Streptococcus cristatus bacteremia in a patient with poor oral hygiene: a case report

BACKGROUND: Streptococcus cristatus is a member of the Mitis streptococcus group. Like other members of this group, it resides on mucosal surfaces of the oral cavity. However, little is known about its ability to cause disease as there are only a handful of cases in the literature. Two of these cases involved infective endocarditis with significant complications. However, these cases involved additional microbes, limiting the inferences about the pathogenicity of Streptococcus cristatus. CASE PRESENTATION: A 59-year-old African American male with end-stage cryptogenic cirrhosis and ascites presented with fatigue and confusion. A paracentesis was negative for spontaneous bacterial peritonitis, but two separate blood cultures grew Streptococcus cristatus. Our patient had a history of dental caries and poor oral hygiene, which were likely the source of the infection. Echocardiograms revealed new aortic regurgitation, indicating “possible endocarditis” per the Modified Duke Criteria. However, since his clinical picture and cardiac function were reassuring, we elected against treatment for infective endocarditis. He was treated for bacteremia with a 2-week course of cephalosporins consisting of 8 days of ceftriaxone, transitioning to cefpodoxime after discharge. Despite having end-stage liver disease, our patient did not experience any significant complications from the infection. CONCLUSION: A patient with end-stage cirrhosis and poor oral hygiene developed bacteremia with an oral bacterium called Streptococcus cristatus. Unlike previous cases in literature, our patient did not meet criteria for a definitive diagnosis of infective endocarditis, and he experienced no other complications from the infection. This suggests coinfectants may have been primarily responsible for the severe cardiac sequelae in prior cases, whereas isolated Streptococcus cristatus infection may be relatively mild. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13256-023-03818-z.