Infective endocarditis: diagnosis, antimicrobial therapy, and management of complications: a statement for healthcare professionals from the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease in the Young, and the Councils on Clinical Cardiology, Stroke, and Cardiovascular Surgery and Anesthesia, American Heart Association: endorsed by the Infectious Diseases Society of America

Infective endocarditis with negative blood cultures

Culture-negative endocarditis is important as it has a relatively poor prognosis. The principal reason for negative cultures is prior antibiotic therapy although fastidious organisms such as Bartonella spp. and Coxiella burnetii are also important. PCR may offer significant advantages in diagnosis but tests require standardisation. Modification of current diagnostic criteria is required. Empirical cover of MRSA needs to be considered.

Modern epidemiology, prophylaxis, and diagnosis and therapy for infective endocarditis

Infective endocarditis (IE) is a rare disease. Although its incidence and bacteriology have remained relatively stable in outpatient populations without injection drug use, health care-associated infections, particularly with staphylococcus, are becoming more common. Large-scale prospective clinical trials are unavailable to guide strategies for preventing IE, timing surgical intervention, and avoiding complications. We continue to rely on new data from smaller series and large observational databases to track these changes and improve care of patients. At the present time, there are several controversies regarding best practices in IE. In this review, we address the following questions: What is the future of recommendations for antibiotic prophylaxis against IE? How should we best use echocardiography in diagnosis, management and follow up of IE patients? What are the most appropriate antibiotic regimens for different patients in the face of shifting microbiology and demographics? Lastly, how should patients be selected for early surgery to avoid the complications of these infections?

Endocarditis and associated complications

Echocardiography is a most useful bedside tool to help in the diagnosis and subsequent management of patients with infective endocarditis. Transesophageal echocardiography provides complementary and often incremental information necessary in making a diagnosis, and in identifying associated intracardiac complications. This chapter will focus on the role of echocardiography in the diagnosis and management of infective endocarditis.

Recomendaciones GEIPC-SEIMC y GTEI-SEMICYUC para el tratamiento antibiótico de infecciones por cocos grampositivos en el paciente crítico

In recent years, an increment of infections caused by gram-positive cocci has been documented in nosocomial and hospital-acquired infections. In diverse countries, a rapid development of resistance to common antibiotics against gram-positive cocci has been observed. This situation is exceptional in Spain but our country might be affected in the near future. New antimicrobials active against these multi-drug resistant pathogens are nowadays available. It is essential to improve our current knowledge about pharmacokinetic properties of traditional and new antimicrobials to maximize its effectiveness and to minimize toxicity. These issues are even more important in critically ill patients because inadequate empirical therapy is associated with therapeutic failure and a poor outcome. Experts representing two scientific societies (Grupo de estudio de Infecciones en el Paciente Critico de la SEIMC and Grupo de trabajo de Enfermedades Infecciosas de la SEMICYUC) have elaborated a consensus document based on the current scientific evidence to summarize recommendations for the treatment of serious infections caused by gram-positive cocci in critically ill patients.

Tricuspid valve endocarditis with Group B Streptococcus after an elective abortion: the need for new data

Streptococcus agalactiae, commonly known as Group B streptococcus (GBS), was originally discovered as a cause of bovine mastitis. GBS colonizes the genital tract of up to 40% of women and has become a major pathogen in neonatal meningitis. GBS endocarditis is thought to be an uncommon manifestation of this infection and carries a higher mortality compared to other streptococcal pathogens. Studies have shown that endocarditis after abortion has an incidence of about one per million. However, this figure was published prior to routine use of echocardiography for diagnosis. The American Heart Association has recently declared transesophageal echocardiography the gold standard for endocarditis diagnosis. This case report illustrates that, given the potentially devastating consequences of endocarditis, there is a need for updated studies to adequately assess the true incidence of this infection. Pending the outcome of these studies, routine GBS screening and prophylactic antibiotics prior to abortion should be recommended.

Principles of Antimicrobial Use in Older Adults

The fundamental principles of treating infectious diseases apply to elderly patients, but certain aspects of therapy such as the selection of empiric regimens and risk stratification for severe or atypical disease are influenced by comorbidities, lifestyle, and immunosenescence. Knowledge of age-related changes in pharmacokinetic parameters and potential drug-drug interactions assists the clinician in determining appropriate dosing and monitoring parameters. Based on current evidence, the recommended approach includes careful selection and aggressive dosing of initial broad-spectrum antimicrobials followed by de-escalation to appropriate agents to maximize clinical outcomes and minimize toxicity and adverse effects. Greater enrollment of the elderly in therapeutic studies is needed to detect differences in the efficacy and safety of antimicrobials.

