Performance of a new immunochromatographic assay for detection of adenoviruses in children

Development of a prototype immunochromatographic test for rapid diagnosis of respiratory adenovirus infection

Human adenoviruses comprise an important group of etiologic agents that are responsible for various diseases in adults and children, such as respiratory, ocular, gastroenteric, and urinary infections. In immunocompromised and organ-transplanted individuals, these agents can cause generalized infections. Rapid diagnostic methods for detecting these infectious agents are not widely available.

The aim of this work was to produce monoclonal and polyclonal anti-adenovirus antibodies to be used in a rapid diagnostic test for respiratory infections.

Adenovirus hexons were satisfactorily purified by ultracentrifugation and chromatography. After virus purification, anti-hexon monoclonal antibodies were produced and characterized, following classical methods. Antibodies were specific for adenoviruses 2, 3, 5, and 41. The proposed immunochromatographic test was standardized using colloidal gold.

The standardization of the rapid test was sufficient to detect adenovirus antigens (in nasopharyngeal lavage samples) with sensitivity of 100% and specificity of 85% when compared to direct immunofluorescence.

The immunochromatographic assay prototype was sufficiently sensitive to detect B (3), C (2 and 5), and F (41) adenovirus samples. Although based on preliminary data, the test demonstrated the same performance as direct immunofluorescence, but with the advantage of being a point-of-care test. Further studies are still needed to confirm its effectiveness in clinical practice.

[Adenoviral keratoconjunctivitis]

Keratoconjunctivitis caused by adenoviruses (epidemic keratoconjunctivitis, EKC, ICD-10 B30.0+) is common, can be severe and may cause significant morbidity. In the early stages of adenoviral infections it is often difficult to differentiate the clinical presentation from other causes of a red eye. Because of its highly contagious nature that can rapidly lead to epidemic outbreaks, prompt viral identification and prevention of further spread are major challenges. Even today the diagnosis is still mainly clinical, with laboratory tests only rarely contributing. New diagnostic tests, such as the Rapid Pathogen Detector (RPS, Sarasota FL) AdenoPlus detection kit, that are practical, rapid and inexpensive to use in the general practice may obviate these problems. Because of its highly resistant properties to desiccation and highly developed escape mechanisms which protect the virus from the host's immune response, long-term problems often remain. Remnants of viral proteins often persist on the corneal surface of Bowman's layer for a long time and may lead to the formation of subepithelial infiltrates. No treatment other than symptomatic eye drops is available. The major sequelae are subepithelial infiltrates, which are difficult to treat. Cyclosporin A eye drops are a good option with a low risk profile. The use of topical steroids can possibly be disadvantageous but can be discussed at all stages of the disease. As nosocomial spread of adenoviruses is relatively common, preventive measures remain a major responsibility for ophthalmologists.

Viral exanthems: An update on laboratory testing of the adult patient

Although classic viral exanthems of childhood are well described, they are rarely differentiated in adults. Laboratory techniques for viral identification have advanced without substantial literature to suggest how a dermatologist ought to conduct a cost-effective and diagnostic viral panel. Certain clinical features such as petechiae, vesicles, and dusky macular or morbilliform exanthems point strongly toward a viral exanthem. Differentiation of drug and viral causes of morbilliform eruptions has proven difficult. It is possible that with further diagnostic refinement that unnecessary and fruitless workups of an exanthem and unneeded discontinuation of drugs can be avoided. We review viral exanthems based on clinical features and discuss the available and optimal laboratory techniques to assist the dermatologist in a targeted workup.

Evaluation of new immunochromatographic assay kit for adenovirus detection in throat swab: comparison with culture and real-time PCR results

A new immunochromatographic (IC) assay kit, BD Veritor System Adeno was evaluated to comparing with commercial available kit, BD Adeno Examan, cell culture, and real-time PCR using throat swab samples. Specimens were collected from 146 pediatric patients between July 2011 and January 2012. Mean age of patients was 4 years (8 months-15 years old). Patients were diagnosed with pharyngitis (n = 67), tonsillitis (n = 45), pharyngoconjunctival fever (n = 26), upper respiratory tract infection (n = 6), conjunctivitis (n = 1), or bronchitis (n = 1). Thirty-one of the patients (21.2%) had more than one disease. Among all samples, 61 (41.8%) were positive for adenovirus with BD Veritor System Adeno; 68 (46.6%) with BD Adeno Examan; 63 (43.2%) with real-time PCR; and 65 (44.5%) with cell culture. Serotype 3 (n = 41; 63.1%) was predominant among the 65 adenovirus isolates, followed by serotype 2 (n = 12; 18.5%), 1 (n = 6; 9.2%), 5 (n = 4; 6.2%), and 4 (n = 2; 3.1%). Relative sensitivity and specificity of BD Veritor System Adeno, BD Adeno Examan, and real-time PCR were 93.8% and 98.7%, 96.9% and 93.8%, and 96.9% and 100%, respectively. Positive predictive and negative predictive values for these methods were 98.4% and 95.1%, 92.6% and 97.4%, and 100% and 97.6%, respectively. The sensitivity and specificity of real-time PCR was greater than that of IC assay kits. However, IC assay kits also showed high sensitivity and specificity appropriate for clinical use.

