Case Presentation: A 30-year-old Caucasian male with a past medical history of shoulder impingement, remote intravenous drug use presents as a transfer from outside hospital with 2 weeks of fever and sweats. He was febrile to 106 F at home and also endorsed headaches and blurry vision for four days. He initially denied current use of intravenous drugs. Vital signs were significant for hypotension, tachycardia and tachypnea consistent with sepsis. His labs were notable for thrombocytopenia, anemia and leukocytosis. His urine drug screen was positive for buprenorphine. He was empirically treated for meningitis with intravenous acyclovir, ceftriaxone and vancomycin.
On presentation to our hospital, he continued to have fevers and headaches without any altered mentation or neck stiffness. He admitted to injecting crushed suboxone tablets with tap water at his home. With little suspicion for acute meningitis, antibiotics were changed to intravenous Vancomycin and Cefepime. His labs now were notable for leukocytosis to18.7 with neutrophil predominance, anemia to 9 g/dL, platelets 306K and elevated lactate. CT Scan of chest, abdomen and showed multifocal pneumonia with bilateral pleural effusions, as well as, hepatosplenomegaly with splenic infarct, consistent septic emboli. A transthoracic echocardiogram showed a possible mass or vegetation in the mitral valve position. This prompted a transesophageal echocardiogram. It showed a 2.3 cm x 0.8 cm mass seen on mitral valve consistent with vegetation, moderate to severe mitral regurgitation and regurgitant jet is highly eccentric. Invasive mitral annular infection and probable abscess involving the annulus at the crux. His blood cultures at outside hospital resulted positive for Serratia marcescens sensitive to meropenem and cefepime in both aerobic and anaerobic bottles. His urine culture was also positive for the same bacteria. He was then started on intravenous meropenem and referred to cardiothoracic surgery due to the presence of mitral valve abscess. He underwent mitral annular patch with a mechanical mitral valve replacement. His postoperative course was unremarkable and he was discharged on long-term intravenous antibiotics with meropenem for 6 weeks.

Discussion: Serratia is ubiquitous in the environment and has a predilection for water, isolated from a wide range of water sources both natural and municipal. Tap water used by our patient to inject suboxone could be the likely source of S. marcescens. Endocarditis due to S. marcescens is indistinguishable from that due to any other organism in terms of clinical picture. Only 20 cases of Serratia endocarditis have been reported since 1980. More than half of those patients had involvement of left sided valves even among IVDUs. Treatment in Serratia endocarditis is guided by culture and sensitivity results, appropriate antimicrobial therapy is not well defined based on guidelines. Endocarditis due to Serratia spp. is a highly morbid disease. Valve destruction, paravalvular abscesses, embolic events are frequently described.

Conclusions: S. marcescens is a relatively rare cause of infective endocarditis but has been increasing in incidence. S. marcescens should remain an important consideration in IVDUs. Our case illustrates, infective endocarditis due to Serratia can present with perivalvular complications, distant septic emboli even in healthy young patients. This propensity for rapidly progressive disease likely reflects a selection for particularly virulent strains of the organism.