Endocarditis due to group D streptococci. Comparison of disease caused by streptococcus bovis with that produced by the enterococci

The group D streptococci include the nonenterococcal Streptococcus bovis in addition to the classic enterococci. Endocarditis due to Strep. bovis has received little previous attention in the medical literature. A review of all cases of group D streptococcal endocarditis seen at the Massachusetts General Hospital between 1964 and 1973 revealed 14 cases caused by Strep. bovis and 15 by enterococci. There were only minor differences in the clinical presentations of endocarditis caused by these two groups of organisms. Although it contains the group D antigen Strep. bovis behaved like Strep. viridans in producing endocarditis. Moreover, the strains of Strep. bovis in this study were much more susceptible to penicillin than the enterococci. Therapy of severe enterococcal infections requires penicillin plus an aminoglycoside antibiotic whereas the present study strongly suggests that penicillin alone is adequate therapy for endocarditis due to Strep. bovis.     

感染性心内膜炎730例病原菌构成及药敏分析

目的 分析感染性心内膜炎（infective endocarditis,IE）患者病原菌构成及药敏结果,为本地区经验性抗感染方案的制订提供依据.方法 对2006年1月至2012年9月在广东省人民医院住院的730例IE患者的血培养结果资料进行回顾性分析.结果 （1）血培养阳性率为28.6％,病原菌构成：革兰阳性球菌157例（75.1％）,革兰阳性杆菌15例（7.2％）,革兰阴性杆菌18例（8.6％）,假丝酵母菌18例（8.6％）;最常见细菌为链球菌（40.7％）、葡萄球菌（23.4％）、肠球菌（10.5％）.（2）药敏：在革兰阳性球菌中,链球菌、肠球菌对氨苄西林和青霉素的敏感性比较,差异无统计学意义（94.9％ vs.90.6％,P=0.25; 77.8％ vs.84.2％,P=0.53）;但葡萄球菌对氨苄西林的敏感性显著高于青霉素,差异有统计学意义（58.8％ vs.7.0％,P＜0.001）.革兰阳性菌对糖肽类药物普遍敏感,氨基糖甙类对葡萄球菌及革兰阴性杆菌都有较高的抗菌活性.结论 广东省人民医院IE患者病原菌血培养阳性率低,病原菌以革兰阳性球菌多见;病原菌未明时,宜选择氨苄西林或糖肽类联合氨基糖苷类抗生素作为本区域经验性抗感染方案.     

Issues in the management of endocarditis caused by resistant gram-positive organisms

Most cases of infective endocarditis (IE) are caused by gram-positive bacteria such as enterococci, streptococci, and staphylococci. Increasing resistance among these organisms has eroded the utility of mainstay antibiotics and complicated the management of this difficult-to-treat infection. Clinical experience with newer gram-positive antibiotics to treat IE is limited.     

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.     

Swedish guidelines for diagnosis and treatment of infective endocarditis

Swedish guidelines for diagnosis and treatment of infective endocarditis (IE) by consensus of experts are based on clinical experience and reports from the literature. Recommendations are evidence based. For diagnosis 3 blood cultures should be drawn; chest X-ray, electrocardiogram, and echocardiography preferably transoesophageal should be carried out. Blood cultures should be kept for 5 d and precede intravenous antibiotic therapy. In patients with native valves and suspicion of staphylococcal aetiology, cloxacillin and gentamicin should be given as empirical treatment. If non-staphylococcal etiology is most probable, penicillin G and gentamicin treatment should be started. In patients with prosthetic valves treatment with vancomycin, gentamicin and rifampicin is recommended. Patients with blood culture negative IE are recommended penicillin G (changed to cefuroxime in treatment failure) and gentamicin for native valve IE and vancomycin, gentamicin and rifampicin for prosthetic valve IE, respectively. Isolates of viridans group streptococci and enterococci should be subtyped and MIC should be determined for penicillin G and aminoglycosides. Antibiotic treatment should be chosen according to sensitivity pattern given 2-6 weeks intravenously. Cardiac valve surgery should be considered early, especially in patients with left-sided IE and/or prosthetic heart valves. Absolute indications for surgery are severe heart failure, paravalvular abscess, lack of response to antibiotic therapy, unstable prosthesis and multiple embolies. Follow-up echocardiography should be performed on clinical indications.     

