Predictive Accuracy and Densitometric Analysis of Point-of-Care Immunoassay for Adenoviral Conjunctivitis.

Purpose: Accurate diagnosis of adenoviral conjunctivitis (Ad-Cs) is important for timely and appropriate patient management to reduce disease transmission. This study assessed the diagnostic accuracy of a commercially available point-of-care adenovirus immunoassay and determined whether its predictive accuracy is influenced by signal intensities of test result bands. Methods: Point-of-care immunoassay (AdenoPlus) testing and quantitative polymerase chain reaction (qPCR) testing was performed on conjunctival swab samples obtained from eyes of 186 eligible adult participants with presumed infectious conjunctivitis and symptoms of ≤4 days. Masked observers assessed signal intensities of the immunoassay test and control bands using densitometry. Results: Ad-Cs was confirmed by qPCR in 28 of the 56 eyes that tested positive on the AdenoPlus, a 50% positive predictive value (95% confidence interval [CI] = 36.9, 63.1). No adenovirus was detected by qPCR in 128 of 130 eyes that tested negative on AdenoPlus, a 98.5% negative predictive value (CI = 96.3, 100). Sensitivity and specificity were 93% (CI = 84.4, 100) and 82% (CI = 76.0, 88.1), respectively. Viral titers significantly correlated with ratio of test band signal intensities (R2 = 0.32, P = 0.002). Higher positive predictive value was associated with higher densitometry ratios (receiver operating characteristic [ROC] area = 0.71; 95% CI = 0.59, 0.83). Conclusions: Densitometric analyses suggest that the diagnostic accuracy of AdenoPlus is influenced by the signal intensity of the test result bands. Visual comparison of the test band intensities by clinicians could reduce the false positive rate of point-of-care immunoassays and aid in the diagnosis of viral infections. Translational Relevance: Ratiometric densitometry of point-of-care immunoassays could aid clinicians' decision making in diagnosing infectious diseases, including Ad-Cs.

Efficacy of a Single Administration of 5% Povidone-Iodine in the Treatment of Adenoviral Conjunctivitis.

PURPOSE: To evaluate the safety and efficacy of a single, in-office administration of 5% povidone-iodine (PVP-I) compared to artificial tears (AT) for adenoviral conjunctivitis (Ad-Cs). DESIGN: Double-masked pilot randomized trial. METHODS: Patients presenting with presumed adenoviral conjunctivitis were screened at 9 U.S. clinics. INCLUSION CRITERIA: ≥18 years of age, symptoms ≤4 days, and a positive AdenoPlus test. EXCLUSION CRITERIA: thyroid disease, iodine allergy, recent ocular surgery, and ocular findings inconsistent with early-stage Ad-Cs. Randomization was to a single administration of 5% PVP-I or AT in 1 eye and examinations on days 1-2, 4, 7, 14, and 21 with conjunctival swabs taken at each visit for quantitative polymerase chain reaction. Primary outcome was percent reduction from peak viral load. Secondary outcomes were improvement in clinical signs and symptoms. RESULTS: Of 56 patients randomized, 28 had detectable viral titers at baseline. Day 4 posttreatment, viral titers in the 5% PVP-I and AT groups were 2.5% ± 2.7% and 14.4% ± 10.5% of peak, respectively (P = .020). Severity of participant-reported tearing, lid swelling, and redness as well as clinician-graded mucoid discharge, bulbar redness, and bulbar edema were lower in the 5% PVP-I group than AT group on day 4 (P < .05). After day 4, viral titers and severity of signs and symptoms decreased markedly in both groups and no differences between groups were detected. CONCLUSIONS: Pilot data suggest a single, in-office administration of 5% PVP-I could reduce viral load and hasten improvement of clinical signs and symptoms in patients with Ad-Cs.

Analytical performance determination and clinical validation of the novel Roche RealTime Ready Influenza A/H1N1 Detection Set.

