Bartonella quintana and Coxiella burnetii as causes of endocarditis, India.

To the Editor: In industrialized countries, blood culture is negative for 2.5%-31% of infectious endocarditis cases (1). In developing countries such as South Africa (2), Algeria (3), and Pakistan (4), culture is negative for 48% to 56%. Negative cultures delay diagnosis and treatment, which profoundly affects clinical outcome. Negative blood cultures commonly result from previous administration of antimicrobial drugs, right-sided endocarditis, or fastidious or noncultivable pathogens (1). Our aim was to identify fastidious agents of blood culture-negative endocarditis by serology. Because of recent attention to zoonotic microorganisms as agents of this condition in developing countries (1), we investigated the prevalence of Coxiella burnetii, Bartonella spp., and Brucella melitensis among endocarditis patients in India.

We cultured blood from 111 patients admitted to the Government General Hospital, Chennai, India, from August 2005 through December 2006, with a diagnosis of infectious endocarditis according to the Duke criteria (5). Informed consent was obtained from all patients. Three blood samples from each patient, collected at hourly intervals, were inoculated into brain-heart infusion broth supplemented with 0.04% sodium polyanethol sulfonate (HiMedia, Mumbai, India). Cultures were incubated at 37[degrees]C in a 5% C[O.sub.2] atmosphere for 14 days and checked each day for turbidity. Subcultures were made on 5% sheep blood and MacConkey agar at 37[degrees]C at 24 hours, 48 hours, and when culture broth appeared turbid.

Blood cultures were negative for 80 (72%) of the 111 patients. Serum from 63 patients was available for serologic testing. Of these patients, 30 were male and 33 were female; age range was 5-65 years and mean age was 25.5 years. Endocarditis involved the native valve for 60 (95.23%) and a prosthetic valve for 3 (4.76%). The most frequent predisposing factor was rheumatic heart disease, found in 38 (60.31%). Of the 60 with native valve endocarditis, the involved valve was mitral for most (36, 60.0%), followed by aortic (8, 13.33%), tricuspid (7, 11.66%), and pulmonary (1, 1.66%); 8 (13.33%) had both valvular and nonvalvular endocarditis. Of the 3 patients with prosthetic valve endocarditis, the involved valve was mitral for 2 and aortic for 1.

Serum samples were screened for Bartonella spp. and C. burnetii by microimmunofluorescence (6, 7). A diagnosis of endocarditis was based on an immunoglobulin (Ig) G titer [greater than or equal to] 800 to phase I C. burnetii; this titer has a positive predictive value of 98% (6). A diagnosis of Bartonella infection was based on the combination of a positive microimmunofluorescence titer (IgG to B. quintana or B. henselae [greater than or equal to] 200) and a Western blot profile consistent with endocarditis (8).

Identification of the causative species was obtained by Western blot after cross-adsorption with either B. henselae or B. quintana antigens (8). Antibodies to B. melitensis were detected by agglutination by using the Rose Bengal and Brucella Wright tests (both from BioRad, Hercules, CA, USA). Of the 63 patients, 9 had a positive antibody response against a tested antigen (Table): 1 to phase I C. burnetii and 8 to Bartonella spp. (IgG [greater than or equal to] 200). Of these, 7 had a 1-fold dilution higher titer to B. quintana than to B. henselae, including 1 with a low-level cross-reaction with C. burnetii, and 1 with identical titers to both. For all 8 patients, Western blot results were consistent with Bartonella endocarditis. For 7, cross-adsorption identified

B. quintana as the causative species; for the other, the infecting Bartonella species remained undetermined because adsorption with B. quintana and B. henselae antigens removed all antibodies. Serologic results for B. melitensis were negative for all patients. B. quintana is mostly associated with human body lice but has also been found in fleas (9). The predisposing factors for B. quintana endocarditis are homelessness, alcoholism, and exposure to body lice (10). For our patients, the common predisposing factors were poor hygiene and low socioeconomic status, which may expose them to ectoparasites including lice and fleas. In contrast with previous study findings, B. quintana infectious endocarditis developed on preexisting valvular lesions in all patients (10). This finding may reflect a different clinical evolution than in Europe, where studies have suggested that B. quintana infectious endocarditis followed chronic bacteremia in patients who did not have previous valvular defects (10).

In summary, prevalence of negative blood culture among patients with infectious endocarditis was high (72%). The most commonly associated risk factor was rheumatic heart disease (Table). C. burnetii and Bartonella spp. were responsible for 8% of all infectious endocarditis cases and 14% of blood culture-negative cases. No case of infectious endocarditis caused by B. melitensis was identified.

Our preliminary study suggests that zoonotic agents, especially Bartonella spp., are prevalent causative organisms of blood culture--negative endocarditis in India. We recommend serologic screening for antibodies to zoonotic microorganisms as diagnostic tools for this disease in India.

