Detection of rhinovirus-associated asthma exacerbations using reverse transcriptase-polymerase chain reaction in Egyptian children

Abstract

Background: Acute exacerbations of asthma are the leading cause of emergency department visits in pediatric patients. The development of sensitive diagnostic polymerase chain reaction (PCR) based techniques permitted demonstration of an already clinically suspected association between common viral respiratory infections and asthma exacerbations. Respiratory viruses have been identified in 80–85% of exacerbations in school-aged children, with human rhinoviruses (HRVs) being the most frequently detected. A recently identified HRV genotype, HRV-C, is circulating worldwide and is an important cause of febrile wheeze and asthmatic exacerbations in children requiring hospitalization.

Objectives: This study aimed to detect HRV- induced asthma exacerbations (including the new HRV-C genotype) among a group of Egyptian children.

Methods: This cross-sectional study was conducted on 31 asthmatic children in exacerbations in the period from September 2014 till October 2015. Patients were recruited from the emergency department and chest clinic, Children's hospital, Ain Shams University. Sputum (for children ≥7years) and nasopharyngeal aspirates (for infants and children<7years) were collected for one-step, real-time pan Rhinovirus reverse transcription polymerase chain reaction (RT-PCR) assay. One step RT-PCR was done to detect Rhinovirus C among positive cases.

Results: This study included 31 asthmatic children in exacerbations. They were 15 males (48.4%) and 16 females (51.6%). Their ages ranged from 7 months to 12 years with a mean and SD of (4.47 ± 3.15) years. Eight (25.8%) of the studied patients showed positive Rhinovirus RT-PCR test and 4 (50%) of the HRV positive patients were of the Rhinovirus C genotype (12.9% of the total population). HRV positive patients showed higher percentage of positive family history of bronchial asthma (p=0.002), higher mean values of respiratory rate (p=0.001) and temperature (p=0.001), but lower mean value of oxygen saturation (p =0.011). There were statistically significant differences regarding the exacerbation severity (p=0.024) and outcome (p=0.048) between HRV positive and negative patients.

Conclusion: HRVs are important triggers of asthma exacerbations among Egyptian children. The newly described HRV-C genotype accounts for a significant proportion of HRV- associated asthma exacerbations. Further studies on a larger scale are needed for HRV-C and other possibly undiscovered HRV genotypes.

Keywords: Rhinovirus, Rhinovirus C genotype, asthma exacerbation, real time RT-PCR