Clostridium perfringens type A infections

M W ODENDAAL, N P J KRIEK AND P HUNTER

GENERAL INTRODUCTION: ENDOSPORE-FORMING GRAM-POSITIVE RODS AND COCCI Clostridium perfringens group infections

Introduction

Although there is uncertainty about the pathogenicity of C. perfringens type A for animals, a number of diseases have, however, been associated with it in domestic and wild animals, poultry and wild birds. Despite its frequent isolation from diseased animals and necropsy specimens, it is usually disregarded as the aetiological agent because of its apparently innocuous ubiquity. Currently, C. perfringens type A is considered to be one of the causes of gas gangrene or malignant oedema arising from trauma associated with penetrating wounds in cattle,^{77, 79} horses^{29, 42, 61} and humans.^{37, 72} It is a rare cause of gangrenous mastitis in cattle^{21, 34, 66} and acute mastitis in sheep.⁴⁰ The enterotoxaemia caused by C. perfringens is characterized in several domestic and wild animal species by a number of distinct syndromes that are usually associated with, and therefore referred to as, ‘sudden death’.^{4, 53}

Clostridium perfringens type A has been associated with lambs that succumb to an enterotoxaemic condition known as yellow lamb disease in California and Oregon,⁴¹ and with enterotoxaemic jaundice in cattle and sheep in Australia in the 1930s.⁶⁴ In addition, enterotoxaemia in sheep and lambs considered to have been caused by C. perfringens type D has, on occasion, revealed only C. perfringens type A.⁵⁹

In South Africa, a form of haemorrhagic enteritis occurs sporadically in sheep in the winter rainfall area of the Western Cape Province. This is a peracute to acute, fatal disease associated with the isolation of C. perfringens type A in pure culture from the intestines of affected sheep.⁸⁴ Similarly, in Germany C. perfringens type A was isolated and alfa toxin demonstrated in the intestinal content from a two-year-old sheep suffering from haemorrhagic enterotoxaemia.⁸³ In the UK a similar disease of unknown cause in lambs has been described as an intestinal haemorrhagic syndrome.^{58, 68}

In cattle, C. perfringens type A is associated with, or is considered to cause, several disease syndromes. It has been isolated from calves suffering from an acute abdominal syndrome caused by abomasitis and abomasal ulceration.⁶³ Enterotoxaemia caused by C. perfringens type A has been described in calves,^{5, 44, 51} wild deer² and water buffaloes (Bubalus bubalis).⁸¹ It has also been associated with fatal gastroenteritis or sudden death of cattle in Canada⁶⁵ and the UK,^{69, 76} and with other enteric lesions in cattle.³

Clostridium perfringens type A is associated in horses with intestinal clostridiosis.⁸⁰ Recently an enterotoxigenic strain of C. perfringens type A was isolated from a case of necro-haemorrhagic enteritis in a two-day-old foal.¹³ Serological evidence also suggests that the enterotoxin of C. perfringens type A may be involved in equine grass sickness, either as an aetiological agent or as a complicating factor,⁵⁴ but this has not been confirmed.²²

Clostridium perfringens type A has been reported as a cause of enterotoxaemia and death in pigs,^{55, 56} and of diarrhoea and emaciation in piglets one to three weeks old.^{4, 45} It has, however, been suggested that no special importance should be attached to the presence of C. perfringens type A in pigs suffering from enteritis.⁴

Clostridium perfringens type A is recognized as the cause of necrotic enteritis in conventionally reared broiler chickens, ³⁶ as well as in germ-free chickens,²⁰ while fatal cases of enterotoxaemia in birds of prey have been directly attributed to the feeding of meat contaminated with C. perfringens type A.³⁵

Certain strains of C. perfringens type A produce an enterotoxin (see the introduction, Clostridium perfringens group) which causes enteritis in humans and, experimentally, in lambs, calves, monkeys and rabbits.^{16, 17, 27, 28, 39, 48, 49, 52} This enterotoxin is not regarded as playing an integral role in the pathogenesis of the classical enterotoxaemia syndrome in animals, although it has been detected in pigs, sheep, goats and cattle.⁷⁵ The enterotoxin exerts a local effect on the intestines, inducing a mild and non-fatal disease.

Aetiology

The cultural, morphological and biochemical characteristics of C. perfringens type A are dealt with in the introduction, Clostridium perfringens group. Although all five toxin types of C. perfringens are produced, the alpha toxin (a phospholipase C) is the main lethal toxin produced by type A. The term lecithinase, used in the older literature, is a synonym for phospholipase C.

Epidemiology

The epidemiology of the various syndromes associated, or thought to be associated, with C. perfringens type A infection is poorly defined, primarily because of uncertainty about the aetiological role of the organism. There is no doubt, however, about its ubiquitous occurrence in the environment. Clostridium perfringens type A is regarded as being a facultative pathogen in contrast to C. perfringens types B, C, D and E, which are regarded as obligate parasites and, while widespread, are not as ubiquitous as type A. Clostridium perfringens type A is considered to be the most common of the five types of C. perfringens and occurs as a vegetative organism in the intestinal tract of almost all warm-blooded animal species and humans, and in soil.^{31, 70–74}

As far as gas gangrene...