Comparison of polymerase chain reaction and pulsed-field gel electrophoresis for the epidemiological typing of Alcaligenes xylosoxidans subsp. xylosoxidans in a burn unit.

Eighteen isolates of Alcaligenes xylosoxidans subsp. xylosoxidans were collected from clinical specimens of 15 patients in a burn unit and a plastic surgery ward over a 16-month period. Pulsed-field gel electrophoresis and polymerase chain reaction (PCR) were compared for the epidemiologic typing of these 18 isolates and fifteen epidemiologically unrelated strains. These 18 isolates demonstrated an identical fingerprint pattern and were easily distinguished from the 15 epidemiologically unrelated strains by pulsed-field gel electrophoresis typing and both enterobacterial repetitive intergenic concensus and repetitive extragenic palindrome-primed PCR fingerprinting. We conclude that pulsed-field gel electrophoresis analysis of XbaI-digested genomic DNA is a highly discriminatory and reproducible method for epidemiological typing of A. xylosoxidans subsp. xylosoxidans isolates. However, poor resolution due to frequent cutting in the smaller fragments (< 145.5 Kb) may lead to difficulty in interpretation. PCR is a rapid and highly discriminatory, but less reproducible, technique with occasional loss of major bands. The fingerprints produced by repetitive extragenic palindrome primed PCR had more intense bands and were easier to read than those produced by enterobacterial repetitive intergenic concensus-primed PCR in this study.