Seasonal and climatic influence on respiratory infections in children with cystic fibrosis

Abstract

Pseudomonas aeruginosa (Pa) and Methicillin susceptible Staphylococcus aureus (MSSA) are the predominant bacteria found in the airways of people with cystic fibrosis (pwCF), significantly contributing to lung disease progression. While various factors influencing the initial acquisition (IA) of these pathogens are known, the impact of environmental conditions remains understudied. This epidemiological study assessed the risk of MSSA and Pa initial acquisitions in relation to seasonality and climatic zones among 1,184 French pwCF under 18 years old. The age at IA for Pa (Pa-IA) and MSSA (MSSA-IA) was estimated using the Kaplan-Meier method. Seasonality and climatic zones were analysed as risk factors using time-varying Cox regression models. The median age at MSSA-IA was notably earlier (2.0 years) than that at Pa-IA (5.1 years). MSSA-IA occurred increasingly younger in more recent birth cohorts, while the age at Pa-IA remained stable over time. The risk of Pa-IA was consistently higher in all seasons compared with spring, peaking in autumn (HR = 1.53), irrespective of climatic zones. In Oceanic and Continental climates, the highest risk for MSSA-IA was in winter (HRs = 1.45 and 1.20 respectively). In the Mediterranean climate, the risk of MSSA-IA was lower in winter compared to spring (HRs = 0.68 and 0.61 respectively), and the median age at MSSA-IA later than for Pa-IA. This study demonstrates that seasonality and meteorological factors may influence acquisition of MSSA and Pa in pwCF. These findings suggest that environmental factors play a role in pathogen acquisition dynamics in CF and could inform the development of preventive strategies.

Keywords: Pseudomonas aeruginosa; Staphylococcus aureus; Climate; Cystic fibrosis; Environmental factors; Seasonality.

Fig. 1

Cumulative incidences of initial acquisitions of P. aeruginosa and MSSA according to age and in the different French climate zones. This figure represents the cumulative incidences of initial acquisitions of Pseudomonas aeruginosa (P. aeruginosa, orange) and Methicillin-Sensitive Staphylococcus aureus (MSSA, blue) according to age: (A) In the overall French cohort of 1,184 young people with cystic Fibrosis (pwCF), with 95% Confidence Intervals; (B) Among the pwCF living in the Mediterranean climate zone; (C) Among the pwCF living in the Oceanic climate zone; (D) Among the pwCF living in the Continental climate zone.

Fig. 2

Hazard ratios for initial acquisitions of P. aeruginosa and MSSA according to season and climate zone. This figure represents the hazard ratios for initial acquisition of Pseudomonas aeruginosa (P. aeruginosa, A) and Methicillin-Sensitive Staphylococcus aureus (MSSA, B) according to season and climate zone (Mediterranean in red, Oceanic in blue, Continental in green). Seasonality was analysed as a time-dependent risk factor in a multivariable proportional hazards regression model. Hazard ratios were adjusted for birth cohort. Dash line represent the seasonal instantaneous risk in the overall cohort of 1,184 pwCF.