Comparison of the IMDx influenza A virus, influenza B virus, and respiratory syncytial virus A/B assay on the m2000 platform with real-time reverse transcriptase PCR assays

Clinical validation of the FluChip-8G Influenza A+B Assay for influenza type and subtype identification

BACKGROUND

The FluChip-8G Influenza A+B Assay is a multiplexed influenza RT-PCR and microarray-based assay with same day turnaround time, developed to subtype seasonal A viruses (H1N1pdm2009 and H3N2), distinguish B viruses as Yamagata or Victoria lineage, and is the only FDA cleared assay capable of positive identification of a wide variety of A subtypes as "non-seasonal" A viruses from human nasal specimens.

OBJECTIVE

To evaluate clinical performance of the FluChip-8G Influenza A+B Assay for detection of seasonal influenza viruses in nasal and nasopharyngeal swab specimens, and to evaluate performance for detection of non-seasonal influenza viruses using contrived samples.

STUDY DESIGN

For seasonal viruses, a multisite study of the FluChip-8G Influenza A+B Assay using prospectively and retrospectively collected nasal and nasopharyngeal swabs was performed using the FDA-cleared CDC Human Flu Dx Panel as the comparator assay. For non-seasonal viruses, testing was performed at a single site using contrived samples from 100 unique non-seasonal strains representing 41 subtypes.

RESULTS

Sensitivity (95% CI) and specificity (95% CI) for each target group, respectively, from results of 1689 clinical specimens were: seasonal H1N1pdm2009: 96.4% (87.9-99.0), 99.3% (98.8-99.6), seasonal H3N2: 91.8% (87.7-94.7), 99.7% (99.2-99.9), Influenza B Victoria: 100% (94.0-100.0), 99.9% (99.6-100.0), and Influenza B Yamagata: 95.6% (89.2-98.3), 99.9% (99.6-100.0). The sensitivity and specificity from contrived influenza A non-seasonal viruses was determined to be 99.0% (94.6-99.8) and 100% (96.7-100.0).

CONCLUSION

The FluChip-8G Influenza A+B Assay has robust sensitivity and specificity for detecting and identifying all target virus groups, including non-seasonal influenza A, with same day results.

Respiratory RNA Viruses

Acute upper and lower respiratory infections are a major public health problem and a leading cause of morbidity and mortality worldwide. At greatest risk are young children, the elderly, the chronically ill, and those with suppressed or compromised immune systems. Viruses are the predominant cause of respiratory tract illnesses and include RNA viruses such as respiratory syncytial virus, influenza virus, parainfluenza virus, metapneumovirus, rhinovirus, and coronavirus. Laboratory testing is required for a reliable diagnosis of viral respiratory infections, as a clinical diagnosis can be difficult since signs and symptoms are often overlapping and not specific for any one virus. Recent advances in technology have resulted in the development of newer diagnostic assays that offer great promise for rapid and accurate detection of respiratory viral infections. This chapter emphasizes the fundamental characteristics and clinical importance of the various RNA viruses that cause upper and lower respiratory tract diseases in the immunocompromised host. It highlights the laboratory methods that can be used to make a rapid and definitive diagnosis for the greatest impact on the care and management of ill patients, and the prevention and control of hospital-acquired infections and community outbreaks.

Performance of the Alere™ i Influenza A&B and the Cepheid Xpert® Flu/RSV XC assays

Aim: To evaluate the Alere™ i Influenza A&B assay and the Xpert® Flu/RSV XC assay using nasopharyngeal aspirates and swabs not provided in the commercial kits. Methods: Specimens were tested with the Alere i Influenza A&B and the Xpert Flu/RSV XC assays and compared with reference methods. Results: Compared with the comparator methods and following discordant analysis, the sensitivity of the i Influenza A&B assay was 63.3% for influenza A and 83.3% for influenza B. For the Xpert Flu/RSV XC assay, sensitivity was 100% for influenza A and B and respiratory syncytial virus. The specificity for all test systems was 100%. Conclusion: The Xpert Flu/RSV XC assay out-performed the Alere i Influenza A&B assay in all diagnostic characteristics evaluated.

Respiratory Outbreak Investigations: How Many Specimens Should Be Tested?

To determine the optimal number of specimens for virus detection in a respiratory outbreak, laboratory results from 2 Canadian public health laboratories were reviewed. The evidence suggests that 3 specimens are sufficient for detection of a virus in >95% of outbreaks, thereby reducing laboratory costs.

Infect. Control Hosp. Epidemiol. 2015;36(11): 1344–1347