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Aerococcus christensenii native aortic valve subacute bacterial endocarditis (SBE) presenting as culture negative endocarditis (CNE) mimicking marantic endocarditis
Heart & Lung 43 (2014) 161e163
Contents lists available at ScienceDirect
Heart & Lung journal homepage: www.heartandlung.org
Aerococcus christensenii native aortic valve subacute bacterial endocarditis (SBE) presenting as culture negative endocarditis (CNE) mimicking marantic endocarditis Anita Jose, MD a, Burke A. Cunha, MD a, b, *, Natalie C. Klein, MD, PhD a, b, Paul E. Schoch, PhD c a
Infectious Disease Division, Winthrop-University Hospital, Mineola, NY, USA State University of New York, School of Medicine, Stony Brook, NY, USA c Microbiology Laboratory, Winthrop-University Hospital, Mineola, NY, USA b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 29 August 2013 Received in revised form 4 October 2013 Accepted 15 November 2013 Available online 15 December 2013
This is a case report of an adult who presented with apparent culture negative endocarditis (CNE) thought to be marantic endocarditis due to a B-cell lymphoproliferative disorder. This was a most perplexing case and was eventually diagnosed as subacute bacterial endocarditis (SBE) due to a rare slow growing organism. Against the diagnosis of SBE was the lack of fever, hepatomegaly, peripheral manifestations and microscopic hematuria. Also, against a diagnosis of SBE was another explanation for the patient’s abnormal findings, e.g., elevated ferritin levels, elevated a1/a2 globulins on SPEP, an elevated alkaline phosphatase, flow cytometry showing B-lymphocytes expressing CD5, and a bone lesion in the right iliac. Findings compatible with both SBE and marantic endocarditis due to a B-cell lymphoproliferative disorder included an elevated ESR, and splenomegaly. Blood cultures eventually became positive during hospitalization. We report a case of native aortic valve (AV) subacute bacterial endocarditis (SBE) due to Aerococcus christensenii mimicking marantic endocarditis due to a B-cell lymphoproliferative disorder. To the best of our knowledge, this is the first reported case of native AV SBE due to A. christensenii presenting as marantic endocarditis. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Mimics of endocarditis Slow growing Gram positive cocci B-cell lymphoproliferative disorder Culture negative endocarditis (CNE) Marantic endocarditis Viridans streptococcal endocarditis mimics Elevated ferritin levels Endocarditis differential diagnosis
Introduction Subacute bacterial endocarditis (SBE) is caused by low virulence microorganisms that infect previously abnormal/damaged heart valves. Most patients with SBE are ill for 1e3 months prior to presentation. A subacute/indolent course of SBE is usual with fevers <102 F and splenomegaly is often present. There may be peripheral signs of SBE, e.g., Roth spots, conjunctival hemorrhages, splinter hemorrhages, Ostler’s nodes, Janeway lesions. Because SBE is, by definition subacute, sufficient time has usually elapsed for clinical and laboratory manifestations of SBE to become apparent, e.g., splenomegaly is often present. The diagnosis of SBE is based on an otherwise unexplained high grade/continuous bacteremia and a cardiac, usually valvular, vegetation: An unchanging murmur is usual, and peripheral signs of SBE are often present.1e4 * Corresponding author. Infectious Disease Division, Winthrop-University Hospital, 222 Station Plaza North (Suite #432), Mineola, NY 11501, USA. Tel.: þ1 516 663 2505; fax: þ1 516 663 2753. E-mail address: [email protected] (B.A. Cunha). 0147-9563/$ e see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.hrtlng.2013.11.005
In patients with fever, a murmur, a valvular vegetation, negative blood cultures, and peripheral manifestations of SBE, the most likely diagnosis is CNE. CNE may be due to infection with fastidious organisms or non-infectious disorders. A common cause of infectious CNE is marantic endocarditis. Marantic endocarditis has the clinical features of CNE but is not due to an infectious agent, e.g., Q fever, brucella. Often marantic endocarditis is due to a noncardiac neoplasm, e.g., lymphoma, lymphoproliferative disorder.3,4 Case A 60 year old male was admitted to the hospital with left hand numbness and clumsiness. His past medical history included hypertension, anemia, a platelet aggregation disorder, aortic valve regurgitation of unknown etiology diagnosed 6 years ago and spontaneous testicular hemorrhage requiring orchiectomy 10 years ago. He recently returned from Argentina with fatigue and malaise. He denied any fevers, chills, dysuria, frequency, urgency, or recent dental work. A repeat echocardiogram done as an outpatient revealed severe aortic regurgitation. He was treated for periodontal
