The occurrence and pathogenicity of Clostridium oedematiens in animals

Abstract

Clostridium oedematiens (Clostridium novyi) is an anaerobic spore forming bacillus. The organism is an important pathogen of sheep and cattle, and can be responsible for gas gangrene in humans. Four tykes designated A, B, C and D are recognised on the basis of serological neutralisation tests. Cl. oedematiens is generally regarded as being very difficult to handle in the laboratory; thus, the recent introduction of a commercially available fluorescent globulin for the identification of this organism has encouraged. workers to disregard the necessity for confirmatory isolation and typing procedures.

Reliable techniques for the isolation and subculture of Ci. oedematiens are an essential prerequisite for a study of the occurrence of this organism, and my initial work soon confirmed that type B, C and D strains of Cl. oedematiens are Lifficul.t to subculture with confidence on solid media. It became clear that much preliminary laboratory work is necessary before a field investigation could yield meaningful data.

The writer considered that the irregular growth of this organism on solid media might be related to (i) failures in the anaerobic environment; (ii) a requirement for a particularly complex nutritional medium; or (iii) the viability of the inoculu'E and each of these variables is carefully studied in the present work. The first part describes a reappraisal of the technique for setting up a modern anaerobic jar. Variations in the technique are assessed, and it is concluded that the irregular growth of these strains is not necessarily related to faults in normal anaerobic procedure.

A variety of culture media are tested for the ability to support regular growth of Cl. oedematiens. The aim. of these experiments is to determine whether the organism crows better on complex media than on relatively simple media; it is found that irregular growth occurs on both types of media.

The viability of a number of different inocula are studied in order to test the assumption that an inoculum containing spores shoul be viable. The results of these experiments are compatible with the view that consistent growth of Cl. oedematiens on solid media may be related to the spore content of the inoculum; however, it is likely that other factors are involved, and a theory is developed that a low redox potential in the mioroenvironment is also necessary for the successful outgrowth of viable particles.

The epidemiological distribution of this organism can be assessed only if adequate descriptions and techniques of identification are available. Thus, the characters of the Cl. oedematiens group are confirmed and extended during the present work. These studies inelude (i) a critical evaluation of the fluorescent staining procedure (ii) a reappraisal of the fermentation reactions of the group; (iii) an assessment of the value of solid indicator media in the identification of this organism; (iv) an intensive study of the soluble products of Cl. oedematiens; and (v) the development of a practical system of typing with cultures grown in cooked-meet medium.

The soluble products of the organism are investigated in various types of media, and particular attention is paid to the production of the factors that are responsible for the pathogenic effects in-vivo. Culture products of Ci. oedematiens are fractionated and it is found that the biological activities are readily separated. by Orel-filtration procedures. A thin-layer chromatographic technique is developed in an attempt to identify more precisely the factors that affect egg - yolk emulsion. A cytopathic effect that is produced by the soluble products of Cl. oedematiens is investigated, and is provisionally attributed to the presence of the alpha antigen.

The experimental observations are discussed in relation to our present knowledge of Cl. oede .atiens e d future lines of research are indicated.