Oral treatment of subacute bacterial endocarditis in children

Treatment of Enterococcus faecalis Infective Endocarditis: A Continuing Challenge

Today, Enterococcus faecalis is one of the main causes of infective endocarditis in the world, generally affecting an elderly and fragile population, with a high mortality rate. Enterococci are partially resistant to many commonly used antimicrobial agents such as penicillin and ampicillin, as well as high-level resistance to most cephalosporins and sometimes carbapenems, because of low-affinity penicillin-binding proteins, that lead to an unacceptable number of therapeutic failures with monotherapy. For many years, the synergistic combination of penicillins and aminoglycosides has been the cornerstone of treatment, but the emergence of strains with high resistance to aminoglycosides led to the search for new alternatives, like dual beta-lactam therapy. The development of multi-drug resistant strains of Enterococcus faecium is a matter of considerable concern due to its probable spread to E. faecalis and have necessitated the search of new guidelines with the combination of daptomycin, fosfomycin or tigecycline. Some of them have scarce clinical experience and others are still under investigation and will be analyzed in this review. In addition, the need for prolonged treatment (6–8 weeks) to avoid relapses has forced to the consideration of other viable options as outpatient parenteral strategies, long-acting administrations with the new lipoglycopeptides (dalbavancin or oritavancin), and sequential oral treatments, which will also be discussed.

Oral antibiotics for infective endocarditis: a clinical review

Current guidelines for management of infective endocarditis (IE) advise 4-6 weeks of IV antibiotics. This is based on historical data from animal models, which set a precedent for high peak serum antimicrobial levels, thought to be only achievable with IV therapy. However, there has been increasing recent interest in oral antibiotics as an alternative to prolonged parenteral therapy, not limited to treatment of IE. This review examines the theory behind parenteral antibiotic administration with reference to the MICs of relevant pathogens. By comparing published serum antimicrobial levels after oral and IV administration we suggest that safe levels of commonly used antibiotics can be achieved orally. We have then reviewed the literature to date on oral antibiotics for IE. The largest randomized controlled trial (RCT) in this area, the POET trial, concluded that oral therapy was non-inferior to prolonged IV therapy in stable patients with left-sided IE. Additionally, there have been two smaller RCTs published, as well as a number of observational studies over the last 50 years, utilizing a variety of different patient groups, methods and treatment strategies. This body of evidence gives weight to a potential shift in practice towards oral therapy, primarily as a step-down treatment. We conclude that pharmacological data offer theoretical reassurance for the safety of oral therapy. This is coupled with a growing evidence base for non-inferiority of oral antimicrobials compared with prolonged parenteral therapy in practice.

Evaluation of a Paradigm Shift From Intravenous Antibiotics to Oral Step-Down Therapy for the Treatment of Infective Endocarditis: A Narrative Review

IMPORTANCE

The requirement of prolonged intravenous antibiotic courses to treat infective endocarditis (IE) is a time-honored dogma of medicine. However, numerous antibiotics are now available that achieve adequate levels in the blood after oral administration to kill bacteria. Moreover, prolonged intravenous antibiotic regimens are associated with high rates of adverse events. Accordingly, recent studies of oral step-down antibiotic treatment have stimulated a reevaluation of the need for intravenous-only therapy for IE.

OBSERVATIONS

PubMed was reviewed in October 2019, with an update in February 2020, to determine whether evidence supports the notion that oral step-down antibiotic therapy for IE is associated with inferior outcomes compared with intravenous-only therapy. The search identified 21 observational studies evaluating the effectiveness of oral antibiotics for treating IE, typically after an initial course of intravenous therapy; none found such oral step-down therapy to be inferior to intravenous-only therapy. Multiple studies described an improved clinical cure rate and an improved mortality rate among patients treated with oral step-down vs intravenous-only antibiotic therapy. Three randomized clinical trials also demonstrated that oral step-down antibiotic therapy is at least as effective as intravenous-only therapy in right-sided, left-sided, or prosthetic valve IE. In the largest trial, at 3.5 years of follow-up, patients randomized to receive oral step-down antibiotic therapy had a significantly improved cure rate and mortality rate compared with those who received intravenous-only therapy.

CONCLUSIONS AND RELEVANCE

This review found ample data demonstrating the therapeutic effectiveness of oral step-down vs intravenous-only antibiotic therapy for IE, and no contrary data were identified. The use of highly orally bioavailable antibiotics as step-down therapy for IE, after clearing bacteremia and achieving clinical stability with intravenous regimens, should be incorporated into clinical practice.

Cefpodoxime proxetil as a therapeutic option in switching therapy for infective endocarditis in children: case reports and literature review

Infective endocarditis (IE) is uncommon in children, affecting predominantly subjects with congenital heart disease (CHD) and patients with indwelling central lines. The principles of antibiotic treatment in paediatric population are similar to those in adults. Prolonged intravenous administration of bactericidal rather than bacteriostatic agents is preferred. Outpatient intravenous therapy after initial treatment in the hospital may be considered only in selected patients. Partial oral treatment has been described in cases of left-sided, uncomplicated IE caused by common pathogens in adult patients. There are no guidelines or trials in paediatric population regarding switching therapy from intravenous to oral route. We present two cases of IE in children caused by uncommon pathogenic bacteria (Abiotrophia defectiva and Haemophilus parainfluenzae) successfully treated with oral third-generation cephalosporin - cefpodoxime proxetil after initial intravenous therapy. This paper provides observations on different therapeutic approach for IE in children as well as another potential use of cefpodoxime proxetil.

