The influence of Mycoplasma pneumoniae (MP) infection on bronchiolitis remains unclear. Additionally, reports on the efficacies of leukotriene receptor antagonists in the treatment of bronchiolitis have been inconclusive.

Children with respiratory syncytial virus (RSV)-induced bronchiolitis were divided into two groups: RSV+MP group and RSV group. Each group was randomly divided into two subgroups: one received routine and placebo treatment, while the other received routine and montelukast treatment for 9 months. The cumulative numbers of wheezing episodes and recurrent respiratory tract infections were recorded. Blood parameters were determined.

Patients in the RSV+MP group exhibited an older average age, fever, more frequent fl aky and patchy shadows in chest X-rays, more frequent extrapulmonary manifestations, and longer hospital stays compared with patients in the RSV group. Additionally, higher baseline blood eosinophil counts, eosinophil cationic protein (ECP), total immunoglobulin E (IgE), interleukin (IL)-4, IL-5, IL-4/interferon-γ ratios, leukotriene (LT) B4, and LTC4, and lower baseline lipoxin A4 (LXA4)/LTB4 ratios were observed in the RSV+MP group compared with the RSV group. Montelukast treatment decreased the cumulative numbers of recurrent wheezing episodes and recurrent respiratory tract infections at 9 and 12 months. This efficacy may be related to the montelukast-induced reductions in peripheral eosinophil counts, ECP and total IgE, as well as the montelukast-dependent recovery in T helper (Th) 1/Th2 balance and LXA4/LTB4 ratios in children with bronchiolitis.

RSV bronchiolitis with MP infection was associated with clinical and laboratory features that differed from those of RSV bronchiolitis without MP infection. Add-on therapy with montelukast for 9 months was benefi cial for children with bronchiolitis at 9 and 12 months after the initiation of treatment.

 

Key words: bronchiolitis; leukotrienes; montelukast; Mycoplasma pneumoniae; respiratory syncytial virus