1226. Nasopharyngeal (NP) Colonization with Pathogenic Bacteria is Associated With Increased Disease Severity in Non-PICU Children with RSV Bronchiolitis
Session: Poster Abstract Session: RSV and Other Viral Respiratory Infections in Children
Saturday, October 22, 2011
Room: Poster Hall B1
Background: Studies have shown that RSV enhances bacterial adhesion to the respiratory epithelium resulting in greater bacterial recovery. In the clinical context however, it is not known the impact of NP bacterial colonization on RSV disease. We sought to assess the frequency of pathogenic bacterial colonization in children with RSV bronchiolitis and, to determine whether bacterial colonization is associated with increased disease severity.

Methods: Previously healthy children < 2 yrs admitted to the Infectious Diseases or the Pediatric Intensive Care Unit (IDU or PICU) with a first episode of RSV bronchiolitis were enrolled from 12/2010 to 3/2011. NP bacterial swabs were collected within 24h of admission and cultured for the presence of S. aureus, S. pneumoniae, M. catarrhalis, H. influenzae, S. pyogenes and S. agalactiae. Demographic, clinical, laboratory, microbiologic and radiologic data were compared between patients who tested positive (RSV+_b+) or negative (RSV+_b-) for bacteria. Disease severity was assessed using a clinical disease severity score [CDSS], length of stay [LOS], and need and length of supplemental O2.

Results: A total of 132 children (60% males; median age 2.5 [1.5-4.4] months) were enrolled (IDU, n=100; PICU, n=32). Bacterial NP swabs were positive in 74/132 (56%) children. Of those with negative culture, 44/58 (76%) had received antibiotics (IDU 41% vs PICU 72%). In both units the most frequent bacteria identifed were S. aureus (26%), S. pneumoniae (15%) and M. catarrhalis (13%). RSV+_b- vs RSV+_b+ children admitted to the IDU had a greater proportion of normal chest-x rays (19% vs 4%; p=0.04) and lower CDSS [6 (4.5-7) vs 7 (5-9); p=0.01]. Adjusting for antibiotic use the % of blood neutrophils (27.4 ±10.9 vs 17.9 ±8.2; p=0.02) was higher in the RSV+_b+ vs RSV+_b- group independent of the admission unit. There were no differences in LOS or need for supplemental O2 between groups.

Conclusion: NP colonization with pathogenic bacteria is common in children with RSV bronchiolitis. Non-PICU children with a bacterial pathogen identified showed increased disease severity as defined by the CDSS and chest-x ray abnormalities. Further studies are needed to elucidate the clinical significance and mechanisms of RSV-bacterial interactions.

Subject Category: P. Pediatric and perinatal infections

María del Carmen Suárez-Arrabal, MD1, Cesar Mella, MD2, Santiago M.C. López, MD1, Gail Arthur3, Paulla Davies3, Cynthia Burch4, Mario Marcon, PhD4, Octavio Ramilo, MD1 and Asuncion Mejias, MD, PhD1, (1)Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, OH, (2)Division of Critical Care Medicine, Nationwide Children's Hospital, Columbus, OH, (3)Department of Clinical Research, Nationwide Children's Hospital, Columbus, OH, (4)Department of Laboratory Medicine, Nationwide Children's Hospital, Columbus, OH


M. D. C. Suárez-Arrabal, None

C. Mella, None

S. M. C. López, None

G. Arthur, None

P. Davies, None

C. Burch, None

M. Marcon, None

O. Ramilo, Medimmune: Grant Investigator, Grant recipient
Qudeil: Scientific Advisor, Consulting fee
Abbott Labs: Consultant, Speaker honorarium
Abbott Molecular: Grant Investigator, Grant recipient
Merck: Consultant, Consulting fee

A. Mejias, Abbott: , Research grant
Mead-Johnson: Investigator, Research grant

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