The emergence of a novel pandemic human strain of influenza A (H1N1/09) virus in April 2009 has demonstrated the need for well-validated diagnostic tests that are broadly applicable, rapid, sensitive, and specific. The analytical performance and clinical validity of results generated with the novel Roche RealTime Ready Influenza A/H1N1 Detection Set using the LightCycler 2.0 instrument were characterized. Analytical performance was assessed by processing respiratory samples spiked with H1N1/09 and seasonal influenza A virus, a set of seasonal influenza A virus subtypes, and samples containing common viral and bacterial respiratory pathogens. The clinical validity of results was assessed in comparison to other assays by analyzing 359 specimens at three clinical sites and one reference laboratory. Direct sequencing was used to resolve samples with discrepant results. The assay detected virus concentrations down to <50 RNA copies per reverse transcription (RT)-quantitative PCR (qPCR). Various influenza A virus subtypes were covered. The analytical specificity was 100%. High clinical validity was demonstrated by the 99% positive agreement between seasonal influenza A viruses, 98% positive agreement between H1N1/09 viruses, and 88% agreement between negative results. The analytical sensitivity was compared to those of three other RT-qPCR assays and was found to be equivalent. The novel Roche RealTime Ready Influenza A/H1N1 Detection Set can be utilized on the widely used LightCycler platform. We demonstrate its usefulness for the rapid detection and surveillance of pandemic H1N1/09 influenza A virus infections.

C-reactive protein mediates protection from lipopolysaccharide through interactions with Fc gamma R.

C-reactive protein (CRP) is a component of the acute phase response to infection, inflammation, and trauma. A major activity of acute phase proteins is to limit the inflammatory response. It has been demonstrated that CRP protects mice from lethal doses of LPS. In the mouse, CRP binds to the regulatory receptor, FcgammaRIIb, and to the gamma-chain-associated receptor, FcgammaRI. The goal ofthis study was to determine whether FcgammaRs are necessary for the protective effect of CRP. The ability of CRP to protect mice from a lethal dose of LPS was confirmed using injections of 500 and 250 micro g of CRP at 0 and 12 h. CRP treatment of FcgammaRIIb-deficient mice increased mortality after LPS challenge and increased serum levels of TNF and IL-12 in response to LPS. CRP did not protect FcR gamma-chain-deficient mice from LPS-induced mortality. Treatment of normal mice, but not gamma-chain-deficient mice, with CRP increased IL-10 levels following LPS injection. In vitro, in the presence of LPS, CRP enhanced IL-10 synthesis and inhibited IL-12 synthesis by bone marrow macrophages from normal, but not gamma-chain-deficient mice. The protective effect of CRP appears to be mediated by binding to FcgammaRI and FcgammaRII resulting in enhanced secretion of the anti-inflammatory cytokine IL-10 and the down-regulation of IL-12. These results suggest that CRP can alter the cytokine profile of mouse macrophages by acting through FcgammaR leading to a down-regulation of the inflammatory response.

Protection from Streptococcus pneumoniae infection by C-reactive protein and natural antibody requires complement but not Fc gamma receptors.

Streptococcus pneumoniae is an important human pathogen and the most common cause of community-acquired pneumonia. Both adaptive and innate immune mechanisms provide protection from infection. Innate immunity to S. pneumoniae in mice is mediated by naturally occurring anti-phosphocholine (PC) Abs and complement. The human acute-phase reactant C-reactive protein (CRP) also protects mice from lethal S. pneumoniae infection. CRP and anti-PC Ab share the ability to bind to PC on the cell wall C-polysaccharide of S. pneumoniae and to activate complement. CRP and IgG anti-PC also bind to Fc gamma R. In this study, Fc gamma R- and complement-deficient mice were used to compare the mechanisms of protection conferred by CRP and anti-PC Ab. Injection of CRP protected wild-type, FcR gamma-chain-, Fc gamma RIIb-, and Fc gamma RIII-deficient mice from infection. Complement was required for the protective effect of CRP as cobra venom factor treatment eliminated the effect of CRP in both gamma-chain-deficient and wild-type mice, and CRP failed to protect C3- or C4-deficient mice from infection. Unexpectedly, gamma-chain-deficient mice were extremely sensitive to pneumococcal infection. This sensitivity was associated with low levels of natural anti-PC Ab. Gamma-chain-deficient mice immunized with nonencapsulated S. pneumoniae produced both IgM- and IgG PC-specific Abs, were protected from infection, and were able to clear the bacteria from the bloodstream. The protection provided by immunization was eliminated by complement depletion. The results show that in this model of systemic infection with highly virulent S. pneumoniae, protection from lethality by CRP and anti-PC Abs requires complement, but not Fc gamma R.