New developments in the treatment of infective endocarditis infective cardiovasculitis

Antibiotic Resistance of Non-pneumococcal Streptococci and Its Clinical Impact

The taxonomy of streptococci has undergone major changes during the last two decades. The present classification is based on both phenotypic and genotypic data. Phylogenetic classification of streptococci is based on 16S rRNA sequences [1], and it forms the backbone of the overall classification system of streptococci. Phenotypic properties are also important, especially for clinical microbiologists. The type of hemolysis on blood agar, reaction with Lancefield grouping antisera, resistance to optochin, and bile solubility remain important for grouping of clinical Streptococcus isolates and therefore treatment options [2]. In the following chapter, two phenotypic classification groups, viridans group streptococci (VGS) and beta-hemolytic streptococci, will be discussed.

A 20-year study on treating childhood infective endocarditis with valve replacement in a single cardiac center in China

BACKGROUND

Children with infective endocarditis (IE) have to undergo valve replacement instead of valve repair in China due to severe valve damage. The present study is to review our experience on surgical treatment of children with IE in reference to the incidence, pathologic status, diagnosis, surgical strategies and outcomes.

METHODS

We reviewed 35 patients with a mean age of 13.7±2.2 years who were underwent valve replacement surgery for IE during the period from January 1993 to December 2013. Preoperative transthoracic echocardiographic (TTE) evaluation and transesophageal echocardiography during operation were performed in all patients. All the children underwent chart review and retrospective risk-hazard analysis.

RESULTS

Among the patients surveyed congenital cardiac lesions were present in 15 (42.8%), rheumatic heart valve disease in 2 (5.7%) and previous heart surgery in 2 (5.7%). The median stay of intensive care unit was 6 days. Intraoperative findings showed that the endocarditis involved mostly the mitral and aortic valves (88.5%). Triple or quadruple valve involvement was found in one patient each. Ten-year freedom from IE-related death and re-intervention was 94.2% and 91.6%, respectively.

CONCLUSIONS

Children undergoing surgery for IE frequently have advanced disease with embolic complications. Although valve replacement is not the primary option for pediatric IE, the rate of 5-year survival and freedom from re-operation was optimal prognostically. Pediatric physicians should pay attention to the common clinical features of IE so that the native valve is preserved well.

Antibiotic Resistance of Non-Pneumococcal Streptococci and Its Clinical Impact

Viridans streptococci (VGS) form a phylogenetically heterogeneous group of species belonging to the genus Streptococcus (1). However, they have some common phenotypic properties. They are alfa- or non-haemolytic. They can be differentiated from S. pneumoniae by resistance to optochin and the lack of bile solubility (2). They can be differentiated from the Enterococcus species by their inability to grow in a medium containing 6.5% sodium chloride (2). Earlier, so-called nutritionally variant streptococci were included in the VGS but based on the molecular data they have now been removed to a new genus Abiotrophia (3) and are not included in the discussion below. VGS belong to the normal microbiota of the oral cavities and upper respiratory tracts of humans and animals. They can also be isolated from the female genital tract and all regions of the gastrointestinal tract (2, 3). Several species are included in VGS and are listed elsewhere (2, 3). Clinically the most important species belonging to the VGS are S. mitis, S. sanguis and S. oralis.

Endocarditis at a tertiary hospital: reduced acute mortality but poor long term prognosis

The outcome in 132 patients with infective endocarditis diagnosed in accordance with the Duke criteria at a tertiary hospital in Denmark in the period 1998-2000 is reported. The total in-hospital mortality was 15%. Indications are that in-hospital mortality over the last decade has been reduced by around a quarter. Mortality after 3 months was 17% (CI 29%), after 3 years 32% (CI 16-47%) and after 5 years 39% (CI 22-55%). This 5-years mortality was 5 times that of an age and gender matched background population. After follow-up for 5-8 y, mortality was highest for prosthetic valve endocarditis (63% vs. 39%, p = 0.05). Heart surgery was performed in 51% of the cases. Patients who underwent surgery had a lower mortality at follow-up (36% vs. 52%, p = 0.04). The 5-year mortality was 30% (CI 9-52%) for patients treated with surgery and 48% (CI 23-72%) for patients treated without surgery. In multivariable analysis surgery was not an independent predictor for lower long-term mortality. Surgery was however an independent predictor for lower intermediate-term mortality. It is concluded that surgery may be associated with lower short- and intermediate-term mortality, while the effect might decline in the long-term. High age, prosthetic valve endocarditis, and Staphylococcus aureus endocarditis were independent predictors for high mortality. Although improvements have occurred over recent years, infective endocarditis is still a high mortality disease.

Optimisation of the prevention and treatment of bacterial endocarditis

This paper reviews currently established guidelines for the prevention and treatment of bacterial endocarditis. Endocarditis remains a life-threatening disease with substantial morbidity and mortality. Primary prevention of endocarditis, whenever possible, is therefore very important. In an individual with endocarditis, rapid diagnosis and effective treatment are essential to good patient outcome. The guidelines discussed here are largely based on those issued by the American Heart Association. While most cases of endocarditis are not attributable to an invasive procedure, certain procedures are associated with bacteraemia by organisms commonly associated with endocarditis, and antibacterial prophylaxis is recommended before such procedures. Patient cardiac conditions are stratified into high, moderate and negligible risk categories based on potential outcome if endocarditis develops. For oral, dental, respiratory tract, and oesophageal procedures (most often associated with viridans streptococci) the standard antibacterial regimen is oral amoxicillin. For gastrointestinal and genitourinary procedures (most often associated with enterococci), parenteral antibacterials are most often recommended. For high-risk patients, intramuscular or intravenous ampicillin and gentamicin (or vancomycin and gentamicin in penicillin-allergic individuals) is recommended. For moderate risk patients, an option of oral amoxicillin or parenteral ampicillin is offered. Treatment of bacterial endocarditis is guided by identification of the causative micro-organism. Approximately 80% of cases of endocarditis are due to the gram-positive cocci: streptococci and staphylococci. Other gram-positive organisms include enterococci (predominantly Enterococcusfaecalis and E. faecium) and the HACEK group of organisms (Haemophilus parainfluenzae, H. aphrophilus, Actinobacillus [Haemophilus] actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae). In general, for uncomplicated cases of endocarditis due to penicillin-susceptible viridans streptococci or Streptococcus bovis 4 weeks of benzylpenicillin (or ceftriaxone) is the preferred regimen for most patients aged >65 years. A 2-week course of treatment can be used when gentamicin is added, in patients at low risk for adverse events caused by gentamicin therapy. When endocarditis is caused by strains of viridans streptococci or S. bovis relatively resistant to penicillin, or by enterococci, both benzylpenicillin and gentamicin are recommended. For staphylococcal endocarditis on native heart valves, nafcillin or oxacillin with or without gentamicin is the preferred regimen. In prosthetic valve staphylococcal endocarditis, nafcillin (or oxacillin) with rifampicin and gentamicin is recommended. For all of the above situations, vancomycin is recommended for the patient allergic to penicillin (or methicillin). Finally, consideration of out-of-hospital therapy in selected patients is discussed.