New trends in the epidemiological and clinical features of infective endocarditis: results of a multicenter prospective study.

BACKGROUND: The clinical and epidemiological profiles of infective endocarditis (IE) are continuously evolving. We report the results of a 2-year multicenter prospective survey that investigated new trends in the epidemiology, microbiological and clinical features and the prognosis of IE. METHODS: From January 2000 through December 2001, a prospective multicenter survey on IE was conducted in the region of Piedmont, Italy (4.2 million inhabitants). RESULTS: A total of 267 patients with suspected IE were enrolled, of whom 147 received a definite diagnosis of IE, as confirmed by pathology or follow-up data. The annual estimated incidence of IE was 36 cases per 1 million inhabitants in urban Turin and 30 cases per 1 million inhabitants in the province of Turin. A predisposing heart disease was detected in 70.8% of cases, with prosthetic valve involvement in 27 (18%). The incidence of injection drug use was 10%. Twenty-two cases (15%) were related to invasive procedures. Causative microorganisms included: streptococci 37.4% (oral streptococci 17.7%, group D streptococci 9.5%, pyogenic streptococci 3.4%, enterococci 6.8%), staphylococci 34%, other pathogens 28.5%. Blood cultures were negative in 25% of cases. The mean time between symptom onset and hospital admission was 39.7 days; this interval was shorter and associated with a poorer prognosis in cases of IE due to Staphylococcus aureus infection (p < 0.001). The delay in carrying out echocardiographic and blood culture evaluation often led to a late diagnosis as defined by the Duke criteria (8.2 +/- 7.4 days after admission). Valve surgery was performed in 31% of patients. The in-hospital mortality was 14% and that at 3 months 18%. CONCLUSIONS: In Piedmont, the incidence of IE is similar to the rates reported in other recent series. Still, the diagnosis and management of IE remain a challenge. The variegated clinical manifestations of IE and its changing epidemiology require constant surveillance.     

Streptococcal meningitis in adult patients: current epidemiology and clinical spectrum.

Streptococci other than Streptococcus pneumoniae are a rare cause of bacterial meningitis in adults. We report 29 cases of streptococcal meningitis (1977-1997). The patients comprised 19 men and 10 women, with a mean age +/- standard deviation of 47 +/- 18 years. Nine cases were secondary to neurosurgical procedures, seven to brain abscess, five to cerebrospinal fluid pericranial fistula, and three to endocarditis. Causative microorganisms included the following: viridans group streptococci, 20 cases; anaerobic streptococci, 3; Streptococcus agalactiae, 3; Streptococcus bovis, 2; and Streptococcus pyogenes, 1. Four Streptococcus mitis strains showed decreased susceptibility to penicillin (MIC, 0.5-2 microg/mL). Five patients (17%) died. The infection is increasing in the hospital setting. Streptococci resistant to penicillin should be considered in the empirical treatment of nosocomial meningitis. In cases of community-acquired infection, anaerobic streptococci or streptococci of the Streptococcus milleri group should alert the clinician to the presence of an undiagnosed brain abscess, whereas oral streptococci of the viridans group suggest the diagnosis of bacterial endocarditis.     

Infective endocarditis: new concepts in pathogenesis

Gram-positive cocci account for the large majority of cases of infective endocarditis. Pathogenesis investigations of endocarditis have therefore focused on purported virulence factors in staphylococci, viridans group streptococci and enterococci. In addition to novel molecular techniques that have been adapted for use in the examination of gram-positive cocci, animal models of experimental endocarditis have been employed to support or discount the role of specific bacterial components in production of infective endocarditis. This review details recent work that addresses endocarditis pathogenesis and highlights pertinent findings from these investigations.     

