Fc rosette inhibition by serum of patients with infective endocarditis

The inhibition of lymphocyte Fc rosette formation was studied in sera of patients with infective endocarditis. The pretreatment value of sensitised chicken erythrocyte (EA) rosette inhibition was 37.9 +/- 7.8%; in controls it was 4.1 +/- 1.3% (P less than 0.001). The posttreatment value was 2.8 +/- 2.1%. Six patients had culture-negative infective endocarditis, and in them the value of EA rosette inhibition was higher than in the others (42.3 +/- 7.1%). The measurement of circulating immune complexes may be a diagnostic tool in patients with culture-negative infective endocarditis.

Serum and tissue immune complexes in infective endocarditis

Serial circulating immune complex (IC) determinations were performed in 24 patients with infective endocarditis (IE) using the solid phase Clq, solid phase conglutinin and 3.5% polyethylene glycol precipitation assays. Circulating IC were detected in 67% of IE patients at presentation, but in only 7% of valve lesion controls. Serial determinations produced a 75% prevalence of IC in IE. The presence of circulating IC correlated with "subacute" disease, the presence of tissue deposits of immunoglobulin and/or complement components and with certain extravalvular manifestations (immune complex type glomerulonephritis cutaneous vasculitis and musculoskeletal manifestations). Effective therapy was associated with a fall in circulating IC levels, an effect which was well demonstrated by 3 patients in whom IC rapidly fell to zero following artificial valve replacement. The results support a role for circulating IC in the pathogenesis of this disorder, and suggest that serial IC determinations are useful in following clinical progress, particularly in culture negative endocarditis.

Detection of bacterial endocarditis with technetium-99m-labeled antistaphylococcal antibody

The reliable diagnosis of bacterial endocarditis is an important but difficult clinical problem. The potential ability of technetium-99m-labeled antistaphylococcal antibody to detect infective endocarditis was investigated in a rabbit model. Radiolabeling of the purified antibody was effected by a mild electrolytic procedure, with full retention of immunologic activity. Infective endocarditis was induced in rabbits by placing a catheter through the carotid artery into the left ventricle, followed by i.v. injection of Staphylococcus aureus. The labeled antistaphylococcal antibody was subsequently injected, and its clearance and distribution were studied in the infected rabbits and in normal controls. The ratio of radioactivity on the aortic valve to that in the surrounding heart tissue or blood pool was significantly higher for the infected animals (> 10:1) than for the normals, and should permit visualization of the infection site. This radiolabeled antibody technique may provide a feasible approach to detection of infective endocardial lesions.

Nature of circulating immune complexes in infective endocarditis

Two percent polyethylene glycol (PEG) precipitation was found to be a useful method for detecting circulating immune complexes (CIC) and could be used diagnostically to implicate infective endocarditis. Complexes consisting of a least Clq, IgG, and IgA were typically detected in sera from patients with infective endocarditis. Serial studies showed that CIC detection and measurement could be used to monitor clinical progress. Successful clinical improvement was reflected by decreasing CIC levels and the disappearance of rheumatoid factor, and, where increasing amounts of CIC were found, this may indicate situations where treatment was insufficient or inappropriate. There was specific free antibody demonstrable in the serum of six out of nine patients against their own infecting organisms, but attempts to identify the specificity of the complexed antibody as being directed against these organisms or their extracellular products failed. We could not detect any radioactive precipitin arcs, indicative of the free antibody also being in the complex, between the F(ab')2 preparation from the complex and the electrophoresed bacterial antigens in a radio-immunoelectrophoresis system. Eleven out of 13 sera that contained Clq, IgG, and IgA in their complexes also contained rheumatoid factor. Immunisation against the patient's own persisting CIC may explain this phenomenon.

