Pseudomonas aeruginosa in the home environment of newly infected cystic fibrosis patients.

The source of acquisition of Pseudomonas aeruginosa in cystic fibrosis (CF) patients remains unknown. Patient-to-patient transmission has been well documented but the role of the environment as a source of initial infection is as yet unclear. In the present study, the origin of the first P. aeruginosa isolate in CF patients was investigated by comparing the P. aeruginosa genotype(s) from newly infected patients with genotypes of P. aeruginosa isolates from the home environment and from other patients from the same CF centre. A total of 50 newly infected patients were studied. P. aeruginosa could be cultured from 5.9% of the environmental samples, corresponding to 18 patients. For nine of these, the genotype of the environmental P. aeruginosa isolate was identical to the patient's isolate. In total, 72% of the environmental P. aeruginosa isolates were encountered in the bathroom. Patient-to-patient transmission within the CF centre could not be ruled out for three patients. In summary, a low prevalence of Pseudomonas aeruginosa was found in the home environment of the newly infected cystic fibrosis patients. The bathroom should be targeted in any preventive cleaning procedures. An environmental source of the new infection could not be ruled out in nine patients.