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Journal of Clinical Microbiology, June 2007, p. 1993-1995, Vol. 45, No. 6
0095-1137/07/$08.00+0     doi:10.1128/JCM.00279-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Performance of a Rapid Assay (Binax NOW) for Detection of Respiratory Syncytial Virus at a Children's Hospital over a 3-Year Period{triangledown}

Andrea T. Cruz,1,2* Andreea C. Cazacu,2 Jewel M. Greer,3 and Gail J. Demmler2,3

Sections of Emergency Medicine,1 Infectious Disease, Department of Pediatrics, Baylor College of Medicine,2 Texas Children's Hospital Diagnostic Virology Laboratory, Houston, Texas3

Received 4 February 2007/ Returned for modification 22 March 2007/ Accepted 29 March 2007


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ABSTRACT
 
A rapid assay, Binax NOW RSV, was compared to viral culture for 14,756 pediatric respiratory specimens obtained from 2003 to 2006. There were 794 viral culture-confirmed respiratory syncytial virus infections. Sensitivity was 81%, and specificity was 93.2%. Sensitivity was greatest for neonates (91.1% versus 80.7% [P < 0.01]).


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TEXT
 
Respiratory syncytial virus (RSV) infection in children is associated with more than 90,000 hospital admissions/year nationally and as many as 1,000,000 deaths/year worldwide (12). It may be difficult to clinically differentiate RSV from other seasonal respiratory viruses. The rapid and accurate detection of RSV facilitates appropriate clinical management, including supportive care, hospital admission, isolation to decrease nosocomial transmission of the virus (3), antiviral treatment, and judicious antibiotic usage (1, 7, 10).

There are currently several commercially available methods for rapid RSV detection. Binax NOW RSV is an in vitro immunochromatographic assay for the detection of RSV fusion protein antigen. During the study period, this was the only rapid test used at our institution.

The study population consisted of all 14,756 consecutive fresh respiratory specimens collected from 10,341 patients at a 715-bed tertiary-care children's hospital between July 1, 2003 and June 30, 2006 for whom both rapid RSV test results and viral cultures were obtained. This study was exempt from the institutional review board. Specimens were obtained by respiratory therapists in a standardized manner and transported on ice to the virology laboratory. By institutional protocol, specimens tested by any rapid viral assay had concomitant viral tissue culture performed. Rapid assays were performed according to the manufacturer's package insert instructions. Results were interpreted by laboratory technicians based on the presence or absence of a pink-to-purple line, with appropriate positive and negative controls. Quality control measures included the use of internal kit positive and negative controls, as well as external laboratory controls on each test kit run.

All specimens were inoculated into three cell lines (rhesus monkey kidney, human foreskin fibroblast, and human lung carcinoma). This protocol allowed for detection of adenovirus, cytomegalovirus, herpes simplex virus, influenza viruses A and B, parainfluenza virus types 1 to 4, picornaviruses, and RSV. Viral culture has classically been the reference standard for the diagnosis of RSV, and positive rapid assays associated with positive viral cultures were considered true positives. Emerging modalities such as PCR or immunofluorescence were not routinely utilized. Sensitivity, specificity, and likelihood ratios were calculated using standard 2-by-2 tables. Seasons were defined as extending from July 1 to June 30 of the given years. High-prevalence months accounted for >75% of positive RSV specimens for a particular season.

A total of 14,756 specimens were obtained from July 1, 2003 through June 30, 2006. Of these, 14,202 (96.2%) were nasal wash specimens, 287 (1.9%) tracheal aspirates, 118 (0.8%) nasopharyngeal swabs, 68 (0.5%) sputum specimens, and 59 (0.4%) bronchoalveolar lavage specimens. Viral cultures were negative for 11,289 (76.5%) specimens, while 3,467 (23.5%) specimens grew at least one virus. The most common viruses isolated were RSV (794 isolates), rhinoviruses (699), influenza A virus (694), parainfluenza viruses (358), adenovirus (307), cytomegalovirus (242), and influenza B virus (162). The median patient age was 13.5 months (range, 0 days to 28.7 years).