Antibiotic duration and timing of the switch from intravenous to oral route for bacterial infections in children: systematic review and guidelines

Few studies are available to inform duration of intravenous antibiotics for children and when it is safe and appropriate to switch to oral antibiotics. We have systematically reviewed antibiotic duration and timing of intravenous to oral switch for 36 paediatric infectious diseases and developed evidence-graded recommendations on the basis of the review, guidelines, and expert consensus. We searched databases and obtained information from references identified and relevant guidelines. All eligible studies were assessed for quality. 4090 articles were identified and 170 studies were included. Evidence relating antibiotic duration to outcomes in children for some infections was supported by meta-analyses or randomised controlled trials; in other infections data were from retrospective series only. Criteria for intravenous to oral switch commonly included defervescence and clinical improvement with or without improvement in laboratory markers. Evidence suggests that intravenous to oral switch can occur earlier than previously recommended for some infections. We have synthesised recommendations for antibiotic duration and intravenous to oral switch to support clinical decision making and prospective research.

Oral antibiotic therapy for the treatment of infective endocarditis: a systematic review

Background

The role of oral antibiotic therapy in treating infective endocarditis (IE) is not well established.

Methods

We searched MEDLINE, EMBASE and Scopus for studies in which oral antibiotic therapy was used for the treatment of IE.

Results

Seven observational studies evaluating the use oral beta-lactams (five), oral ciprofloxacin in combination with rifampin (one), and linezolid (one) for the treatment of IE caused by susceptible bacteria reported cure rates between 77% and 100%. Two other observational studies using aureomycin or sulfonamide, however, had failure rates >75%. One clinical trial comparing oral amoxicillin versus intravenous ceftriaxone for streptococcal IE reported 100% cure in both arms but its reporting had serious methodological limitations. One small clinical trial (n = 85) comparing oral ciprofloxacin and rifampin versus conventional intravenous antibiotic therapy for uncomplicated right-sided S. aureus IE in intravenous drug users (IVDUs) reported cure rates of 89% and 90% in each arm, respectively (P =0.9); however, drug toxicities were more common in the latter group (62% versus 3%; P <0.01). Major limitations of this trial were lack of allocation concealment and blinding at the delivery of the study drug(s) and assessment of outcomes.

Conclusion

Reported cure rates for IE treated with oral antibiotic regimens vary widely. The use of oral ciprofloxacin in combination with rifampin for uncomplicated right-sided S. aureus IE in IVDUs is supported by one small clinical trial of relatively good quality and could be considered when conventional IV antibiotic therapy is not possible.

Oral antibiotic therapy in infective endocarditis

The mortality of IE remains fairly high despite the aggressive use of intravenous antibiotics. Oral treatment of IE is an intriguing concept with many potential advantages over conventional intravenous therapy. Unfortunately, there are insufficient data to justify predominantly oral regimens for the treatment of IE. Trials have shown that oral therapy may have a role in follow-up to short courses of parenteral antibiotics, but these trials are limited by the small number of patients studied. It is important to note that most data for oral treatment of IE have been obtained from studies in patients with histories of IVDA and right-sided S. aureus endocarditis. As mentioned previously, the course of IE in this patient population tends to be less severe, which makes extrapolation of these data to the general population difficult. A need exist for the development of oral antimicrobials with the properties previously mentioned, making them appropriate for use in IE. Currently available oral agents require further study before general recommendations regarding their use in patients with IE can be made. Although successful oral treatment of prosthetic valve endocarditis has been reported, such patients in general should not be considered as appropriate candidates for oral therapy. For now, oral antimicrobial therapy may be appropriate only as follow-up to short-course intravenous therapy, or use in combination with intravenous therapy for IE in select populations whose disease course is less severe or in whom prolonged intravenous therapy is impractical (i.e., intravenous drug users).

Improving survival in bacterial endocarditis

Twenty six cases of bacterial endocarditis in infancy and childhood were treated with a mortality of less than 8%. Twenty two had recognised congenital heart disease and four had previously normal hearts. Thirteen out of the 24 cases with positive blood cultures had staphylococcal infection. Appropriate antibiotics were identified by measurement of the minimum bactericidal concentration as an indicator of antibiotic sensitivity. The bactericidal activity of the patient's serum during treatment was monitored by back titration against the causative organism to assess the optimal antibiotic combination and dosage. Treatment was continued for six weeks in most cases, comprising intravenous treatment for at least the first three weeks, but then being substituted with oral treatment in some. Twenty one cases were successfully treated medically. Five developed complications requiring surgery, two of whom died.

Anti-infective therapy of infectious endocarditis

Because of its high morbidity and mortality, endocarditis will remain an important pediatric problem. Obtaining adequate culture information prior to starting antibiotics to ensure an accurate early diagnosis coupled with aggressive medical and surgical management is likely to give the best outcome. These patients are generally best handled by a team approach with the child's primary physician, cardiologist, infectious disease consultant, and cardiovascular surgeon working in close harmony.

Infective endocarditis in thirteen children: a retrospective study (1974-1981)

Thirteen children (11 African, two Indian) with infective endocarditis are described. Rheumatic heart disease was present in nine of the children and was therefore a major determinant of infective endocarditis whereas a congenital cardiac abnormality (Fallot's tetralogy) was detected in only one child. Staphylococcus aureus was the commonest infecting organism, being found in five children, and Streptococcus viridans was isolated in one. Fever, murmurs and anaemia were the most frequent clinical expression of the disease. Renal problems were trivial except in two children with endocarditis due to Staphylococcus aureus in whom they were serious. Staphylococcus aureus endocarditis was uniformly fatal. Among eight children who died neurological complications caused death in four. The patterns of infective endocarditis in developed and Third-World countries are compared.