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disease several years ago. On admission, his temperature was 98.6 F, pulse was 69/min, blood pressure was 133/70 mm Hg, respiratory rate was 18/min. Physical examination revealed an aortic regurgitant murmur but no signs of peripheral emboli. Admission laboratory tests revealed a white blood cell (WBC) count of 7 K/uL (66% neutrophils, 23% lymphocytes, 8% monocytes, 3% eosinophils), hemoglobin (Hb) of 9.2 g/dl, hematocrit (Hct) of 27.1%, platelet count of 197 K/uL, erythrocyte sedimentation rate (ESR), by Westergren, of 39 mm/h, C-reactive protein (CRP) of 43.2 mg/L, creatinine of 1.4 mg/ dL, alanine aminotransferase (ALT) of 18 IU/L, aspartate aminotransferase (AST) of 21 IU/L, alkaline phosphatase of 114 IU/L (n ¼ 25e100 IU/L), ferritin of 246 ng/mL (n ¼ 14e35 ng/ml), a negative rheumatoid factor (RF), a negative urinalysis, and a prostate-specific antigen (PSA) total of 0.4 ng/ml. Magnetic resonance imaging (MRI) of the brain revealed a small acute infarct in the right frontoparietal region. Two days later, a transesophageal echocardiogram (TEE) revealed severe AV regurgitation as well as a small mobile echodensity on the ventricular aspect of the aortic valve. Admission blood cultures were negative. The patient was afebrile, had no peripheral signs of SBE, had a normal WBC, and had a serum electrophoresis (SPEP) with elevated a-1/a-2 fractions. The working diagnosis was marantic endocarditis secondary to a B-cell lymphoproliferative disorder. Flow cytometric analysis of the peripheral blood showed a population of B-cells expressing CD5 and diminished expression of light chains suspicious for a B-cell lymphoproliferative disorder. To rule out malignancy, CT scans of the chest, abdomen and pelvis were performed. The CT scans showed hepatosplenomegaly, a splenic infarct, and a 1.5 cm lytic lesion in the right iliac. Bone marrow biopsy of the right iliac lesion showed a focal increase in B lymphocytes, but no lymphoma. Positron emission tomography (PET) scan performed a week into the hospital admission was negative for malignancy. After a week in hospital two sets of blood cultures drawn on admission became positive with slow-growing Gram positive cocci in pairs and clusters. Ampicillin and gentamicin were started. Two sets of blood cultures drawn on day 3 of hospitalization and 3 sets drawn on day 9 of hospitalization later became positive. Colonies of the organism on sheep blood agar were slow growing at 36 C under 6% CO2, gray-white and non-hemolytic. Catalase was not produced. The organism appeared as Gram-positive cocci in pairs and small clusters. Tests for pyrrolidonyl arylamidase (PYR), bile-esculin, esculin hydrolysis and arginine hydrolysis were negative and positive for leucine aminopeptidase (LAP), growth in 6.5% NaCl, and hippurate hydrolysis. B-glucuronidase activity was measured using the RapID NF Plus system (Remel Labs) was negative. The organism was non-motile and sensitive to vancomycin by disk diffusion. This combination of reactions differentiated the organism from other members of the Aerococcus genus and other catalase-negative cocci. The blood culture isolate was ultimately identified as Aerococcus christensenii. On the tenth hospital day, the patient underwent AV replacement. Gram stain of the removed aortic valve revealed Gram positive cocci in pairs and clusters, but valve culture was negative. Subsequent blood cultures drawn on day 10, 13 and 19 were negative. He was treated with a six-week course of ceftriaxone. Discussion This is a most unusual case of SBE. Although the patient had previous aortic valve disease, he was afebrile. Also, against the diagnosis of SBE was hepatosplenomegaly. Splenomegaly, but not hepatomegaly or hepatosplenomegaly, are SBE findings. The absence of rheumatoid factors (RFs) and microscopic hematuria also argued against the diagnosis of SBE.1 Cardiac echocardiography showed a small mobile echodensity on the aortic valve (possible vegetation or fibroelastoma).2,3 In favor of a lymphoproliferative
