Rapid serodiagnosis of gram-positive bacterial endocarditis

OBJECTIVES: To characterize a serological test for diagnosing endocarditis caused by Gram-positive cocci. METHODS: We have developed an indirect enzyme-linked immunosorbent assay (ELISA) for the serological detection of Gram-positive infections. The test measures serum IgG directed towards lipid S, a recently identified exocellular glycolipid antigen which is related to lipoteichoic acid. We have previously shown the test to be of value in serodiagnosis of central venous catheter-associated sepsis and infection of orthopaedic prostheses caused by coagulase-negative staphylococci. We now describe the application of this test in endocarditis. RESULTS: Serum IgG levels to lipid S were significantly elevated in 34 patients with Gram-positive bacterial endocarditis confirmed as 'definite' by the Duke criteria as compared to 50 control patients. The test had a sensitivity of 88% and a specificity of 88%. CONCLUSIONS: The assay is independent of culture results or endocardial imaging, making it complementary to currently used investigations. It may therefore be possible to refine the current Duke criteria for diagnosing endocarditis. We describe an algorithm which incorporates lipid S serology into a positive diagnostic strategy.     

Autoimmunohistochemistry: a new method for the histologic diagnosis of infective endocarditis

BACKGROUND: Although the pathologic examination of cardiac valves remains the reference standard for the diagnosis of infective endocarditis, the detection of microorganisms often poses a challenge for pathologists. This can be done by use of nonspecific histochemical stains or by immunohistochemical analysis, but specific antibodies are often not available. We describe a novel method for the detection of microorganisms in valve specimens from patients with infective endocarditis. METHODS: Detection of microorganisms was performed in valve specimens from patients with endocarditis caused by gram-positive cocci (25 specimens), blood culture-negative endocarditis (15 specimens: 6 cases caused by Coxiella burnetii, 5 caused by Tropheryma whipplei, and 4 caused by Bartonella species), or noninfective degenerative damage (30 specimens, used as negative controls), using the patients' own serum. This technique, called "autoimmunohistochemistry," is an immunohistochemical peroxidase-based method that we compared with results of culture and polymerase chain reaction (PCR) assay. RESULTS: Bacteria were detected by autoimmunohistochemistry in 20 (80%) specimens from patients with endocarditis caused by gram-positive cocci and in 15 (100%) specimens from patients with blood culture-negative endocarditis but in no control specimens. The rate of detection of bacteria by autoimmunohistochemistry was significantly higher than that by culture but was similar to that by PCR. CONCLUSIONS: Autoimmunohistochemistry may be useful for the detection of microorganisms in samples of valves from patients with infective endocarditis. This new diagnostic tool may be particularly useful in cases of blood culture-negative endocarditis.     

Native valve endocarditis and femoral embolism due to Granulicatella adiacens: a rare case report

The fastidious Gram-positive cocci Granulicatella adiacens, previously known as nutritionally variant streptococci (NVS) are unusual but significant cause of endocarditis due to increased mortality and morbidity. Difficulties in reaching correct bacteriological identification, increased resistance to beta-lactam antibiotics and macrolides and complicated clinical course have contributed to problems in management of cases of infective endocarditis caused by this bacterium. We present the first Indian case of endocarditis with arterial embolus by G. adiacens in an elderly male with no pre-existing cardiac abnormality.     

Culture-negative infective endocarditis of the aortic valve due to Aerococcus urinae: a rare aetiology

Bacteria of the species Aerococcus urinae are Gram-positive, catalase-negative cocci that are arranged in pairs, tetrads, or clusters resembling enterococci or staphylococci. They are rare causative agents of infective endocarditis. Repetitive urinary tract infections based upon underlying genitourinary tract abnormalities could involve these bacteria. Due to their similarity to other Gram-positive cocci misinterpretation may occur along the line of microbiologic differentiation, which could potentially lead to a fatal outcome. We herein report on the clinical course of a 68 year-old male patient who in the setting of an embolic stroke was initially diagnosed with a culture-negative acute infective endocarditis of the aortic valve.     

Infective endocarditis caused by Streptococcus mutans.

