Nippon Saikingaku Zasshi

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Clostridium perfringens type A causes gas gangrene, which is a serious disease caused by wound infection. α-Toxin produced by C. perfringens is known to be the primary pathogenic factor of gas gangrene. Although it has been proposed to induce tissue damage by impairing the host immune system and peripheral circulation, sufficient findings have not been obtained to explain the high virulence of C. perfringens. For the purpose of elucidating the pathogenic mechanism of this bacterium, I focused on the disease progressions such as the bacterial colonization, muscle tissue destruction and repair, and sepsis. In this review, focusing on the action of α-toxin, it will be explained together with the latest research results that the toxin suppresses the activation of the host immune response, represents toxicity to vascular endothelial cells, induces peripheral circulatory disorders due to hematopoietic disorders, inhibits muscle tissue repair, and induces excessive immune response. These mechanisms suggest that α-toxin acts in multiple steps to disrupt host defense and that C. perfringens attacks the host with a highly sophisticated mechanism. It is expected that the onset mechanism of gas gangrene would be elucidated, and I hope that new therapeutic strategies are developed.

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Antimicrobial resistance in bacterial infections is a major concern for clinical settings. In recent years, the number of Extended-spectrum β-lactamase producing (ESBL)- and fluoroquinolones (FQ)-resistant Escherichia coli has been increasing in Japan, especially against third-generation cephalosporins and FQs, which are frequently used in medical practice. On the other hand, antimicrobial agents such as tazobactam-piperacillin, colistin, and tigecycline, which are not general-purpose agents but last-line drugs for multidrug-resistant bacteria, are also important. Enterobacteriaceae that are resistant to these antimicrobials have been reported, although the isolation rate of resistant bacteria is lower than that of frequent used antimicrobial resistance. The author has been studying antimicrobial drug resistance and multidrug resistance of bacteria isolated from clinical settings. In particular, bacteriological analysis of antimicrobial resistance, which is important for treatment, has been conducted mainly on E. coli isolated from clinical specimens at medical facilities in Sapporo City. In this article, the author describes the findings obtained so far.

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