disorder was hepatosplenomegaly, elevated alkaline phosphatase, elevated ferritin levels, elevated a-1/a-2 fractions on SPEP, and peripheral blood flow cytometry suspicious for a B-cell lymphoproliferative disorder.4 There also was a 1.5 cm lytic bone lesion in the right iliac crest. The elevated ESR was unhelpful in distinguishing between lymphoma and SBE. Bone marrow biopsy showed an increase in B-lymphocytes, but no lymphoma. Lymphoma was eventually ruled out by a negative PET-CT scan. A. christensenii is a weakly catalase-positive, slow-growing Gram positive coccus that tends to form tetrads or clusters; and is a-hemolytic on sheep blood agar and can grow in 6.5% NaCl.5,6 Aerococcus species are rare human pathogens. Aerococcus spp. have been isolated from air, dust, meat and meat products, crustaceans, raw vegetables, as well as the hospital environment. Aerococcus spp. may also be part of the normal flora of the upper respiratory tract and skin. They have low pathogenic potential and tend to infect damaged tissues.7 Risk factors for infection include granulocytopenia, oral mucositis, prolonged hospitalization, invasive procedures, prior antibiotic treatment, and implanted devices.8 Aerococcus spp. have been reported to cause urinary tract infections (UTIs), urosepsis, bacteremia, SBE, meningitis, empyema, and wound infections.9 The first Aerococcus spp. identified, Aerococcus viridans, rarely may cause UTIs, wound infections, SBE, septic arthritis, osteomyelitis, or meningitis.5 Due to the rarity of Aerococcus spp. infections, optimal antibiotic therapy for Aerococcus spp. has not been determined. Other Aerococcus spp. isolated in humans include Aerococcus urinae, Aerococcus urinaehominis, and Aerococcus sanguinicola.10,11 More recently, Aerococcus urinaeequi (originally classified as Pediococcus urinaeequi), a horse pathogen, and Aerococcus suis, a pig pathogen, have been reported to cause human infection. In immunocompromised patients with a history of urogenital abnormalities, A. sanguinicola is an opportunistic organism that may cause urosepsis or SBE. Neurologic deficiencies and alcohol abuse also appear to be risk factors for A. sanguinicola infection.12 Infection with Aerococcus spp. should be suspected in patients with urine or blood cultures revealing slow growing catalase negative Gram positive cocci in pairs and clusters. Aerococcus spp. colonies are convex and shiny with light-green a-hemolysis, resembling viridans streptococci. Phenotypic methods and 16S rRNA gene sequencing have improved the ability to identify Aerococcus spp.16,17 Patients with Aerococcus spp. SBE may not initially present with fever or peripheral findings of SBE, and our patient presented with an acute embolic stroke.13e33 The patient had poor dentition and AV disease for many years. The source of A. christensenii in this case remains unclear but like veridans streptococcal SBE was probably the mouth.13e15 References 1. Cunha BA. Diagnostic significance of non-specific laboratory tests in infectious diseases. In: Gorbach SL, Bartlett JB, Blacklow NR, eds. Infectious Disease in Medicine and Surgery. 3rd ed. Philadelphia: W.B. Saunders Co.; 2002:158e165. 2. Rubenson DS, Tucker CR, Stinson EG. The use of echocardiography in diagnosing culture-negative endocarditis. Circulation. 1981;64:641e646. 3. Van Scoy RE. Culture-negative endocarditis. Mayo Clin Proc. 1982;57:149e154. 4. Cunha BA. The mimics of endocarditis. In: Brusch JL, ed. Infective Endocarditis: Management in the Era of Intravascular Devices. New York, NY: Informa Healthcare; 2007:345e353. 5. Pien FD, Wilson WR, Kunz K, Washington JA. Aerococcus viridans endocarditis. Mayo Clin Proc. 1984;59:47e48. 6. Zbinden R, Santanam P, Hunziker L, Leuzinger B, von Graevenitz A. Endocarditis due to Aerococcus urinae: diagnostic tests, fatty acid composition and killing kinetics. Infection. 1999;27:48e50. 7. Janosek J, Eckert J, Hudac A. Aerococcus viridans as a causative agent of infectious endocarditis. J Hyg Epidemiol Microbiol Immunol. 1980;24:92e96. 8. Chen L, Yu W, Huang S, et al. Successful treatment of Aerococcus viridans endocarditis in a patient allergic to penicillin. J Microbiol Immunol Infect. 2012;45:158e160.