Experimental Streptococcus sanguis endocarditis: immune complexes and renal involvement

An increase of agglutinins and circulating immune complexes (CIC) was observed in the sera of rabbits after the induction of bacterial endocarditis (BE) by intravenous injection of live streptococci into animals with a non-bacterial thrombotic endocarditis. Rabbits immunized for 12 days with heat-killed streptococci developed higher levels of agglutinins and CIC than did those unimmunized during BE. The levels remained elevated in the immunized rabbits after the induction of streptococcal endocarditis. In rabbits with very high levels of CIC complement activation occurred in vivo, possibly via the classical pathway. Kidneys from both unimmunized and immunized rabbits with streptococcal endocarditis contained bacteria and also showed inflammatory reactions but only the renal tissue of immunized rabbits with endocarditis showed a little mesangial deposition of immunoglobulin. The findings in this study indicate that in rabbits, renal inflammation due to BE is initiated more often by septic emboli than by immune complex deposition, at least during the first 12 days after infection.

Clinical value of teichoic acid antibody titers in the diagnosis and management of the staphylococcemias

Differentiation of endocarditic from nonendocarditic Staphylococcus aureus (SA) septicemia is prognostically and therapeutically important. A study of 68 cases of either SA or streptococcal sepsis, including 50 cases of SA sepsis of both cardiac and noncardiac origin, was done to determine the presence and titer of serum teichoic acid antibodies (TAA's) by double immunodiffusion. Thirty-seven uninfected controls were also examined. There was no statistical difference in either incidence or peak TAA titers in endocardial versus deepseated, extracardiac SA sepsis. However, in both of these groups, incidence and peak titers were significantly higher than in intravascular catheter-related SA sepsis, streptococcal endocarditis and controls (P<0.05). Peak TAA titers in SA sepsis develop on admission or shortly thereafter (6 to 11 days) and permit early decisions on degree of tissue infection, likelihood of metastatic seeding and necessity for higher-dose, longer-term antibiotic therapy. Cases of catheter-related SA sepsis with no clinical evidence of metastatic SA seeding and with negative or low-titered (1:1) TAA's were classified as superficial sepsis. Treatment consisted of short-term, low-dose antistaphylococcal regimens and catheter removal. In posttherapy follow-up after 6 to 12 weeks, all of the patients were cured and no signs of endocarditis or deepseated SA infection developed.

Prognostic value of teichoic acid antibodies in Staphylococcus aureus bacteremia: a reassessment

Teichoic acid antibodies were measured in serum using counter immunoelectrophoresis and immunodiffusion technics with a partially purified antigen. Immunodiffusion titers of greather than or equal to 1:4 were obtained in 15/16 patients with S aureus endocarditis but in only two of 122 noninfected individuals and in no patients with endocarditis caused by other gram-positive bacteria. These same elevated titers of antibody were noted in seven of 23 patients with nonendocarditis S aureus infections. These seven patients all had either prolonged, untreated staphylococcal bacteremia or a primary site of infection which was not promptly eradicated. Six of these seven patients responded to four weeks or less of antimicrobial therapy without developing any complications. The development of high titers of teichoic acid antibodies during the course of S aureus bacteremia could not be reliably used to determine the appropriate duration of antistaphylococcal treatment.

[Monocional immunoglobulins associated with bacterial endocarditis. Two case reports (author's transl)]

An IgGK monoclonal gammopathy occured in two patients with streptococcus viridans bacterial endocarditis. The gammopathy has been unchanged, respectively for 32 and 21 months following its detection. The alternate physiopathologic hypothesis are argued.

Influence of preformed antibody on experimental Streptococcus sanguis endocarditis

The influence of preformed, anti-whole organism antibody on the development of Streptococcus sanguis endocarditis was examined in both in vivo and in vitro systems. Antibody prevented, rather than potentiated, endocarditis in rabbits. The infectious dose in 30 control animals was 10(6.5) +/- 0.33 (mean +/- standard deviation); this increased to 10(7.71 +/- 0.05 in 36 immunized animals (P less than 0.01). No differences in bacterial clearance mechanisms were apparent between groups. Antibody also prevented the adherence of S. sanguis to the constituents of nonbacterial thrombotic endocarditis (fibrin and platelets) in vitro. When preincubated in high-titer antisera, adherence of S. sanguis was reduced compared with controls (adherence ratio mean +/- standard error of the mean, X 10(4): 174 +/- 5 versus 427 +/- 10, P less than 0.001). Preadsorption of immune sera with intact S. sanguis restored adherence to normal values, whereas preadsorption with dextran was partially effective. These studies demonstrate that preformed antibody had a protective role in vivo and suggest that a possible mechanism is blockade of adherence, a crucial early step in the pathogenesis of endocarditis.

