Detection of viral, Chlamydia pneumoniae and Mycoplasma pneumoniae infections in exacerbations of asthma in children

Background: A high frequency of virus infections has been recently pointed out in the exacerbations of asthma in children. Objectives: To confirm this, using conventional and molecular detection met hods, and expanding the study to younger children. Study design: One hundred and thirty-two nasal aspirates from 75 children h ospitalized for a severe attack of asthma were studied (32 infants, mean ag e 9.1 months; and 43 children, mean age 5.6 years). According to the virus, a viral isolation technique, immunofluorescence assays (IFA) or both were used for the detection of rhinovirus, enterovirus, respiratory syncytial (R S) virus, adenovirus, coronavirus 229E, influenza and parainfluenza virus. Polymerase chain reaction (PCR) assays were used for the detection of rhino virus, enterovirus, RS virus, adenovirus, coronavirus 229E and OC43, Chlamy dia pneumoniae and Mycoplasma pneumoniae. Results: Using IFA and viral isolation techniques, viruses were detected in 33.3% of cases, and by PCR techniques, nucleic acid sequences of virus, Ch lamydia pneumoniae and Mycoplasma pneumoniae were obtained in 71.9% of case s. The combination of conventional and molecular techniques detects 81.8% o f positive samples. Two organisms were identified in the same nasal sample in 20.4% of the cases. The percentage of detections was higher (85.9%) in t he younger group than in the other (77%). The most frequently detected agen ts were rhinovirus (46.9%) and RS virus (21.2%). Using PCR rather than conv entional techniques, the detection rates were increased 5.8- and 1.6-fold i n rhinovirus and RS virus infections, respectively. The detection levels of the other organisms are as follows: 9.8, 5.1, 4.5, 4.5, 4.5, 3.7, and 2.2% for enterovirus, influenza virus, Chlamydia pneumoniae, adenovirus, corona virus, parainfluenza virus, and Mycoplasma pneumoniae, respectively. Conclusion: These results confirm the previously reported high frequency of rhinovirus detection in asthmatic exacerbations in children. They also poi nt out the frequency of RS virus detection, and emphasize the fact that PCR assays may be necessary to diagnose respiratory infections in asthma. (C) 1999 Published by Elsevier Science B.V. All rights reserved.