Gene Therapy to Inhibit the Calcium Channel β Subunit

Calcium cycling figures prominently in excitation-contraction coupling and in various signaling cascades involved in the development of left ventricular hypertrophy. We hypothesized that genetic suppression of the L-type calcium channel accessory beta-subunit would modulate calcium current and suppress cardiac hypertrophy. A short hairpin RNA template sequence capable of mediating the knockdown of the L-type calcium channel accessory beta-subunit gene was incorporated into a lentiviral vector (PPT.CG.H1.beta(2)). Transduction of ventricular myocytes in vivo with the active short hairpin RNA partially inhibited the L-type calcium current. In neonatal rat cardiomyocytes, L-type calcium channel accessory beta-subunit gene knockdown reduced calcium transient amplitude. Similarly, [(3)H]leucine incorporation was attenuated in PPT.CG.H1.beta(2)-transduced neonatal rat cardiomyocytes compared with nonsilencing controls in a phenylephrine-induced hypertrophy model. In vivo gene transfer attenuated the hypertrophic response in an aortic-banded rat model of left ventricular hypertrophy, with reduced left ventricular wall thickness and heart weight/body weight ratios in PPT.CG.H1.beta(2)-injected rats at four weeks post transduction. Fractional shortening was preserved in rats treated with PPT.CG.H1.beta(2). These findings indicate that knockdown of L-type calcium channel accessory beta-subunit is capable of attenuating the hypertrophic response both in vitro and in vivo without compromising systolic performance. Suppression of the calcium channel beta subunit may represent a novel and useful therapeutic strategy for left ventricular hypertrophy.

Surgery for infective endocarditis

Infective endocarditis (IE) is estimated to have an incidence of five to seven cases per 100,000 person-years. Although not a common clinical entity, IE is associated with substantial morbidity and risk of mortality. IE, especially infections due to Staphylococcus aureus, are increasingly healthcare-associated infections. Despite significant advances in diagnosis and management, mortality from IE has changed little since the availability of penicillin; however, this lack of improvement in mortality is likely due to an increasing number of infections from more virulent and drug-resistant pathogens coupled with infections that occur in patients with other comorbidities and those associated with prosthetic valves. Surgery is an important part of therapy for many patients, but surprisingly, little evidence is available to help clinicians determine which patients will benefit most from surgical therapy for the management of IE.

Pulmonary and cardiac infections in athletes

Pulmonary and cardiac infections in the athlete can have a wide range of presentations and complications. These infections may present few problems for the training athlete or become life threatening. The team physician must be able to make an accurate diagnosis, give the appropriate treatment, understand the potential complications, and ensure proper follow-up and return-to-play protocols.

Efficacy of telavancin in the treatment of experimental endocarditis due to glycopeptide-intermediate Staphylococcus aureus

The efficacy of telavancin, a novel lipoglycopeptide, was evaluated in experimental endocarditis in rabbits using two clinical isolates of glycopeptide-intermediate Staphylococcus aureus: ATCC 700788 and HIP 5836. Infected rabbits were treated for 2 days with telavancin (10 mg/kg of body weight once daily intravenously) or vancomycin (1 g twice daily intravenously), administered with a computer-controlled infusion pump system simulating human serum kinetics. Vegetations were harvested at 16 h postinoculation in the control group and at the end of treatment in the drug-treated group. For ATCC 700788, MICs and minimal bactericidal concentrations (MBCs), respectively, were 1 mg/liter and 4 mg/liter for telavancin and 8 mg/liter and 128 mg/liter for vancomycin. For HIP 5836, MICs and MBCs, respectively, were 4 mg/liter and 8 mg/liter for telavancin and 8 mg/liter and 128 mg/liter for vancomycin. Peak and trough levels were 90 microg/ml and 6 microg/ml, respectively, for telavancin and 46 microg/ml and 6 microg/ml, respectively, for vancomycin. In glycopeptide-intermediate S. aureus ATCC 700788, telavancin sterilized 6 of 16 vegetations (37%), whereas vancomycin sterilized 4 of 20 (20%) (P = 0.29) compared with 0 of 17 in the control group. In HIP 5836 experiments, telavancin and vancomycin sterilized 5 of 16 (31%) and 1 of 15 (7%) vegetations (P = 0.17), respectively, compared with none in the control group. Telavancin reduced vegetation titers by 2.0 and 2.3 logs greater than vancomycin for the ATCC 700788 (4.6 [2.0 to 5.8] versus 6.6 [2.0 to 6.9] log CFU/g vegetation; P = 0.05) and HIP 5836 (4.4 [2.0 to 7.4] versus 6.7 [4.5 to 8.7] log CFU/g vegetation; P = 0.09) strains, respectively; these differences did not reach statistical significance. All isolates from vegetations remained susceptible to telavancin after therapy. The results suggest that telavancin may be an effective treatment for endocarditis caused by glycopeptide-intermediate S. aureus.