Patient age and specimen source were analyzed a priori. There were 643 true-positive, 13,015 true-negative, 947 false-positive, and 151 false-negative assay results during the study period. Performance is shown in Table 1. The ability to rapidly and accurately diagnose RSV in young infants is important for at least two reasons. First, the risk of complications such as apnea may lead to admission of a baby with RSV bronchiolitis who otherwise appears well. Second, the diagnostic evaluation of a febrile neonate may be altered by knowledge of RSV status, given the appreciable risk of urinary tract infections and the decreased rate of other serious bacterial infections in this patient population (8). The sensitivity of the test was consistently and significantly higher for neonates under the age of 1 month.


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  		TABLE 1. Performance of the immunochromatographic assay compared to viral culture for the detection of RSV

Performance was analyzed by specimen source, because many rapid assays, though licensed for upper respiratory tract specimens, are often used to test lower respiratory tract specimens, such as tracheal aspirates (4, 6). While decreased sensitivity was noted for non-nasal wash specimens relative to nasal wash specimens, the preponderance of nasal wash specimens in this study population precluded statistical analysis.

Different studies have noted variable performance of similar assays. Five studies have evaluated Binax NOW with pediatric and adult populations (2, 6, 9, 11, 13); sensitivities of 74 to 100% were noted in pediatric studies using upper respiratory tract specimens, while the test demonstrated a sensitivity of only 33% for a small cohort of adult lower respiratory tract secretions. The specificities reported have been consistently higher, from 88.5 to 100%. In our center, the performance of this test, in terms of both sensitivity and specificity, was consistent over a 3-year period. The relatively lower sensitivity of the assay in the first year of the study may have been influenced by factors external to the test: the influenza A epidemic of 2003 resulted in an RSV epidemiologic curve that was both temporally shifted later into winter and of lower magnitude than that typically seen in this region. The stability of test performance in the latter two years of the study is reassuring, given the frequency with which clinical decisions are based on these rapid tests.

One limitation of the present study was that based on virology laboratory records, it was not possible to determine why patients had rapid viral testing performed. It is possible that, under certain circumstances, rapid assays are more clinically relevant than viral culture. For example, patients at the end of the natural course of RSV may have shedding of nonviable virions, which may be detected by a rapid assay but would not result in growth in tissue culture. Another limitation is that a sensitive method, such as direct fluorescence assays or RT-PCR, was not used to resolve discrepant results. Recent studies suggest that these methods may offer an advantage over traditional methods in some settings (5).

In summary, the Binax NOW RSV assay was sensitive and specific in detecting RSV infections over three consecutive winter seasons. This test performed particularly well for neonates, those children at highest risk for apnea and other severe complications of RSV disease. However, in view of the fact that both false-positive and false-negative results occurred, viral culture is recommended to confirm the rapid assay result and to detect the presence of other viruses for which rapid tests do not yet exist. The knowledge of the performance characteristics of different rapid viral assays is important for clinicians whose decisions may be influenced in part by the results of these diagnostic studies.

(These data were presented in part at the Society for Pediatric Research/Pediatric Academic Societies' annual meetings in May, 2005 [Washington, DC] and May, 2006 [San Francisco, CA].)


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FOOTNOTES
 
* Corresponding author. Mailing address: Texas Children's Hospital, 6621 Fannin Street, Suite A210/MC 1-1481, Houston, TX 77030-2399. Phone: (832) 824-5582. Fax: (832) 825-5424. E-mail: atcruz{at}texaschildrenshospital.org Back