A. Jose et al. / Heart & Lung 43 (2014) 161e163 9. Christensen JJ, Gutschik E, Friis-Moller A, Korner B. Urosepticemia and fatal endocarditis caused by Aerococcus-like organisms. Scand J Infect Dis. 1991;23: 717e721. 10. Ebnother C, Altwegg M, Gottschalk J, Seebach JD, Kronenberg A. Aerococcus urinae endocarditis: case report and review of the literature. Infection. 2002;30: 310e313. 11. de Jong MFC, Soetekouw R, ten Kate RW, Veenendaal D. Aerococcus urinae: severe and fatal bloodstream infections and endocarditis. J Clin Microbiol. 2010;48:3445e3447. 12. Ibler K, Jensen KT, Ostergaard C, et al. Six cases of Aerococcus sanguinicola infection: clinical relevance and bacterial identification. Scand J Infect Dis. 2008;40:761e765. 13. Brusch JL. Infective Endocarditis: Management in the Era of Intravascular Devices. New York, NY: Informa Healthcare; 2007. 14. Cunha BA, Gill MV, Lazar J. Acute infective endocarditis. Infect Dis Clin N Am. 1996;10:811e834. 15. Kaye D. Infective Endocarditis. 2nd ed. New York: Raven Press; 1992. 16. Versalovic J. Manual of Clinical Microbiology. 10th ed., vol. 1. Washington, DC: ASM Press; 2011. 17. Wilson GS, Miles A. Topley and Wilson’s Principles of Bacteriology, Virology and Immunity. 16th ed.vol. 1. Baltimore: The Williams and Wilkins Company; 1975. 18. Rasmussen M. Aerococci and aerococcal infections. J Infect. 2013;66:467e474. 19. Senneby E, Petersson AC, Rasmussen M. Clinical and microbiological features of bacteremia with Aerococcus urinae. Clin Microbiol Infect. 2012;18:546e550. 20. Untereker WJ, Hanna BA. Endocarditis and osteomyelitis caused by Aerococcus viridans. Mt Sinai J Med. 1976;43:248e252. 21. Colman G. Aerococcus-like organisms isolated from human infections. J Clin Pathol. 1967;20:294e297.
