Valvular Vegetations Research Articles

Epidemiologic and clinical characteristics of Bartonella quintana and Bartonella henselae endocarditis: a study of 48 patients.

Epidemiologic and clinical characteristics of Bartonella quintana and Bartonella henselae endocarditis: a study of 48 patients.

Endocarditis infecciosa mitral tras ablación con catéter y radiofrecuencia de una vía accesoria lateral izquierda

A 2-years-old child with Wolff-Parkinson-White syndrome associated with life-threatening symptoms underwent radiofrequency ablation of a left lateral accessory pathway. A deflectable 5F bipolar electrode catheter positioned above the atrioventricular groove by transeptal approach was used for ablation. The catheters were repeatedly used after ethylene oxide sterilisation. Although immediate post-ablation echocardiography demonstrated no complications, the patient was readmitted two days later with fever and a new mitral murmur. Penicillin-susceptible Staphylococcus aureus was isolated and intravenous antibiotics were administered. In the following weeks, the patient developed constrictive pericarditis requiring surgical treatment and acute hemiplegia caused by brain embolism arising from valvular vegetation. At 5 years of follow-up the patient presents residual hemiparesia and grade II/IV mitral insufficiency.

Fatal Prosthetic Valve Endocarditis due to Campylobacter fetus

Campylobacter fetus subspecies fetus has a predilection for vascular endothelium. This report describes a case of a prosthetic valve infective endocarditis due to this microorganism. Despite adequate antibiotic combination treatment, valvular vegetations and perivalvular suppurative complications evolved, leading to valvular dysfunction, heart failure and death. Only three other cases of C. fetus prosthetic valve endocarditis have been described previously.Campylobacter fetus bacteraemia must be considered cautiously, because of the risk of late cardiac or vascular complications.

Usefulness of Motion Patterns Indentified by Tissue Doppler Echocardiography for Diagnosing Various Cardiac Masses, Particularly Valvular Vegetations

Usefulness of Motion Patterns Indentified by Tissue Doppler Echocardiography for Diagnosing Various Cardiac Masses, Particularly Valvular Vegetations

Prosthetic Biologic Valve Endocarditis Caused by a Vancomycin-Resistant (vanA) Enterococcus faecalis: Case Report

We recently observed (February 1999) a 68-year old patient with endocarditis on a prosthetic biologic valve caused by a vancomycin-resistant Enterococcus faecalis. Broth dilution tests showed susceptibility to ampicillin (MIC=0.5 μg/ml), no high resistance to aminoglycosides (MIC for gentamicin <500 μg/ml) and resistance to vancomycin (MIC >256 μg/ml) and teicoplanin (MIC>16 μg/ml). A PCR assay detected vanA gene in this strain. A trans-thoracic echocardiogram did not show valvular vegetations. A possible endocarditis was diagnosed and the patient received ampicillin for 8 weeks and gentamicin for 6 weeks. The patient remained afebrile after a 4-month follow-up when he underwent surgical replacement of the dysfunctional bioprosthetic valve. Mitral valve was sterile on culture, but histology confirmed the diagnosis of previous endocarditis. This is the third case of endocarditis caused by vancomycin-resistant E. faecalis reported to date.

Usefulness of motion patterns identified by tissue Doppler echocardiography for diagnosing various cardiac masses, particularly valvular vegetations

