Rapid antigen testing for detecting RSV in neonates found effective

Yen AB. Pediatr Infect Dis J. 2011;30:234-237.

Using rapid antigen testing to detect respiratory syncytial virus in neonates was effective, according to researchers in Houston.

Researchers from the Baylor College of Medicine retrospectively analyzed a database of respiratory syncytial virus (RSV) antigen testing in children aged 30 days or younger. The database spanned from 1997 to 2008 and was provided by the Diagnostic Virology Laboratory at Texas Children’s Hospital.

Of the 3,691 neonate samples, 21% were positive for RSV by rapid RSV testing. Viral cultures from 25.4% of specimens indicated the growth of at least one virus; the top three viruses isolated were RSV (n=445), rhinovirus (n=195) and influenza A (n=138).

Respiratory specimens obtained tended to be nasal wash specimens (n=3,590). There were 76 tracheal aspirates and 25 unspecified respiratory samples. Researchers found no statistical difference in sensitivity, specificity, positive predictive value or negative predictive value based on specimen type; however, when samples were analyzed according to RSV season, nasal washes were more sensitive than tracheal aspirates (P=.017) in-season. Most specimens (87.8%) were in-season samples. Sensitivity of the rapid RSV test was higher in RSV in-season samples (P=.048); specificity was lower in RSV in-season samples (P≤.001), according to the study’s lead author, Amy B. Yen, MD.

Samples were collected in the ED (70.3%), the inpatient floor (3.9%), the neonatal ICU (13.2%) and from unspecified areas of the hospital (12.6%). The rapid test seemed less specific in samples from neonates evaluated in the ED compared with those collected from neonates elsewhere in the hospital (P≤.001).

During RSV in-season months, neonate samples collected in the ED has less specificity compared with samples collected in the inpatient (P=.019), neonatal ICU (P≤.001) and unspecified areas (P≤.001). During periods when RSV was considered out of season, samples collected in areas other than the ED, inpatient and neonatal ICU areas were less sensitive (P=.028, .046 and .025, respectively).

“The rapid and accurate diagnosis of RSV infection in neonates has major implications for patient care, including appropriate isolation and cohorting measures to prevent nosocomial and community transmission, prudent antibiotic usage, appropriate use of expensive anti-viral medications such as ribavirin in selected patients, public health awareness of seasonal RSV occurrences to guide RSV prophylaxis measures with expensive agents such as palivizumab (Synagis, MedImmune), and identification of complications unique to this virus,” researchers wrote.

Disclosure: The researchers report no relevant financial disclosures.

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