Extracardiac manifestations of bacterial endocarditis

Bacterial endocarditis is an elusive disease that challenges clinicians' diagnostic capabilities. Because it can present with various combinations of extravalvular signs and symptoms, the underlying primary disease can go unnoticed.A review of the various extracardiac manifestations of bacterial endocarditis suggests three main patterns by which the valvular infection can be obscured. (1) A major clinical event may be so dramatic that subtle evidence of endocarditis is overlooked. The rupture of a mycotic aneurysm may simulate a subarachnoid hemorrhage from a congenital aneurysm. (2) The symptoms of bacterial endocarditis may be constitutional complaints easily attributable to a routine, trivial illness. Symptoms of low-grade fever, myalgias, back pain and anorexia may mimic a viral syndrome. (3) Endocarditis poses a difficult diagnostic dilemma when it generates constellations of findings that are classic for other disorders. Complaints of arthritis and arthralgias accompanied by hematuria and antinuclear antibody may suggest systemic lupus erythematosus; a renal biopsy study showing diffuse proliferative glomerulonephritis may support this diagnosis. The combination of fever, petechiae, altered mental status, thrombocytopenia, azotemia and anemia may promote the diagnosis of thrombotic thrombocytopenic purpura. When the protean guises of bacterial endocarditis create these clinical difficulties, errors in diagnosis occur and appropriate therapy is delayed. Keen awareness of the varied disease presentations will improve success in managing endocarditis by fostering rapid diagnosis and prompt therapy.

Effect of type-specific active immunization on the development and progression of experimental Pseudomonas aeruginosa endocarditis

Rabbits with intracardiac catheters were immunized with heat-killed Pseudomonas aeruginosa or saline and challenged with either 10(9) (high inoculum) or 10(7) (low inoculum) pseudomonas. Immunization did not decrease the incidence of endocarditis when compared with controls, but it did significantly prolong survival. The longer survival of immunized rabbits after high-inoculum challenge was not due to prolongation of the course of endocarditis but to type-specific protection from early, overwhelming bacteremia. However, after low-inoculum challenge there were no early deaths and there was a significantly (P < 0.01) longer survival of immunized (17.4 days) than unimmunized (10.6 days) animals dying of endocarditis. Increased survival was associated with higher total and 2-mercaptoethanol-resistant hemagglutinating antibody titers 1 week after challenge in immunized as compared with unimmunized rabbits. Early (48 h after challenge) vegetation colonization was also significantly (P < 0.05) greater after type-specific as opposed to non-type-specific or saline immunization and low-inoculum challenge. However, whereas 67% of type-specifically immunized rabbits had colonized vegetations at 48 h, only 38.9% died with bacteremic endocarditis. Another 19.2% of immunized rabbits had vegetations colonized with > 10(5) colony-forming units of pseudomonas at elective sacrifice 2 weeks after challenge but no bacteremia; no unimmunized rabbit exhibited similar late colonization. Preexisting antibody may be important in the pathogenesis of pseudomonas endocarditis in drug addicts, and its presence may explain the subacute and often protracted course of the disease.

Fate of circulating immune complexes in infective endocarditis

To examine the role of circulating immune complexes (CIC) in infective endocarditis, we studied 64 patients with infective endocarditis for the presence of CIC by the polyethylene-glycol (PEG)-precipitation test and the Clq binding test. This study was repeated during the course of the disease in 23 patients. CIC were found in 84 per cent of patients (66 per cent with acute infective endocarditis, 89 per cent with subacute infective endocarditis) during the active phase of the disease. Higer PEG precipitates were associated with typical cutaneous signs, cryoglobulins and nonstreptococcic culture-positive infective endocarditis. Under appropriate antibiotic treatment, the PEG precipitate levels of 17 patients fell within 1 month to the normal range, with a concomitant drop in cryoglobulinemia and rheumatoid factor. Conversely, uncontrolled sepsis always (six of six) yielded a rising level of CIC. These findings support the hypothesis that CIC may be important in the pathogenesis of peripheral lesions in infective endocarditis.

