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Streptococcus gallolyticus, Infective Endocarditis, and Colon Carcinoma: New Light on an Intriguing Coincidence

ME Hensler - Journal of Infectious Diseases, 2011 - The coincidence of infective endocarditis (IE) caused by the organism Streptococcus gallolyticus (subsp gallolyticus, also referred to as Streptococcus bovis biotype I) and colon carcinoma has piqued the interest of infectious disease clinicians since an association ...

The coincidence of infective endocarditis (IE) caused by the organism Streptococcus gallolyticus (subsp gallolyticus, also referred to as Streptococcus bovis biotype I) and colon carcinoma has piqued the interest of infectious disease clinicians since an association between enterococcal endocarditis and sigmoid carcinoma was first documented in 1951 [1]. For more than 5 decades, the association between S. bovis IE and carcinoma of the colon has been the subject of numerous case reports [2–4]. In fact, statistics from the 1980s suggest that upwards of two-thirds of patients with S. bovis endocarditis were subsequently found to have malignant gastrointestinal tumors [5]. This well-documented association of IE of suspected S. bovis origin with colon carcinoma has changed contemporary clinical practice such that a diagnosis of S. gallolyticus subsp gallolyticus (SG) endocarditis or bacteremia often results in immediate referral of the patient for colonoscopy, in many cases prior to discharge from the hospital. Despite more than 2 dozen case reports, there has been no explanation for the coincidence of SG IE and colon carcinoma, and, in fact, this area of research has been relatively neglected until the past decade.

In this issue of the Journal, Boleij and colleagues [6] provide important data pointing to several virulence characteristics of SG that may play key roles in the pathogenesis of this remarkably adaptable organism. These investigators replicated the route of SG infection in vitro by using differentiated human epithelial colorectal adenocarcinoma cells (Caco-2) in a series of assays focusing on both bacterial and host cell responses. These studies focused on SG adhesion, invasion, translocation, biofilm formation, and ability to elicit an immune response in order to identify virulence characteristics that could provide an explanation for the ...