Performance of a rapid multi-analyte 2-photon excitation assay in children with acute respiratory infection

The purpose of this study is to evaluate the diagnostic performance of the novel 2-photon excitation-based mariPOC© Assay (ArcDia Laboratories, Turku, Finland) for antigen detection of respiratory viruses versus real-time polymerase chain reaction (PCR). The mariPOC Assay and 2 multiplex real-time PCR techniques were performed on nasopharyngeal samples from pediatric patients with suspicion of acute respiratory infection admitted to a children's hospital in Spain during October 2011 to January 2013. A total of 233 samples were studied. Sensitivities and specificities (95% confidence interval) of the mariPOC Assay were for respiratory syncytial virus (RSV), 78.4% (69.7-85.6) and 99.2% (96.3-100.0); influenza virus (IFV) A, 66.7% (26.2-94.0) and 99.6% (97.9-100.0); IFV-B, 63.6% (33.6-87.2) and 100.0% (98.7-100.0); human metapneumovirus (hMPV), 60.0% (34.5-81.9) and 100.0% (98.6-100.0); adenovirus (ADV), 12.5% (0.6-48.0) and 100.0% (98.7-100.0), respectively. The mariPOC Assay is a highly specific method for simultaneous detection of 8 respiratory viruses but has sensitivities that range from moderately high for RSV to moderate for IFV and hMPV and low for ADV.

Immunochromatographic test for detection of adenovirus from respiratory samples: is it a real solution for pediatric emergency department?

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Rapid diagnosis of adenoviral respiratory infections is required in order to decide optimal treatment strategies.

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We evaluated the adenovirus antigen IC test Adeno Respiratory Letitest, versus the shell-vial culture and multiplex PCR.

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Using multiplex-PCR as the reference standard, the overall sensitivity was 77.89% and the specificity was 73.64%.

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It is a simple and rapid method for detection of adenovirus in pediatric respiratory samples.

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It would be necessary to improve the specificity and sensitivity of the test.

Rapid diagnosis of adenoviral respiratory infections is required in order to decide optimal treatment strategies. The adenovirus antigen immunochromatography Adeno Respiratory Card Letitest (Leti diagnostics, Barcelona, Spain), was evaluated versus the shell-vial culture and multiplex PCR (Clart Pneumovir Version 3.0, Genomica, Madrid, Spain), in nasopharyngeal washes and oropharyngeal swabs specimens from subjects with respiratory tract infections.

Between April 2011 and November 2012, 224 patients were included. The IC Adeno Respiratory Card Letitest was positive for 77.9% (74 of 95) of patients diagnosed at bedside. Using multiplex-PCR as the reference standard, the overall sensitivity was 77.9% and the specificity was 73.6%. Taking shell-viral culture as the reference method, the Adeno Respiratory Card Letitest (Leti diagnostics, Barcelona, Spain) sensitivity and specificity values were 80.0% and 60.9%, respectively. Using RT-PCR (Clart Pneumovir Version 3.0, Genomica, Madrid, Spain) as the reference standard, the viral culture sensitivity was 53.2% and the specificity was 100%.

The Adeno Respiratory Card Letitest (Leti diagnostics, Barcelona, Spain) assay could be a simple and rapid method for antigenic detection of adenovirus in pediatric respiratory samples although it would be necessary to improve the specificity and sensitivity of the test.

Non-invasive sample collection for respiratory virus testing by multiplex PCR

Background

Identifying respiratory pathogens within populations is difficult because invasive sample collection, such as with nasopharyngeal aspirate (NPA), is generally required. PCR technology could allow for non-invasive sampling methods.

Objective

Evaluate the utility of non-invasive sample collection using anterior nare swabs and facial tissues for respiratory virus detection by multiplex PCR.

Study design

Children aged 1 month–17 years evaluated in a pediatric emergency department for respiratory symptoms had a swab, facial tissue, and NPA sample collected. All samples were tested for respiratory viruses by multiplex PCR. Viral detection rates were calculated for each collection method. Sensitivity and specificity of swabs and facial tissues were calculated using NPA as the gold standard.

Results

285 samples from 95 children were evaluated (92 swab-NPA pairs, 91 facial tissue-NPA pairs). 91% of NPA, 82% of swab, and 77% of tissue samples were positive for ≥ 1 virus. Respiratory syncytial virus (RSV) and human rhinovirus (HRV) were most common. Overall, swabs were positive for 74% of virus infections, and facial tissues were positive for 58%. Sensitivity ranged from 17 to 94% for swabs and 33 to 84% for tissues. Sensitivity was highest for RSV (94% swabs and 84% tissues). Specificity was ≥95% for all viruses except HRV for both collection methods.

Conclusions

Sensitivity of anterior nare swabs and facial tissues in the detection of respiratory viruses by multiplex PCR varied by virus type. Given its simplicity and specificity, non-invasive sampling for PCR testing may be useful for conducting epidemiologic or surveillance studies in settings where invasive testing is impractical or not feasible.

Conjunctivitis: systematic approach to diagnosis and therapy

Conjunctivitis is a common problem in primary health care. Inflammation of the conjunctiva may result from infection or noninfectious causes. Microbial conjunctivitis may be caused by bacteria, viruses, or parasites. Although usually a benign, self-limited disease in healthy individuals, serious complications (eg, keratitis) may be sight-threatening. Accurate diagnosis and specific treatment of conjunctivitis remain challenging. History taking and physical examination are occasionally insufficient for correct diagnosis, thus laboratory testing may play a vital role in identification of specific pathogen(s). However, diagnostic testing has several limitations, including time-consuming methods, increased cost, and requirement for expertise in performance and interpretation. Treatment with empirical topical antibiotics for suspected infectious conjunctivitis is controversial. Although antibiotic treatment can diminish risk of adverse events and shorten the course of disease, drug resistance, toxicity, and expense are important considerations in management of acute infectious conjunctivitis.