Infections caused by anaerobic bacteria are common, and may be serious and life-threatening. Anaerobes predominant in the bacterial flora of normal human skin and mucous membranes, and are a common cause of bacterial infections of endogenous origin. Infections due to anaerobes can evolve all body systems and sites. The predominate ones include: abdominal, pelvic, respiratory, and skin and soft tissues infections. Because of their fastidious nature, they are difficult to isolate and are often overlooked. Failure to direct therapy against these organisms often leads to clinical failures. Their isolation requires appropriate methods of collection, transportation and cultivation of specimens. Treatment of anaerobic bacterial infection is complicated by the slow growth of these organisms, which makes diagnosis in the laboratory only possible after several days, by their often polymicrobial nature and by the growing resistance of anaerobic bacteria to antimicrobial agents.

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Wednesday, April 1, 2015

Is Fusobacterium associated with colon cancer?


Numerous cancers have been linked to microorganisms. Warren et al. from British Columbia Cancer Agency, Vancouver, Canada; investigated the relationship between gut mucosal microbiome and colorectal cancer using genetic methods. The investigation revealed an association between Fusobacterium species and colorectal carcinoma in eleven patients. These investigators have extended their studies with deeper sequencing of a much larger number (n = 130) of colorectal carcinoma and matched normal control tissues.


The new report has revealed differently abundant microbial genome sequence signatures of significance in tumor samples, including those belonging to the Fusobacterium, Campylobacter and Leptotrichia genera. These Gram-negative anaerobes are typically considered to be oral bacteria. However, tumor isolates for Fusobacterium and Campylobacter were genetically diverged from their oral counterparts and carry potential virulence genes. They also observed that sequence signatures from Fusobacterium co-occur with those from Leptotrichia and Campylobacter and that Fusobacterium and Campylobacter strains isolated from tumor tissue co-adhere in culture. A non-invasive assay to detect this polymicrobial signature of colorectal carcinoma may have utility in screening and risk assessment.

It remains unknown whether there is any etiological link between microorganisms and colorectal carcinoma. Any such link could provide a potential mode of intervention in the prevention of colonic cancer.


Fusobacterium necrophorum Gram stain