Infective Endocarditis Due to Penicillin-Resistant Viridans Group Streptococci

BACKGROUND

The emergence of viridans group streptococci that are relatively or fully resistant to penicillin is increasingly being recognized worldwide, but only a scant number of penicillin-resistant isolates have been described as a cause of infective endocarditis. Because of the paucity of data, it has been difficult to define optimal treatment regimens for this syndrome. Thus, recommendations for therapy have largely been made on the basis of consensus opinion.

METHODS

We retrospectively identified a cohort of patients with infective endocarditis due to penicillin-resistant viridans group streptococci who were seen at the Mayo Clinic (Rochester, MN) between January 1967 and April 2006. Demographic characteristics, clinical features, treatment regimens, and outcomes were analyzed. Mean values are shown with standard deviations.

RESULTS

Twenty-nine patients were identified over the 38.5-year study period. Nineteen patients with native valve endocarditis were cured; 9 of these 19 patients received a 2.3+/-0.4-week antibiotic regimen consisting of penicillin and an aminoglycoside, and 8 of these 19 patients received treatment courses of 5.1+/-1.4 weeks' duration that consisted of either a bimodal combination regimen with a penicillin or ceftriaxone and an aminoglycoside or ceftriaxone monotherapy. Nine of 10 patients with prosthetic valve infection were cured with 4.1+/-0.6-week regimens that consisted of either a combination regimen or monotherapy with vancomycin or ceftriaxone. Mean duration of follow-up after hospital discharge was 9.1 years.

CONCLUSIONS

Outcomes of this relatively large population of patients with endocarditis with a prolonged duration of follow-up indicate that the application of current treatment guidelines should be successful in most patients.

Dexamethasone as adjuvant therapy to moxifloxacin attenuates valve destruction in experimental aortic valve endocarditis due to Staphylococcus aureus

Although the beneficial effects of dexamethasone have frequently been investigated in various serious-infection settings, insufficient data on valve histology and cardiac function for infective endocarditis are available. The efficacy of moxifloxacin for the treatment of experimental aortic valve endocarditis due to methicillin-susceptible Staphylococcus aureus and the long-term effects of dexamethasone were evaluated in the current study. Sixty-eight rabbits were randomly assigned to four groups: A, B, C, and D. Group A consisted of 18 animals and functioned as a control group. Groups B and C consisted of 11 and 23 subjects, respectively, which received moxifloxacin for 5 days in a human-like pharmacokinetic simulation. Group D consisted of 16 animals that were administered moxifloxacin plus dexamethasone (0.25 mg/kg of body weight twice a day intravenously). The group B animals were sacrificed a day after the completion of treatment, and group C and D animals were sacrificed after 12 days in order to monitor any possible relapse and allow microbiological, histopathological, and echocardiographic evaluation of the long-term effects of glucocorticoids. No differences in survival, sterilization rates, or inflammatory infiltration and calcification of valve tissue were observed among the treated groups. However, the degrees of valve damage and collagenization were significantly worse, the fibroblast content was higher, and fractional shortening of the left ventricle fluctuated significantly in group C compared to group D (all groups, P < 0.05). We concluded that dexamethasone treatment for experimental S. aureus endocarditis attenuates valve destruction and preserves overall cardiac function without impeding the efficacy of moxifloxacin.

Epidemiology and clinical outcomes of infective endocarditis in hemodialysis patients

BACKGROUND

Infective endocarditis is one of the most serious complications of bacteremia in patients undergoing chronic hemodialysis and is more frequent than previously recognized. The aim of our study was to describe the clinical characteristics, outcome, and factors predicting mortality of infective endocarditis in hemodialysis patients.

METHODS

In this retrospective review, all patients on chronic hemodialysis admitted to a 600-bed urban teaching hospital with infective endocarditis over a 15-year period (1990 to 2004), were identified using discharge codes. Modified Duke criteria were retrospectively applied, and patients fulfilling the criteria for definite endocarditis were included in the study.

RESULTS

Sixty-nine patients on hemodialysis with definite endocarditis were identified. The predominant type of vascular access was double-lumen catheter (66.7%). The mean duration of dialysis was 37 +/- 32 months. The predominant organism was Staphylococcus aureus (57.9%), of which 57.5% were methicillin susceptible. The most frequently infected valve was mitral (49.3%), followed by aortic (21.7%) and tricuspid (10.1%) valves. The cardiac and neurologic complication rates were 40.6% and 37.7%, respectively. Fifteen patients underwent valvular heart surgery. The overall in-hospital mortality was 49.3% (34 of 69). More patients who had surgery survived than patients who did not (12 of 15 versus 23 of 54; p = 0.018, odds ratio = 5.39, 95% confidence interval: 1.3 to 17.6). On logistic regression, valve surgery was the only independent factor predicting survival (p = 0.023).