Members of the viridans group of streptococci are the commonest causes of bacterial endocarditis. However, Streptococcus mutans, a member of this group associated with dental caries which might be expected to be commonly associated with endocarditis, has only rarely been reported. This is possibly because of difficulties in isolation and identification. Differing blood culture media may affect the chances of isolation of these organisms, and, though brain-heart infusion, thiol, tryptic soy, and glucose-brain infusion broths have all proved satisfactory, subcultures may require increased CO2 concentrations for growth. Plemorphism in the resultant colonies and in the individual organisms may give rise to a hazardous misinterpretation of this appearance as contamination. Strep. mutans and the similarly penicillin sensitive Strep. bovis may be differentiated from the penicillin resistant enterococci by their lincomycin sensitivity and intolerance of 6-3 per cent sodium chloride. Precise differentiation of streptococci in bacterial endocarditis is of value both epidemiologically and in the management of the disease.     

Methicillin-resistant Staphylococcus aureus prosthetic aortic valve endocarditis with paravalvular abscess treated with daptomycin

Prosthetic valves have been used extensively for severe cardiac valvular dysfunction for the past 3 decades. Prosthetic cardiac valves may be infected with organisms causing bacteremia, particularly gram-positive cocci. Staphylococcus epidermidis (coagulase negative staphylococci) and Staphylococcus aureus , both methicillin-susceptible S. aureus and methicillin-resistant S. aureus (MRSA) strains, are the most frequent pathogens causing prosthetic valve endocarditis (PVE). Vancomycin has been the cornerstone of therapy for serious MRSA infections including bacteremia and endocarditis. Clinicians have noted that MRSA bacteremias treated with vancomycin often fail to clear even with prolonged therapy. Persistent or prolonged MRSA bacteremia unresponsive to vancomycin therapy has led to the treatment of these infections by other agents, that is, quinupristin, dalfopristin, linezolid, or daptomycin. These antibiotics have been found particularly useful in treating MRSA bacteremias unresponsive to vancomycin therapy. We report a case of a patient who presented with MRSA PVE complicated by perivalvular aortic abscess with persistent MRSA bacteremia unresponsive to vancomycin therapy. The patient's MRSA bacteremia was cleared with daptomycin therapy (6 mg/kg/d). Because the patient refused surgery, daptomycin therapy was continued in hopes of curing the endocarditis and sterilizing the perivalvular aortic abscess. Transesophageal echocardiogram revealed a decrease in abscess in the aortic perivalvular abscess after 1 week of daptomycin therapy. The patient made an uneventful recovery. The cure of PVE and perivalvular abscesses usually requires removal of the prosthetic device and abscess drainage. In this case, in which surgery was not an option, medical therapy of PVE and a decrease in size of the aortic perivalvular abscess were accomplished with daptomycin therapy. Daptomycin is an alternative to vancomycin therapy in patients with prolonged or persistent MRSA bacteremia secondary to endocarditis or abscess.     

Endocarditis due to anaerobic bacteria

This review describes the microbiology, diagnosis and management of endocarditis due to anaerobic bacteria. Anaerobic bacteria are an uncommon but important cause of endocarditis. Most cases of anaerobic endocarditis are caused by anaerobic cocci, Propionibacterium acnes and Bacteroides fragilis group. Predisposing factors and signs and symptoms of endocarditis caused by anaerobic bacteria are similar to those seen in endocarditis with facultative anaerobic bacteria with the following exceptions: the gastrointestinal tract was the most common source for B. fragilis group endocarditis, the head and neck were the most common origin for Fusobacterium and Bacteroides spp., and the head and neck and genitourinary tract were the most common source for peptostreptococci. Complications with anaerobic endocarditis include valvular destruction, multiple mycotic aneurysms, aortic-ring abscess, aortitis, cardiogenic shock, dysrhythmias and septic shock. The mortality rate for patients with anaerobes endocarditis is 21-43%. Treatment of endocarditis involving anaerobic bacteria includes the use of antibiotic therapy effective against these organisms.     

