A rare pathogen causing endocarditis: Streptococcus constellatus/Endokardite neden olan ender hir patojen: Streptococcus constellatus.

Herein we reported a 35-year-old man who developed endocarditis caused by Streptococcus (S) constellatus, a member of S. milleri group. Unlike other viridans streptococci, members of the S. milleri group rarely cause infective endocarditis.

A 35- year-old male patient was admitted to our clinic with complaints of tiredness, night sweating, cough and fever lasting two months. On clinical examination, vital signs except body temperature (39.5[degrees]C) were within normal limits. We detected 2/4th grade diastolic murmur along left sternal border. His blood analysis revealed hematocrit 45%, leucocytes 16500/ mm3, ESR 75 mm/h. On his transthoracic echocardiographic examination severe aortic regurgitation, mild degree aortic stenosis (peak gradient 21 mmHg) and multiple vegetations on the aortic cusps (maximum diameter 9X5 mm) were seen (Fig.1). Two blood cultures for aerobic and anaerobic pathogens were immediately taken and therapy with penicillin G-gentamycin combination was initiated.

From blood cultures evaluated with The BacT/ALERT and the BACTEC 9240 systems viridans streptococci were isolated. Despite intensive antibiotic therapy, the patient's general condition was not improved, and hence, another set of blood cultures was obtained. The isolates grew well and had pinpoint colonies of alpha-hemolysis on 5% defibrinated sheep blood agar (Salubris, Turkey) in 5% C02 and ambient air at 37[degrees]C. They were catalase-negative and gram-positive cocci. The isolate was identified as S. constellatus by both the API Rapid ID32 Strep system (bioMerieux, France) and REMEL Rapid STR system (Apogent-USA). The isolate was susceptible to ceftriaxone, chloramphenicol, erythromycin, ofloxacin, cefotaxime, tetracycline, levofloxacin, and vancomycin but resistant to penicillin G. We immediately changed the antibiotic treatment to cefotaxime 2x4 g IV per day. However, the persistence of vegetations on control transthoracic echocardiogram repeated three days later led us to transfer the patient to cardiac surgery clinic for aortic valve replacement with St Jude mechanical valve. Intraoperative and postoperative course was uneventful. We continued cefotaxime therapy for another six week and the patient discharged on the postoperative 20th day.

Nearly all microorganisms can cause infective endocarditis especially gram-positive cocci and the so-called HACEK microorganisms (1). Furthermore, viridans streptococci are the leading cause of native valve endocarditis especially in subacute cases (1).

[FIGURE 1 OMITTED]

The S. milleri group consists of three species: S. constellatus, S. anginosus and S. intermedius. This group of streptococci is part of the normal flora of the mucous membranes, but is often involved in suppurative infections especially in the presence of cirrhosis, diabetes, malignancy and immunodeficiency (2). They are also rare causes of infective endocarditis with S. anginosus predominance (3).

Although a high degree of clinical suspicion and correct interpretation of clinical findings still has paramount importance in infective endocarditis diagnosis, the possibility of rarely detected microorganism as a causative agent should be keep in mind. In our case, penicillin-gentamycin combination was unsuccessful which prompted for searching another organism. Moreover, the results of cefotaxime therapy were also unsatisfactory in the presence of persistent vegetations.

Early valve surgery with cefotaxime therapy, as in our case, may be more appropriate therapeutic approach in penicillin-resistant S. constellatus endocarditis cases (4, 5).

References

(1.) Petzsch M, Krause R, Reisinger EC. Current treatment options of infective endocarditis. J Clin Basic Cardiol 2001; 4: 25-30.

(2.) Salavert M, Gomez L, Rodriguez-Carballeira M, Xercavins M, Freixas N, Garau J. Seven-year review of bacteremia caused by Streptococcus milleri and other viridans streptococci. Eur J Clin Microbiol Infect Dis 1996; 15:365-71.

(3.) Kitada K, Inoue M, Kitano M. Experimental endocarditis induction and platelet aggregation by Streptococcus anginosus, Streptococcus constellatus and Streptococcus intermedius. FEMS Immunol Med Microbiol 1997; 19: 25-32.

(4.) Ejima K, Ishizuka N, Tanaka H, Tanimoto K, Shoda M, Kasanuki H. Prosthetic valve endocarditis caused by Streptococcus constellatus infection complicated with perivalvular abscess: serial observation by transesophageal echocardiography: a case report. J Cardiol 2003; 42: 129-33.

(5.) Baran J Jr, Abdo WM, Merritt KW, Khatib R. Tricuspid valve endocarditis due to a moderately susceptible Streptococcus constellatus: persistent bacteremia and fatal outcome despite penicillin plus gentamicin therapy. Scand J Infect Dis 1998; 30: 420-1.

Zeynep Senses, Mehmet Yokusoglu *, Bilgehan Savas Oz **, Aylin uskudar Guclu, Hakan Erdem ***, Oben Baysan *, Mehmet Baysallar

From Departments of Microbiology and Clinic Microbiology, * Cardiology, ** Cardiovascular Surgery and Infectious Diseases, Gulhane Military Medical Academy, Ankara, Turkey

Address for Correspondence/Yazisma Adresi: Doq. Dr. Mehmet Yokusoglu, GATA Kardiyoloji Anabilim Dali, Gn Tevfik Saglam Cad. 06018, Etlik -Ankara Phone: + 90 312 304 42 67 Fax: + 90 312 304 42 50 E-mail: [e-mail]

The case report was presented as a poster presentation at the 23d World Congress of Pathology and Laboratory Medicine, Istanbul Turkey, May 26m 3P 2W5