DOC

Aortic Valve Endocarditis Possibly Caused by a

By Lorraine Roberts,2014-05-28 17:16
12 views 0
Aortic Valve Endocarditis Possibly Caused by a

     JOURNAL OF CLINICAL MICROBIOLOGY, Oct. 2010, p. 37913793 Vol. 48, No. 10 0095-1137/10/$12.00 doi:10.1128/JCM.00238-10 Copyright ? 2010, American Society for Microbiology. All Rights Reserved.

    Aortic Valve Endocarditis Possibly Caused by a

    Haematobacter-Like Species

    1,245April Buscher,Linda Li,Xiang Y. Han,and Barbara W. Trautner1,2,3 *

    2Section of Infectious Diseases, Department of Internal Medicine, Baylor College of Medicine, Houston, Texas; Houston Center for 1Quality of Care and Utilization Studies, Houston, Texas; Michael E. DeBakey Veterans Affairs Medical Center, Houston, 34Texas; Department of Surgery, Baylor College of Medicine, Houston, Texas; and Department of Laboratory Medicine, 5The University of Texas M. D. Anderson Cancer Center, Houston, Texas

    Received 4 February 2010/Returned for modication 3 March 2010/Accepted 28 June 2010

    Haematobacter is a newly proposed genus for a group of fastidious Gram-negative aerobic bacilli isolated mostly from blood samples from patients with septicemia. The Haematobacter genus currently includes two species, H. massiliensis and H. missouriensis. We report isolation of a novel Haematobacter-like species from the blood of a 65-year-old man who suffered from probable aortic valve endocarditis. The possible causative role was suggested by the monomicrobial culture and the absence of another causative agent in a patient with probable endocarditis by Duke criteria. This fastidious organism could not be identi;ed by routine biochemical tests. Sequencing analysis of the 16S rRNA gene (1,425 bp) best matched the known Haematobacter species yet was substantially different with a nucleotide similarity of 96.7%. This strain also reduced nitrate to nitrite, unlike known species. This case is likely the ;rst reported case of endocarditis possibly caused by a Haema- tobacter-like organism.

     urinary catheter placement revealed large amounts of blood CASE REPORT and 71 red blood cells per high-power microscopy eld. HIV A 65-year-old man presented to the emergency room in test results were negative. December 2008 with a 3-week history of worsening shortness Admission chest X-ray showed patchy densities in the right of breath, orthopnea, subjective fevers, chills, night sweats, dry upper and lower lung elds as well as the perihilar region of cough, and sore throat. The shortness of breath occurred ini- the left lung consistent with pulmonary edema. An electrocar- tially during exertion, but on the day of presentation, it also diogram showed sinus tachycardia with premature atrial com- occurred at rest. The patient had little prior medical care. He plexes, a right bundle branch block, and left ventricular hyper- had a 50-pack-per-year history of smoking as well as a history trophy. A bedside transthoracic echocardiogram showed of alcohol abuse. moderate to severe aortic insufciency as well as a lesion on the On physical examination, the patient was in moderate respi- aortic valve. ratory distress. He was afebrile with a heart rate of 116/min and Blood cultures using two sets of aerobic and anaerobic bot- blood pressure of 149/88 mm Hg. Chest auscultation revealed tles were obtained on admission. Antimicrobial therapy with diffuse wet rales in the lung elds, a III/VI early diastolic vancomycin and piperacillin-tazobactam was initiated 6 h later, murmur heard best at the left upper sternal border with radi- along with a regimen of diuretics, beta-blockers, and statins for ation to the apex, and an S3 gallop. Oral thrush, bilateral his heart failure and hypertension. On hospital day 3, a trans- axillary lymphadenopathy (1 to 2 cm), and bilateral lower ex- esophageal echocardiogram revealed further details of the dis- tremity pitting edema were also noted. eased aortic valve, i.e., a partially ail left coronary cusp along Laboratory tests revealed a white blood cell count of 18.9 3with the presence of two small mobile vegetations, one (0.4 by 10/ l with 85% neutrophils, hemoglobin level of 11.4 g/dl, 0.3 cm) on the tip and another (0.2 by 0.1 cm) at the base. The blood urea nitrogen level of 42 mg/dl, creatinine level of 2.4 ejection fraction was slightly impaired (45 to 49%) (normal mg/dl, total bilirubin level of 2.2 IU/ml (normal range, 0.2 to value, 55%). 1.2 IU/ml), and erythrocyte sedimentation rate of 94 mm/h Meanwhile, a Gram-negative bacillus, strain BC14248, grew (normal range, 0 to 20 mm/h). The following laboratory results in one of the two aerobic bottles after an incubation of 5 days were also abnormal: lactate dehydrogenase level of 346 U/ml in the BacT/Alert automated culturing system (bioMe?rieux (normal range, 100 to 190 U/ml), creatinine kinase level of 524 Inc., Durham, NC). The patient then met Duke criteria for U/ml (normal range, 25 to 250 U/ml), creatinine kinase level in probable endocarditis (echocardiographic ndings of infective muscle and brain of 15.4 ng/ml (normal range, 0 to 5 ng/ml), endocarditis, positive blood culture not meeting major criteria, and troponin I level of 7.70 ng/ml (normal range, 0.01 to 0.08

