Restriction endonuclease analysis of clinical Pseudomonas aeruginosa strains: useful epidemiologic data from a simple and rapid method.

Newer genetic techniques have replaced phenotypic methods of subtyping Pseudomonas aeruginosa strains. Widespread application of newer methodologies, however, may be limited by technologic complexity and the cost of equipment. We conducted restriction endonuclease analysis (REA) of sheared genomic DNAs from 48 clinical P. aeruginosa strains using the enzyme SalI and electrophoresis in horizontal, low-concentration (0.3 to 0.6%) agarose gels. Each REA profile consisted of a smear of lower-molecular-mass bands as well as a countable number of well-resolved bands in the 8.3- to 48.5-kbp range which could easily be compared when isolates were run side-by-side on the same gel. In general, the REA patterns of strains recovered from different patients differed by at least seven bands, and those of serial isolates from individual patients were identical or differed by, at most, two bands over this 8.3- to 48.5-kbp range. REA of strains already subtyped by field inversion gel electrophoresis revealed that the two techniques generally paralleled each other. Overall, some unrelated strains had similar REA profiles, but the relative simplicity and low cost of the approach coupled with the ability to demonstrate differences between most unrelated strains should make this type of REA an attractive first step in the investigation of institutional P. aeruginosa problems.