Circulating immune complexes in experimental streptococcal endocarditis: a monitor of therapeutic efficacy

An important problem in the management of infective endocarditis has been the delineation of laboratory procedures that are sensitive, reliable indicators of therapeutic efficacy. Because circulating, complement-containing immune complexes of the IgG type (CICs) have been demonstrated in most humans with infective endocarditis, serum CIC levels during the natural course of the infection and in response to penicillin therapy were studied in 42 rabbits with right-sided endocarditis due to Streptococcus salivarius. A significant rise in the level of CICs in both 21 control rabbits and 21 treated rabbits was observed after induction but before treatment of infective endocarditis (P less than 0.01). In the 17 successfully treated rabbits, CIC levels fell sharply during the first week of therapy and remained at preinduction levels thereafter (P less than 0.005). In contrast, CIC values did not change significantly either in control animals or in the four treated animals with refractory endocarditis, although in the latter animals, serum bactericidal titers remained less than or equal to 1:32. These findings suggest that serial measurements of CIC levels during antimicrobial therapy of infective endocarditis may aid in monitoring therapeutic efficacy.

Use of circulating immune complex levels in the serodifferentiation of endocarditic and nonendocarditic septicemias

Distinguishing endocarditic from nonendocarditic septicemias is prognostically and therapeutically important. One hundred two patients with both valvular and nonvalvular sepsis were studied for the presence and quantitation of circulating immune complexes. Ninety per cent of the patients with infective endocarditis versus 50 per cent of septic patients without infective endocarditis had circulating immune complex levels (p less than 0.005). Mean circulating immune complex levels in patients with infective endocarditis were significantly higher than in those without infective endocarditis, 106 +/- 18.58 microgram/ml versus 31 +/- 7.4 microgram/ml (p less than 0.005). Only three of 52 patients without infective endocarditis had circulating immune complex levels greater than 100 microgram/ml, as opposed to 16 of 50 patients with infective endocarditis (p less than 0.005). Similarly, one of 52 patients without infective endocarditis has circulating immune complex levels greater than 200 microgram/ml, as opposed to eight of 50 patients with infective endocarditis (p less than 0.05). In 92 per cent of the patients without infective endocarditis and 76 per cent of those with infective endocarditis peak circulating immune complex levels developed within 14 days after their entry into the study, often on the initial sampling. In febrile, septicemic patients with clinical symdromes nonclassic for endocarditis, measurements of serial circulating immune complex levels may be of adjunctive diagnosis importance. If circulating immune complex levels are undetectable, endocarditis would appear less likely; alternatively, levels above 100 to 200 microgram/ml would suggest a valvular rather than nonvalvular septic focus.

Nephelometric detection of soluble immune complexes: methodology and clinical applications

We have developed a method for the detection of immune complexes by laser nephelometry which is simple, reproducible, suitable for automation, and generally adaptable for diagnostic testing. Light dispersion by antigen-antibody complexes in the test samples is measured after addition of polymeric buffer, which enhances the aggregation of complexes but does not significantly affect unbound immunoglobulins. The method was used to measure immune complexes formed in vitro by incubation of tetanus toxoid with serum from a rabbit previously hyperimmunized with the same antigen, and to compare the levels of immune complexes in human sera obtained from normal adults and from 37 patients with collagen vascular diseases or endocarditis. When precautions were taken to avoid interference produced by the presence of lipoproteins or by freezing of the samples, the results obtained with human sera were consistent with those expected for normal controls and for patients with conditions thought to be associated with the presence of soluble immune complexes.

