Etiology and Clinical Characteristics of Single and Multiple Respiratory Virus Infections Diagnosed in Croatian Children in Two Respiratory Seasons

Hindawi Publishing Corporation Journal of Pathogens Volume 2016, Article ID 2168780, 8 pages http://dx.doi.org/10.1155/2016/2168780 Research Article Etiology and Clinical Characteristics of Single and Multiple Respiratory Virus Infections Diagnosed in Croatian Children in Two Respiratory Seasons SunIanica Ljubin-Sternak,1,2 Tatjana Marijan,2 Irena IvkoviT-JurekoviT,3,4 Jasna Hepin-BogoviT,3 Alenka Gagro,3 and Jasmina Vraneš1,2 1 Medical Microbiology Department, School of Medicine, University of Zagreb, Zagreb, Croatia Clinical Microbiology Department, Teaching Institute of Public Health “Dr. Andrija Stampar”, Zagreb, Croatia 3 Department of Pulmonology, Allergy, Immunology and Rheumatology, Children’s Hospital Zagreb, Zagreb, Croatia 4 Pediatric Department, Faculty of Medicine, University of Osijek, Osijek, Croatia 2 Correspondence should be addressed to Sunčanica Ljubin-Sternak; Received 8 June 2016; Revised 20 July 2016; Accepted 16 August 2016 Academic Editor: Nathan W. Bartlett Copyright © 2016 Sunčanica Ljubin-Sternak et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The aim of this study was to determine the causative agent of acute respiratory infection (ARI) in hospitalized children, as well as investigate the characteristics of ARIs with single and multiple virus detection in two respiratory seasons. In 2010 and 2015, nasopharyngeal and pharyngeal swabs from a total of 134 children, admitted to the hospital due to ARI, were tested using multiplex PCR. Viral etiology was established in 81.3% of the patients. Coinfection with two viruses was diagnosed in 27.6% of the patients, and concurrent detection of three or more viruses was diagnosed in 12.8% of the patients. The most commonly diagnosed virus in both seasons combined was respiratory syncytial virus (RSV) (28.6%), followed by parainfluenza viruses (PIVs) types 1–3 (18.4%), rhinovirus (HRV) (14.3%), human metapneumovirus (10.1%), adenovirus (AdV) (7.1%), influenza viruses types A and B (4.8%), and coronaviruses (4.2%). In 2015, additional pathogens were investigated with the following detection rate: enterovirus (13.2%), bocavirus (HBoV) (10.5%), PIV-4 (2.6%), and parechovirus (1.3%). There were no statistical differences between single and multiple virus infection regarding patients age, localization of infection, and severity of disease (𝑃 > 0.05). AdV, HRV, HBoV, and PIVs were significantly more often detected in multiple virus infections compared to the other respiratory viruses (𝑃 < 0.001). 1. Introduction Acute respiratory infections (ARIs) are the most common infections in humans of all ages. Children and infants are one of the most vulnerable groups of the population, and ARIs are the most common cause of children’s hospitalization worldwide [1]. Although bacteria, fungi, and parasites can cause ARIs, respiratory viruses cause the majority of infections. Most respiratory virus infections in early childhood are confined to the upper respiratory tract. About one-third of infants develop lower respiratory tract infection (LRTI) [2]. The most common causative viral agents of ARIs in children, respiratory syncytial virus (RSV), human metapneumovirus (HMPV), influenza viruses (Flu), and adenoviruses (AdV), were the subject of intensive research for years; therefore, clinical characteristics and regional epidemiological features of those ARIs in Croatia are well known [3–6]. However, the list of respiratory viruses is growing due to the rapid advance of laboratory diagnostic methods. In the last ten years, newly discovered viruses have been identified including human bocavirus (HBoV), coronaviruses NL63 (HCoV-NL63) and HKU1 (HCoV-HKU1), new enterovirus (HEV), parechovirus (HPeV), and rhinovirus (HRV) strains [7]. Additionally, despite the fact that some of the respiratory viruses have been well known for a long time, particularly parainfluenza type 4 (PIV-4), the technically demanding cultivation methods and unavailability of commercial tests made it difficult to diagnose PIV-4’s infection [8, 9]. Infections caused by some 2 of the newly discovered viruses (i.e., HBoV, HCoV-NL63, and HCoV-HKU1) as well as those difficult to cultivate (PIV-4) have not been recorded in the country yet. There are few recent studies from the region providing valuable but still insufficient data regarding regional epidemiology of infections caused by the abovementioned viruses [10, 11]. Furthermore, the issue of multiple respiratory virus detection, which occurred because of high sensitivity of molecular methods, complicates the interpretation of laboratory diagnosis. The aim of this study was to determine the viral etiology for sixteen viruses tested by multiplex PCR method among children with ARI admitted to the hospital in Zagreb region in two respiratory seasons, in order to demonstrate the need for molecular diagnostics introduced in routine practice. Also, we aimed to investigate the characteristics of infections with single and multiple virus detection, especially regarding the type of virus involved and severity of infection. 2. Materials and Methods 2.1. Patients and Specimens. A total of 134 children admitted to Children’s Hospital Zagreb during two winter seasons (January to March) in 2010 and 2015 with symptoms of ARI and suspected for viral etiology (normal or slightly elevated inflammatory markers, i.e., white cell count) were included in the study. Patients were categorized into three groups according to age (<1, 1–3, and ≥4 years of age) and two groups according to the localization of infection in those with upper respiratory tract infection (URTI) and lower respiratory tract infection (LRTI). URTI was defined by symptoms of the common cold, coryza, cough, and hoarseness often accompanied with fever. Clinical syndromes of respiratory catarrh, rhinitis, and/or pharyngitis are included in URTI category. LRTI was defined according to the clinical symptoms of tachypnea, wheeze, severe cough, breathlessness, and respiratory distress accompanied by LRTI signs such as nasal flaring, jugular, intercostal, and thoracic indrawings, rarely cyanosis, and, on auscultation of the chest, wheeze, crackles, crepitations, and inspiratory rhonchi or generally reduced breath sounds [2]. Clinical syndromes of bronchitis, bronchiolitis, and pneumonia were included in LRTI category. To avoid unnecessary X-ray exposure, chest radiographs were taken only for some of the patients to exclude or confirm bacterial pneumonia. Severe disease and acute respiratory distress syndrome (ARDS) were defined with need for oxygen supplementation and/or mechanical ventilation. The patients’ underlying conditions data were collected retrospectively from medical charts. The most common underlying diseases were asthma, anamnestic recurrent wheezing episodes, neurological diso (...truncated)