Computer-aided densitometric analysis of protein patterns of Clostridium difficile.

The applicability of whole-cell protein patterns obtained by sodium dodecylsulfate-polyacrylamide gel electrophoresis as a typing method for Clostridium difficile was examined using a total of 227 strains isolated from 191 patients and their surroundings. Computer-aided densitometric analysis was used to establish a reliable standardization technique with which a large number of protein patterns could be efficiently classified. The normalized tracks could be electronically superimposed and compared to give reproducible results. The influence of sample preparation for electrophoresis was found to be negligible. By this technique 35 subgroups could be differentiated, and further discrimination was possible within each subgroup using minor, even very weak protein bands. Epidemiologically related strains of Clostridium difficile yielded absolutely identical patterns, allowing unequivocal identification. Thus protein electrophoresis combined with densitometric analysis was shown to be useful for typing Clostridium difficile isolates.