Proximity to blue spaces and risk of infection with Pseudomonas aeruginosa in cystic fibrosis: A case-control analysis.
BACKGROUND
The acquisition of Pseudomonas aeruginosa in cystic fibrosis (CF) is associated with lower survival, decreased lung function, worse radiological scores, increased exacerbations and reduced nutritional status. Open water is a known reservoir and a potential source of exposure to P. aeruginosa.


METHODS
Twenty eight adult CF patients who had no history of P. aeruginosa and had negative P. aeruginosa IgG antibody levels, were matched by age and sex with 28 CF patients with chronic P. aeruginosa colonization. Straight line and closest walking distance from patient's residence to the nearest "blue space", i.e. surface water as determined by Google Earth, were compared between the two groups, and odds ratios (OR) were estimated using conditional logistic regression.


RESULTS
Patients who were never infected with P. aeruginosa lived significantly further away from a natural water source than P. aeruginosa colonized patients, both when considering shortest walking distance (mean 487 m vs 308 m, p=0.014) and beeline (mean 324 m vs 202 m, p=0.021). Conditional logistic regression (correcting for FEV1%) revealed ORs for chronic P. aeruginosa colonization of 0.35 (95% CI 0.13-0.98; p=0.045) and 0.12 (95% CI 0.02-0.81; p=0.028) for each doubling in the beeline or walking distance, respectively, between residence and open water.


CONCLUSIONS
We discovered that adult CF patients without P. aeruginosa infection live significantly further from blue space than CF patients with chronic P. aeruginosa colonization. Within the limitations of a case-control study, this may indicate that natural open water represents a source of infection by P. aeruginosa in CF.


BACKGROUND
The study was approved by the local ethical committee of the UZ Leuven, Belgium (ML-5028).
Department of Respiratory Disease, University Hospital of Leuven, Belgium. Electronic address: pieter.goeminne@student.kuleuven.be.
Pieter C
PC
Goeminne
Center for Environmental Sciences, Hasselt University, Hasselt, Belgium; Centre for Environment and health, Department of Public Health and Primary Care, KU Leuven, Leuven, Belgium.
Tim S
TS
Nawrot
Department of Paediatrics, University Hospital of Leuven, Belgium.
Kris
K
De Boeck
Centre for Environment and health, Department of Public Health and Primary Care, KU Leuven, Leuven, Belgium.
Ben
B
Nemery
Department of Respiratory Disease, University Hospital of Leuven, Belgium.
Lieven J
LJ
Dupont
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D003550:Cystic Fibrosis / Q000150:complications*; D005260:Female; D006801:Humans; D060106:Lakes; D008297:Male; D008875:Middle Aged; D061005:Ponds; D011552:Pseudomonas Infections / Q000453:epidemiology* / Q000209:etiology*; D011550:Pseudomonas aeruginosa; D012307:Risk Factors; D045483:Rivers; D055815:Young Adult
Cystic fibrosis; Pseudomonas aeruginosa; Water