1232. Comparison of Molecular and Conventional Methods to Identify Respiratory Viruses in Hospitalized Infants and Toddlers with and without Symptoms of Respiratory Viral Illness (RVI)
Session: Poster Abstract Session: RSV and Other Viral Respiratory Infections in Children
Saturday, October 22, 2011
Room: Poster Hall B1
Background:Molecular diagnostics reportedly have increased sensitivity to detect respiratory viruses. Our objective was to compare molecular and conventional methods in a cohort of hospitalized children with and without symptoms of RVI and to determine the utility of molecular tests in hospitalized children. 

Methods: Retrospective cohort study of infants and toddlers hospitalized between December 1 2007 and March 15 2008. Conventional tests were performed on all patients and molecular tests were performed on available samples. Presence or absence of RVI symptoms was assessed by medical record review of all patients. Viruses were grouped into those routinely and those not routinely detected by conventional methods (Group 1 - adenovirus, influenza, respiratory syncytial virus, and parainfluenza; Group 2 - human metapneumovirus, rhinovirus, enterovirus and coronavirus).

Results:514 of 577 children (89%) were tested on admission; 306 (60%) had specimens available for molecular testing. In children with RVI symptoms (N=148) there was no difference in percent positive for Group 1 viruses comparing conventional vs. molecular methods (48.6% v 55.4%, p=0.24). Molecular tests identified Group 2 viruses in an equal percentage of symptomatic and asymptomatic patients (27.7% and 31.7%, p=0.45) and more Group 1 viruses in asymptomatic patients (10.1% v 4.4%, p=0.05). 

Conclusion: Molecular diagnostics did not significantly increase the detection of Group 1 viruses in patients with RVI symptoms. Molecular diagnostics detected an almost equal percentage of Group 2 viruses in symptomatic and asymptomatic children. These data highlight the importance of interpreting a positive test result using clinical context, the pretest probability of infection and local epidemiology.

 

Table 1. Patients with a positive test by RVI symptoms

 

RVI  Symptoms    (n=148)

No  RVI symptoms (n=158)

All patients     (n=306)

Conventional Testing1

     Group 1 viruses

72 (48.6%)

7 (4.4%)

86 (28.1%)

Molecular Testing 2

     Group 1 viruses

82 (55.4%)

16 (10.1%)

104 (34%)

     Group 2 viruses only

41 (27.7%)

50 (31.7%)

84 (27.4%)

1- immunochromatography, direct fluorescent antibody, shell vial culture, tube culture

2- Real time PCR, conventional PCR (amplicon detection by  mass spectrometry or flow cytometry)


Subject Category: P. Pediatric and perinatal infections

Sonali Advani, MBBS, MPH1, Michael Forman1, Arnab Sengupta, MBBS, MPH1, Charlotte Gaydos, DrPH2, Alexandra Valsamakis, MD, PhD1 and Aaron Milstone, MD, MHS1, (1)Johns Hopkins Medical Institutions, Baltimore, MD, (2)Sch. of Medicine, Johns Hopkins University, Baltimore, MD

Disclosures:

S. Advani, None

M. Forman, None

A. Sengupta, None

C. Gaydos, Ibis Biosciences: Grant Investigator, Grant recipient

A. Valsamakis, DHI/Quidel: Reagent support, one time advisory board participant, Consulting fee and Research support
Qiagen: Reagent support, one time advisory board participant, Consulting fee and Research support
Abbott/Ibis: funded diagnostic studies, Consulting fee and Research support

A. Milstone, None

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