Endocarditis sustained by Streptococcus viridans with normal levels of procalcitonin: an unexpected finding.

OBJECTIVE: Procalcytonin is a useful marker of bacterial infections. Several studies have reported elevated serum levels of PCT in patients with infective endocarditis (IE) and/or other infections sustained by cocci. We report a rare case of IE attributed to Streptococcus viridans in whom levels of PCT were normal.

CASE REPORT: A 67 years-old male was admitted to the Emergency Department for a 25-day history of recurring night fever. Upon admission, patient underwent blood test, including PCT, showing normal levels, except for a slight increased creatinine concentration (1.6 mg/dl). CBC showed WBC levels of 10.24 x 10^9/l with neutrophil concentration of 8.64 x 10^9/l. Three blood culture were performed, and all of them were positive for Streptococcus viridans (S. oralis). Dosage of PCT was then repeated two times within the next 2 days after the admission, with negative results. An echocardiogram was performed, showing a lesion of the left anterior aortic leaflet. This finding was confirmed by a transoesophageal echocardiogram. The patient was then treated with G penicillin (6 million of Units quid) for 3 weeks; during the course of antibiotic therapy fever disappeared and blood cultures become negative.

CONCLUSIONS: In the literature, there are just few data about the association between PCT levels and endocarditis and sepsis but there are not etiological differentiations particularly for those sustained by Streptococcus viridans. Only one study suggests that a Streptococcus viridans' infection could reduce PCT accuracy in diagnosis oh endocarditis. So, our observation although come from a single case, could merits, further investigation.