This study sought to test whether anomalous cardiac and aortic structures can be differentiated from native tissue and artifacts by physical properties of tissue motion using transesophageal tissue Doppler echocardiography (TDE). TDE was employed in 85 consecutive patients after anomalous structures had been detected by conventional transesophageal echocardiography (TEE). The control group consisted of 40 randomized patients. Certainty of diagnosis was divided into 4 categories, and TDE signals were related to particular anomalous structures by a blinded second observer. A mechanical model of a beating ventricle was constructed and suspended in a water bath. Synthetic material was utilized to simulate anomalous intracavitary structures with varying shape, consistency, and attachment. Incoherent motion was present in endocarditic vegetations, freely oscillating thrombi, fourth-degree aortic plaques, Chiari network, valvular prolapse, tumors, and in normal valve leaflets and papillary muscles. Within 15 seconds vegetations could be detected in 17 patients (68%) using TDE versus 5 patients (20%) using only conventional imaging. Coherent motion with a phase difference occurred due to damped oscillation. This phenomenon occured in 5 patients with thrombi of the left atrial appendage (100%), in 3 ventricular clots (75%), and in 2 hypernephroma in the right atrium (100%). Rapid identification of clots could be achieved in 15 patients (71%) versus 12 patients (57%). Concordant motion was shown in third-degree aortic plaques, postrheumatic valvular lesions, and aortic intramural hematomas, but diagnostic benefit could not be demonstrated. In 41 patients (48%) histopathologic and intraoperative results confirmed echocardiographic findings. Motion patterns could be reproduced independently of the heart rate by model experiments. This study demonstrates that TDE expedites the detection of vegetations in infective endocarditis. Diagnostic certainty can be increased as well for thrombus formations.

Epidemiological approach to quality assessment in echocardiographic diagnosis

OBJECTIVESThis study sought to determine whether statistical analysis of a computerized clinical diagnostic database can be used as a tool for quality assessment by determining the contribution of reader bias to variance in diagnostic output.BACKGROUNDIn industry, measurement of product uniformity is a key component of quality assessment. In echocardiography, quality assessment has focused on review of small numbers of cases, or prospective determination of reader variability in selected and relatively small subsets. However, diagnostic biases in clinical practice might be discerned utilizing large computerized databases to determine interreader differences in diagnostic prevalence and, with use of appropriate statistical methods, to determine the association of reader selection with diagnostic prevalence independently of other covariates.METHODSWe analyzed 6,026 echocardiograms in a computerized database, read by one of three level 3 (American Society of Echocardiography) readers, for differences in frequency among four coded echocardiographic diagnoses: mitral valve prolapse, valvular vegetations, left ventricular (LV) thrombus, and LV regional wall-motion abnormality.RESULTSSignificant differences (up to fourfold) were found between readers, which persisted after statistical adjustment for those population characteristics, which differed slightly between readers. The low population prevalence of these conditions would have made it unlikely that these interreader differences could be detected by nonstatistical methods. Additionally, chamber dimensions differed between readers and were not normally distributed.CONCLUSIONSStatistically based quality assessment analysis of computerized clinical databases facilitates ongoing monitoring of interreader bias despite low diagnostic prevalence, and targets opportunities for subsequent quality improvement.

