Comparison of hepatitis C viral loads in patients with or without human immunodeficiency virus.

A better understanding of how human immunodeficiency virus (HIV) coinfection affects the course of hepatitis C virus (HCV) infection is required to select patients with HIV who would benefit from current HCV therapy. Between June 1996 and March 2000, HCV RNA levels were quantified for 1,279 patients at the Louisiana State University Health Sciences Center; 28 of these patients were coinfected with HIV. HCV loads were quantified by the Bayer branched-DNA assay with a lower limit of detection of 0.2 Meq/ml. We compared the median HCV RNA levels of for patients coinfected with HIV and HCV and patients infected only with HCV who were in the same age range (23 to 55 years). The median HCV load for the 28 patients coinfected with HCV and HIV (17.8 Meq/ml) was significantly greater (P < 0.05) than that for similarly aged patients infected only with HCV (6.1 Meq/ml). The HCV load did not correlate with age or sex for either group of patients. A significant (R = -0.4; P < 0.05) negative correlation was observed between HCV load and CD4 count in the coinfected group, for whom the CD4 counts at the time of HCV load analysis ranged from 6 to 1,773/mm(3). The increased HCV load in patients coinfected with HCV and HIV compared to that in patients infected only with HCV and the inverse relationship of the HCV load to the CD4 count indicate that immunosuppression results in decreased control of HCV replication. In addition, we report significantly higher HCV loads among coinfected African Americans than Caucasians.

Validation of the Roche COBAS Amplicor system for Chlamydia trachomatis.

OBJECTIVE: Validation of the Roche Amplicor polymerase chain reaction (PCR) using the Comprehensive Bio-Analytical System (COBAS) automated PCR analyzer in our laboratory. DESIGN: Endocervical swab specimens for both EIA and PCR were collected from a total of 193 women. EIA for chlamydia was performed using the MicroTrak Chlamydia Kit (Wampole Labs, Cranbury, NJ). PCR was performed using Roche Amplicor reagents on the COBAS instrument. SETTING: Louisiana State University Health Sciences Center at Shreveport, Shreveport LA. PATIENTS: All cervical swab specimens, (n = 193), collected from patients presenting either to the Women's Health or Primary Care Clinic (Obstetrics and Gynecology and Family Practice) were included in this study. RESULTS: Most of the specimens, 138/193 or 71.5%, tested negative by both techniques. Three of the 193 specimens, 1.5%, were inhibitory for PCR since the internal control was negative. Fifty-one specimens, 26.4%, tested positive by both techniques or by PCR alone. No specimens were positive by EIA only. Twenty-eight of the 51 were positive by both methods, (14.5% of the total tested; 54.9% agreement among the specimens testing positive). An additional 23 were positive by PCR alone, i.e., 11.9% total discrepant positive specimens; 45% discordant results among the specimens testing positive). Seventeen PCR-positive specimens divided among four separate runs were retested by PCR. Of these, 15 were repeat positive, giving the test a reproducibility of 88.2%. CONCLUSIONS: Our results concur with previously published comparison data for EIA and PCR testing. We conclude that the PCR should detect a significantly increased number of chlamydia infections among our LSUHSC-S population, but there are drawbacks to using this technique. Specimen preparation time for PCR is almost twice as long as EIA, and the Roche PCR assay is not licensed for ocular specimens as is our EIA procedure. In addition, since neither technique is accepted for testing for medicolegal purposes, we must continue the use of culture for cases of suspected sexual abuse.

Clinical laboratory evaluation of a PCR assay for the detection of HCMV.

OBJECTIVE: In limited laboratory space and consonant with limited opportunities for contamination, to implement and incorporate into our diagnostic virology laboratory, a polymerase chain reaction assay for human cytomegalovirus detection with maximum sensitivity. DESIGN: Polymerase chain reaction, adapted for use with the enzyme uracil-n-glycosylase to avoid the potential for false positive reactions due to amplicon carryover was developed, optimized using two primer pairs, and performed on 361 specimens, i.e., body fluids and tissues submitted to the viral laboratory for detection of human cytomegalovirus. Polymerase chain reaction results were compared to shell vial assay. SETTING: Louisiana State University Health Sciences Center, Shreveport LA. MAIN OUTCOME MEASUREMENTS: Using the shell vial assay as the reference, analytical sensitivity (lower limit of detection) as well as laboratory sensitivity and specificity of both primer pairs. RESULTS: The lower limit of detection of our polymerase chain reaction assay was determined to be one focus-forming unit. Using the shell vial assay as the reference test, the sensitivity and specificity of both primer pairs were 96.5% and 94.3%, respectively. Polymerase chain reaction detected human cytomegalovirus in 6% of our culture-negative specimens. CONCLUSION: Based upon this study, our recommendations include the following: 1) a housekeeping gene amplification control is required for diagnostic polymerase chain reaction; 2) a single primer pair can be utilized for clinical work without sacrificing too much sensitivity; and 3) the laboratory should maintain close contact with clinicians to discuss polymerase chain reaction interpretation.