Activation of the alternate complement pathway in Staph. aureus infective endocarditis and its relationship to thrombocytopenia, coagulation abnormalities, and acute glomerulonephritis

Twenty-four patients with infective endocarditis (IE) are described, fourteen with Staph. aureus and ten with other organisms. Despite the acute nature of the infection, ten of the fourteen with Staph. aureus IE were hypocomplementaemic; six of these ten had normal levels of C4 associated with low C3 levels, suggesting activation of the alternate complement pathway. Factor B (C3PA) was also low in three of these six cases. In the ten patients with non-Staph. IE, three had hypocomplementaemia with low levels of C4, C3, and Factor B, probably due to C1 (classical pathway) activation with feedback activation of the alternate pathway. In addition, thrombocytopenia was noted in nine of the twenty-four patients and was associated with hypocomplementaemia; the degree of renal insufficiency noted in these patients also correlated with hypocomplementaemia. In Staph. aureus IE thrombocytopenia and hypocomplementaemia, occurring early in the course of the disease, may be due to a non-immune interaction of Staph. cell wall products (Protein A) with immunoglobulin, complement components, and thrombocytes.

Teichoic acid antibodies in chronic staphylococcal osteomyelitis

Gel-diffusion and the enzyme-linked immunosorbent assay (ELISA) were used to quantify and to identify the immunoglobulin class of teichoic acid antibodies in patients with chronic staphylococcal osteomyelitis and a wide variety of other infections. Teichoic acid antibodies were identified by gel-diffusion in 14 of 23 patients with staphylococcal endocarditis, six of 30 with staphylococcal bacteremia without endocarditis, four of 35 with staphylococcal skeletal infections, and one of 45 with nonstaphylococcal infections. None of the 20 patients with chronic staphylococcal osteomyelitis had positive gel-diffusion assays, even though many had had their infections for several years. The ELISA method was more sensitive than gel-diffusion in measuring teichoic acid antibodies, but was also much less specific. Teichoic acid antibodies were detected predominantly in the IgG fraction of serum. Our findings suggest that the presence and degree of antigenemia are more important than the duration of the staphylococcal infection in stimulating production of teichoic acid antibodies.

Solid-phase radioimmunoassay for immunoglobulin G Staphylococcus aureus antibody in serious staphylococcal infection

Clinical features of 99 patients with staphylococcal infection were reviewed, and sera were tested by solid-phase radioimmunoassay and gel diffusion for staphylococcal antibodies to ascertain whether these variables predict the extent of infection and the need for prolonged therapy. Clinical features, including the presence of a primary site of infection or a continuous pattern of bacteremia, were not sufficient for differentiating endocarditis or complicated bacteremia from uncomplicated bacteremia. Patients with uncomplicated bacteremia were cured by 3 weeks of antibiotic therapy. Positive serologic tests for staphylococcal antibody helped distinguish patients with endocarditis or complicated bacteremia from patients with uncomplicated bacteremia. Radioimmunoassay was more sensitive than gel diffusion for identifying patients with complicated bacteremia. Our results indicate that patients with a positive antibody result 14 days after the onset of infection should be considered to have endocarditis or complicated bacteremia, but a negative antibody result would support short-term antibiotic therapy.

Solid-phase radioimmunoassay for detection of staphylococcal antigen in serum of rabbits with endocraditis due to Staphylococcus aureus

To aid in the rapid diagnosis of staphylococcal infection, a solid-phase radioimmunoassay for Staphylococcus aureus antigen was developed and evaluated in rabbits with staphylococcal endocarditis. Test specimens containing antigen were added to polystyrene tubes coated with antibody to S. aureus. Antigens immobilized on the tube were detected by adding radiolabeled antibody to S. aureus. Sensitivity for antigen was 0.312 microgram/ml in buffer and 1.25 microgram/ml in 50% rabbit serum. Cross-reactions were not observed with antigens extracted from streptococci; however, antigen extracted from Staphylococcus epidermidis (which contained ribitol-teichoic acid) could also be detected at low concentrations. Antigen was detected in each of 12 rabbits with S. aureus endocarditis but not in control rabbits. This assay is sensitive, specific, reproducible, and capable of detecting antigens in the serum of rabbits with endocarditis.

