A 38-year-old male farm worker with relapsing acute lymphoblastic leukemia spontaneously developed an ulcerating ulcer on his anterior thigh which was surrounded by a non-tender area of erythema. Bacillus cereus was isolated from the ulcer and blood, and the patient received intravenous penicillin and vancomycin for one week. When sensitivity studies were returned he was treated with gatifloxacin orally. After two weeks of combined antimicrobial therapy and negative blood cultures, the patient received combination chemotherapy with vincristine, prednisone, doxorubicin and cyclophosphamide. He was hospitalized a day after completing chemotherapy with neutropenic sepsis due to B. cereus. He received similar antimicrobial therapy as previously, but died three days later. At autopsy, the patient was found to have acute mitral valve endocarditis and bilateral brain abscesses. This was the first case of B. cereus endocarditis reported in a patient with acute lymphoblastic leukemia.

Background and aim of the study: Endocarditis due to Abiotrophia sp. is rare and often associated with negative blood cultures. The rates of treatment failure, infection relapse and mortality are higher than in endocarditis caused by other viridans streptococci.

Methods: A retrospective review of A. defectiva endocarditis in a patient with prosthetic aortic valve and in a patient with Marfan syndrome was performed.

Results: A. defectiva, susceptible to penicillin (MIC 0.064 mg/l and 0.016 mg/l, respectively) was isolated from blood cultures of both patients. Treatment with penicillin and gentamicin was started in both patients. Since the first patient developed a macular rash and leukopenia, penicillin was substituted with ceftriaxone. Both patients responded well to antibiotic treatment, did not need prosthetic valve insertion or reinsertion, and were without any sequelae at one year follow up.

Conclusion: Standard treatment of bacterial endocarditis with penicillin and gentamicin was effective in both patients. In contrast to previous reports, the present patients had a favorable outcome on completion of treatment and at one-year follow up.

Background and aim of the study: Staphylococcus aureus is a leading cause of bacteremia and is often associated with endocarditis. The diagnosis of endocarditis may be missed when relying on clinical risk prediction, and this has led others to recommend transesophageal echocardiography (TEE) for diagnosis in most cases of S. aureus bacteremia (SAB). The study aim was to determine the likelihood of finding vegetations on TEE in patients with SAB in a suburban teaching hospital setting, and to identify risk factors predictive of vegetation on TEE.

Methods: All cases of SAB at Walter Reed Army Medical Center between January 2000 and May 2003 were evaluated. The prevalence of vegetations was determined in those cases selected for TEE. Potential risk factors for endocarditis were analyzed by review of medical records.

Results: A total of 176 patients had documented SAB during the time frame of the study, and 64 of these had TEE performed. Among the latter patients, 14% had a previously unidentified vegetation discovered by TEE. Patients with vegetation on TEE were as likely as those without vegetation to have nosocomial bacteremia, an alternate source of infection, and lack of valvular disease by prior surface echocardiography. Patients with a vegetation were significantly older (mean age 68.4+/-10.9 versus 54.6+/-19.6 years; p = 0.04).

Conclusion: TEE identified a significant number of vegetations resulting from SAB. The clinical risk profile and transthoracic echocardiography did not reliably exclude vegetation. These findings support the liberal use of TEE for the diagnosis of SAB.

Background and aim of the study: Cardiac surgery for active infective endocarditis remains a challenging and high-risk procedure. The outcome from early surgical intervention for active native valve endocarditis (ANVE) was studied, the aim being to identify significant predictors of mortality and the relationship between duration of preoperative antibiotics and outcome.

Methods: Between January 1996 and February 2002, 61 patients with ANVE underwent surgery within four weeks of diagnosis. Preoperatively, 29 patients received antibiotics for <2 weeks (group A), and 32 received antibiotics for 2-4 weeks (group B). The median follow up period was 37.4 months (range: 21-55 months). Data were collected retrospectively and analyzed. To determine factors related to mortality, Kaplan-Meier survival analysis was employed, utilizing log-rank statistics to identify evidence of significant differences between the groups. The relationship between the duration of preoperative antibiotics and morbidity was determined using chi-square and Fisher's Exact tests, as appropriate.

