Role of Rhinovirus in Hospitalized Infants With Respiratory Tract Infections in Spain

Cristina Calvo; Maria Luz García-García; Carolina Blanco; Francisco Pozo; Inmaculada Casas Flecha; Pilar Pérez-Breña

Disclosures

Pediatr Infect Dis J. 2007;26(10):904-908. 

In This Article

Materials and Methods

Patients and Samples

This was a substudy of an ongoing prospective investigation on respiratory tract infections in children <2 years of age. The study was conducted at the Severo Ochoa Hospital Pediatrics Department, Madrid, Spain. All children recruited were under 2 years of age, consecutively admitted to our hospital for acute respiratory infections, from September 2003 to July 2005. The children's parents were duly advised, upon admission, that clinical data might be used for clinical research purposes. Furthermore, in each case, informed verbal consent was obtained from each of the parents or legal guardians. The study was approved by the ethics committee.

NPA were taken from each of the patients, upon admission, and sent to the Influenza and Respiratory Viruses Laboratory at the National Centre for Microbiology (ISCIII), Madrid, Spain. Samples were processed for virologic study within 24 hours of collection.

Two independent aliquots of 200 µL each were done; one of them was immediately processed and the second one was stored at -80°C for confirmation of results. All NPAs were tested for influenza virus A, B, and C, RSV A and B, and adenovirus by indirect immunofluorescence, virus isolation, and multiplex RT-nested PCR.[13] Samples were also tested for parainfluenza viruses 1 to 4, human coronaviruses 229E and OC43, enteroviruses, and RV by a second multiplex RT-nested PCR.[14] Human metapneumovirus was investigated in all samples using a RT-nested PCR designed in matrix gene.[15]

Nucleic acids from a total of 200 µL of clinical specimens were automatically extracted using the BioRobot M48 workstation and the MagAttract Virus Mini M48 Kit (Qiagen, Hilden, Germany).

Clinical Assessment and Statistical Analysis

Throughout each child's time in hospital, one of the physicians directly involved in the study used questionnaires in recording the following variables: age, sex, month of admission, clinical diagnosis, history of prematurity and underlying chronic diseases, need for oxygen therapy (evaluated via transcutaneous oxygen saturation), axillary temperature (≥38°C), presence of infiltrates and/or atelectasis in chest radiographs, administration of antibiotic therapy, length of hospital stay, total white blood cell (WBC) count, C-reactive protein (CRP) serum levels, and blood culture results (for those cases where such tests had been performed). Asthma, or recurrent wheezing, was not considered an underlying chronic disease.

Upper respiratory tract infection was diagnosed in patients with: rhinorrhea and/or cough, no signs of wheezing, dyspnea, crackles, or bronchodilator use, with or without fever. Classic criteria were applied in diagnosing bronchiolitis:[16] first-time episode of expiratory dyspnea, with acute onset and prior signs of viral respiratory infection-whether or not these were associated to respiratory distress or pneumonia. Children known to have had previous similar episodes of wheezing or breathlessness or airways-obstruction-related respiratory infections were diagnosed with recurrent wheezing. Where there was no wheezing, cases in which the chest radiograph showed focal infiltrates with consolidation were classified as pneumonia. Children with cold symptoms associated with inspiratory stridor were classified as acute laryngitis.

To compare the clinical characteristics associated with rhinovirus and RSV infections, a sample of 88 hospitalized infants with documented RSV infection, aged <2 years, was randomly selected from the same population. Excel data-analysis functions were used to perform simple random sampling.

Values were expressed as percentages for discrete variables, or as mean and standard deviation for continuous variables. Clinical characteristics and laboratory variables were compared using the Student's t test, the Mann-Whitney U test, the χ2 test, and Fisher's exact test. A 2-sided value of P < 0.05 was considered statistically significant. All analyses were performed with the Statistical Package for the Social Sciences (SPSS), Version 11.0.

A total of 382 children were hospitalized with respiratory tract infection. No significant age, sex, or diagnosis differences were found between the excluded patients and the study group.

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