In search of an effective DNA typing technique for hospital epidemiology use, the performance and convenience of a PCR melting profile (PCR MP) technique based on using low denaturation temperatures during ligation-mediated PCR (LM PCR) of bacterial DNA was tested. A number of Escherichia coli isolates from patients of the Clinical Hospital in Gdańsk, Poland, were examined. We found that the PCR MP technique is a rapid method that offers good discriminatory power and excellent reproducibility and may be applied for epidemiological studies. The usefulness of the PCR MP for molecular typing was compared with the pulsedfield gel electrophoresis method, which is currently considered the gold standard for epidemiological studies of isolates recovered from patients and the environment. Clustering of PCR MP fingerprinting data matched pulsed-field gel electrophoresis data. The features of the PCR MP technique are discussed in comparison with conventional methods. Data presented here demonstrate the complexity of the epidemiological situation concerning E. coli that may occur in a hospital.Over the past 20 years, a significant number of DNA-based techniques have been introduced into the field of bacterial characterization and taxonomy. These genomic fingerprinting methods were developed to detect DNA sequence polymorphisms by using general principles, such as restriction endonuclease analysis, molecular hybridization, and PCR amplification. DNA fingerprinting involves the display of a set of DNA fragments from a specific DNA sample. A variety of DNA fingerprinting techniques are presently available (1-7, 11-13), most of which use PCR for detection of fragments. The choice of fingerprinting technique depends on the type of application. Ideally, a fingerprinting technique should require no prior investments in terms of sequence analysis, primer synthesis, or characterization of DNA probes. A number of fingerprinting methods which meet these requirements have been developed. The fingerprints are obtained by visualizing many parts of the genome. Differences in these fingerprints between individuals are interpreted as genetic distances. Obviously, the differences should reflect variations in DNA rather than artifacts due to a nonrobust method. Furthermore, the method should provide the appropriate level of discriminatory power, and it should be relatively rapid and cheap, especially in large-scale population genetic studies. Macrorestriction analysis of genomic DNA followed by pulsed-field gel electrophoresis (REA-PFGE) has become the "gold standard" for molecular typing (10). In recent years, some alternative techniques have been successfully applied for the typing of bacteria below the species level. These include amplification-based methods, such as amplified fragment length polymorphisms (11), random amplification of polymorphic DNA (3, 12, 13), and amplification of DNA fragments surrounding rare restriction sites (5, 6, 8). These techniques are now applied more and more because they involve less time, comparably low cos...
