Background. A broad array of pathogens causes influenza-like illness (ILI). Knowing etiology aids treatment and prevention. Novel multiplex diagnostic panels have been developed. Evaluating their performance on clinical isolates is warranted.
Methods. An observational study of febrile ILI among otherwise healthy subjects (0-65y, majority outpatient) is ongoing at five US military hospitals. Nasopharyngeal specimens are tested by single reaction PCR for influenza, human rhinovirus (HRV), and adenovirus. A subset of 403 specimens (78 influenza PCR-positive, 54 HRV PCR-positive, 10 adenovirus PCR-positive, 263 influenza-, HRV- and adenovirus PCR-negative) was tested by a target‐enriched multiplex PCR (TEM-PCR) panel for 13 bacterial and 10 viral respiratory pathogens (Diatherix Laboratories, Inc.; Huntsville, AL).
Results. Of 403 specimens, 387 were evaluated by TEM-PCR with 259 (67%) positive for at least one virus. Compared to single reaction PCR, the sensitivity/specificity of TEM-PCR was as follows: influenza A (94%, 99%); influenza B (65%, 99%); HRV (68%, 90%); adenovirus (40%, 100%). Viral detection rates were: HRV, n = 61 (16%); Influenza A, n = 51 (13%); Coxsackie/Echovirus, n = 45 (12%); Coronavirus, n = 42 (11%); RSV, n = 40 (10%); Parainfluenza, n = 32 (8%); Human Metapneumovirus, n = 18 (5%); Influenza B, n = 17 (4%); Adenovirus, n = 4 (1%); Bocavirus, n = 1 (0.3%). Decreased TEM-PCR panel sensitivity can be explained by suboptimal sample volume used for nucleic acid extraction.
A total of 304 (75.4%) specimens were positive for at least one bacterium. Bacterial detection rates were: pneumococcus (37.4%); Staphylococcus aureus (28.7%); Haemophilus influenzae (26.4%); Moraxella catarrhalis (23.2%). Influenza A detection was not associated with detection of pneumococcus, S. aureus, or H. influenzae. Influenza B detection was associated with detection of H. influenzae, while specimens positive for RSV were also positive for pneumococcus.
Conclusion. The sensitivity and specificity of the Diatherix panel for detecting Influenza A, the most clinically relevant of the viral pathogens, was high. It is unknown whether bacterial co-detection represents colonization or co-infection. Multiplex panels improve diagnostic yield for ILI.
Disclosures. L. Malone, Diatherix Laboratories, Inc.: Employee, Salary E. Grigorenko, Diatherix Laboratories, Inc. Employee, Salary