Wadsworth-ktl anaerobic bacteriology manual - Wadsworth Anaerobic Bacteriology Manual - AbeBooks

Organisms of the genus  Clostridium  are important members of the humans’ anaerobic gastrointestinal and cervical-vaginal flora. Clostridia are ubiquitous and are found in the soil, marine sediment, decaying vegetation and intestinal tract of humans, other vertebrate and insects. Human infections with clostridia can result from endogenous or exogenous infection ( 5 ).

Infections caused by these organisms range from a variety of localized wound contamination to overwhelming systemic disease ( 5 , 7 , 29 ). Clostridial histiotoxic syndromes are mediated by toxins and include soft tissue infections such as gas gangrene (caused by  C. perfringens ), enteric diseases such as clostridial food poisoning, enteritis necroticans, antibiotic associated colitis (caused by  C. difficile  ), discussed elsewhere, and neutropenic enterocolitis (caused by  C. septicum ) and neurological syndromes such as tetanus and botulism (both discussed elsewhere).

C. septicum can cause spontaneous, non-traumatic gas gangrene, and C. sordellii can induce gas gangrene of the uterus, as a consequence of spontaneous abortion, normal vaginal delivery and traumatic injury. ( 29 ).  Clostridial bacteremia account for clinically significant anaerobic bacteremia second only to  Bacteroides  spp. Clostridia are also often isolated from polymicrobial intraabdominal, biliary, pleuropulmonary, central nervous system, genitourinary and skin and soft tissue infections ( 5 ).

Isolation of  Clostridia  from wound, pus, blood or faeces, along with toxin and serological assays aid in the diagnosis of clostridial infections. The significance of clostridia in polymicrobial isolates is unknown. Clinical diagnosis is especially important in infections such as gas gangrene in which demonstration of clostridial myonecrosis is critical in the diagnosis.

Toxins mediate the Clostridial histiotoxic syndromes. Toxins are biologically active proteins that are antigenic and capable of neutralization by specific antisera.  C. perfringens  produces 4 major lethal toxins, based on which it is classified into 5 serological types classified A to E. Additional virulence factors include enterotoxin, neuraminadase and haemolysins. The role of clostridia in the pathogenesis of polmicrobial infections is unclear ( 28 , 29 ).

Clostridium perfringens is the most common clinical isolate of the genus. It is a ubiquitous bacterium associated with several exotoxin-mediated clinical diseases. There are 12 recognized toxins, and the species is divided into types A through E on the basis of the spectrum of toxins produced ( 16 ).  The disease syndromes caused by C. perfringens are food poisoning, necrotizing enteritis, and gas gangrene.