Topic:

Bacterial infections

Abstract No.:

ISE.282

Title:

Streptococcus gallolyticus in metastatic colonic carcinoma: a potential metastatic focus of possible infective endocarditis

Author(s):

E. Tantisattamo, R. Young; University of Hawaii John A. Burns School of Medicine, Medicine, Honolulu, HI/US

Abstract:

Background: Being the well-recognized sentinel event of colon cancer, Streptococcus gallolyticus (S. gallolyticus) bacteremia is one of the most common causes of bacterial endocarditis and empirical treatment is warranted. We report a case of man with known metastatic adenocarcinoma of colon presenting with S. gallolyticus sepsis.
Methods: A 46-year-old man presented with intestinal obstruction 1 year ago when he was diagnosed with stage IV colon cancer with liver metastasis. He underwent colonic stent placement to relieve the symptom and had received palliative chemotherapy. The last dose of chemotherapy was 1 week prior to admission. He was admitted due to sepsis and gastrointestinal bleeding. Vital signs showed a fever of 103.6 F, heart rate of 107/minutes, and blood pressure of 92/60 mmHg. There was no murmur or skin findings suggesting vascular or immunologic phenomena. CBC reveled hemoglobin of 7.9 g/dl requiring blood transfusion. He was initially treated with broad-spectrum antibiotics including cefepime, vancomycin, and metronidazole. Stool Clostridium difficile toxin assays were negative. Two sets of blood cultures grew S. gallolyticus which were sensitive to penicillin and ceftriaxone. Penicillin and ceftriaxone MICs were 0.064 and 0.125 μg/ml, respectively. The antibiotics were switched to ceftriaxone. Transthoracic and transesophageal echocardiography did not reveal evidence of vegetation or endocarditis. Ceftriaxone was continued for 2 weeks and the patient resolved his sepsis. Follow-up blood culture showed no growth.
Results: S. gallolyticus, also referred to as S. bovis biotype I, has long been associated with colon cancer. In our patient, who had known colon cancer, gastrointestinal bleeding as well as the presence of a colonic stent may have disrupted the integrity of his GI mucosa. His weakened enteric mucosal barrier may have lead to bacterial translocation and subsequent bacteremia. Since S. gallolyticus bacteremia is one of the most common causes of native valve endocarditis, empiric antibiotic therapy for possible streptococcal endocarditis should be promptly initiated.
Conclusion: Our case emphasizes the association between S. gallolyticus bacteremia and colonic cancer. While awaiting microbiology results and evaluation for infective endocarditis, empiric therapy for streptococcal endocarditis should be considered in patients with colon cancer and bacteremia.