Mark Crislip, MD, Infectious Diseases, 10:43PM Aug 12, 2013
Patient is admitted with fevers and mild abdominal pain. After a day one of the blood cultures is growing S. milleri and, looking for a source, a CT is done.
Five years ago she had an abdominal aneurism repair and now, right where it crosses the duodenum, there is a good 5 cm of air in and around the graft but minimal inflammation.
Not good. But.
Patient has no teeth. No teeth usually means no endovascular infection from alpha streptococci. It is at the interface of teeth and gums that is the presumed access point by which various oral alpha get into the blood stream.
It is an old graft and it would be odd for a graft to be seeded late, especially in the middle of the graft. Usually the infections occur at the anastomotic site, although I speak from experience, not from data.
Streptococcal graft infections are rare, less than two handfuls in the literature.
And the gas. Where did the gas come from? Anyone who has teenage boys at home knows the huge amounts of gas that some living organisms can make. But not S. milleri. Clostridia? S. aureus? E. coli? Candida? All can make gas faster than tissues can absorb it, but not Streptococci. The gas had to be coming from the bowel due to an incipient aorto-duodenal fistula.
And in the OR that is what why found. And then I found this today:
"We described seven patients with Streptococcus milleri group aortic (six patients) or vena cava (one patient) graft infection secondary to a vasculo-digestive fistula. Time between vascular graft setting and first clinical signs varied from eight months to more than thirteen years. Six patients had fever. Three patients presented with recurrent fever for more than nine months and in two of these cases, delay before diagnosis was long because repeated blood cultures were sterile. Three patients had abdominal pain and/or digestive haemorrhage. Abdominal CT-scan S. milleri was not contributive for the diagnosis in four patients. Streptococcus anginosus was isolated in four patients, Streptococcus constellatus in three patients. One patient died before surgical management. The other six patients were cured by a surgical management associated with a prolonged antibiotic (lactams) treatment. S. milleri group graft infections are rare (or misdiagnosed) while we found only 4 similar cases in the English medical literature. We conclude that a peri-prosthetic infection secondary to a digestive fistula must be insistently searched (and blood cultures must be repeated many times) in any patient with an aortic (or any other vascular) graft presenting prolonged or recurrent fever or acute digestive symptoms."
There is a smug satisfaction from getting to the correct answer by reasoning. Of course, that just means I am going to get slapped down big time in the near future. Those whom the gods would destroy, they first make smug diagnosticians.
Infection. 2007 Jun;35(3):182-5. Streptococcus milleri group infection associated with digestive fistula in patients with vascular graft: report of seven cases and review.