Clostridia: Clostridium botulinum and Clostridium difficile: Ubiquitous Spore-Forming Bacteria as New Zoonotic Pathogens?

Abstract

Clostridium spp., anaerobic spore-forming bacteria, are not commonly counted among the classical zoonotic agents. They are regularly found in the environment, e. g. in soil, dust or sludge, and also in the intestine of healthy humans and animals without causing any symptoms. Botulism is a typical intoxication, normally caused by the ingestion of contaminated food or animal feeding stuff or in rare cases by the bacterial contamination of deep wounds. Based on the classical foodborne transmission route, the European Union classified botulism as a zoonotic intoxication. During the last few years some scientists thought to have indications for a zoonotic transmission of an infective form of botulism, the so-called “chronic botulism”. However, currently there is no resilient evidence for this theory. An infection with Clostridium difficile can result in heavy diarrhea in humans and is supposed to infect also animals, but the zoonotic potential of these bacteria, e. g. the transmission via food or the classical way of zoonotic infection, the direct transmission between human and animal, is discussed controversially. However, scientific data suggest that the zoonotic potential of the organism might not be very high and the contact with contaminated food or animals, carrying C. difficile, is not a decisive risk factor for an infection.