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22. Rasmussen M. Aerococci: hard to find and classify. Rev Argent Microbiol. 2011;43:312. 23. Rasmussen M. Which aerococcus? Turk Kardiyol Dern Ars. 2011;39:630. 24. Calik AN, Velibey Y, Cagdas M, Nurkalem Z. An unusual microorganism, Aerococcus viridans, causing endocarditis and aortic valvular obstruction due to a huge vegetation. Turk Kardiyol Dern Ars. 2011;39:317e319. 25. Tekin A, Tekin G, Turunc T, Demiroglu Z, Kizikllic O. Infective endocarditis and spondylodiscitis in a patient due to Aerococcus urinae: first report. Int J Cardiol. 2007;115:402e403. 26. Christensen JJ, Jensen IP, Faerk J, Kristensen B, Skov R, Korner B. Bacteremia/ septicemia due to aerococcus-like organisms: report of seventeen cases. Danish ALO Study Group. Clin Infect Dis. 1995;21:943e947. 27. Skov RL, Klarlund M, Thorsen S. Fatal endocarditis due to Aerococcus urinae. Diagn Microbiol Infect Dis. 1995;21:219e221. 28. Kristensen B, Nielsen G. Endocarditis caused by Aerococcus urinae, a newly recognized pathogen. Eur J Clin Microbiol Infect Dis. 1995;14:49e51. 29. Ebnother C, Altwegg M, Gottschalk J, Seeback JD, Kronenberg A. Aerococcus urinae endocarditis: case report and review of the literature. Infection. 2002;30: 310e313. 30. Slany M, Freiberger T, Pavlik P, Cerny J. Culture-negative infective endocarditis caused by Aerococcus urinae. J Heart Valve Dis. 2007;16:203e205. 31. Kass M, Toye B, Veinot JP. Fatal infective endocarditis due to Aerococcus urinae e case report and review of literature. Cardiovasc Pathol. 2008;17:410e412. 32. Ho E, Coveliers J, Amsel BJ, et al. A case of endocarditis due to Aerococcus urinae. J Heart Valve Dis. 2010;19:264e266. 33. Alozie A, Yerebakan C, Westphal B, Steinhoff G, Podbielski A. Culture-negative infective endocarditis of the aortic valve due to Aerococcus urinae: a rare aetiology. Heart Lung Circ. 2012;21:231e233.
Contents lists available at ScienceDirect
Heart & Lung journal homepage: www.heartandlung.org
Aerococcus christensenii native aortic valve subacute bacterial endocarditis (SBE) presenting as culture negative endocarditis (CNE) mimicking marantic endocarditis Anita Jose, MD a, Burke A. Cunha, MD a, b, *, Natalie C. Klein, MD, PhD a, b, Paul E. Schoch, PhD c a
Infectious Disease Division, Winthrop-University Hospital, Mineola, NY, USA State University of New York, School of Medicine, Stony Brook, NY, USA c Microbiology Laboratory, Winthrop-University Hospital, Mineola, NY, USA b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 29 August 2013 Received in revised form 4 October 2013 Accepted 15 November 2013 Available online 15 December 2013
This is a case report of an adult who presented with apparent culture negative endocarditis (CNE) thought to be marantic endocarditis due to a B-cell lymphoproliferative disorder. This was a most perplexing case and was eventually diagnosed as subacute bacterial endocarditis (SBE) due to a rare slow growing organism. Against the diagnosis of SBE was the lack of fever, hepatomegaly, peripheral manifestations and microscopic hematuria. Also, against a diagnosis of SBE was another explanation for the patient’s abnormal findings, e.g., elevated ferritin levels, elevated a1/a2 globulins on SPEP, an elevated alkaline phosphatase, flow cytometry showing B-lymphocytes expressing CD5, and a bone lesion in the right iliac. Findings compatible with both SBE and marantic endocarditis due to a B-cell lymphoproliferative disorder included an elevated ESR, and splenomegaly. Blood cultures eventually became positive during hospitalization. We report a case of native aortic valve (AV) subacute bacterial endocarditis (SBE) due to Aerococcus christensenii mimicking marantic endocarditis due to a B-cell lymphoproliferative disorder. To the best of our knowledge, this is the first reported case of native AV SBE due to A. christensenii presenting as marantic endocarditis. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Mimics of endocarditis Slow growing Gram positive cocci B-cell lymphoproliferative disorder Culture negative endocarditis (CNE) Marantic endocarditis Viridans streptococcal endocarditis mimics Elevated ferritin levels Endocarditis differential diagnosis