Streptococcal endocarditis: single vs. combination antibiotic therapy and role of various species

Forty-eight patients with 51 episodes of infective endocarditis caused by streptococci were studied in a comparison of the efficacy of single antibiotic therapy versus that of combination therapy. There was no statistical difference in terms of clinical course, toxicity, and mortality between the group given a single drug and that given combination therapy. However, one patient experienced two relapses, in both instances after high-dose penicillin therapy. The species and antibiotic susceptibilities of the infecting organisms were determined. The majority of isolates were alpha-hemolytic, with Streptococcus sanguis recovered most commonly. Streptococcus bovis and group B beta-hemolytic streptococci were the next most frequent isolates.     

Etiology of infectious endocarditis at the Instituto Nacional de Cardiologia Ignacio Chavez from 1976 to 1986

We studied 85 cases of infectious endocarditis (IE) with an anatomical diagnosis (biopsy or necropsy). Most cases occur between the second and fourth decade of life; male/female ratio was 1/0.8; 45 had IE in a natural valve; 40 had prosthetic IE. Clinical diagnosis was established or at least suspected in 61 cases (72%); the most common misdiagnosis was acute rheumatic fever. Blood cultures were positive in 25 cases of natural valve IE (56%) and in 25 cases of prosthetic IE (63%). Half of those negative culture cases had a history of antimicrobial use before their arrival at the hospital. Those microorganisms which cause natural valve IE were: staphylococci (9), streptococci (8), Gram negatives (5), Candida sp (1), and two non-identified cases; 1 patient had a polymicrobial infection. Prosthetic IE was divided into early and late infections. The former was due to: staphylococci (4), streptococci (1), Candida sp (1); the latter: staphylococci (7), streptococci (4), Gram negatives (4), Candida sp, Mycobacterium fortuitum and Peptococcus (1 each), and in a single case Lactobacillus sp, presumably a contaminant.     

Infective endocarditis in patients with kidney failure: Chronic dialysis and kidney transplant

Physicians who treat patients with infective endocarditis (IE) are encountering a growing number of dialysis and kidney transplant patients. Both groups have 30 to 100 times higher risk of IE, with 1-year mortalities of 40% to 60%. The predominant organisms causing IE are gram positive, with 60% to 80% of cases due to Staphylococcus aureus, and another 10% to 20% of cases due to coagulase-negative staphylococci. Renal transplant patients may develop fungal IE, but this risk is primarily in the first 3 months after transplant. In addition to blood cultures, transesophageal echocardiogram is the most useful diagnostic examination for IE in these patients. Initial antibiotic therapy, pending final culture and antibiotic susceptibility results, should provide coverage against the most common organisms and allow for the potential of either methicillin or vancomycinresistant species. Removal of infected hemodialysis access devices and at least 4 to 6 weeks of intravenous antibiotics are recommended. Antibiotic prophylaxis against IE has been recommended for all dialysis and renal transplant patients, but this strategy is controversial and unproven.     

Infective endocarditis: changing epidemiology and predictors of 6-month mortality: a prospective cohort study.

AIMS: The aim here is to analyse epidemiology, optimal treatment, and predictors of 6-month mortality in infective endocarditis (IE). METHODS AND RESULTS: A prospective observational cohort study included 193 patients with 203 episodes of definite IE by the modified Duke criteria. Thirty-four percent of episodes involved prosthetic valves. Thirty-three percent of episodes were nosocomial. Forty-three percent included staphylococci, 26% streptococci, and 17% enterococci. At least one complication occurred in 79% of the episodes and 63% had surgical intervention. Six-month mortality was 22%: 33% for staphylococci, 24% for enterococci, and 8% for streptococci. Seventy-four percent of patients with a contraindication to surgery died when compared with 7% with medical treatment without a contraindication and 16% with surgical treatment. In multivariable logistic regression, predictors of 6-month mortality were age (P=0.03), the causative microorganism (P=0.04), and treatment group (P<0.001). CONCLUSION: Compared with older series, we observed more prosthetic valve IE, nosocomial IE, and surgery. Staphylococcus aureus and Enterococcus faecalis were predominant microorganisms. Age, staphylococci, and a contraindication to surgery predicted 6-month mortality. Nearly half of deaths had a contraindication to surgery. Six-month mortality did not differ significantly between patients who received surgical treatment as against those who received medical treatment without a contraindication to surgery.     