Prosthetic valve endocarditis due to methicillin-resistant Staphylococcus epidermidis and Micrococcus species successfully treated with rifampicin combined with other antibiotics

Two patients with prosthetic valve endocarditis due to methicillin-resistant Gram-positive cocci (Staphylococcus epidermidis and Micrococcus spp.) are described. They were successfully treated with rifampicin combined first with an aminoglycoside and later with co-trimoxazole or co-trimoxazole plus vancomycin. The addition of rifampicin to these antibiotics resulted in enhanced serum bactericidal activity. High doses of rifampicin (1200-1800 mg) for 7-8 weeks did not cause any serious side-effect. Surgery was not required. During surveillance for more than 2 years endocarditis did not recur.     

The role of two-dimensional echocardiology in the diagnosis of infective endocarditis [corrected

Two-dimensional echocardiography has had a significant impact on and is considered the technique of choice for the diagnosis and management of infective endocarditis. Over a thirty-six month period, 106 patients were evaluated by echocardiography for the possibility of endocarditis. The diagnosis of endocarditis was determined by strict clinical and laboratory criteria. All clinical histories, blood cultures, echocardiograms, and autopsy results were reviewed. Five echocardiograms were technically inadequate, resulting in a study population of 101 patients. The age of the patients ranged from forty-five days to eighty-eight years (mean fifty-seven years). The clinical manifestations of endocarditis included fever (83%), chills (60%), congestive heart failure (25%), and splenomegaly (18%). Twelve patients had preexisting valvular or congenital heart disease. Gram-positive cocci were the most common microorganisms. Complications included mitral regurgitation, subarachnoid hemorrhage, renal infarction, stroke, and a pulmonary embolus. The patients were divided into two groups: Group I consisted of 36 patients with definite vegetations by echocardiography, and Group II had 65 patients with no vegetations. In Group I, acute infective endocarditis was present in 35 patients, whereas only 4 patients had endocarditis in Group II. The sensitivity of two-dimensional echocardiography for detecting endocarditis was 90%. The specificity was 98%. The predictive accuracy for a positive test was 97%, and the predictive accuracy for a negative test was 94%. Thus, two-dimensional echocardiography appears to have a high sensitivity, specificity, and predictive value in the evaluation of patients with suspected endocarditis.     

A case of infective Aerococcus urinae endocarditis successfully treated by aortic valve replacement

Aerococcus urinae is a endocarditis rare causative organism with low virulene. We report an A. urinae endocarditis case treated by aortic valve replacement. An 80-year-old woman hospitalized for urinary tract infection and hydronephrosis due to three-week renal calculi. Blood culture on admission isolated Streptococcus acidominimus. During the course, she was transferred to our care for surgical intervention after developing congestive heart failure due to severe aortic regurgitation. Echocardiographic findings indicated infective endocarditis. She underwent aortic valve replacement, and gram staining of the resected valve tissue showed gram-positive cocci, although valve culture was negative. PCR amplification and DNA sequencing using the valve material matched an A. urinae sequence. The woman recovered and was discharged six weeks after antibiotic treatment.     

中国标准和Duke标准诊断感染性心内膜炎比较研究

目的比较中国试行标准和修订的Duke标准对感染性心内膜炎的诊断价值,讨论感染性心内膜炎的临床特征。方法经病理确诊的感染性心内膜炎患者65例,平均年龄33岁,以修订的Duke标准和中国试行标准对其进行诊断评价,比较两种诊断标准对感染性心内膜炎诊断的敏感性。结果做2次以上血培养的40例(61.5%),其中血培养阳性并为相同病原菌的16例(24.6%),超声心动图发现心内膜受累征象49例(75.4%),有基础心脏病者61例(93.8%),胃肠外药物滥用者2例(3.1%),病变累及左心58例(89.2%),累及右心5例(7.7%),累及全心2例(3.1%)。按修订的Duke标准,符合临床确诊的15例(23.1%),按中国试行标准,符合临床确诊的41例(63.1%),两种结果的差异有统计学意义(χ2=21.21,P<0.01)。结论中国试行标准明显优于修订的Duke标准,采用经胸超声心动图结果作为心内膜受累证据和2项临床次要指标作为临床确诊依据,提高了感染性心内膜炎诊断的敏感性,在诊断感染性心内膜炎中更有价值。     