{triangledown} Published ahead of print on 11 April 2007. Back


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REFERENCES
 
    1
  1. Adcock, P. M., G. G. Stout, M. A. Hauck, and G. S. Marshall. 1997. Effect of rapid viral diagnosis on the management of children hospitalized with lower respiratory tract infection. Pediatr. Infect. Dis. J. 16:842-846.[CrossRef][Medline]
    2. 2
  2. Borek, A. P., S. H. Clemens, V. K. Gaskins, D. Z. Aird, and A. Valsamakis. 2006. Respiratory syncytial virus detection by Remel Xpect, Binax NOW RSV, direct immunofluorescent staining, and tissue culture. J. Clin. Microbiol. 44:1105-1107.[Abstract/Free Full Text]
    3. 3
  3. Doherty, J. A., D. S. Brookfield, J. Gray, and R. A. McEwan. 1998. Cohorting of infants with respiratory syncytial virus. J. Hosp. Infect. 38:203-206.[CrossRef][Medline]
    4. 4
  4. Englund, J. A., P. A. Piedra, A. Jewell, K. Patel, B. B. Baxter, and E. Whimbey. 1996. Rapid diagnosis of respiratory syncytial virus in immunocompromised adults. J. Clin. Microbiol. 34:1649-1653.[Abstract]
    5. 5
  5. Freymuth, F., A. Vabret, D. Cuvillon-Nimal, S. Simon, J. Dina, L. Legrand, S. Gouarin, J. Petitjean, P. Eckart, and J. Brouard. 2006. Comparison of multiplex PCR assays and conventional techniques for the diagnosis of respiratory syncytial virus in children admitted to hospital with an acute respiratory illness. J. Med. Virol. 78:1498-1504.[CrossRef][Medline]
    6. 6
  6. Jonathan, N. 2006. Diagnostic utility of Binax NOW RSV—an evaluation of the diagnostic performance of Binax NOW RSV in comparison with cell culture and direct immunofluorescence. Ann. Clin. Microbiol. Antimicrob. 5:13-17.[CrossRef][Medline]
    7. 7
  7. Kneyber, M. C., A. H. Brandenburg, R. de Groot, K. F. Jooster, P. H. Rothbarth, A. Ott, and H. A. Moll. 1998. Risk factors for respiratory syncytial virus associated apnoea. Eur. J. Pediatr. 157:331-335.[CrossRef][Medline]
    8. 8
  8. Levine, D. A., S. L. Platt, P. S. Dayan, C. G. Macias, J. J. Zorc, W. Krief, J. Schor, D. Bank, N. Fefferman, K. N. Shaw, N. Kupperman, and the Multicenter RSV-SBI Study Group of the Pediatric Emergency Medicine Collaborative Research Committee of the American Academy of Pediatrics. 2004. Risk of serious bacterial infection in young febrile infants with respiratory syncytial virus infections. Pediatrics 113:1728-1734.[Abstract/Free Full Text]
    9. 9
  9. Mackie, P. L., E. M. McCormick, and C. Williams. 2004. Evaluation of Binax NOW RSV as an acute point-of-care screening test in a paediatric accident and emergency unit. Commun. Dis. Public Health 7:328-330.[Medline]
    10. 10
  10. Nichols, W. G., T. Gooley, and M. Boeckh. 2001. Community-acquired respiratory syncytial virus and parainfluenza virus infections after hematopoietic stem cell transplantation: the Fred Hutchinson Cancer Research Center experience. Biol. Blood Marrow Transplant. 7(Suppl.):11S-15S.[CrossRef][Medline]
    11. 11
  11. Ohm-Smith, M. A., P. S. Nassos, and B. L. Haller. 2004. Evaluation of the Binax NOW, BD Directigen, and BD EZ assays for detection of respiratory syncytial virus. J. Clin. Microbiol. 42:2996-2999.[Abstract/Free Full Text]
    12. 12
  12. Simoes, E. A. 1999. Respiratory syncytial virus infection. Lancet 354:847-852.[Medline]
    13. 13
  13. Zheng, X., S. Quianzon, Y. Mu, and B. Z. Katz. 2004. Comparison of two new rapid antigen detection assays for respiratory syncytial virus with another assay and shell vial culture. J. Clin. Virol. 31:130-133.[CrossRef][Medline]

Journal of Clinical Microbiology, June 2007, p. 1993-1995, Vol. 45, No. 6
0095-1137/07/$08.00+0     doi:10.1128/JCM.00279-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



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