Performance evaluation of two multiplex qualitative RT-PCR assays for detection of respiratory infection in paediatric population.

INTRODUCTION: Acute respiratory infection (ARI) contributes to significant mortality and morbidity worldwide and is usually caused by a wide range of respiratory pathogens. This study aims to describe the performance of QIAstat-Dx® Respiratory Panel V2 (RP) and RespiFinder® 2SMART assays for respiratory pathogens detection. MATERIALS AND METHODS: A total of 110 nasopharyngeal swabs (NPS) were collected from children aged one month to 12 years old who were admitted with ARI in UKMMC during a one-year period. The two qPCR assays were conducted in parallel. RESULTS: Ninety-seven samples (88.2%) were positive by QIAstat-Dx RP and 86 (78.2%) by RespiFinder assay. The overall agreement on both assays was substantial (kappa value: 0.769) with excellent concordance rate of 96.95%. Using both assays, hRV/EV, INF A/H1N1 and RSV were the most common pathogens detected. Influenza A/H1N1 infection was significantly seen higher in older children (age group > 60 months old) (53.3%, p-value < 0.05). Meanwhile, RSV and hRV/EV infection were seen among below one-year-old children. Co-infections by two to four pathogens were detected in 17 (17.5%) samples by QIAstat-Dx RP and 12 (14%) samples by RespiFinder, mainly involving hRV/EV. Bacterial detection was observed only in 5 (4.5%) and 6 (5.4%) samples by QIAstat-Dx RP and RespiFinder, respectively, with Mycoplasma pneumoniae the most common detected. CONCLUSION: The overall performance of the two qPCR assays was comparable and showed excellent agreement. Both detected various clinically important respiratory pathogens in a single test with simultaneous multiple infection detection. The use of qPCR as a routine diagnostic test can improve diagnosis and management.

Microtexture characterization of PZT ceramics and thin films by electron microscopy.

Crystallographic orientations of lead zirconate titanate, Pb(Zr(x),Ti(1-x))O(3) abbreviated PZT, were investigated by the technique of electron backscatter diffraction pattern (EBSP) in the scanning electron microscope (SEM). The samples included unpoled and poled ceramics and a thin film. Several hundreds of crystal orientations in the bulk ceramics and thin films were examined by EBSP and the results were plotted in microtexture pole- and inverse pole-figures for determination of the average and local preferred orientations. In addition, local textures in certain selected regions in PZT ceramics and the misorientations between the nearest neighboring grains were also determined.