Pseudoaneurysm of the descending aorta caused by Candida albicans

Infection of normal arterial intima is very uncommon [1]. Staphylococcus aureus and Salmonella species are the two most common organisms associated with microbial arteritis and pseudoaneurysm formation; Candida arteritis is extremely rare, occurring in less than 1% of all reported cases [2]. Infection with candida is the result of hematogeneous dissemination in patients with impaired cellular immunity [3]. A pseudoaneurysm results from initial hematogeneous seeding of an injured or diseased intima, often by atherosclerosis with endothelial colonization followed by an invasive arterial infection; the arterial wall subsequently weakens with pseudoaneurysm formation [3]. The clinical presentation of patients with pseudoaneurysm or mycotic aneurysm of major arteries is pain in the aneurysm location and clinical bacteriemia signs. An elevated sedimentation rate and leukocytosis are common, but blood cultures are frequently negative [4]. Diagnosis, once suspected, should be pursued vigorously because rupture of such an aneurysm is often fatal [5]. Lifelong antifungal therapy following surgical repair may be necessary to treat these life-threatening infections [6]. A 35-year-old man with a history of intravenous drug abuse was admitted to the hospital with persistent fever and a mucocutaneous candida infection episode three months before the episode described here: the infection cleared without treatment. The patient had suffered from fever with chills and sweats, asthenia, productive cough and chest pain for about 15 days. His physical examination was remarkable for a fever of 39°C, respiratory rate of 25 breaths per minute, blood pressure of 135/80 mmHg and signs of peripheral venous puncture. No mucocutaneous candida infection was found. There were no murmurs on cardiac auscultation. The white blood cell count was 20×109 with neutrophilia, while haemoglobin and platelet counts were normal. The erythrocyte sedimentation rate was 66 mm/h. Chest X-ray showed a left para-hiliar pneumonia and antibiotic treatment with amoxicillin—clavulanic acid was started. Blood, urine and sputum cultures showed no growth for any organims. Human immunodeficiency virus-1 antibody test was negative. Computer tomography revealed a pseudoaneurysm arising from the thoracic descending aorta near the left pulmonar artery and contiguous parenchymatous consolidation consistent with asociated pneumonia in the lower lobe left lung. The patient suffered a massive hemoptysis. He was intubated and kept under mechanical ventilation and subseqently referred to our hospital. Transesophageal echocardiography showed no valvular vegetations, but an aortic pseudoaneurysm arising from the thoracic descending aorta and located 10 cms distal to the subclavian artery. This false aneurysm had an initial echolucent cavity 3×3 cms, connected to the aortic lumen and surrounded by 9×9 cms cavitated tissue mass, consistent with subacute thrombus formation (Fig 1). Color doppler showed flow within the echocardiographic cavities (Fig 2). The patient underwent urgent surgery. A perforated psudoaneurysm was found at the descending aorta, with invasion of lung tissue. The visualized aorta was free of atherosclerotic debris. False aneurysm resection, necrotic tissue debridement and patch repair of the descending aorta was performed. Cultures of the surgical specimen of aorta grew Candida albicans. Postoperatively he was treated with intravenous vancomicin A and amfotericin B (liposomal). The patient recovered and 6 months later is well.

Acute Aortic Regurgitation Due to Spontaneous Rupture of a Fenestrated Cusp: Report in a 65-Year-Old Man and Review of Seven Additional Cases

A 65-year-old man with chronic hypertension developed dyspnea, a cough, and a new diastolic murmur. Two-dimensional echocardiography showed severe aortic regurgitation. No valvular vegetations were identified and blood cultures were negative. Surgical intervention was recommended, but the patient died of an acute intracranial hemorrhage two weeks later. At autopsy, the posterior aortic cusp was flail, due to rupture of the residual cord above two large fenestrations. There was no acute or healed endocarditis. To our knowledge, this is the eighth reported case of aortic valve incompetence due to spontaneous rupture of a fenestrated cusp. Patients ranged in age from 31–67 years (mean, 54), and 4 (50%) were older than 60 years. Seven (88%) of the 8 were men, and 4 (57%) of 7 had chronic hypertension. Analogously, in another four reported cases, aortic insufficiency developed following spontaneous rupture of the fenestrated raphe of an atypical congenitally bicuspid aortic valve. Noninfective and nontraumatic rupture of cord-like aortic valve structures may result in severe acute aortic regurgitation, particularly in men with chronic hypertension.

Combinations of vancomycin and beta-lactams are synergistic against staphylococci with reduced susceptibilities to vancomycin.