Abiotrophia endocarditis: case report and review of the literature

Abiotrophia is a separate genus of gram-positive cocci formerly classified as nutritionally variant streptococci. These organisms cause 1% to 2% of all infective endocarditis. Unlike Enterococcus or viridans group streptococci, these organisms do not usually grow on conventional blood agar plates. Therefore, Abiotrophia endocarditis is often falsely lumped into the category of culture-negative endocarditis. Adequate diagnosis and treatment of this entity requires a high index of suspicion for the organisms, even if cultures are negative. Nutritional supplementation of the growth media and/or newer 16S ribosomal RNA gene sequencing may be necessary to identify Abiotrophia as the causative organism. Specific antimicrobial therapy and continued surveillance are needed to prevent the significant morbidity and mortality associated with this infection.     

The value of the Von Reyn and the Duke diagnostic criteria for infective endocarditis in internal medicine practice. A study of 38 cases

BACKGROUND: The aim of our study was to compare the value of the Von Reyn and the Duke diagnostic criteria for infective endocarditis (IE) in internal medicine practice. METHODS: We determined the sensitivity and negative predictive value of these two sets of diagnostic criteria in 38 patients with established infective endocarditis who were followed in two departments of general internal medicine. The patients essentially had subacute endocarditis of the aortic valve (79%) with several systemic manifestations (100%). Microbial documentation included mainly gram-positive cocci (60%). RESULTS: With transthoracic echocardiography (TTE), the sensitivities of the Duke and the Von Reyn criteria were 65% and 35%, respectively, while with transesophageal echocardiography (TEE), these sensitivities were 75% and 35%, respectively. With TTE and TEE, the negative predictive values were 100% for the Duke diagnostic criteria versus only 71% for the Von Reyn criteria. CONCLUSIONS: This study confirms that the Duke diagnostic criteria are useful in practice for the management of patients with infective endocarditis followed in internal medicine.     

Association of brucella endocarditis with intracerebral haemorrhage

We describe a case of brucella endocarditis which was strongly suspected on clinical grounds and subsequently confirmed by bacteriological, serological and echocardiographic investigations. The endocarditis, in a 42-year-old Saudi male, was complicated by intracerebral haemorrhage, presumably from a ruptured mycotic aneurysm. Although such a complication is well documented in other forms of infective endocarditis, it has not been reported in brucellosis.     

Q-FEVER ENDOCARDITIS IN ENGLAND AND WALES, 1975-81

Endocarditis was recorded in 92 (11%) of 839 confirmed Q-fever infections reported for the Communicable Disease Report by laboratories between 1975 and 1981; Q-fever endocarditis accounted for approximately 3% of all cases of endocarditis reported. Two- thirds of the 92 reports were of men, and in both men and women endocarditis affected mainly young and middle-aged adults. Only one-third of Q-fever endocarditis patients were noted to have an underlying heart-valve lesion. There were also 30 reports of chronic Q-fever infection, and in 10 the primary clinical feature was liver disease. The laboratory data do not support the view that Q-fever endocarditis is a rare complication of Coxiella burnetii infection, and the condition may be considerably underdiagnosed. Joint veterinary and medical investigations should be undertaken to establish the natural history of Coxiella burnetii infection in the U.K. in order to formulate policies for prevention of acute and chronic infection.     

Special issues in the management of infective endocarditis caused by gram-positive cocci

Gram-positive cocci, mainly streptococci and staphylococci, continue to cause the majority of cases of infective endocarditis. Among the streptococci causing IE, the long-standing predominance of oral or viridans-group streptococci has progressively faded, while the number of cases caused by "enteric streptococci" (Streptococcus bovis and enterococci) has increased. While most oral streptococci and S. bovis strains remain fully sensitive to penicillin, nutritionally variant streptococci--now renamed Abiotrophia--and enterococci can exhibit resistance to penicillin and/or glycopeptides that makes endocarditis more difficult to treat. Among the staphylococci causing endocarditis, the increasing proportion of coagulase-negative and methicillin-resistant strains observed in recent years has changed the approach to choice of antibiotic therapy. The purpose of this paper is to focus on some new aspects of the management of antibiotic therapy of IE due to streptococci and staphylococci, including recent developments such as once-daily aminoglycoside administration in IE, outpatient antibiotic therapy, and the evaluation of new antibiotics.     