Group B streptococcal infective endocarditis

From 1970 to 1983, five patients with group B streptococcal endocarditis were treated at the Mayo Clinic, Rochester, Minn. The minimal inhibitory concentration and the minimal bactericidal concentration of penicillin were 0.09 microgram/mL or less and 1.56 micrograms/mL or less, respectively. The in vitro activity of cefazolin against group B streptococci was similar to that of penicillin. In three of the five cases, penicillin and streptomycin acted synergistically in vitro against group B streptococci. Four of the five patients were cured, three by use of an aminoglycoside combined with penicillin, ampicillin, or vancomycin. Three of the five patients had multiple large systemic emboli, and one of the three died of brain-stem infarct. Penicillin alone or in combination with an aminoglycoside is effective therapy for group B streptococcal endocarditis. Patients unable to tolerate penicillin may be treated with cefazolin or vancomycin. Clindamycin therapy should be avoided in patients with endocarditis caused by strains that are tolerant in vitro to clindamycin.     

La endocarditis infecciosa en el siglo xxi: cambios epidemiológicos,terapéuticos y pronósticos

Infective endocarditis (IE) is an uncommon and severe disease. Nowadays, in developed countries, IE patients are older, usually have a degenerative heart valve disease, and up to 30% acquire this infection within the health care system. In consequence, staphylococci species are the most frequently isolated microorganisms. Antimicrobial treatment for IE has significantly changed over the last decades. In IE episodes due to Staphylococcus aureus, cloxacillin-resistance makes antimicrobial election more difficult. Other microorganisms, such as enterococci and some species of streptococci, show high rates of resistance to antimicrobial agents established in guidelines. Despite improvements in the diagnosis, and medical and surgical treatment of IE, this disease continues to be associated with high rates of in-hospital mortality. At present, due to epidemiological changes, antimicrobial prophylaxis can avoid few cases of IE. Prevention of nosocomial bacteremia, an early diagnosis of IE, prompt identification of IE patients at a higher risk of mortality, and a multidisciplinary approach of this disease could be valid strategies in order to improve the outcome of these patients.     

Non-valvular cardiac devices endocarditis

The risk of infective endocarditis on pacemaker or ICD is not negligible and has increased in recent years. Several host-related, procedure-related, or device-related risk factors have been recognized. Owing to its potential severity, the possibility of infective endocarditis should be envisaged in patients with repeated pulmonary infections or documented bacteremia and transesophageal echocardiography should then be used. The most common germs causing pacemaker endocarditis are staphylococci. Treatment requires prolonged antibiotic therapy and retrieval of the pacemaker and leads.     

Effect of penicillin resistance on presentation and outcome of nonenterococcal streptococcal infective endocarditis

BACKGROUND AND AIMS: Most cases of infective endocarditis are caused by nonenterococcal streptococci. The emergence of strains resistant to penicillin is increasingly recognized worldwide. This study sought to assess the effect of penicillin resistance on presentation and outcome of streptococcal endocarditis. METHODS: A retrospective study was conducted in a single tertiary care hospital. RESULTS: Between August 1996 and December 2004, patients infected with nonenterococcal streptococcal endocarditis and known minimal inhibitory concentrations (MICs) to penicillin were included in this study. A total of 62 cases were identified: 48 (77%) cases of the streptococcal endocarditis were caused by viridans streptococci. The most common species groups identified were Streptococcus mitis in 12 (19%) cases, Streptococcus oralis in 9 (15%) cases, Streptococcus sanguis in 7 (11%) cases and Streptococcus mutans in 7 (11%) cases. There were 36 male and 26 female patients with a median age of 46 years (range: 1-85). Twenty-two patients (35%) had peripheral embolization and 10 patients (16%) died in hospital. Twenty-eight (45%) of the 62 patients were infected with streptococcal strains of MICs > or =0.125 microg/ml to penicillin. Infection with streptococcal strains of MICs > or =0.125 microg/ml to penicillin was associated with a lower incidence of all-site embolization, but was not associated with higher mortality or increased frequency of surgery. CONCLUSIONS: High-level penicillin resistance of the streptococci responsible for endocarditis was increasingly common and medical therapy with vancomycin had a good response. Penicillin resistance was associated with a decreased risk of embolization, but was not associated with higher mortality.     