Case report. Cardiobacterium hominis: review of prior infections and report of endocarditis on a fascia lata prosthetic heart valve

The clinical spectrum of disease caused by Cardiobacterium hominis, a small, gram-negative coccobacillus, is little known to physicians. From analysis of a new case of C hominis endocarditis on a fascia lata aortic valve, and from review of all previous reports of infection due to this microorganism, a remarkably consistent clinical picture emerged. C hominis only causes endocarditis, affects middle-aged individuals with structurally abnormal, left-sided cardiac valves, and follows a subacute course associated with the frequent occurrence of mycotic aneurysms and embolic phenomena. The methodology and therapeutic importance of identifying this organism and separating it from the closely related Actinobacillus actinomycetemcomitans, Eikenella corrodens, and Haemophilus aphrophilus is emphasized. Either penicillin alone or penicillin plus an aminoglycoside is recommended for therapy.

Atrio-ventricular shuntinfections and endocarditis due to Staphylococcus epidermidis

Two groups of patients (with endocarditis and with atrioventricular shunt infections due to Staphylococcus epidermidis) are presented together with analysis of the causative agents by bio- and phage-typing. Additionally phagocytic function of polymorphonuclear leukocytes of selected patients was investigated but no decreased phagocytic function was found. A possible way of treatment is discussed.

[The rheumatoid rosette test in bacterial endocarditis. A non-specific test for inflammation (author's transl)]

The rheumatoid rosette test was performed in 33 patients with febrile valvular cardiopathy. In 19 cases bacterial endocarditis was proved by blood culture or by histological examination. The test was positive in 3 cases out of 5 during the first ten days of the fever (group A1), in 6 cases out of 6 after the tenth day (group A2), and in 4 out of the 8 already treated patients (group A3). In 3 positive cases, successive measurements, before and during treatment, showed a rapid fall in rosette levels. In controls patients, the test was positive 8 out of 9 cases with febrile valvular cardiopathy without endocarditis (group B) and in 5 out of 5 cases in which bacterial endocarditis was probable but not proved (group C). The increase in rheumatoid rosette levels seems therefore to be non specific of bacterial endocarditis. Nevertheless it could be a good test for biological activity of the disease in treated patients. The origin and signification of the rheumatoid rosette forming cells are discussed.

[Circulating immuns complexes and infections endocarditis. 64 cases (author's transl)]

An immunological study, with examination for circulating immune complexes (CIC) by precipitation by polyethylene-glycol (PEG) and by fixation of labelled C1q, was carried out in 64 patients with infectious endocarditis (IE). One or more complementary studies during the course of the illness were possible in 23. CIC were found in 84 p. 100 of cases (66 p. 100 of acute IE and 89 p. 100 of subacute IE), during the active phase of the disease. High levels of PEG precipitate were correlated with typical cutaneous signs (including Osler's nodes), with the presence of cryoglobulins. With effective antibiotic treatment, the level of PEG precipitate (17 patients) returned to normal within one month, in parallel with a fall in rheumatoid factor and in cryoglobulins. By contrast, ineffective treatment was invariably reflected (6 patients) by a rise in levels of PEG precipitate. The estimation of CIC using the PEG technique during IE would already appear to be a value aid in cases of difficult diagnosis, and a research area worthy of further exploration within the context of IE.

Correlation of antistaphylococcal antibody titers with severity of staphylococcal disease

Counterimmunoelectrophoresis (CIE) was utilized to determine antistaphylococcal precipitin antibody titers in patients with various staphylococcal diseases and in control subjects. Patients with staphylococcal disease comprised five cases of endocarditis, 22 of deep tissue infection (including seven cases of osteomyelitis), six of bacteremia and six of skin infection. Control subjects consisted of 31 patients with nonstaphylococcal bacteremias, 29 hospitalized patients without infection and 30 healthy subjects. Antistaphylococcal antibodies were present in all patients with staphylococcal endocarditis and deep tissue staphylococcal infection, and all but three had titers greater than or equal to 1:4. No significant difference in titers was found between these two groups of patients. Antibodies, although present in some patients in the other categories, were detected less frequently; only two patients had titers greater than or equal to 1:4. Thus, an antistaphylococcal antibody titer by CIE of 1:4 or greater may be an additional diagnostic parameter helpful in distinguishing patients with staphylococcal endocarditis or deep tissue infection from those with other forms of staphylococcal infection and from noninfected subjects.

