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Clinical and Virological Characteristics of Early and Moderate Preterm Infants Readmitted With Viral Respiratory Infections

García-Garcia, Maria Luz PhD, MD*; González-Carrasco, Ersilia MD*; Quevedo, Sergio MD*; Muñoz, Cristina MD*; Sánchez-Escudero, Veronica MD*; Pozo, Francisco PhD; Casas, Inmaculada PhD; Calvo, Cristina PhD, MD*

The Pediatric Infectious Disease Journal: July 2015 - Volume 34 - Issue 7 - p 693–699
doi: 10.1097/INF.0000000000000718
Original Studies

Background: Rehospitalization of children born prematurely (referred to as preterm children) caused by severe respiratory infections is common. Most studies have focused on respiratory syncytial virus infection. We designed a study to determine the virological and clinical characteristics of severe respiratory infections of children born early (<32 weeks) and moderate preterm (32 to 36 weeks), and compared them with full term (FT; ≥37 weeks) children who were subsequently admitted with respiratory illness.

Methods: A 7-year observational prospective study was conducted on preterm and FT children, less than 14 years old hospitalized with respiratory infection. The presence of 16 respiratory viruses in nasopharyngeal aspirates was sought. Clinical and virological characteristics of subjects were compared among term and preterm children.

Results: We studied 411 respiratory hospital admissions of 262 preterm children who were compared with 2057 respiratory hospital admissions of term children. In 78.6% of preterm episodes, at least 1 respiratory virus was identified. The most frequent viruses were respiratory syncytial virus (29%), rhinovirus (25%) and human bocavirus (13%). Human metapneumovirus and parainfluenza virus were significantly more frequent in preterm than in term children (P < 0.001 and P = 0.017, respectively). Early preterm (EPT) infants admitted with bronchiolitis presented more hypoxia (P = 0.08), longer hospital stay (P = 0.05), more infiltrate on chest radiograph (P = 0.02) and more antibiotic treatment (P = 0.02) than moderate preterm (MPT) infants. Moreover, MPT needed more intensive care unit admission than FT infants (P < 0.001). Regarding wheezing episodes, EPT patients showed significantly more infiltrate/atelectasis (P < 0.001), longer oxygen therapy (P = 0.039) and longer hospital stay (P = 0.07) than MPT children, although similar percentage of intensive care unit admission was seen in both groups. MPT-wheezy children needed longer hospital stay than FT (P = 0.05). Previous bronchiolitis and EPT were independent factors associated with multiple wheezing admissions.

Conclusion: Our results demonstrate that besides respiratory syncytial virus, other viruses mainly rhinovirus and human bocavirus are important pathogens in severe respiratory infections in preterm children. Human metapneumovirus and parainfluenza virus seem also to play a significant role in this group of children. There is increased medical resource utilization, not only among EPT but also in MPT hospitalized children with respiratory infections as many of them require more medical support than FT children.

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From the *Pediatrics Department, Severo Ochoa Hospital, Leganes; and Respiratory Viruses and Influenza Laboratory, Centro Nacional de Microbiología, ISCIII, Madrid, Spain.

Accepted for publication December 11, 2014.

Partially supported by FIS (Fondo de Investigaciones Sanitarias – Spanish Health Research Fund) Grants No: PI06/0532, PS09/0024, and PI12/0129.

The authors have no conflicts of interest to disclose.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (

Address for correspondence: Maria Luz García-García, PhD, MD, Pediatrics Department, Severo Ochoa Hospital, Avenida Orellana s/n, Leganés, 28911 Madrid, Spain. E-mail:

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