Concurrent infection with Clostridium chauvoei, Clostridium septicum and Clostridium perfringens type A in cattle: a case report

Blackleg, caused by Clostridium chauvoei , is an acute, fatal infectious disease characterized by necrotizing myositis and toxemia primarily affecting cattle and sheep. Gas gangrene (malignant edema), a similar necrotizing myositis, is caused by multiple anaerobes including C. chauvoei , C. septicum , and C. perfringens type A, often entering via wounds. Symptoms overlap with blackleg, featuring edema, emphysema, and toxemia, complicating clinical differentiation. Concurrent clostridial infections exacerbate severity, necessitating molecular diagnostics. This study investigated two bovine cases initially suspected as blackleg to identify the etiological agents. Specimens from two cows from traditional free-grazing herds in Mazandaran Province, northern Iran, were examined. Both exhibited blackleg-like symptoms such as lethargy, lameness, and recumbency with postmortem findings of skeletal muscle necrosis, cyanotic skin, and rancid odor. Bacteriological culture on sheep blood agar yielded grayish colonies with complete (Case #1) or weak (Case #2) hemolysis, with gram-positive bacilli. Histopathology confirmed multifocal necrotizing myositis with leukocyte infiltration and fibrin deposition in both. PCR targeting fliC genes detected C. chauvoei and C. septicum in both cases. Multiplex PCR identified only the cpa gene in Case #2, confirming concurrent C. perfringens type A infection. Molecular analysis revealed concurrent C. chauvoei and C. septicum infections in both cases, with additional C. perfringens type A in Case #2, diagnosing gas gangrene rather than blackleg, and suggesting the infection propagation from an exogenous route. Morphological and biochemical similarities among these clostridia pose diagnostic challenges, but fliC -based PCR enables accurate differentiation. These findings underscore the need for enhanced surveillance, and development of multivalent vaccines also targeting C. perfringens type A in rural Iranian herds.