Canadian Journal of Cardiology 30 (2014) 1462.e1e1462.e2 www.onlinecjc.ca

Case Report

First Reported Human Case of Native Mitral Infective Endocarditis Caused by Streptococcus canis Myriam Amsallem, MD, Bernard Iung, MD, Claire Bouleti, MD, PhD, Laurence Armand-Lefevre, MD, Anne-Line Eme, MD, Aziza Touati, MD, Matthias Kirsch, MD, PhD, Xavier Duval, MD, PhD, and Alec Vahanian, MD Department of Cardiology, Bichat Claude Bernard Hospital, AP-HP, Paris Diderot University, Paris, France

ABSTRACT

  RESUM E

A 65 year-old woman was admitted for acute heart failure and severe sepsis revealing definite mitral infective endocarditis with severe regurgitation, complicated by multiple embolisms. Three blood cultures yielded a group G Streptococcus canis strain. Urgent surgery was performed with bioprosthetic valve replacement. Polymerase chain reaction analysis of the valve found S canis DNA. Amoxicillin and gentamicin were given for 2 weeks followed by 4 weeks of amoxicillin alone. She reported contact with a dog without bite. S canis has been reported to cause zoonotic septicemia but to our knowledge, this is the first human case of native valve infective endocarditis.

e en raison d’une insuffisance cardiaque Femme de 65 ans, hospitalise vère re  ve lant une endocardite infectieuse sur aiguë et d’un sepsis se vère, complique e d’embols multiples. valve mitrale native avec fuite se mocultures ont mis en e vidence une souche de Streptococcus Trois he canis du Groupe G. Un remplacement valvulaire mitral chirurgical par  te  re alise . L’analyse de la valve par PCR (re action en bioprothèse a e rase) a re ve le  de l’ADN de S. canis. La patiente a chaîne par polyme reçu de l’Amoxicilline et Gentamycine durant 2 semaines puis de  te  en contact l’Amoxicilline durant 4 semaines. Elle rapporte avoir e  te  rapporte  avec un chien sans subir de morsure. Le S. canis a e mie zoonotique, mais il s’agit, à notre concomme cause de septice naissance du premier cas humain d’endocardite sur valve native.

A 65-year-old woman was admitted for fatigue, weight loss, fever of 10-day duration, and severe dyspnea (New York Heart Association class IV). She had a medical history of uterine carcinoma in remission, but no known valvular disease. She presented with severe sepsis (blood pressure at 80/60 mmHg, tachycardia at 140 beats per minute, temperature 39 C with marbling), confusion with a Glasgow coma scale score of 14, rapidly improving after intravenous saline infusion. Examination found a holosystolic mitral murmur associated with bilateral crackles. Electrocardiogram showed sinus tachycardia with left anterior hemiblock. C-reactive protein was 190 mg/mL, associated with leukocytosis (16 g/L). Echocardiography found severe mitral regurgitation due to complete prolapse of P1 associated with appended vegetations (maximum 15 mm length) (Fig. 1), highly suggestive of infective endocarditis (IE). There was neither abscess nor

involvement of another valve. Left ventricular ejection fraction was 60%. IE was complicated with emboli in the right retina, right kidney, and multiple cerebral microabscesses according to magnetic resonance imaging, without any mycotic aneurysms on the preoperative arteriography. Three of 7 independent peripheral blood cultures drawn during the first 12 hours were positive for a group G Streptococcus strain, identified as Streptococcus canis using mass spectrometry (MALDI Biotyper, Bruker, Wissembourg, France), susceptible to penicillins with low-level resistance to gentamicin. The patient was initially treated with intravenous amoxicillin 200 mg/kg/d with gentamicin 3 mg/kg/d. Urgent surgery was performed because of heart failure due to massive regurgitation and the large vegetation with a history of multiple embolisms. Intraoperative analysis of the valve found mitral prolapse secondary to chordae rupture at the level of the anterior commissure and several vegetations without annular abscess. The patient underwent bioprosthetic mitral valve replacement. Overall, the patient received 2 weeks of double antibiotic therapy followed by 4 weeks of intravenous amoxicillin alone. The course was rapidly favourable with negative blood cultures and resolution of the inflammatory syndrome (C-reactive protein 12 mg/mL at discharge). At 2 months after the end of antibiotic