Staphylococcus aureus bacteremia: relationship between formation of antibodies to teichoic acid and development of metastatic abscesses

Of 50 patients with bacteremia due to Staphylococcus aureus but without clinical evidence of endocarditis, 24 developed antibodies to the cell wall teichoic acid of S. aureus that were demonstrable by counterimmunoelectrophoresis. However, only 16 of the 24 patients developed titers of antibodies high enough for detection by passive gel diffusion. Eleven of the 16 patients developed evidence of complications due to metastatic infection. In contrast, of the 34 patients who were antibody-negative by gel diffusion, only one patient developed evidence of metastatic seeding. Thus, the development of antibodies to teichoic acid at a level detectable by the gel diffusion technique is regularly associated with complicated infections due to S. aureus that require more prolonged therapy, whereas bacteremic patients not developing such an antibody response rarely develop complications and may be treated with a two-week course of therapy.

Musculoskeletal manifestations of bacterial endocarditis

In a retrospective analysis of bacterial endocarditis, 84 of 192 cases (44%) were found to have musculoskeletal manifestations of one or more types. Common manifestations were arthralgias (32 cases), arthritis (26 cases), low back pain (24 cases), diffuse myalgia (16 cases), and myalgias localized to the thigh or calf (11 cases). The joint manifestations typically were monarticular or oligoarticular, and the myalgias were commonly unilateral. No association was found between the pattern of rheumatic symptoms and other clinical manifestations, laboratory tests, or causative bacterial organisms. In 52 patients (27%), musculoskeletal complaints were the first or among the first symptoms of bacterial endocarditis. The frequency and character of these manifestations and their tendency to occur early in the course of the disease indicate that they are an important feature of endocarditis which, if not recognized, may cause a delay in the diagnosis by mimicking a rheumatic disease.

Skin immunofluorescence in infective endocarditis

Immunofluorescent microscopy was performed on the clinically normal skin of 3 patients with infective endocarditis, 3 patients with bacteremia, and 6 normal subjects. Perivascular deposition of immunoglobulin and complement was demonstrated in two of the three patients with infective endocarditis and in none of the bacteremic or control subjects.

Teichoic acids in pathogenic Staphylococcus aureus

Twenty-six strains of Staphylococcus aureus obtained from patients with endocarditis were studied for the production of alpha- and/or beta-ribitol teichoic acid (TA), using highly specific anti-TA antibodies prepared in rabbits. A counterimmunoelectrophoretic assay was used. Beta-TA was the predominant residue produced by all strains; alpha-TA was found in all strains, but in smaller amounts and with much strain-to-strain variations. Antibodies in patients' sera were found against beta-TA in higher titers and for longer periods than were anti-alpha-TA antibodies. Antibodies against one or both TA residues were present in all but one of 26 patients.

Detection of IgG antibodies to type-specific Pseudomonas aeruginosa lipopolysaccharides by solid-phase radioimmunoassay

Previous studies have suggested that IgG serotype-specific antibodies are protective against infections with pseudomonas aeruginosa. In the present study, type-specific IgG antibodies to P. aeruginosa were detected by solid-phase radioimmunoassay in sera from 15 volunteers before and after vaccination with lipopolysaccharides from P. aeruginosa and from four patients with endocarditis due to P. aeruginosa. Significant type-specific increases in IgG antibody occurred after both vaccination and infection. The correlation coefficients comparing net counts per minute by solid-phase radioimmunoassay with hemagglutination titers in the 15 vaccinees were 0.940, 0.874, 0.792, 0.903, 0.882, 0.869, and 0.704 for serotypes 1--7, respectively.