Evidence of synergism between combinations of vancomycin and beta-lactam antibiotics against 59 isolates of methicillin-resistant staphylococci (Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus haemolyticus) for which vancomycin MICs ranged from 1 to 16 microg/ml were tested by broth microdilution checkerboard, disk diffusion, agar dilution, and time-kill antimicrobial susceptibility tests. The combination of vancomycin and oxacillin demonstrated synergy by all test methods against 30 of 59 isolates; no antagonism was seen. Synergy with vancomycin was also found by modified disk diffusion testing for ceftriaxone, ceftazidime, cefpodoxime, and amoxicillin-clavulanate but not for aztreonam. Evidence of synergy correlated directly with vancomycin MICs. The efficacy of vancomycin given alone and in combination with nafcillin was tested in the rabbit model of experimental endocarditis caused by three clinical isolates of glycopeptide-intermediate-susceptible S. aureus (GISA) (isolates HIP5827, HIP5836, and MU50). Two of the GISA isolates (isolates MU50 and HIP5836) were extremely virulent in this model, with 27 of 42 (64%) animals dying during the 3-day trial. Therapy with either vancomycin or nafcillin given as a single agent was ineffective for animals infected with HIP5827 or MU50. However, the combination of vancomycin and nafcillin resulted in a mean reduction of 4.52 log10 CFU/g of aortic valvular vegetations per g compared to the reduction for controls for animals infected with HIP5827 and a reduction of 4. 15 log10 CFU/g for animals infected with MU50. Renal abscesses caused by HIP5827 were sterilized significantly better with the combination of vancomycin and nafcillin than by either treatment alone. We conclude that the combination of vancomycin and beta-lactams with antistaphylococcal activity is an effective regimen for the treatment of infections with clinical strains of staphylococci which demonstrate reduced susceptibility to glycopeptides.

Mycotic axillary artery aneurysm

Mycotic axillary aneurysms, not commonly encountered today, are generally the consequence of arterial trauma. A case of an axillary aneurysm secondary to a septic embolus from valvular vegetations in an intravenous drug abuser was studied. The case is reminiscent of those sporadically reported cases of the preantibiotic era. (J Vasc Surg 1998;28:708-9.)

Noninfective mitral valve vegetations identified by transesophageal echocardiography as a cause of stroke

Transesophageal echocardiography (TEE) is a useful procedure to evaluate selected stroke patients for cardiac sources of embolism. To date, noninfective valvular vegetations have not been described in large studies using transesophageal echocardiography to detect cardiac sources of embolism. We sought to investigate the frequency of noninfective valvular vegetations in patients with unexplained stroke referred for TEE and to determine the relationship of these vegetations to unrecognized thrombophilic disorders. We evaluated 641 consecutive patients referred for TEE as a result of unexplained stroke or transient ischemic attack for the presence of valvular vegetations. Of those with vegetations identified, serial blood cultures were obtained to evaluate for an infectious etiology. Patients also had serum testing for thrombophilic disorders and selected patients underwent cerebral angiography. Thirteen patients (2%) who underwent TEE evaluation for unexplained stroke or transient ischemic attack were found to have noninfective valvular vegetations, all involving the mitral valve; none were identified by transthoracic echocardiography. Antiphospholipid antibodies were identified in 8 of these 13 patients (62%) and a protein C deficiency in 1 patient (8%). Noninfective valvular vegetations are a potential cardiac source of embolism in patients with unexplained stroke that can be better identified using transesophageal echocardiography. A large percentage of these individuals have a previously unrecognized thrombophilic disorder.

Pacemaker infective endocarditis

We identified 33 patients with definite pacemaker endocarditis—that is, with direct evidence of infective endocarditis, based on surgery or autopsy histologic findings of or bacteriologic findings (Gram stain or culture) of valvular vegetation or electrode-tip wire vegetation. Most of the patients (75%) were ≥60 years of age (mean 66 ± 3; range 21 to 86). Pouch hematoma or inflammation was common (58%), but other predisposing factors for endocarditis were rare. At the time that pacemaker endocarditis was found, the mean number of leads was 2.4 ± 1.1 (range 1 to 7). The interval from the last procedure to diagnosis of endocarditis was 20 ± 4 months (range 1 to 72). Endocarditis appeared after pacemaker implantation, early (<3 months) in 10 patients and late (≥3 months) in 23 patients. Fever was the most common symptom, being isolated in 36%, associated with a poor general condition in 24%, and associated with septic shock in 9%. Transthoracic echocardiography showed vegetations in only 2 of 9 patients. Transesophageal echocardiography demonstrated the presence of lead vegetations (n = 20) or tricuspid vegetations (n = 3) in 23 of 24 patients (96%; p <0.0001 compared with transthoracic echocardiography). Pulmonary scintigraphy showed a typical pulmonary embolization in 7 of 17 patients (41%). Pathogens were mainly isolated from blood (82%) and lead (91%) cultures. The major pathogens causing pacemaker endocarditis were Staphylococcus epidermidis (n = 17) and S. aureus (n = 7). S. epidermidis was found more often in early than in late endocarditis (90% vs 50%; p = 0.05). All patients were treated with prolonged antibiotic regimens before and after electrode removal. Electrode removal was achieved by surgery (n = 29) or traction (n = 4). Associated procedures were performed in 9 patients. After the intensive care period, only 17 patients needed a new permanent pacemaker. Overall mortality was 24% after a mean follow-up period of 22 ± 4 months (range 1 to 88). Eight patients who were significantly older (74 ± 3 vs 63 ± 3 years; p = 0.05) died ≤2 months after electrode removal, whereas 25 were alive and asymptomatic.

