Technical and clinical validation of three commercial real-time PCR kits for the diagnosis of neuroborreliosis in cerebrospinal fluid on three different real-time PCR platforms

This study reports the evaluation of the technical and clinical validation of the O-DiaBorburg kit (DIA), Borrelia burgdorferi PCR kit, ISEX (GENE), and Borrelia burgdorferi sensu lato Real-TM (SAC) for the diagnosis of neuroborreliosis in cerebrospinal fluid based on both Borrelia DNA and CSF samples from patients with clinical suspicion of neuroborreliosis. This validation study was done by analysing the kits on the Rotorgene Q (RGQ), CFX96, and LightCycler480 (LC480). For all kits, the linear range was larger on RGQ than on CFX96 and LC480. A good reproducibility was obtained for all assays on all instruments. Storage at -20 °C resulted in a decreased reproducibility for SAC. Results of the limit of detection (LOD₉₅) experiments indicated a better sensitivity than described in the kit insert for all kits on all PCR platforms. No cross-reactivity was found for genetically related organisms nor for other pathogens which may be present in CSF. All species of the Borrelia burgdorferi sensu lato complex were detected with the GENE and SAC kits. The DIA kit failed to detect B. lusitaniae. The results seemed to indicate a better overall performance for the GENE kit on RGQ. However, its diagnostic value could not be confirmed in the clinical validation study, wherein none of the 103 CSF samples from clinical neuroborreliosis cases showed a positive real-time PCR result with the GENE kit analysed on RGQ.

Timely diagnosis of respiratory tract infections: evaluation of the performance of the Respifinder assay compared to the xTAG respiratory viral panel assay

Background

Respiratory tract infections are the most common cause of hospitalization in infants and young children and are typically caused by viral or, less commonly, bacterial pathogens.

Existing non-molecular diagnostic methods have several drawbacks such as limited sensitivity, long turn-a-round time and limited number of pathogens that can be detected.

Objectives

Nucleic acid amplification methods can increase sensitivity and enable the initiation of appropriate interventions without delay.

Broad-spectrum detection and identification circumvent the use of individual diagnostic DNA or RNA based assays. At present, several commercial assays are available for broad-spectrum detection.

Study design

We compared the performance of the xTAG Respiratory Viral Panel (RVP) (Luminex Molecular Diagnostics, Toronto, Canada) with that of the Respifinder (Pathofinder, Maastricht, Netherlands) for 9 external quality assurance (EQA) panels (QCMD, Scotland) consisting of a total of 106 EQA samples.

Results

Both the RVP and the Respifinder assay have an excellent specificity. Sensitivity was 33% and 78% for the RVP and the Respifinder assay, respectively. For both assays, sensitivity was low for weak positive samples.

Discussion

The results of our study seem to indicate a better sensitivity for the Respifinder. Analysis of patient samples is necessary to evaluate the clinical performance.

Reflections and proposals to assure quality in molecular diagnostics

Molecular diagnostic testing has become an important tool in clinical laboratories. Accreditation according to the international quality standard ISO15189:2007 for medical laboratories is required for reimbursement of several molecular diagnostic tests in Belgium. Since the ISO15189:2007 standard applies to medical laboratories in general, the particular requirements for quality and competence are mentioned in general terms, not taking into account the specificities of molecular biology testing. Therefore, the working group "MolecularDiagnostics.be" described a consensus interpretation of chapter 5, Technical requirements, of the ISO standard for application in molecular diagnostic laboratories. The manuscript can be used as an instrument to prepare internal and external audits that meet the 15015189:2007 (chapter 5) criteria.

Outbreak of Klebsiella pneumoniae strain harbouring an AmpC (DHA-1) and a blaSHV-11 in a Belgian hospital, August-December 2006

A hospital in the northwest of Belgium has recorded 22 clinical isolates of Klebsiella pneumoniae expressing an unusual pattern of antibiotic susceptibility when testing for extended-spectrum beta-lactamases (ESBL) between August and December 2006.