Infective endocarditis: a current review

Infective endocarditis is a dynamic disease for which various infective organisms may be responsible in different patient populations. Antimicrobial therapy should be directed against the specific organism after it has been identified by blood culture. An agent with a spectrum that includes the enterococci should be given in the meantime. Prophylactic use of a bactericidal agent is necessary for patients with valvular or congenital heart disease. Recent advances in microbiologic and cardiac diagnostic procedures offer the clinician various methods of following the activity of the disease, and immunobiology has provided new insights into its pathogenesis.

Use of bovine conglutinin for the assay of immune complexes

We have used purified bovine conglutinin to develop a solid state radioimmune assay for immune complexes. Employing aggregated human IgG incubated with fresh normal human serum (complement) as a model for immune complexes, we have shown that our conglutinin assay is sensitive and highly specific for immune complexes that have fixed complement. The assay preferentially detects large complexes, is minimally influenced by monomeric IgG, and can be inhibited by high ionic strength, calcium chelation, and acetamido sugars. In addition, we have surveyed several hundred clinical sera from patients with various immunopathologic disorders and find evidence of immune complexes in some.

Protective role of complement in experimental Escherichia coli endocarditis

Fourteen strains of Escherichia coli were tested for ability to cause infective endocarditis in rabbits prepared by prior placement of an intracardiac catheter. Strains that were resistant to the bactericidal action of serum caused E. coli endocarditis in 91.4% of rabbits, whereas serum-sensitive strains usually failed to cause persisting infection (11.3% infected, P less than 0.001). Although serum-sensitive E. coli lodged on heart valves within 1 h after intravenous injection, they survived less than 24 h in most normal rabbits. In contrast to normals, all five C6-deficient rabbits injected with a serum-sensitive strain of E. coli developed infective endocarditis (P less than 0.005). No correlation was found between the presence of K1 antigen and the incidence of experimental E. coli endocarditis. Thus, the ability of strains of E. coli to establish persisting endocardial infection in rabbits appears to be directly associated with resistance to the complement-mediated serum bactericidal system. These findings may explain in part the rarity of gram-negative bacillary endocarditis in patients; they also indicate that in certain special circumstances the serum bactericidal system can play a decisive role in host defense.

Circulating immune complexes in infective endocarditis

To examine further the role of immune-complex deposition in infective endocarditis, we studied 29 patients with infective endocarditis for presence of complement-containing circulating immune complexes. Ninety-seven per cent (28 of 29) had serum levels of immune complexes greater than 12 mug per milliliter. Mean levels in these patients were significantly higher than in patients with sepsis without endocarditis or in normal controls (P less than 0.05). Circulating immune-complex levels were correlated with longer duration of illness (P less than 0.025), extravalvular manifestations of endocarditis (P less than 0.025) and hypocomplementemia (P less than 0.05). Patients with right-sided endocarditis had significantly higher circulating immune-complex levels than patients with left-sided involvement (P less than 0.025). In general, levels fell to zero with successful antimicrobial or surgical therapy. This drop was concurrent with disappearance of extravalvular signs, blood cultures becoming sterile, and rise in serum complement levels. These findings support the concept that immune complexes may be important in the pathogenesis of infective endocarditis.

Rheumatoid factor in acute bacterial endocarditis

Sera from 55 parenteral drug abusers with endocarditis due to Staphylococcus aureus were assayed for the presence and titer of rheumatoid factor. Thirteen (24%) of the 55 patients with endocarditis had sera positive for rheumatoid factor at one point or another in their courses; only 2 (7%) of 30 noninfected drug users were found to be positive. It appeared that more severe cases, as evidenced by duration of fever after initiation of antibiotic therapy, were more likely to develop rheumatoid factor.

Glomerulonephritis associated with Coxiella burnetii endocarditis

A patient with endocarditis associated with chronic Coxiella burnetii infection is described in whom glomerulonephritis developed with granular deposits containing immunoglobulins and complement in the glomeruli. The serum was notable for the variety of circulating antibodies detected, which included antibodies directed against native DNA.