Introduction Subacute bacterial endocarditis (SBE) is caused by low virulence microorganisms that infect previously abnormal/damaged heart valves. Most patients with SBE are ill for 1e3 months prior to presentation. A subacute/indolent course of SBE is usual with fevers <102 F and splenomegaly is often present. There may be peripheral signs of SBE, e.g., Roth spots, conjunctival hemorrhages, splinter hemorrhages, Ostler’s nodes, Janeway lesions. Because SBE is, by definition subacute, sufficient time has usually elapsed for clinical and laboratory manifestations of SBE to become apparent, e.g., splenomegaly is often present. The diagnosis of SBE is based on an otherwise unexplained high grade/continuous bacteremia and a cardiac, usually valvular, vegetation: An unchanging murmur is usual, and peripheral signs of SBE are often present.1e4 * Corresponding author. Infectious Disease Division, Winthrop-University Hospital, 222 Station Plaza North (Suite #432), Mineola, NY 11501, USA. Tel.: þ1 516 663 2505; fax: þ1 516 663 2753. E-mail address: [email protected] (B.A. Cunha). 0147-9563/$ e see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.hrtlng.2013.11.005
In patients with fever, a murmur, a valvular vegetation, negative blood cultures, and peripheral manifestations of SBE, the most likely diagnosis is CNE. CNE may be due to infection with fastidious organisms or non-infectious disorders. A common cause of infectious CNE is marantic endocarditis. Marantic endocarditis has the clinical features of CNE but is not due to an infectious agent, e.g., Q fever, brucella. Often marantic endocarditis is due to a noncardiac neoplasm, e.g., lymphoma, lymphoproliferative disorder.3,4 Case A 60 year old male was admitted to the hospital with left hand numbness and clumsiness. His past medical history included hypertension, anemia, a platelet aggregation disorder, aortic valve regurgitation of unknown etiology diagnosed 6 years ago and spontaneous testicular hemorrhage requiring orchiectomy 10 years ago. He recently returned from Argentina with fatigue and malaise. He denied any fevers, chills, dysuria, frequency, urgency, or recent dental work. A repeat echocardiogram done as an outpatient revealed severe aortic regurgitation. He was treated for periodontal
162
A. Jose et al. / Heart & Lung 43 (2014) 161e163
disease several years ago. On admission, his temperature was 98.6 F, pulse was 69/min, blood pressure was 133/70 mm Hg, respiratory rate was 18/min. Physical examination revealed an aortic regurgitant murmur but no signs of peripheral emboli. Admission laboratory tests revealed a white blood cell (WBC) count of 7 K/uL (66% neutrophils, 23% lymphocytes, 8% monocytes, 3% eosinophils), hemoglobin (Hb) of 9.2 g/dl, hematocrit (Hct) of 27.1%, platelet count of 197 K/uL, erythrocyte sedimentation rate (ESR), by Westergren, of 39 mm/h, C-reactive protein (CRP) of 43.2 mg/L, creatinine of 1.4 mg/ dL, alanine aminotransferase (ALT) of 18 IU/L, aspartate aminotransferase (AST) of 21 IU/L, alkaline phosphatase of 114 IU/L (n ¼ 25e100 IU/L), ferritin of 246 ng/mL (n ¼ 14e35 ng/ml), a negative rheumatoid factor (RF), a negative urinalysis, and a prostate-specific antigen (PSA) total of 0.4 ng/ml. Magnetic resonance imaging (MRI) of the brain revealed a small acute infarct in the right frontoparietal region. Two days later, a transesophageal echocardiogram (TEE) revealed severe AV regurgitation as well as a small mobile echodensity on the ventricular aspect of the aortic valve. Admission blood cultures were negative. The patient was afebrile, had no peripheral signs of SBE, had a normal WBC, and had a serum electrophoresis (SPEP) with elevated a-1/a-2 fractions. The working diagnosis was marantic endocarditis secondary to a B-cell lymphoproliferative disorder. Flow cytometric analysis of the peripheral blood showed a population of B-cells expressing CD5 and diminished expression of light chains suspicious for a B-cell lymphoproliferative disorder. To rule out malignancy, CT scans of the chest, abdomen and pelvis were performed. The