Date Published: August 29, 2017
Author(s): K. H. Chan, K. K. W. To, P. T. W. Li, T. L. Wong, R. Zhang, K. K. H. Chik, G. Chan, C. C. Y. Yip, H. L. Chen, I. F. N. Hung, J. F. W. Chan, K. Y. Yuen.
This study evaluated a new multiplex kit, Luminex NxTAG Respiratory Pathogen Panel, for respiratory pathogens and compared it with xTAG RVP Fast v2 and FilmArray Respiratory Panel using nasopharyngeal aspirate specimens and culture isolates of different swine/avian-origin influenza A subtypes (H2N2, H5N1, H7N9, H5N6, and H9N2). NxTAG RPP gave sensitivity of 95.2%, specificity of 99.6%, PPV of 93.5%, and NPV of 99.7%. NxTAG RPP, xTAG RVP, and FilmArray RP had highly concordant performance among each other for the detection of respiratory pathogens. The mean analytic sensitivity (TCID50/ml) of NxTAG RPP, xTAG RVP, and FilmArray RP for detection of swine/avian-origin influenza A subtype isolates was 0.7, 41.8, and 0.8, respectively. All three multiplex assays correctly typed and genotyped the influenza viruses, except for NxTAG RRP that could not distinguish H3N2 from H3N2v. Further investigation should be performed if H3N2v is suspected to be the cause of disease. Sensitive and specific laboratory diagnosis of all influenza A viruses subtypes is especially essential in certain epidemic regions, such as Southeast Asia. The results of this study should help clinical laboratory professionals to be aware of the different performances of commercially available molecular multiplex RT-PCR assays that are commonly adopted in many clinical diagnostic laboratories.
Respiratory tract infections (RTIs) are caused by various pathogens that are often indistinguishable from one another by clinical diagnosis. RTIs are a major cause of mortality, morbidity, and hospitalization, especially in children aged below five years, and pose significant economic burden [1–6]. Most RTIs are caused by viruses. Common respiratory viruses include influenza virus, adenovirus, parainfluenza virus, respiratory syncytial virus (RSV), human coronaviruses, human metapneumovirus (hMPV), and rhinovirus [7, 8].
In the recent years, the availability of molecular diagnostic tests has revolutionized the diagnosis and surveillance of infectious diseases and treatment of RTIs. Multiplexed molecular assays simultaneously detect multiple pathogens from the same sample in a single reaction vessel, providing a more comprehensive picture of infection. In this study, the clinical performance of the Luminex NxTAG RPP (CV-IVD) in NPA specimens was found to have high sensitivity (95.2%) and specificity (99.6%) for detection of respiratory viruses. These findings are similar to those reported in recent evaluation studies using NxTAG RPP (RUO) kit by other groups [18–20]. The performances of the NxTAG RPP, xTAG RVP, and FilmArray RP were also compared. Their results were highly concordant, with the highest concordance reported between NxTAG RRP and xTAG RVP [Kappa value = 0.97 (95% Cl: 0.95–0.99)].
In this study, the results showed that NxTAG RPP, xTAG RVP, and FilmArray RP assays had high sensitivity and specificity for diagnosis of respiratory diseases. They are suitable for use in clinical diagnostic laboratories for detection of respiratory pathogens in patients with RTIs. However, awareness should be raised that H3N2 could not be distinguished from H3N2v by NxTAG RPP. Further investigation should be performed if H3N2v is suspected to be the cause of disease.