Effects of exopolysaccharide production by viridans streptococci on penicillin therapy of experimental endocarditis

The influence of exopolysaccharide production by viridans streptococci on penicillin therapy of endocarditis was studied in rabbits with experimental aortic-valve endocarditis. Animals were first infected with penicillin-susceptible streptococci known to produce varying amounts of exopolysaccharide in cardiac vegetations. Treatment with procaine penicillin, 300,000 U every 12 hr, was begun one to two days after infection. After five days of therapy, animals infected with Streptococcus sanguis II and Streptococcus morbillorum, both vigorous exopolysaccharide producers, continued to have infected vegetations, while animals infected with Streptococcus salivarius and a different Streptococcus sanguis II, both deficient in exopolysaccharide production, had sterile vegetations. These findings indicate that failure to eradicate streptococci from vegetations correlates with exopolysaccharide production and that this property may be important in determining outcome of therapy.     

Surgical aortic valve replacement for acute Streptococcus viridans endocarditis with simultaneous moderate hemophilia A

This is a report of a 25-year-old patient with known aortic valve stenosis since early youth and hemophilia A, showing recurrent joint bleeding. Acute Streptococcus endocarditis induced aortic valve insufficiency resulting in cardiac failure. Aortic valve replacement was performed after substitution of factor VIII, during which intra- and postoperative bleeding was prolonged by pericardial adhesions. Heparin was administered during cardiopulmonary-bypass as usual, but usual postoperative cumarin therapy was not initiated due to prolonged PTT time. One year postoperatively, the patient was in an excellent condition and fully rehabilitated.     

beta-Lactamase production in experimental endocarditis due to aminoglycoside-resistant Streptococcus faecalis

We used a beta-lactamase-producing (beta L+) strain of Streptococcus faecalis that also had high levels of resistance to all aminoglycosides to induce experimental endocarditis in rats. The rats were treated for five or 10 days with procaine penicillin, vancomycin, gentamicin, rifampin, or ciprofloxacin (alone or in various combinations), or with penicillin plus clavulanic acid. The levels of penicillin in serum and vegetations declined rapidly in the beta L+-infected rats treated with procaine penicillin alone, unlike the sustained levels of penicillin in either beta L- -infected rats treated with procaine penicillin or beta L+-infected rats treated with penicillin plus clavulanic acid. For the beta L+-infected rats, the enterococcal counts in vegetations were significantly reduced (greater than 3 log10 cfu/g) only by vancomycin and by penicillin plus clavulanic acid. The efficacy of the latter regimen probably resulted from the inhibition of penicillin inactivation by clavulanic acid in vegetations infected with the beta L+ strain. Our in vivo findings document the biologic significance of beta-lactamase production.     

Clinical, echocardiographic and prognostic profile of Streptococcus viridans left-sided endocarditis

INTRODUCTION AND OBJECTIVES: Published case series on Streptococcus viridans endocarditis are scarce and outdated. The aims of our study were multiple: to analyze the profile of the Streptococcus viridans endocarditis, to compare it with other types of left-sided endocarditis and with cases caused by Staphylococcus aureus, and to determine predictors of poor outcome in Streptococcus viridans endocarditis. PATIENTS AND METHOD: We analyzed 441 episodes of endocarditis: 330 left-sided and 54 caused by Streptococcus viridans (16%). We compared the 54 cases due to Streptococcus viridans with the remaining cases of left-sided endocarditis in our series, and also with cases caused by Staphylococcus aureus. We also analyzed the predictors of death and urgent surgery in Streptococcus viridans endocarditis. RESULTS: Left-sided endocarditis due to Streptococcus viridans led to a similar degree of valvular destruction, showed acute onset less frequently, and led to less renal failure, septic shock and mortality than the remaining cases of left-sided endocarditis in our series. The same differences were found in comparison to Streptococcus viridans endocarditis. Prognostic factors for Streptococcus viridans left-sided endocarditis were heart failure and periannular complications. CONCLUSIONS: Although Streptococcus viridans is a nonaggressive microorganism, valvular destruction is similar to that caused by other pathogens when it causes left-sided endocarditis. Nonetheless its prognosis is better, a feature which may be related to the fact that the systemic infectious syndrome can be treated more effectively. Prognostic factors in left-sided endocarditis due to Streptococcus viridans are heart failure and periannular complications.     

主动脉瓣感染性心内膜炎并主动脉瓣穿孔的临床特点及超声心动图应用

目的 :探讨主动脉瓣感染性心内膜炎 ( AVIE)并发主动脉瓣穿孔 ( AVP)的临床及超声心动图( UCG)的特点。方法 :对 11例经临床及 UCG诊断的 AVIE并发 AVP患者的资料进行分析 ,并与手术结果进行对照。结果 :临床特点 :基础心脏病以主动脉瓣畸形多见 ;主要表现发热、贫血、心脏杂音、急性左心衰竭 ;UCG特点 :二维超声心动图 ( 2 DE)显示瓣体的回声连续缺失 ,彩色多普勒血流显像 ( CDFI)显示穿瓣偏心血流 ,U CG诊断 AVP特异性为 90 .9% ;术后患者的心脏血流动力学均明显改善。结论 :U CG检查是正确诊断 AVIE并发 AVP及评价其手术治疗效果的首选方法 ,对早期正确诊断本病有十分重要的临床意义     