    fevers, and hematuria) (4). On subculture, the organism grew ng/ml). The levels of transaminases and alkaline phosphatase

    were within normal limits. A urinalysis conducted 5 days after best on 5% sheep blood agar, but the appearance of colonies

     (1-mm size) required 48-hour incubation at 37?C with 5% CO. 2 The colonies were light gray, round, raised, glistening, mucoid, * Corresponding author. Mailing address: Michael E. DeBakey Vet- and sticky. There was no hemolysis. Similar growth was also erans Affairs Medical Center (102), 2002 Holcombe Boulevard, Hous- seen with nonselective buffered charcoal yeast extract agar. ton, TX 77030. Phone: (713) 794-8610. E-mail: trautner@bcm.edu. However, the organism grew even more slowly on chocolate Published ahead of print on 7 July 2010.

    3791

     3792 CASE REPORTS J. CLIN. MICROBIOL.

     original Gram-negative bacillus, was found in multiple blood cultures. To identify the fastidious Gram-negative rod, we amplied and sequenced its 16S rRNA gene using the MicroSeq 500 system (Applied Biosystems, Inc., Foster City, CA) and two more sets of 16S primers, primers 5 -TGCCAGCAGCCGCGGTAATAC and 5 -CGCTCGTTGCGGGACTTAACC and primers 5 -GCA CAAGCGGTGGAGCATGTG and 5 -AGGAGGTGATCCA ACCGCA (3). Nearly the full length (1,425 bp) of the gene was obtained (GenBank accession no. GU396991), and BLAST searches showed the best match with an uncultured bacterium (6) with 98.9% identity (1,402 of 1,417 bp without gap sites). The second best matches were with Haematobacter massiliensis (GenBank accession no. AF452106) for 96.7% identity (1,354/ 1,400 bp), with Haematobacter missouriensis (GenBank acces-

    sion no. DQ342315) for 96.8% identity (1,342/1,387 bp), and

    with Haematobacter genomospecies (GenBank accession no.

     DQ342319) for 96.5% (1,339/1,387 bp). Yet, these matches all

     contained four gap sites. Other close matches were with two Rhodobacter species (GenBank accession no. DQ342322 and CP000661) for identities of 96.5% to 95.0%. Therefore, this or- ganism probably represents a novel Haematobacter-like species.

     FIG. 1. Gram stain of the organism showing serpentine rod forms.

     Discussion. Denitive or probable infective endocarditis (IE) by modied Duke criteria consists of either a pathological agar or plain Trypticase soy agar and did not grow at all on cardiac specimen or fulllment of a range of clinical criteria MacConkey agar. With Gram staining, the organism was seen (4). This patient fullled the clinical criteria for probable IE.

    He satised one major criterion by having oscillating mobile as short to long serpentine rods (Fig. 1).

    Biochemically, the organism was positive for catalase, oxi- vegetations attached to the aortic valve and a new valvular dase, and urease. It reduced nitrate to nitrite and produced regurgitation. He also met three minor criteria in that he had

    subjective fevers at home prior to admission, a positive blood HS by the lead acetate method. However, it did not produce 2indole or hydrolyze gelatin or esculin. The API 20NE system culture of an organism not known to cause endocarditis, and (bioMe?rieux) yielded a biocode of 1041044 at 48 h, and the hematuria (albeit after urinary catheter placement). The pa- Vitek GNI card result was 40504004140, but neither code </