DOI: 10.3201/eid1407.071374

References

(1.) Brouqui P, Raoult D. New insight into the diagnosis of fastidious bacterial endocarditis. FEMS Immunol Med Microbiol. 2006;47:1-13. DOI: 10.1111/j.1574-695X. 2006.00054.x

(2.) Koegelenberg CF, Doubell AF, Orth H, Reuter H. Infective endocarditis in the Western Cape Province of South Africa: a three-year prospective study. QJM. 2003;96:217-25. DOI: 10.1093/qjmed/ hcg028

(3.) Benslimani A, Fenollar F, Lepidi H, Raoult D. Bacterial zoonoses and infective endocarditis, Algeria. Emerg Infect Dis. 2005;11:216-24.

(4.) Tariq M, Alam M, Munir G, Khan MA, Smego RA Jr. Infective endocarditis: a five-year experience at a tertiary care hospital in Pakistan. Int J Infect Dis. 2004;8:163-70. DOI: 10.1016/j.ijid.2004.02.001

(5.) Li JS, Sexton DJ, Mick N, Nettles R, Fowler VG Jr, Ryan T, et al. Proposed modifications to the Duke criteria for the diagnosis of infective endocarditis. Clin Infect Dis. 2000;30:633-8. DOI: 10.1086/313753

(6.) Dupont HT, Thirion X, Raoult D. Q fever serology: cutoff determination for microimmunofluorescence. Clin Diagn Lab Immunol. 1994;1:189-96.

(7.) Fournier PE, Mainardi JL, Raoult D. Value of microimmunofluorescence for diagnosis and follow-up of Bartonella endocarditis. Clin Diagn Lab Immunol. 2002;9:795-801. DOI: 10.1128/ CDLI.9.4.795-801.2002

(8.) Houpikian P, Raoult D. Western immunoblotting for Bartonella endocarditis. Clin Diagn Lab Immunol. 2003;10:95-102. DOI: 10.1128/CDLl.10.1.95-102.2003

(9.) Marie JL, Fournier PE, Rolain JM, Briolant S, Davoust B, Raoult D. Molecular detection of Bartonella quintana, B. elizabethae, B. koehlerae, B. doshiae, B. taylorii, and Rickettsia felis in rodent fleas collected in Kabul, Afghanistan. Am J Trop Med Hyg. 2006;74:436-9.

(10.) Fournier PE, Lelievre H, Eykyn SJ, Mainardi JL, Marrie TJ, Bruneel F, et al. Epidemiologic and clinical characteristics of Bartonella quintana and Bartonella henselae endocarditis: a study of 48 patients. Medicine (Baltimore). 2001;80:245-51. DOI: 10.1097/00005792-200107000-00003

Address for correspondence: Didier Raoult, Unite des Rickettsies, IFR 48 CNRS, UMR 6020 Universite de la Mediterranee, Faculte de Medecine, 27 blvd Jean Moulin , 13385 Marseille Cedex 05, France; email: didier. [e-mail]

Nandhakumar Balakrishnan, * Thangam Menon, * Pierre-Edouard Fournier, ([dagger]) and Didier Raoult ([dagger])

* University of Madras, Taramani, Chennai, India; and ([dagger]) Universite de la Mediterranee, Marseille, France

Table. Clinical findings and causative agent for 9 patients with
blood culture-negative endocarditis, India, August
2005-December 2006 *

Patient         Underlying cardiac
age, y/sex           condition

25/F           Right atrium fistula
46/M          Rheumatic heart disease
14/M          Rheumatic heart disease
13/M          Rheumatic heart disease
28/M           Bicuspid aortic valve
                      disease
30/M          Rheumatic heart disease
50/F          Rheumatic heart disease
40/M           Bicuspid aortic valve
                      disease
40/M           Double chamber right
              ventricle and subaortic
                  perimembranous
             ventricular septal defect

Patient                                            IgG titer to
age, y/sex       Echocardiographic findings       Bartonella spp.

25/F               Vegetation attached to               400
                      tricuspid valve
46/M                Vegetation attached                  0
                 to anterior mitral leaflet
14/M           Vegetation attached to tip of            200
                  anterior mitral leaflet
13/M               Vegetation attached to               200
                  anterior mitral leaflet
28/M               Vegetation attached to               400
                 anterior coronary cusp of
                        aortic valve
30/M            Vegetation attached to both             200
               anterior and posterior mitral
                leaflet extending to chordae
                          tendinae
50/F            Vegetation attached to non-             400
               coronary cusp of aortic valve
40/M               Calcified aortic valve               400
40/M            Vegetation attached to right            800
             atrium anterior leaf of tricuspid
                 valve and lateral cusp of
                      pulmonary valve

Patient      IgG titer to Coxiella
age, y/sex     burnetii phase I        Causative agent

25/F                  100            Bartonella quintana
46/M                  800             Coxiella burnetii
14/M                   0                 B. quintana
13/M                   0                 B. quintana
28/M                   0                 B. quintana
30/M                   0                 B. quintana
50/F                   0               Bartonella spp.
40/M                   0                 B. quintana
40/M                   0                 B. quintana

* Ig, immunoglobulin.