Received for publication April 28, 2014. Accepted July 14, 2014. Corresponding author: Dr Myriam Amsallem, Department of Cardiology, Bichat Claude Bernard Hospital, AP-HP, Paris Diderot University, 46 Rue Henri Huchard, 75018 Paris, France. Tel.: þ33(0)685890344; fax: þ33(0) 140256732. E-mail: [email protected] See page 1462.e2 for disclosure information.

http://dx.doi.org/10.1016/j.cjca.2014.07.013 0828-282X/Ó 2014 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

Amsallem et al. Infective Endocarditis Caused by Streptococcus canis

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Figure 1. Preoperative transesophageal echocardiography 70 of the mitral native valve. Two-dimensional transesophageal echocardiography (left) showing complete prolapse of the anterolateral scallop of the posterior mitral valve leaflet with an added mass appended to the valve (arrow), highly suggestive of vegetation. Colour Doppler (right) showing a large swirling colour jet of mitral regurgitation. LA, left atrium; LV, left ventricle.

therapy, the patient was apyretic, with no sign of heart failure nor sequelae of septic emboli, except for diminished visual acuity involving the right eye. The diagnosis of IE caused by S canis, definite according to the presence of 2 major Duke criteria, was confirmed by amplification of the 16S ribosomal RNA gene in DNA extracted from the cardiac valve tissue, and standard valve culture was negative. The patient reported contact with a dog in the weeks preceding symptom onset but was not bitten. To our knowledge, this is the first reported human case of IE caused by S canis, involving a native valve. In humans, S canis bacteremia was first described in 1997.1 Since then, several cases of septicemia2 caused by this zoonotic streptococcus were reported, secondary to dog or cat bite or even to simple contact. Only 1 case of IE was described, involving a prosthetic aortic valve, in which blood cultures were negative.3 The diagnosis of endocarditis due to S canis was made using mass spectrometry on blood cultures and DNA amplification on the valve. In fact, infections caused by S canis are probably underestimated because identification of b-hemolytic streptococci usually relies on the Lancefield classification and is not systematically performed to the species level.4 Furthermore, this case brings new clinical insight into the pathogenicity of S canis, highlighting its virulence. Several virulence factors have been recently identified in S canis, involved in invasion, colonization, or tissue damage, such as the antiphagocytic M-like protein, which has been characterized as one of the most important virulence mechanisms in group A Streptococcus.5

This case illustrates S canis tropism for endocardium and the need to consider IE, particularly in cases of recurrent bacteremia. The early and accurate identification of streptococci species associated with a high virulence has implications on patient management because it should increase awareness of endocarditis complications and indications for early surgery. New routine identification methods, such as mass spectrometry, are useful in this setting. Disclosures The authors have no conflicts of interest to disclose. References 1. Bert F, Lambert-Zechovsky N. Septicemia caused by Streptococcus canis in a human. J Clin Microbiol 1997;35:777-9. 2. Galperine T, Cazorla C, Blanchard E, et al. Streptococcus canis infections in humans: retrospective study of 54 patients. J Infect 2007;55:23-6. 3. Takamura T, Tanabe M, Onishi K, et al. Molecular diagnosis of prosthetic valve endocarditis with aorto-right atrial fistula. Int J Cardiol 2009;135: e13-5. 4. Lam MM, Clarridge JE 3rd, Young EJ, Mizuki S. The other group G Streptococcus: increased detection of Streptococcus canis ulcer infections in dog owners. J Clin Microbiol 2007;45:2327-9. 5. Richards VP, Zadoks RN, Pavinski Bitar PD, et al. Genome characterization and population genetic structure of the zoonotic pathogen, Streptococcus canis. BMC Microbiol 2012;12:293.

First reported human case of native mitral infective endocarditis caused by Streptococcus canis.

A 65 year-old woman was admitted for acute heart failure and severe sepsis revealing definite mitral infective endocarditis with severe regurgitation,...
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