negative 10 days after initiation of treatment and 1 to 5 days after the clearance of viable organisms detected by culture (P = .03). Convenience and cost considerations favor antigen detection methods. This study suggests that antigen detection methods can be used for situations in which test of cure is indicated, such as therapy noncompliance, circumstances supporting reinfection, pregnancy, complicated infections, requests for psychological reassurance, and evidence of persistent cervicitis.

Rapid screening of urine for significant bacteriuria by Gram stain, acridine orange stain, and the Autobac MTS system.

Urine specimens submitted for microbiologic examination were screened for evidence of bacteriuria by three rapid methods: Gram staining, acridine orange staining, and the Autobac MTS system. The screening results were compared with those obtained by semiquantitative colony counts on agar plates. In this comparative study 1055 urine specimens were examined, of which 146 (13.8%) had colony counts of greater than or equal to 1 X 10(5)/ml. All three urine screening methods detected this level of bacteriuria at a sensitivity of 98% and a specificity of 55.2% (acridine orange), 66.0% (Gram stain), and 83.2% (Autobac), respectively. Of the 1055 urine specimens examined, 185 (17.5%) had colony counts of greater than or equal to 1 X 10(4)/ml, at which level the sensitivity of the three methods was 93% and the specificity was 56.7% (acridine orange), 68.0% (Gram stain), and 86.0% (Autobac), respectively. For any level of sensitivity, the Autobac urine screen was shown to be more specific than either the Gram stain or the acridine orange method. The acridine orange stain was the least specific urine screen, especially at the upper limits of sensitivity.