CT scans showed hepatosplenomegaly, a splenic infarct, and a 1.5 cm lytic lesion in the right iliac. Bone marrow biopsy of the right iliac lesion showed a focal increase in B lymphocytes, but no lymphoma. Positron emission tomography (PET) scan performed a week into the hospital admission was negative for malignancy. After a week in hospital two sets of blood cultures drawn on admission became positive with slow-growing Gram positive cocci in pairs and clusters. Ampicillin and gentamicin were started. Two sets of blood cultures drawn on day 3 of hospitalization and 3 sets drawn on day 9 of hospitalization later became positive. Colonies of the organism on sheep blood agar were slow growing at 36 C under 6% CO2, gray-white and non-hemolytic. Catalase was not produced. The organism appeared as Gram-positive cocci in pairs and small clusters. Tests for pyrrolidonyl arylamidase (PYR), bile-esculin, esculin hydrolysis and arginine hydrolysis were negative and positive for leucine aminopeptidase (LAP), growth in 6.5% NaCl, and hippurate hydrolysis. B-glucuronidase activity was measured using the RapID NF Plus system (Remel Labs) was negative. The organism was non-motile and sensitive to vancomycin by disk diffusion. This combination of reactions differentiated the organism from other members of the Aerococcus genus and other catalase-negative cocci. The blood culture isolate was ultimately identified as Aerococcus christensenii. On the tenth hospital day, the patient underwent AV replacement. Gram stain of the removed aortic valve revealed Gram positive cocci in pairs and clusters, but valve culture was negative. Subsequent blood cultures drawn on day 10, 13 and 19 were negative. He was treated with a six-week course of ceftriaxone. Discussion This is a most unusual case of SBE. Although the patient had previous aortic valve disease, he was afebrile. Also, against the diagnosis of SBE was hepatosplenomegaly. Splenomegaly, but not hepatomegaly or hepatosplenomegaly, are SBE findings. The absence of rheumatoid factors (RFs) and microscopic hematuria also argued against the diagnosis of SBE.1 Cardiac echocardiography showed a small mobile echodensity on the aortic valve (possible vegetation or fibroelastoma).2,3 In favor of a lymphoproliferative
disorder was hepatosplenomegaly, elevated alkaline phosphatase, elevated ferritin levels, elevated a-1/a-2 fractions on SPEP, and peripheral blood flow cytometry suspicious for a B-cell lymphoproliferative disorder.4 There also was a 1.5 cm lytic bone lesion in the right iliac crest. The elevated ESR was unhelpful in distinguishing between lymphoma and SBE. Bone marrow biopsy showed an increase in B-lymphocytes, but no lymphoma. Lymphoma was eventually ruled out by a negative PET-CT scan. A. christensenii is a weakly catalase-positive, slow-growing Gram positive coccus that tends to form tetrads or clusters; and is a-hemolytic on sheep blood agar and can grow in 6.5% NaCl.5,6 Aerococcus species are rare human pathogens. Aerococcus spp. have been isolated from air, dust, meat and meat products, crustaceans, raw vegetables, as well as the hospital environment. Aerococcus spp. may also be part of the normal flora of the upper respiratory tract and skin. They have low pathogenic potential and tend to infect damaged tissues.7 Risk factors for infection include granulocytopenia, oral mucositis, prolonged hospitalization, invasive procedures, prior antibiotic treatment, and implanted devices.8 Aerococcus spp. have been reported to cause urinary tract infections (UTIs), urosepsis, bacteremia, SBE, meningitis, empyema, and wound infections.9 The first Aerococcus spp. identified, Aerococcus viridans, rarely may cause UTIs, wound infections, SBE, septic arthritis, osteomyelitis, or meningitis.5 Due to the rarity of Aerococcus spp. infections, optimal antibiotic therapy for Aerococcus spp. has not been determined. Other Aerococcus spp. isolated in humans include Aerococcus urinae, Aerococcus urinaehominis, and Aerococcus sanguinicola.10,11 More recently, Aerococcus urinaeequi (originally classified as Pediococcus urinaeequi), a horse pathogen, and Aerococcus suis, a