Successful treatment of a staphylococcal endocarditis vegetation with tissue plasminogen activator

A 930 gm premature infant had Staphylococcal endocarditis with a tricuspid valvular vegetation that was unresponsive to antibiotics and not amenable to resection. Infusion of tissue plasminogen activator over a 3-day period completely lysed the vegetation. The infection cleared with continued antibiotics, and the infant recovered without sequelae. (J Pediatr 1998;132:535-7)

Effect of cardiac embolism sources on origin of territorial cerebral infarcts

To test the association of cardiac sources of embolism with territorial type brain infarcts. From a prospective cerebral ischemia data base the 106 consecutive patients with territorial type cerebral infarcts on computerized tomography were analyzed. The 85 consecutive patients with lacunar lesions served as a comparison group. The association of cardiac sources of embolism with territorial types infarcts was assessed using univariate Chi Square tests and logistic regression models. Cardiac sources of embolism were defined as:atrial fibrillation, left cardiac thrombi, valvular vegetations, wall motion and valvular abnormalities, left atrial enlargement, open foramen ovale, septal aneurysm, mitral valve prolaps, and aortic arch atherothrombosis (all findings--except for atrial fibrillation--assessed by echocardiography). Atrial fibrillation was significantly associated with territorial type infarcts (odds ratio 2.2, 95% confidence interval 1.01-4.8). This effect was independent of additional cardiac diseases, other cardiac abnormalities, carotid artery stenosis, and patient age. Most likely due to the small sample size, left cardiac thrombi only showed a non-significant trend towards an association with territorial infarcts (odds ratio 3.0, 95% confidence interval 0.7-12.3). The rate of all other cardiac findings did not differ significantly between the comparison groups. Atrial fibrillation and cardiac thrombi showed an association with territorial type infarcts. Other so-called cardiac sources of embolism--except for mechanical valves and bacterial endocarditis which were not represented in our sample--revealed no clinically relevant association with embolic brain infarct pattern.

Role of Echocardiography in Systemic Arterial Embolism: A Review with Recommendations

The ability of echocardiography to diagnose sources of embolism and the role of the examination in the prediction of thromboembolism are reviewed. In addition, the yield of transthoracic (TTE) and transoesophageal echocardiography (TEE) is analysed in patients with suspected embolism and guidelines are proposed for performing echocardiography in this setting. In general, echocardiography is reliable for diagnosing sources of embolism and this applies in particular to TEE in the case of atrial, valvular, and aortic abnormalities. However, the method is useful for predicting embolism in a few cases only. There is a substantial risk in the event of mobile or protruding thrombi, but screening for these and other markers of thromboembolism seems to be unproductive in most groups of risk patients. Yet, in the presence of atrial fibrillation, echocardiography may be helpful in defining patients with an otherwise normal heart and low risk of embolism - and in defining the relatively rare patient with a clinically low-risk profile but moderate-to-severe left ventricular systolic dysfunction and a high risk of embolism. TEE-guided conversion of atrial fibrillation without weeks of preceding anticoagulation may prove useful, after further investigation. The risk of embolism in relation to the size and mobility of valvular vegetations has remained controversial. In patients with suspected recent embolism, TTE results in less than 5% new therapeutic consequences. In those with a normal TTE, the yield of TEE seems to be equally low. We therefore recommend a selective strategy: TTE and TEE can be omitted when a cardiac source of embolism appears from the clinical setting and in most patients with an obvious predisposition to cerebrovascular disease. However, in the latter cases TTE should be performed if indicated by the clinical situation, e.g. in the presence of fever and murmur. TTE is also recommended when there are no obvious markers of primary vascular disease. To preclude very rare sources of embolism (e.g. atrial thrombi despite sinus rhythm), supplementary TEE is recommended in younger patients in whom primary vascular disease is very unlikely. The diagnosis by TEE of common conditions such as atrial septal aneurysms and patent foramen ovale cannot, however, be taken as proof of the mechanism of a systemic arterial occlusive event; thus it is difficult to change therapy on the basis of such diagnoses.