Results: Overall operative mortality was 14.8% (group A, 13.8%; group B, 15.6%). Rates of early and late prosthetic valve endocarditis were 1.8% and 1.9% (only in group B) respectively. The overall survival rate for the follow up period was 81.9%. Predictors of mortality were extensive infection (p = 0.01), poor left ventricular function (p <0.0001), progressive cardiac failure as an indication for surgery (p <0.0001), postoperative sepsis (p <0.0001), renal failure after surgery (p = 0.0002) and use of a bioprosthetic valve (p = 0.045). There were no significant inter-group differences for extensive infection (p = 1.00), postoperative sepsis (p = 1.00), reoperation (p = 1.00) and mortality (p = 1.00).

Conclusion: In patients with ANVE, early aggressive surgical intervention before the onset of cardiac failure and spread of infection is warranted. The present data suggest that, in these patient groups, the duration of preoperative antibiotics had no significant influence on postoperative morbidity and mortality.

Background and aim of the study: Patients undergoing chronic hemodialysis are at increased risk of infective endocarditis (IE), and mortality is high in this group. The study aim was to determine clinical features and outcome of IE in patients with chronic renal failure and receiving hemodialysis.

Methods: Between 1987 and 2002, all consecutive patients with infective endocarditis treated at the authors' institution who were not intravenous drug abusers were selected prospectively. A comparative analysis was performed of patients undergoing hemodialysis and other patients in the series.

Results: A total of 241 cases of IE was diagnosed, and 14 patients (6%) were receiving hemodialysis. A lower frequency of known predisposing heart disease (14% versus 74%, p <0.01) and prosthetic valve endocarditis (0% versus 35%, p <0.05) and a higher rate of negative blood cultures (21% versus 12%, p <0.05) were detected in hemodialysis patients. Early surgery was performed in 50% of patients in both groups. The frequency of complications was similar in both groups, but early (43% versus 16%, p = 0.03) and late (22% versus 9%, p <0.05) mortality were higher in hemodialysis patients.

Conclusion: Patients with IE who are undergoing hemodialysis have a lower frequency of predisposing heart disease and higher rates of negative blood cultures. Although patient groups were similarly treated, early and late mortality was significantly higher among those receiving dialysis.

Background and aim of the study: Valvular calcification is an active, cell-mediated process that results in significant morbidity and mortality. In standard culture, valvular interstitial cells (VICs) elicit significant calcification as a result of myofibroblast activation, and this limits their use in characterization studies. The study aim was to identify culturing substrates that would suppress atypical VIC calcification, and to investigate culture substrates representing a more physiological system.

Methods: Several culture platforms were selected to compare and contrast the influence of biochemical and mechanical properties on VIC calcification. Substrates investigated included: tissue culture polystyrene (TCPS), TCPS coated with either fibronectin or fibrin, and an elastic poly(ethylene glycol) (PEG) hydrogel, also with fibronectin or fibrin coupled to the surface. Experiments were repeated with profibrotic growth factor transforming growth factor-beta 1 (TGF-beta1). VIC calcification was characterized by calcific nodule formation, alkaline phosphatase activity and calcium accumulation. Gene and protein expression of alpha smooth muscle actin (aSMA) and core binding factor-1 (CBFa-1) were analyzed with qRT-PCR and immunostaining.

Results: Unmodified TCPS substrates had an innate ability to promote the markers of calcification studied. The addition of TGF-beta1 enhanced levels of all osteoblastic markers studied. When TCPS surfaces were modified with fibronectin, all markers for calcification were repressed, but alphaSMA - a marker for myofibroblastic activity was unchanged. Meanwhile, fibrin-modified TCPS surfaces enhanced calcification over unmodified TCPS substrates. On soft PEG hydrogels, all markers for calcification were repressed, regardless of the surface chemistry, while alphaSMA expression remained unaffected.

Conclusion: Collectively, VIC properties are highly linked to the culture microenvironment. Both, the biochemical and mechanical environment of tissue culture has an effect on the spontaneous calcification of VICs, and may also have a profound effect on their molecular properties, as related to an understanding of the disease process in vivo.