Streptococcus bovis Bactremia and Colon Cancer: A Well Established but Frequently Forgotten Association

Abstract

Colorectal cancer represents a major health problem, being the third most common cancer in men and women. Streptococcus bovis (S. bovis) is strongly associated with colorectal cancer. However, clinicians may overlook this association likely because of the rarity of S. bovis infection. We present a case of delayed diagnosis of colon cancer associated with prior S. bovis bactremia. An 85-y.o. male, with history of PUD, chronic A-fib on dabigatran and diastolic CHF, presented to ER with 2-month history of worsening low back pain. He had no other symptoms. Physical exam showed lumbar spine tenderness and apical systolic murmur. Blood work showed acute blood loss anemia with Hb of 6.9 g/dL (baseline is 11-12) and positive occult blood in stool. He received blood transfusion and underwent EGD and colonoscopy after stopping dabigatran. MRI showed osteomyelitis (OM) of the lumbar spine. Patient was started on broad spectrum IV antibiotics and IR guided biopsy was done that was consistent with OM but no organism was identified at this time. EGD showed mild gastritis but colonscopy showed an infiltrative and ulcerated non-obstructing medium-sized cecal mass. Biopsy showed moderately differentiated adenocarcinoma of the cecum. CT chest,abdomen and pelvis did not demonstrate evidence of metastasis. On further review of his history, family mentioned that he was admitted 2 months prior to another hospital for possible pneumonia. Records from that hospital showed that patient had positive blood cultures for S. bovis, not treated with IV antibiotics and no further work up was done. At this time, association between prior S. bovis bactremia and current diagnosis of colon cancer was made. TTE was done to rule out possible association with endocarditis and interestingly it showed severe mitral regurgitation with ruptured chordae tendinae and left atrial vegetation suggesting endocarditis. He was discharged to complete a course of IV antibiotics for both OM and end ocarditis and to follow up with surgical oncology and CT surgery. In 25 to 80% of patients with S. bovis (currently named S. gallolyticus) bacteremia, they have concomitant colorectal tumors. We believe that the association between S. bovis and colon cancer should not be underestimated and that full bowel examination is highly recommended for patients presenting with S. bovis bacteremia. Proper recognition of this association can be a life-saving event for S. bovis-infected individuals with undiagnosed colon cancer.1456_A Figure 1. MRI findings consistent with osteomyelitis at L2-L31456_B Figure 2. Colonoscopy shows cecal mass1456_C Figure 3. Colonoscopy shows cecal mass