Observations of apparent early valvular endocarditis in swine.

Figure 1. Left atrioventricular valve. Note the dark area with hemorrhages under the endocardium. Valvular endocarditis is often a serious consequence of bacterial infection in animals as well as in humans.3,11,15 The mechanisms behind this endocardial infection and the pathogenesis of the lesions that develop in the valves are, however, incompletely known. There are two possible routes for bacteria in the blood to reach the endocardium of the valves: 1) by contact with the surface endothelium of the endocardium, and 2) from the capillaries in the valves. The generally accepted theory of today in both human and veterinary medicine is that transient or persistent bacteremia, via an endothelial lesion with thrombus formation or through some other immunopathological mechanisms, adhere to the endocardial endothelium and, from there, initiate an inflammation in the valve.1,8,13 In humans, it has been found that endocardial lesions, induced by, e.g., hemodynamic disorders, are predisposing factors,13 but also that infectious endocarditis may appear in previously normal hearts.3 Experimentally, it has also been shown that a single intravenous injection of specific bacteria can cause valvular endocarditis in normal pigs.5,7 At necropsy, endocarditis usually appears as valvular vegetations. These are mostly prominent, and their development is difficult to deduce. In order to study the pathogenesis of bacterial valvulitis, the early, prevegetative lesions must be identified. Such early lesions, characterized by swelling, ulceration, and hemorrhages of the valves, have previously been observed in pigs slaughtered at the age of 1 year or older.6,12 Local hemorrhages are sometimes seen at slaughter in the atrioventricular valves of the heart in young, clinically normal pigs. The aim of this study was to see if the histology of such hemorrhages could reveal morphologically important changes that could progress to valvular endocarditis. Atrioventricular heart valves with local hemorrhages were collected from 14 clinically normal, electrically stunned, and normally slaughtered pigs about 6 months old. The valves were fixed in 10% formalin, embedded, sectioned, and stained with hematoxylin and eosin (HE), van Gieson’s stain combined with Weigert’s resorcinol fuchsin for elastic fibers, and the Prussian blue method, according to Perls, for iron pigment. In 6 cases, samples from the hemorrhages were also subjected to bacteriological investigation. The left atrioventricular (mitral) valves (LAV) were most commonly affected. In one of the pigs there were hemorrhages also in the right atrioventricular (tricuspid) valve. The hemorrhages were solitary or multiple and, when multiple, partly confluent within the same valve (Fig. 1). Their sizes varied from about 1 mm up to 10–15 mm in diameter. Hemorrhages were usually present on the atrial side of the valve

Role of Transesophageal Echocardiography in the Management of Thromboembolic Stroke

