ABSTRACT
Clostridia, both in the human and animal body and in the environment, have to attach themselves firmly to the host cells through cell surface molecules to avoid being flushed away. Different from other bacteria, clostridia seem to adhere to the host cells through one of the most commonly used strategies, the afimbrial adhesins, which are bacterial surface proteins without a rodlike structure. In fact, the presence of fimbriae or pili has never been clearly associated with adhesive properties in these bacteria. The most studied proteins associated with adhesion activity, so far, have been the surface-layer (S-layer) proteins, mainly in Clostridium difficile, some proteins from cellulolytic clostridia that mediate attachment to substrates, and other cell surface proteins of Clostridium difficile.