经食管三维超声心动图在主动脉瓣位感染性心内膜炎中的应用

目的 探讨经食管三维超声心动图（three-dimensional transesophageal echocardiography,3D-TEE）在诊断感染性心内膜炎（infective endocarditis,IE）主动脉瓣病变中的价值.方法 对49例通过经胸超声心动图（transthoracic echocardiography,TTE）与3D-TEE诊断IE主动脉瓣病变患者的超声诊断特点进行分析,以心脏外科术中所见为“金标准”,将超声特点（赘生物、瓣叶穿孔、瓣周脓肿）与手术结果进行对照.结果 3D-TEE对赘生物、瓣叶穿孔、瓣周脓肿诊出的敏感性及特异性均高于TTE,差异有统计学意义（P＜0.05）.对于检测长度＜（4.5±0.7）mm的赘生物,3D-TEE较TTE更加敏感,差异有统计学意义（P＜0.05）.对于检测瓣周脓肿,3D-TEE较TTE更加敏感,差异有统计学意义（P＜0.05）,且容易发现瓣周脓肿早期组织水肿的情况.结论 与TTE相比较,3D-TEE能更准确检测IE主动脉瓣病变,有效评价此类患者瓣周脓肿情况,具有重要的临床应用价值.     

Percutaneous aortic valve in severe valvular regurgitation caused by infective endocarditis

Recently, the feasibility and safety of percutaneous aortic valve replacement (PAVR) have been reported in the treatment of degenerative aortic valve stenosis in patients at high-risk for surgical aortic valve replacement (AVR). However, so far this therapy has been limited to patients with severe stenosis of the native valve. We report the case of an 84 year old patient with severe aortic regurgitation caused by infective endocarditis who was successfully treated by implantation of a CoreValve (CoreValve Inc, Irvine. Calif) prosthesis with a totally percutaneous approach.     

Penicillin therapy for treatment of experimental endocarditis caused by viridans streptococci in animals

We studied the efficacy of penicillin and penicillin combined with streptomycin in the treatment of experimental endocarditis caused by viridans streptococci that are susceptible, tolerant, or relatively resistant to penicillin. Rabbits with experimental endocarditis were treated with procaine penicillin (1.5 X 10(5) U/kg) administered twice daily or with procaine penicillin (1.5 X 10(5) U/kg) plus streptomycin (20 mg/kg) administered twice daily for five days. Compared with control animals, animals treated with penicillin alone experienced a significant reduction (P less than .001) of colony forming units per gram of cardiac valve vegetations when infected with streptococci that are susceptible, tolerant, or resistant to penicillin. This antibiotic alone was less effective against streptococci that were tolerant or resistant to penicillin than against streptococci susceptible to the drug (P less than .01). The combination of penicillin and streptomycin was more effective therapy than was penicillin alone in animals with penicillin-tolerant or penicillin-resistant streptococci causing endocarditis (P less than .01). Penicillin-streptomycin therapy was less active against penicillin-resistant strains than against either penicillin-tolerant (P less than .04) or penicillin-susceptible (P less than .01) strains. The results of our study suggest that tolerance or relative resistance to penicillin in strains of viridans streptococci influences the response to therapy with penicillin alone or penicillin combined with streptomycin in the treatment of experimental endocarditis caused by viridans streptococci.     

Uptake of hematoporphyrin derivative by valvular vegetations in experimental infective endocarditis

Drugs that localize in valvular vegetations may be useful in the diagnosis and treatment of infective endocarditis. We therefore tested the hypothesis that parenterally injected hematoporphyrin derivative (HPD), which is concentrated in tumors and atherosclerotic plaques, localizes in the vegetations of experimental infective endocarditis. In 14 rabbits, various bacteria were given intra-arterially immediately after injury to the aortic valve. In 12 additional rabbits, sterile vegetations on the aortic valve were produced by the trauma caused by an indwelling catheter that had been in place over a long period. HPD, 2.5 mg/kg, was injected intravenously 1 to 2 days before the animals were killed in six rabbits with sterile vegetations and in seven rabbits with infected vegetations. In all rabbits, multiple vegetations on the aortic valve leaflets were identified. On exposure to ultraviolet light, strong porphyrin fluorescence of all vegetations, whether sterile or infected, was observed only in rabbits given HPD. In two rabbits given HPD 10 weeks after catheter implantation across the aortic valve, however, only mild fluorescence could be detected in healing endocardial vegetations. In frozen sections of HPD-laden lesions, a patchy distribution of fluorescence was observed that was similar to the pattern of HPD localization in atheromatous plaques. Since vegetations in experimental infective endocarditis selectively concentrate HPD, porphyrins could be useful in the diagnosis and treatment of infective endocarditis.     

Effect of exercise on indices of valvular aortic stenosis

Changes in the physiologic state of the patient may affect indices of valvular aortic stenosis. We determined the effects of supine exercise on the Gorlin valve area, Cannon valve area, aortic valve resistance, and a modified stroke work loss index in 80 patients with aortic stenosis. Exercise caused a significant increase in the Gorlin and Cannon valve area, while work loss and valve resistance decreased significantly. The average percent change in work loss, 12.2%, was lower than the other indices (P < 0.02), i.e., 15.3% for valve resistance, 18.6% for the Gorlin area, and 19.3% for the Cannon area. The correlation between the rest and exercise measurements was highest for work loss (r = 0.94), compared to 0.93, 0.88, and 0.89 for the other 3 indices, respectively. In patients with a Gorlin area below 1 cm², exercise caused a significant decrease in work loss, but not Cannon area or valve resistance. However, the percent change was significantly lower and the correlation was better with the work loss index. We conclude that the work loss index is less affected by supine exercise than other indices of aortic stenosis.