Cardiac causes of stroke account for approximately 20% of strokes occurring in the United States. Transthoracic echocardiography (TTE) remains the cornerstone of noninvasive cardiac imaging, but transesophageal echocardiography (TEE) is superior for identifying potential cardiac sources of emboli, including left atrial thrombi, valvular vegetations, thoracic aortic plaque, patent foramen ovale, and spontaneous left atrial echocardiographic contrast. The diagnostic yield of TEE for potential cardiac causes of thromboembolism exceeds 50%. The impact of TEE on the clinical management of this group, however, remains undefined for most TEE-specific diagnoses. Thus, routine use of TEE in these patients has been questioned. The diagnostic yield is highest if the clinical history/physical examination suggests a cardiac source. However, the clinical scenario often dictates patient management, and TEE data are used to “validate” the clinical impression. Data from large, prospective, randomized (aspirin/warfarin) studies, in which TEE data are obtained from patients with suspected cardiac thromboembolism, are needed. If specific TEE diagnoses can be identified in which defined therapies are beneficial, “source of embolism” will continue to be the most common indication for TEE referral. In this paradigm, TEE (without initial TTE) will probably become a more direct diagnostic pathway. However, if these studies demonstrate that all patients with suspected cardiac source benefit from one (or no) therapy, independent of TEE data, referrals for TEE will decline. Results of ongoing randomized trials to evaluate the efficacy of TEE in patients with cryptogenic stroke or transient ischemic attack are awaited.

Incidence and prognosis of embolic events and metastatic infections in infective endocarditis.

In infective endocarditis, the true incidence of embolic events and metastatic infections remains unknown probably because a large number of events are asymptomatic. The consequences of the prognosis of such events have never been evaluated by a prospective follow-up. This study aimed to assess the incidence of symptomatic or asymptomatic embolic events and metastatic infections in definite infective endocarditis and to determine whether these events carry a risk of mortality. From January 1991 to December 1993, 102 patients with suspected or known infective endocarditis were referred to our institution. Among them, we selected 68 patients (50 males, 18 females, mean age = 52.7 years) exhibiting definite infective endocarditis according to the Duke University criteria. Blood cultures were positive in 49 cases (72%). Echocardiography revealed valvular vegetations in 55 cases (81%). Irrespective of the clinical presentation, patients were examined radiologically by cerebral computed tomography scanning (n = 60), magnetic resonance imaging (n = 3), abdominal computed tomography scanning (n = 32) or abdominal echocardiography (n = 20). Depending on the symptoms, thoracic computed tomography scanning (n = 22), pulmonary angiography (n = 2), ventilation-perfusion scintigraphy (n = 4), or gallium citrate radionuclide scanning (n = 7) were also performed. All patients were prospectively followed-up for a mean period of 21.4 +/- 17.5 months. In 35 patients (51%), 51 embolic or metastatic events were revealed, involving the central nervous system (n = 23), spleen (n = 7), kidney (n = 5), lung (n = 5), liver (n = 4), bone and joint (n = 4), iliac (n = 2) or mesenteric (n = 1) arteries. During the hospital stay, the mortality rate was higher in patients exhibiting embolic or metastatic events (20 vs 12%), but the difference did not reach statistical significance. Kaplan-Meier analysis demonstrated no difference in long-term follow-up. Our data suggest that embolic or metastatic events had a high incidence (51%) during infective endocarditis, but were not associated with significant attributable mortality.

Host-pathogen interactions in bacterial endocarditis: streptococcal virulence in the host.

To identify streptococcal genes that are expressed during experimental endocarditis, we developed a promoter-less dual reporter gene-fusion (amy, cat) plasmid, pAK36. Chromosomal DNA from S. gordonii V288 was digested with Sau3A1. The resulting fragments were ligated into pAK36. Following transformation into S. gordonii, the library of random gene fusion clones was inoculated into a rabbit to induce experimental endocarditis. Chloramphenicol treatment effected positive selection. Upon euthanization of the rabbits, the valvular vegetations were excised in a sterile field. Surviving clones were isolated and screened in vitro for chloramphenicol sensitivity and negative amylase activity. From the 48 randomly picked, double-negative clones, DNA was isolated and analyzed by Southern hybridization with labeled pAK36 probe. Different insertion patterns were identified, suggesting that no fewer than 13 S. gordonii genes were induced. Therefore, S. gordonii genes are induced during experimental endocarditis, which may contribute to virulence.