Direct detection of Mycobacterium tuberculosis by means of a commercial ligase chain reaction DNA amplification method (LCx M. tuberculosis; Abbott Diagnostics Division, Abbott Park, Ill.) was investigated with 511 (including 147 extrarespiratory) specimens collected from 358 patients. LCx results were compared with standard microbiological data, and conflicting cases were resolved according to the final clinical diagnosis. M. tuberculosis was detected in 45 of 358 subjects by means of the LCx test. The test was negative for all 30 specimens with mycobacteria other than M. tuberculosis. The sensitivity, specificity, and positive and negative predictive values for the LCx test, compared with culture results, were 93.90, 92.31, 70.00, and 98.75%, respectively; these values rose in resolved cases to 95.53, 99.25, 97.27, and 98.75%, respectively. With respiratory specimens, for which the LCx system is licensed, the sensitivity reached 98.97%. In patients with a final clinical diagnosis of tuberculosis the sensitivity of the LCx system was 89.36% compared to 82.98% for cultures and 78.72% for microscopy. We conclude that the LCx test is user friendly, rapid, fairly sensitive, and highly specific. It can also be effectively used on extrapulmonary specimens provided possible false-negative results are taken into account. However, the use of LCx test appears to be less appropriate for the monitoring of antituberculosis therapy, as the majority of samples from treated tuberculosis patients gave consistently positive results, despite the sterilization of cultures.

No abstract

A panel of 104 isolates belonging to the species Mycobacterium kansasii and 78 mycobacterial isolates belonging to other species was tested in parallel with the present commercially available DNA probe (Accu-Probe; Gen-Probe) and with a new probe just developed by the same manufacturer. While the old version of the probe confirmed the previously reported low sensitivity (only 59% of the M. kansasii isolates reacted), the new one was 100% sensitive. Only two non-M. kansasii strains, both M. gastri isolates, gave false-positive hybridization results.

Background and aims: Hepatitis C virus (HCV) represents a major worldwide public health problem requiring global action for the diagnosis, treatment and prevention of this infection. HCV is the leading cause of chronic liver disease, including chronic hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma and it is responsible for about 350,000 deaths yearly. Anti-HCV assays remain the first choice for screening HCV infection in most clinical laboratories. The anti-HCV VIDAS® (bioMérieux, Marcy L’Etoile, France) test has been recently launched and we aimed to evaluate its performance compared with other widely used methods. <br />Materials and methods: Routine anti-HCV screening of clinical samples was carried out on the ARCHITECT® i2000SR platform (Abbot Laboratories, Abbott Park, IL, USA); out of 8876 samples tested from October 2012 to May 2013, 70 sera with low positive anti-HCV results (1≤S/CO&lt;8) were collected. These samples were tested for the presence of anti-HCV antibodies using anti-HCV VIDAS® and INNO-LIATM HCV score assays (Innogenetics NV, Ghent, Belgium). <br />Results and conclusions: Positive anti-HCV results were obtained in 61.4% and 41.4% of sera tested with VIDAS® and INNO-LIATM, respectively. Concordance between methods was 63.2% for ARCHITECT® and VIDAS®, 42.6% for ARCHITECT® and INNO-LIATM, and 79.4% for VIDAS® and INNO-LIATM. Anti-HCV VIDAS® demonstrated superior specificity compared to the anti-HCV test ARCHITECT®; therefore, this assay has been introduced in our routine analysis as a second level screening test to select samples to be subjected to confirmatory anti- HCV immunoblot.

The LCx Mycobacterium tuberculosis ligase chain reaction system (Abbott Diagnostic Division, Abbott Park, Ill.) was used to detect M. tuberculosis in 150 consecutive BACTEC vials on the day on which a positive growth index (GI) was recorded. By LCx, M. tuberculosis DNA was detected in BACTEC vials on average 2.6 days before the presence of acid-fast bacilli could be confirmed by microscopic examination. A total of 106 of 108M. tuberculosis isolates were detected without centrifugation from bottles presenting very low GIs (average, 70; median, 33). No false-positive result was obtained from nontuberculous mycobacteria or from isolates with contaminants.