Introduction
Inhaled corticosteroids (ICS) are among the main choices in managing and treating asthma and are recommended for mild-to-severe asthma in children and adults. 1,2 It is essential to consider active molecules, patients’ preferences, and user abilities while prescribing an ICS for asthma. Metered dose inhalers (MDIs) and dry powder inhalers (DPIs) are common ICS inhaler devices.3,4 MDI inhalers are well-known, compact, convenient devices requiring actuation coordination to be used correctly. The breath and actuation coordination sometimes makes using the MDI inhalers difficult for some patients with low cognitive ability or difficulty actuating. MDI can be used with a spacer to improve medication delivery by extending the time of inhaling and allowing the lungs to absorb the medication more slowly and smoothly. In addition, using a spacer simplifies the inhaling process by reducing the need for actuation coordination in MDI users, especially in children. 5MDI inhalers are cheaper than DPIs, and propellants are essential for their formulation. Breath-dose coordination is unnecessary while using DPI inhalers because DPIs are designed to release the medication in response to the patient’s inhalation effort. However, sufficient respiratory force is required for DPI inhalers to inhale the powder effectively. User instruction is inconsistent among different DPI inhalers, and a preparation step is usually needed before inhalation.3,4,6,7
The airway microbiome has been associated with the development and severity of asthma. 6,8 It was shown that bacterial diversity and enriched pathogenic species are higher in the airways of asthma patients compared to healthy individuals. 8,9The lung microbiome is partly derived from the upper respiratory tract, as well as its composition is being influenced due to interactions with the oropharynx microbiome. 10 Hence, saliva may be a more feasible and completely non-invasive source for microbiome studies, especially in children where other samples like induced sputum, biopsies, and bronchoalveolar collection are challenging and invasive.11 The saliva microbiome is in direct contact with both airway and gastrointestinal (GI) entries. Different environmental factors may influence the saliva microbiome, like food, drinks, and medications. It has been previously shown that ICS treatment is associated with the airway microbiome composition and diversity.12,13 However, more research is needed to better understand the association between inhaled corticosteroid intake and salivary microbiome in children to optimize risk assessment, monitoring, and management strategies to protect patients’ oral and overall health while using inhaled corticosteroids.
Local deposition of ICS in the oropharynx and larynx may lead to side effects like dysphonia (hoarse voice), and oropharyngeal candidiasis (thrush). The severity and frequency of side effects depend on medication type, dose, administration rate, inhaler techniques, and device type, which can be prevented by rinsing the mouth and throat with water after using all ICS types. 14-16 The risk of oral candidiasis and dysphonia was higher by using MDI devices than DPI devices when compared to a placebo group.17 We hypothesized that differences in formulation and ICS device types may influence oral cavity microbiota composition. This study aims to compare the saliva bacterial microbiome in children with moderate-to-severe asthma under regular ICS treatment via MDI versus DPI devices.