pig pathogen, have been reported to cause human infection. In immunocompromised patients with a history of urogenital abnormalities, A. sanguinicola is an opportunistic organism that may cause urosepsis or SBE. Neurologic deficiencies and alcohol abuse also appear to be risk factors for A. sanguinicola infection.12 Infection with Aerococcus spp. should be suspected in patients with urine or blood cultures revealing slow growing catalase negative Gram positive cocci in pairs and clusters. Aerococcus spp. colonies are convex and shiny with light-green a-hemolysis, resembling viridans streptococci. Phenotypic methods and 16S rRNA gene sequencing have improved the ability to identify Aerococcus spp.16,17 Patients with Aerococcus spp. SBE may not initially present with fever or peripheral findings of SBE, and our patient presented with an acute embolic stroke.13e33 The patient had poor dentition and AV disease for many years. The source of A. christensenii in this case remains unclear but like veridans streptococcal SBE was probably the mouth.13e15 References 1. Cunha BA. Diagnostic significance of non-specific laboratory tests in infectious diseases. In: Gorbach SL, Bartlett JB, Blacklow NR, eds. Infectious Disease in Medicine and Surgery. 3rd ed. Philadelphia: W.B. Saunders Co.; 2002:158e165. 2. Rubenson DS, Tucker CR, Stinson EG. The use of echocardiography in diagnosing culture-negative endocarditis. Circulation. 1981;64:641e646. 3. Van Scoy RE. Culture-negative endocarditis. Mayo Clin Proc. 1982;57:149e154. 4. Cunha BA. The mimics of endocarditis. In: Brusch JL, ed. Infective Endocarditis: Management in the Era of Intravascular Devices. New York, NY: Informa Healthcare; 2007:345e353. 5. Pien FD, Wilson WR, Kunz K, Washington JA. Aerococcus viridans endocarditis. Mayo Clin Proc. 1984;59:47e48. 6. Zbinden R, Santanam P, Hunziker L, Leuzinger B, von Graevenitz A. Endocarditis due to Aerococcus urinae: diagnostic tests, fatty acid composition and killing kinetics. Infection. 1999;27:48e50. 7. Janosek J, Eckert J, Hudac A. Aerococcus viridans as a causative agent of infectious endocarditis. J Hyg Epidemiol Microbiol Immunol. 1980;24:92e96. 8. Chen L, Yu W, Huang S, et al. Successful treatment of Aerococcus viridans endocarditis in a patient allergic to penicillin. J Microbiol Immunol Infect. 2012;45:158e160.
A. Jose et al. / Heart & Lung 43 (2014) 161e163 9. Christensen JJ, Gutschik E, Friis-Moller A, Korner B. Urosepticemia and fatal endocarditis caused by Aerococcus-like organisms. Scand J Infect Dis. 1991;23: 717e721. 10. Ebnother C, Altwegg M, Gottschalk J, Seebach JD, Kronenberg A. Aerococcus urinae endocarditis: case report and review of the literature. Infection. 2002;30: 310e313. 11. de Jong MFC, Soetekouw R, ten Kate RW, Veenendaal D. Aerococcus urinae: severe and fatal bloodstream infections and endocarditis. J Clin Microbiol. 2010;48:3445e3447. 12. Ibler K, Jensen KT, Ostergaard C, et al. Six cases of Aerococcus sanguinicola infection: clinical relevance and bacterial identification. Scand J Infect Dis. 2008;40:761e765. 13. Brusch JL. Infective Endocarditis: Management in the Era of Intravascular Devices. New York, NY: Informa Healthcare; 2007. 14. Cunha BA, Gill MV, Lazar J. Acute infective endocarditis. Infect Dis Clin N Am. 1996;10:811e834. 15. Kaye D. Infective Endocarditis. 2nd ed. New York: Raven Press; 1992. 16. Versalovic J. Manual of Clinical Microbiology. 10th ed., vol. 1. Washington, DC: ASM Press; 2011. 17. Wilson GS, Miles A. Topley and Wilson’s Principles of Bacteriology, Virology and Immunity. 16th ed.vol. 1. Baltimore: The Williams and Wilkins Company; 1975. 18. Rasmussen M. Aerococci and aerococcal infections. J Infect. 2013;66:467e474. 19. Senneby E, Petersson AC, Rasmussen M. Clinical and microbiological features of bacteremia with Aerococcus urinae. Clin Microbiol Infect. 2012;18:546e550. 20. Untereker WJ, Hanna BA. Endocarditis and osteomyelitis caused by Aerococcus viridans. Mt Sinai J Med. 1976;43:248e252. 21. Colman G. Aerococcus-like organisms isolated from human infections. J Clin Pathol. 1967;20:294e297.
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