Epidemiologic characterization of Pseudomonas aeruginosa in patients with cystic fibrosis

Abstract

Objective: To determine persistence and variability of colonization with Pseudomonas aeruginosa in cystic fibrosis patients over long time periods, and to look for possible cross-colonization.

Methods: In total, 469 Pseudomonas aeruginosa isolates were obtained from 30 patients during the period from April 1994 to April 1996. The sources were mainly sputum and a few deep throat swabs. All grown strains dissimilar in macromorphology were processed separately. Typing with PFGE was carried out by contour-clamped homogeneous electric field electrophoresis. Genomic DNA was subjected to the rare-cutting restriction enzyme SpeI. For pyocin typing, the procedure described by Fyfe was applied.

Results: After typing with PFGE, we observed 40 restriction profiles. Eighteen different pyocin types were found. The most frequent pyocin type was type 3, followed by types 1 and 5. Twenty-two patients were persistently colonized by one clone specific and different for each patient, and four were co-colonized by a second clone also different for each of these patients. Cross-colonization had apparently been rare in the cystic fibrosis center of Leipzig.

Conclusions: Typing with PFGE is well suited for detailed investigations of colonization with Pseudomonas aeruginosa in cystic fibrosis patients. Pyocin typing can provide additional information for epidemiologic purposes.