Performance Evaluation of the Verigene Gram-Positive and Gram-Negative Blood Culture Test for Direct Identification of Bacteria and Their Resistance Determinants from Positive Blood Cultures in Hong Kong.

BACKGROUND: A multicenter study was conducted to evaluate the diagnostic performance and the time to identifcation of the Verigene Blood Culture Test, the BC-GP and BC-GN assays, to identify both Gram-positive and Gram-negative bacteria and their drug resistance determinants directly from positive blood cultures collected in Hong Kong. METHODS AND RESULTS: A total of 364 blood cultures were prospectively collected from four public hospitals, in which 114 and 250 cultures yielded Gram-positive and Gram-negative bacteria, and were tested with the BC-GP and BC-GN assay respectively. The overall identification agreement for Gram-positive and Gram-negative bacteria were 89.6% and 90.5% in monomicrobial cultures and 62.5% and 53.6% in polymicrobial cultures, respectively. The sensitivities for most genus/species achieved at least 80% except Enterococcus spp. (60%), K.oxytoca (0%), K.pneumoniae (69.2%), whereas the specificities for all targets ranged from 98.9% to 100%. Of note, 50% (7/14) cultures containing K.pneumoniae that were missed by the BC-GN assay were subsequently identified as K.variicola. Approximately 5.5% (20/364) cultures contained non-target organisms, of which Aeromonas spp. accounted for 25% and are of particular concern. For drug resistance determination, the Verigene test showed 100% sensitivity for identification of MRSA, VRE and carbapenem resistant Acinetobacter, and 84.4% for ESBL-producing Enterobacteriaceae based on the positive detection of mecA, vanA, blaOXA and blaCTXM respectively. CONCLUSION: Overall, the Verigene test provided acceptable accuracy for identification of bacteria and resistance markers with a range of turnaround time 40.5 to 99.2 h faster than conventional methods in our region.

In-house human immunodeficiency virus-1 genotype resistance testing to determine highly active antiretroviral therapy resistance mutations in Hong Kong.

OBJECTIVE: To determine the frequency of highly active antiretroviral therapy resistance mutations in the viral pol gene of human immunodeficiency virus-1 (HIV-1) genotypes that circulate in Hong Kong, by means of an in-house HIV-1 genotyping system. DESIGN: Retrospective study. SETTING: Two HIV clinics in Hong Kong. PATIENTS: A modified in-house genotyping resistance test was used to sequence the partial pol gene in 1165 plasma samples from 965 patients. The performance of our test was cross-compared with the US Food and Drug Administration-approved ViroSeq HIV-1 genotyping system. The results of genotyping were submitted to the Stanford HIV-1 drug resistance database for analysis. RESULTS: The cost-effective in-house genotypic resistance test (US$40) demonstrated comparable performance to the US Food and Drug Administration-approved ViroSeq system. The detection limit of this in-house genotypic resistance test could reach 400 copies/mL for both HIV-1 subtype B and CRF01_AE, which were the predominant genotypes in Hong Kong. Drug resistance mutations were detected only in post-treatment samples from treatment-failure patients. However, there was no significant difference in the frequency of drug resistance mutations between subtype B and CRF01_AE. CONCLUSION: Our cost-effective in-house genotypic resistance test detected no significant difference in drug resistance-related mutations frequencies between HIV-1 subtype B and CRF01_AE in Hong Kong. A drug resistance-related mutations database for different HIV-1 genotypes should be established in Hong Kong to augment guidance for HIV treatment.

Berberine and its more biologically available derivative, dihydroberberine, inhibit mitochondrial respiratory complex I: a mechanism for the action of berberine to activate AMP-activated protein kinase and improve insulin action.

OBJECTIVE: Berberine (BBR) activates AMP-activated protein kinase (AMPK) and improves insulin sensitivity in rodent models of insulin resistance. We investigated the mechanism of activation of AMPK by BBR and explored whether derivatization of BBR could improve its in vivo efficacy. RESEARCH DESIGN AND METHODS: AMPK phosphorylation was examined in L6 myotubes and LKB1(-/-) cells, with or without the Ca(2+)/calmodulin-dependent protein kinase kinase (CAMKK) inhibitor STO-609. Oxygen consumption was measured in L6 myotubes and isolated muscle mitochondria. The effect of a BBR derivative, dihydroberberine (dhBBR), on adiposity and glucose metabolism was examined in rodents fed a high-fat diet. RESULTS; We have made the following novel observations: 1) BBR dose-dependently inhibited respiration in L6 myotubes and muscle mitochondria, through a specific effect on respiratory complex I, similar to that observed with metformin and rosiglitazone; 2) activation of AMPK by BBR did not rely on the activity of either LKB1 or CAMKKbeta, consistent with major regulation at the level of the AMPK phosphatase; and 3) a novel BBR derivative, dhBBR, was identified that displayed improved in vivo efficacy in terms of counteracting increased adiposity, tissue triglyceride accumulation, and insulin resistance in high-fat-fed rodents. This effect is likely due to enhanced oral bioavailability. CONCLUSIONS: Complex I of the respiratory chain represents a major target for compounds that improve whole-body insulin sensitivity through increased AMPK activity. The identification of a novel derivative of BBR with improved in vivo efficacy highlights the potential importance of BBR as a novel therapy for the treatment of type 2 diabetes.