Ann Thorac Surg 2012;93:e93-e95. doi:10.1016/j.athoracsur.2011.11.051
© 2012 The Society of Thoracic Surgeons
Case Reports
Bartonella as a Cause of Mechanical Prosthetic Aortic Root Endocarditis
Jamil Hajj-Chahine, MDa,*,
Hassan Houmaida, MDa,
Chloé Plouzeau, MDb,
Jacques Tomasi, MDa,
Pierre Corbi, MD, PhDa
a Department of Cardiothoracic Surgery, University Hospital of Poitiers, Poitiers, France
b Department of Bacteriology, University Hospital of Poitiers, Poitiers, France
Accepted for publication November 14, 2011.
* Address correspondence to Dr Hajj-Chahine, Department of Cardiothoracic Surgery, Centre Hospitalier Universitaire de Poitiers, 2 Rue de la Milétrie, 86021 Poitiers, France (Email: jamilhajjchahine{at}yahoo.fr).
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Abstract
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Bartonella henselae infection is typically associated with cat scratch disease. This microorganism can also lead to culture-negative infective endocarditis in immunocompromised patients. We present a rare case of a previously healthy 65-year-old man with B henselae–associated endocarditis of a prosthetic aortic root. All blood cultures, as well as cultures of the resected aortic valve vegetations, remained negative. Polymerase chain reaction with specific bacterial primers with DNA sequencing was used to identify B henselae as the etiologic agent. This was successfully managed by an aortic root re-replacement using a mechanical conduit, reimplantation of coronaries ostia, and antibiotic therapy.
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Introduction
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Bartonella henselae is classically associated with cat scratch disease; it is also responsible for bacillary angiomatosis and life threatening meningoencephalitis. This disease is transmitted to human after a scratch from a contaminated cat. This gram-negative microorganism can also lead to culture-negative infective endocarditis (IE) in immunocompromised patients [1–4]. We present a rare case of a previously healthy man with B henselae–associated IE of a prosthetic aortic root.
The patient was a 65-year-old man with a history of severe aortic valve regurgitation and aneurysmal aortic root who had undergone uneventful aortic root replacement surgery with a Hall-Medtronic valve conduit (27 mm; Medtronic, Inc, Minneapolis, MN) 3 years earlier. The patient was well for the intervening 2.5 years before being admitted to the hospital. He had a 3-month history of increasing fatigue, dyspnea on exertion, night sweats, and a 15-kg weight loss. He did not smoke or drink alcohol, and he had no contact with animals or drug abusers.
On admission, he was febrile (38°C) with a systolic murmur and a crisp, mechanical, second heart sound. Findings from examination of the lungs, abdomen, extremities, and neurologic functioning were unremarkable, except for nail bed splinter hemorrhages of the third digit of the right hand, and bilateral conjunctival hemorrhages were also noted. There was no regional lymphadenopathy.
His international normalized ratio was 4.1, hemoglobin level was 9.6 g/dL, white blood cell count was 5,600 leukocytes/mm3, and C-reactive protein level was 38 mg/L. He had normal renal and hepatic function. Chest radiography showed mild cardiomegaly, and electrocardiogram revealed first-degree heart block.
Transthoracic echocardiogram showed a well-seated prosthetic valve without evidence of endocarditis. Six blood cultures (aerobic and anaerobic) showed no growth at 14 days. A transesophageal echocardiogram (Fig 1) documented two 15-mm vegetations attached to the prosthetic aortic valve with trivial regurgitation, and multislice cardiac-gated computed tomography scan (Fig 2) revealed evidence of a large aortic root abscess with minimal peripheral enhancement and normal coronary arteries. These findings were compatible with the diagnosis of blood culture–negative endocarditis; therefore intravenous vancomycin, gentamycin, and rifampin were commenced. Meanwhile, the antibody titers of Coxiella burnetii, Mycoplasma species, and Chlamydia species were undetectable, and only a slightly elevated level of serum antibodies to Bartonella species was identified. The surgical indication in this case of blood culture–negative endocarditis was made on the presence of large size vegetations on the bileaflet prosthetic valve.
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Fig 1. Transesophageal echocardiogram demonstrating (A) (mid-oesophageal aortic valve short axis view) vegetations (white arrow) on prosthetic aortic valve and (B) (mid-oesophageal ascending aorta short axis view) dark cavity (black arrow) corresponding to aortic root abscess. (Ao = aorta; LA = left atrium; RA = right atrium).
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Fig 2. Multidetector computerized tomographic scan demonstrating large aortic root abscess (arrows) with minimal peripheral enhancement. (LM = left main; RCA = right coronary artery.)
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The patient underwent a technically complex aortic valve and root re-replacement. Cardiopulmonary bypass was instituted in the right groin between the femoral artery and femoral vein. Surgery identified an abscess extending from the midpoint of the noncoronary cusp toward the left atrium and no fistula formation. The Hall-Medtronic valve conduit was replaced with a 27-mm Carbomedics valve conduit (Carbomedics, Austin, TX) after extensive debridement of surround tissues. Weaning from cardiopulmonary bypass was uneventful.