Serum triglyceride elevations in patients with septicemia

Among 239 patients with septicemia or endocarditis 41 (17%) had serum triglyceride levels in excess of 2.2 mmol/l (mean 3.1 mmol/l). This was more common in infectious with gram-negative rods than gram-positive cocci (p less than 0.001). A return to normal levels occurred in 22/37 patients during the course of the infection.     

Infective endocarditis: clinical features in young and elderly patients

The elderly constitute an increasing percentage of patients with infective endocarditis. The disease manifestations and outcomes in 53 episodes of endocarditis in patients over the age of 60 were reviewed and compared with 55 episodes of endocarditis in patients less than 40 years of age and 46 episodes of endocarditis in patients aged 40 to 60. The percentage of cases caused by staphylococci and streptococci were roughly equal in all groups. Enterococci, Streptococcus bovis, and coagulase-negative staphylococci were more common in the elderly. In the elderly, invasive vascular procedures were the most common source of infection. Endocarditis acquired nosocomially accounted for 23 percent of all episodes in older patients. The elderly reported fewer symptoms and showed a diminished febrile response. Errors in diagnosis were noted in 68 percent of elderly patients, and a delay in initiating appropriate therapy was more common in this age group. The mortality rate was significantly higher in the elderly (45.3 percent) than in the middle-aged (32.6 percent) and young (9.1 percent). Endocarditis in elderly patients is often nosocomially acquired, is difficult to diagnose, and is associated with a higher mortality than noted in younger patients.     

Staphylococcal endocarditis in the mitral valve prolapse syndrome

A girl, aged 13 8/12 years, in whom has been known a syndrome of the mitral valve prolapse since the 10th year of age, fell ill with an acute endocarditis by staphylococcus aureus. As the therapy with antibiotics remained without any effects and due to an early embolic dispersion including the brain an operative approach was no more possible death occurred. The pathologic-anatomical investigations resulted in a distinct ulceropolypous endocarditis of the mitral valve. At the instance of this case report the most important facts nowadays known about the relation between the syndrome of mitral valve prolapse and endocarditis are summed up.     

Haemophilus parainfluenzae endocarditis. Two cases and review of the literature in the past decade.

Twenty-five cases of Haemophilus parainfluenzae endocarditis have been reported in the past 10 years, providing a better current perspective of this disease. We have recently diagnosed and treated two patients with H. parainfluenzae endocarditis, and both underwent surgical intervention for complications of their disease. H. parainfluenzae and the other Haemophilus species causing endocarditis often present with a subacute course, often escape early cultural detection and mimic fungal endocarditis in the propensity for large vessel embolization. Multiple emboli and occlusion of major arterial vessels are especially notable features of H. parainfluenzae endocarditis and have occurred in approximately 30 per cent of the cases reported in the past 10 years. In contradistinction to other types of bacterial endocarditis, the most common cause of death in this series has been neurologic complications following embolization.Development of large vegetations appears to be common and may be an intrinsic property of the Haemophilus species, but it is likely that it also reflects the duration of the disease. Delay in recovery of the organism from blood cultures is characteristic of H. parainfluenzae endocarditis and may be due to the strict requirement for V factor exhibited by some strains. Echocardiography has proved useful in suggesting the diagnosis of endocarditis when blood cultures are negative.Optimal antibiotic therapy of H. parainfluenzae endocarditis has not been determined, but the reported clinical experience suggests that combination therapy with ampicillin and an aminoglycoside is the current treatment of choice. Failure to eradicate the organism after a prolonged trial of appropriate antibiotic therapy is not unusual. Indications for surgery in H. parainfluenzae endocarditis may have to be amended to include potential embolization, especially if large vegetations are demonstrated on echocardiography.