Rapid lysis of gram-positive cocci for pulsed-field gel electrophoresis using achromopeptidase

To adapt pulsed-field gel electrophoresis (PFGE) to a busy clinical laboratory, we evaluated the use of achromopeptidase (ACP) as the sole agent for lysis of a variety of gram-positive cocci. Growth in an appropriate broth media was adjusted to a 3.0 McFarland density before aliquotting for washing and plug preparation. ACP incorporated into the agarose plugs, or added to the buffer solution, lysed cells in < 1 h when suspended in a Tris-NaCl buffer. Two 30-min washes in a Tris-EDTA buffer were sufficient to remove cellular debris without additional deproteination. Final PFGE results were obtained in approximately 48 h, including the initial broth subculturing.