Microbiologic examination of the excised tissues showed no organisms on Gram stain. Cultures of aortic root abscess contents, aortic graft tissue, and vegetation were all negative. The patient had a slightly elevated level of serum antibodies to Bartonella species; therefore, the aortic valve was sent to the reference center for molecular diagnosis of rickettsial diseases in Marseille, France. Bartonella henselae was identified. Eventually, the patient was diagnosed as having B henselae prosthetic valve endocarditis. The patient received 6 weeks of intravenous ceftriaxone and oral doxycycline. He then received another 3 months of oral doxycycline (200 mg) once a day. One year after surgery, the patient was afebrile and doing well in New York Heart Association functional class I, and the valve was functioning adequately.
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Comment
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Bartonella species are fastidious gram-negative intracellular rods that constitute 2% of cases of blood culture–negative endocarditis [1, 2]. Although most cases of Bartonella species–induced endocarditis affect native valves, the few case reports describing Bartonella-induced prosthetic valve endocarditis are characterized by vegetations and valvular perforations, in cases of bioprosthesis [3, 4]. Review of the literature demonstrates that B henselae affecting mechanical prosthesis is rare, and it was previously discovered in few cases [5, 6]. To date, six species of Bartonella have been known to cause IE in human. Bartonella quintana (the causative agent of trench fever) IE is associated with homelessness, poor living conditions, and chronic alcoholism, and accounts for 75% of the cases, whereas B henselae (the causative agent of cat scratch disease) IE occurs after exposure to cats or cat fleas and accounts for the remaining 25% [1].
To establish the diagnosis of IE secondary to Bartonella species molecular diagnostic techniques using polymerase chain reaction amplification and direct sequencing of DNA from resected valve specimens is considered a valuable technique, achieving a specificity of 100%. The causative species of Bartonella can be accurately identified at the genomic level by using specific primers [1–4].
On the other hand, serologic testing still has two drawbacks in the setting of Bartonella species IE: first, the cross-reactivity with Chlamydia species and C burnetii, and second, the inability to reliably distinguish between antibody responses to B henselae and B quintana [7]. A remarkable aspect of our case is that the patient was not exposed to cats. We recommend that in the diagnostic workup of patients with culture-negative IE, Bartonella infection should be sought by serologic testing, regardless of the presence or absence of recognized risk factors. If the serologic test is positive, the diagnosis will be confirmed by polymerase chain reaction.
The optimal antimicrobial therapy for Bartonella IE remains controversial. Only aminoglycosides are considered bactericidal toward Bartonella species, and a minimum 2-week course of aminoglycoside therapy has been associated with favorable outcomes. Recent guidelines for the management of IE recommend doxycycline for 6 weeks and gentamicin for the initial 2 weeks of therapy for documented Bartonella IE [4].
In this report, we present a case of B henselae causing a mechanical prosthetic root endocarditis that was managed successfully by an aortic root re-replacement. Aortic root reoperation, even in the setting of endocarditis, can be carried out with excellent results. Femoro-femoral cardiopulmonary bypass represents a valuable technique in the setting of an infected valve conduit, in addition to preoperative computed tomography, which identifies possible pitfalls during resternotomy.
Applying molecular detection and identification techniques on excised heart valves brings particular benefits in the case of culture-negative endocarditis, especially for fastidious and nonculturable microorganisms. Polymerase chain reaction assay of the excised valve is a very sensitive and reliable method, and it substantially improves diagnosis and the patient's outcome. Surgeons constantly need to adjust their algorithms; this useful tool should be considered in the armamentarium of every cardiac surgeon and must become the standard of care.
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References
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- Raoult D, Fournier PE, Vandenesch F, et al. Outcome and treatment of Bartonella endocarditis Arch Intern Med 2003;163:226-230.[Medline]
- Kreisel D, Pasque MK, Damiano Jr RJ, et al.
Bartonella species-induced prosthetic valve endocarditis associated with rapid progression of valvular stenosis J Thorac Cardiovasc Surg 2005;130:567-568.[Free Full Text]
- Ghidoni JJ. Role of Bartonella henselae endocarditis in the nucleation of aortic valvular calcification Ann Thorac Surg 2004;77:704-706.[Abstract/Free Full Text]
- Fournier PE, Lelievre H, Eykyn SJ, et al. Epidemiologic and clinical characteristics of Bartonella quintana and Bartonella henselae endocarditis: a study of 48 patients Medicine (Baltimore) 2001;80:245-251.[Medline]
- Gouriet F, Lepidi H, Habib G, Collart F, Raoult D. From cat scratch disease to endocarditis, the possible natural history of Bartonella henselae infection BMC Infect Dis 2007;7:3018.[Medline]
- Vikram HR, Bacani AK, DeValeria PA, Cunningham SA, Cockerill 3rd FR. Bivalvular Bartonella henselae prosthetic valve endocarditis J Clin Microbiol 2007;45:4081-4084.[Abstract/Free Full Text]
- Lesprit P, Noël V, Chazouillères P, Brun-Buisson C, Deforges L. Cure of Bartonella endocarditis of a prosthetic aortic valve without surgery: value of serologic follow-up Clin Microbiol Infect 2003;9:239-241.[Medline]
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Abstract
Introduction