Infective endocarditis: analysis of 300 episodes]

PURPOSE: Study of clinical features and etiologic agents, treatment and mortality of patients with infective endocarditis (IE). PATIENTS AND METHODS: 300 episodes of IE occurring in 288 patients, ages ranged between 0.2 and 78 (mean 30.76) years; 185 (62%) episodes occurred in males. RESULTS: a) etiologic agents: viridans group streptococci in 93 (31%) episodes, enterococci en 21 (7%), group D-non enterococci in 19 (6%) (13 S. bovis), other streptococci in 14 (5%), Staphylococcus aureus in 59 (20%), Staphylococcus epidermidis in 14 (5%), gram-negative bacteria in 16 (5%), gram-positive bacteria other than streptococci and staphylococci and staphylococci in 8 (3%), fungi in 4 (1%). The etiologic agents were not identified in 52 (17%) episodes; b) underlying cardiac diseases: valvular heart disease in 119 (40%) episodes, congenital heart disease in 37 (12%), prosthetic heart valves in 69 (23%), other heart diseases in 6 (2%). There was no evidence of previous heart disease in 69 (23%); c) treatment: surgical treatment was undertaken in 102 (34%) episodes. The frequency of surgical treatment in relation to the etiologic agents ranged between 1% (non-group D streptococcus) and 62% (negative blood cultures). The frequency of operation in relation to underlying heart disease ranged between 17% (other heart diseases), 19% (congenital heart disease) and 54% (prosthetic heart valve); d) mortality: 78 (26%) patients died, 56 (28%) of the 198 submitted to medical treatment and 22 (21%) of the 102 submitted also to surgical treatment. The mortality in the different groups of etiologic agents ranged between 5% (non group D streptococcus) and 62% (gram-positive bacteria other than streptococci ans staphylococci); in relation to the underlying with other heart disease, 19% in valvular heart disease patients, 21% in patients with congenital heart disease, 23% in patients without known heart disease and 43% in patients with prosthetic heart valves. CONCLUSION: The mortality associated with IE remains still high in spite of modern treatment; the mortality is different in relation to the cardiac status before the IE.     

Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia due to a linezolid "tolerant" strain

Persistent Staphylococcus aureus bacteremia is most frequently related to S. aureus acute bacterial endocarditis, myocardial abscess, extracardiac abscess, or a device-associated infection. Patients with continuous high-grade bacteremia who do not have acute bacterial endocarditis, an abscess, or a device-related infection should be considered to have antimicrobial "tolerance" as a possible cause. Antimicrobial "tolerance" is defined as a wide discrepancy between the minimal inhibitory concentration and the minimal bactericidal concentration of an isolate. Tolerance was first described in S. aureus and has since been described with streptococci and enterococci. Despite apparent in vitro susceptibility, infections caused by "tolerant" strains are not cured by appropriate antimicrobial therapy. The lack of bactericidal activity of the antibiotic becomes apparent when minimal bactericidal concentrations are determined for "tolerant" strains, and there is a great discrepancy between the minimal inhibitory concentration being used. Antibiotic tolerance to S. aureus has been described with a variety of antibiotics. To the best of our knowledge, this is the first case of continuous, high-grade methicillin-resistant S. aureus bacteremia due to a linezolid-tolerant strain.     

Infective endocarditis caused by Streptococcus bovis resistant to the lethal effect of penicillin G.

Penicillin G alone is generally recommended for the treatment of infective endocarditis caused by Streptococcus bovis because clinical isolates of S bovis are represented as being uniformly and markedly susceptible to penicillin G. However, two strains of S bovis recovered from two patients with bacterial endocarditis were resistant to the lethal effect of penicillin G. Combination therapy, cefazolin sodium and gentamicin sulfate in patient 1 and penicillin G and gentamicin in patient 2, was necessary; synergy, as manifested by lethal activity against the infecting strains, was demonstrated in the laboratory. We stress the need to determine the minimal lethal concentration of penicillin G for clinical isolates of S bovis. Until such information is available, particularly in life-threatening infections, combination drug therapy, consisting of an aminocyclitol added to a beta-lactam antimicrobic, should be used.