Molecular characterization of Clostridium species associated with clostridial diseases in ruminants in northern Iran.

Clostridial infections are major causes of mortality in domestic ruminants. This study aimed to isolate and molecularly characterize Clostridium species from suspected cases of clostridial diseases in cattle and sheep in Mazandaran, northern Iran. Forty samples, including intestine, liver, skeletal muscle, and soil, were collected and subjected to anaerobic culture, histopathological examination, and multiplex PCR targeting species-specific and toxin genes. Histopathological results revealed severe intestinal villous degeneration, hepatic necrosis with vascular congestion, and emphysematous changes in skeletal muscles. Out of 40 samples, 47.5% were positive for clostridial species, yielding 32 isolates. The predominant species detected were C. septicum (31.25%) and C. perfringens type A (31.25%), followed by C. chauvoei (18.75%), C. novyi type B (9.37%), C. novyi type A (3.12%), C. perfringens type D (3.12%) and other clostridia (3.12%). Mixed clostridial infections were detected in 27.5% of total samples. Clostridium perfringens type A and C. septicum were detected in different sample types including intestine and soil, as well as liver (C. perfringens type A) and muscle (C. septicum). Clostridium chauvoei was recovered from skeletal muscle and intestinal samples, whereas C. novyi was restricted to liver samples. No isolates of C. haemolyticum or C. perfringens types B, C, E, F, or G were detected. These findings demonstrate the importance of molecular assays for accurate identification of clostridia particularly in cases of mixed infections. They also highlight the potential importance of C. septicum and C. perfringens type A in clostridial diseases in northern Iran, emphasizing the need for region-specific surveillance and vaccination.