Correspondence

Prosthetic-Valve Endocarditis Caused by Penicillin-Resistant Streptococcus mitis

N Engl J Med 1999; 340:1843-1844June 10, 1999

Article

To the Editor:

Penicillin resistance has been an increasing problem in the treatment of infections due to gram-positive cocci over the past 15 years.1 Much of the concern has related to the rising minimal inhibitory concentrations (MICs) of antibiotics required to suppress Streptococcus pneumoniae, but sharp declines in penicillin sensitivity have also been observed in streptococci of the viridans group and S. mitis in particular.2-4 I report a case of prosthetic-valve endocarditis resulting from infection with an S. mitis organism that was fully resistant to penicillin.

The patient, a 48-year-old man with a long history of intravenous drug abuse and three previous episodes of endocarditis, was admitted to the hospital with a two-week history of fever and chills. Nine months before admission, he had received a bovine prosthetic aortic valve for treatment of aortic insufficiency stemming from endocarditis. The patient also had a history of AIDS, hepatitis C, and chronic renal insufficiency caused by heroin-induced glomerulonephropathy. The patient's medications at the time of admission included 1200 mg of azithromycin once weekly. On admission, three of three blood cultures were positive for S. mitis. Sensitivity analyses of S. mitis showed a MIC of penicillin of greater than 4 μg per milliliter, a MIC of ampicillin of 16 μg per milliliter, and a MIC of vancomycin of 0.5 μg per milliliter or less. On hospital day 3, the patient had third-degree heart block, and a pacemaker was placed. Echocardiography revealed a paravalvular leak. The patient was treated for four weeks with vancomycin in doses adjusted for his serum creatinine level of 2.7 mg per deciliter. This resulted in eradication of the S. mitis.

Failure of penicillin therapy for S. mitis endocarditis has been reported previously, but in the reported case the organism itself had tested fully sensitive to penicillin.5 Recent studies have shown that high-level resistance is developing in S. mitis species.2-4 The current case is alarming because it was a life-threatening infection with a viridans-group streptococcus that was fully resistant to penicillin. If additional cases are reported, the “standard” therapy for subacute bacterial endocarditis may undergo substantial change.

Robert E. Levitz, M.D.
Hartford Hospital, Hartford, CT 06102-5037

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Citing Articles (9)

Citing Articles

1. 1

   H.V. Rukke, I.K. Hegna, F.C. Petersen. (2011) Identification of a functional capsule locus in Streptococcus mitis. Molecular Oral Microbiologyno-no
   CrossRef

2. 2

   F. K. Gould, D. W. Denning, T. S. J. Elliott, J. Foweraker, J. D. Perry, B. D. Prendergast, J. A. T. Sandoe, M. J. Spry, R. W. Watkin. (2011) Guidelines for the diagnosis and antibiotic treatment of endocarditis in adults: a report of the Working Party of the British Society for Antimicrobial Chemotherapy. Journal of Antimicrobial Chemotherapy
   CrossRef

3. 3

   B. Knoll, I. M. Tleyjeh, J. M. Steckelberg, W. R. Wilson, L. M. Baddour. (2007) Infective Endocarditis Due to Penicillin-Resistant Viridans Group Streptococci. Clinical Infectious Diseases 44:12, 1585-1592
   CrossRef

4. 4

   Isil Bavunoglu, Serap Sahin, Mesut Yilmaz, Tayfur Toptas, Fehmi Tabak, Aydin Tunckale. (2007) Native triple-valve endocarditis caused by penicillin-resistant Streptococcus sanguis. Nature Clinical Practice Cardiovascular Medicine 4:6, 340-343
   CrossRef

5. 5

   Katarina Westling, Inger Julander, Per Ljungman, Shah Jalal, Carl Erik Nord, Bengt Wretlind. (2006) Viridans group streptococci in blood culture isolates in a Swedish university hospital: antibiotic susceptibility and identification of erythromycin resistance genes. International Journal of Antimicrobial Agents 28:4, 292-296
   CrossRef

6. 6

   Glen E. Hall, Larry M. Baddour. (2002) Apparent Failure of Endocarditis Prophylaxis Caused by Penicillin-Resistant Streptococcus mitis. The American Journal of the Medical Sciences 324:1, 51-53
   CrossRef

7. 7

   Bruno Hoen. (2002) Special issues in the management of infective endocarditis caused by Gram-positive cocci. Infectious Disease Clinics of North America 16:2, 437-452
   CrossRef

8. 8

   Charles S. Levy, Palaniandy Kogulan, Vee J. Gill, Michele B. Croxton, James G. Kane, Daniel R. Lucey. (2001) Endocarditis Caused by Penicillin‐Resistant Viridans Streptococci: 2 Cases and Controversies in Therapy. Clinical Infectious Diseases 33:4, 577-579
   CrossRef

9. 9

   Lonks, John R., , Dickinson, Brian P., , Runarsdottir, Valgerdur, . (1999) Endocarditis Due to Streptococcus mitis with High-Level Resistance to Penicillin and Cefotaxime. New England Journal of Medicine 341:16, 1239-1239
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