CONCLUSIONS

The prognosis of infective endocarditis in hemodialysis patients is poor, with surgery serving as an independent predictor of survival.

Gene Transfer of Connexin43 Mutants Attenuates Coupling in Cardiomyocytes

Modification of electrical conduction would be a useful principle to recruit in preventing or treating certain arrhythmias, notably ventricular tachycardia (VT). Here we pursue a novel gene transfer approach to modulate electrical conduction by reducing gap junctional intercellular communication (GJIC) and hence potentially modify the arrhythmia substrate. The ultimate goal is to develop a nondestructive approach to uncouple zones of slow conduction by focal gene transfer. Lentiviral vectors encoding connexin43 (Cx43) internal loop mutants were produced and studied in vitro. Transduction of neonatal rat ventricular myocytes (NRVMs) revealed the expected subcellular localization of the mutant gene product. Fluorescent dye transfer studies showed a significant reduction of GJIC in NRVMs that had been genetically modified. Additionally, adjacent mutant gene-modified NRVMs displayed delayed calcium transients, indicative of electrical uncoupling. Multi-site optical mapping of action potential (AP) propagation in gene-modified NRVM monolayers revealed a 3-fold slowing of conduction velocity (CV) relative to nontransduced NRVMs. In conclusion, lentiviral vector–mediated gene transfer of Cx43 mutants reduced GJIC in NRVMs. Electrical charge transfer was also reduced as evidenced by delayed calcium transients in adjacent NRVMs and reduced CV in NRVM monolayers. These data validate a molecular tool that opens the prospect for gene transfer targeting gap junctions as an approach to modulate cardiac conduction.

[Guidelines for the diagnosis and treatment of patients with bacteriemia. Guidelines of the Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica]

Bacteremia is a complex clinical syndrome in constant transformation that is an important, growing cause of morbidity and mortality. Even though there is a great deal of specific information about bacteremia, few comprehensive reviews integrate this information with a practical AIM. The main objective of these Guidelines, which target hospital physicians, is to improve the clinical care provided to patients with bacteremia by integrating blood culture results with clinical data, and optimizing the use of diagnostic procedures and antimicrobial testing. The document is structured into sections that cover the epidemiology and etiology of bacteremia, stratified according to the various patient populations, and the diagnostic work-up, therapy, and follow-up of patients with bacteremia. Diagnostic and therapeutic decisions are presented as recommendations based on the grade of available scientific evidence.

Vascular and Parameningeal Infections of the Head and Neck

Vascular and parameningeal infections of the head and neck are rare but frequently life threatening. These infections include intracranial and extracranial septic venous thrombophlebitis, arterial mycotic aneurysms and erosions, subdural empyema, and epidural abscesses. They usually arise as complications of otogenic, oropharyngeal, or paranasal sinus infections, and management involves an aggressive combined medical-surgical approach.

Managing the infected heart

Most infective processes are straightforward and can be diagnosed from bacterial findings in a single test. IE does not always follow this tenet, so establishing the diagnosis can be difficult. The salient features of IE may present atypically or be obscured by the presence of preexisting and coexisting diseases. Flulike symptoms may mask the beginning of this devastating disease. Early diagnosis of IE is important because of its high risk of morbidity and mortality. Management of the patient who has IE is complex and requires interventions by infectious disease specialists, cardiologists, respiratory therapists, and critical care nurses to address the many multifaceted complications. Early evaluation, diagnostic validation, multidisciplinary management, prompt pharmaceutical initiation, and intense critical care nursing intervention are necessary to reduce the probability of long-standing complications and to improve patient outcomes.

Estudio comparativo de pacientes con bacteriemia por Staphylococcus aureus sensible a la meticilina frente a S. aureus resistente a la meticilina: epidemiología y factores pronósticos

BACKGROUND AND OBJECTIVE

The influence of methicillin resistance in Staphylococcus aureus bacteremia (SAB) continues to be controversial. The aim of this study was to evaluate risk factors and mortality predictors in patients with SAB and the influence of methicillin resistance in mortality (SAMSB vs SAMRB).

PATIENTS AND METHOD

Prospective study including 213 in-patients with SAB.

RESULTS

Of 213 episodes of SAB, 131 (61.5%) were due to SAMS and 82 (38.5%) to SAMR. Risk factors associated with SAMRB were: nosocomial infection, presence of an ultimately or rapidly fatal underlying disease, diabetes mellitus, intravenous catheters, previous ICU hospitalization and therapy with broad-spectrum antibiotics. Severity and complications were more frequent in patients with SAMRB. Mortality was 42.6% in SAMRB cases vs 16% in SAMSB cases (p < 0.05). Multivariate analysis showed as independent predictors of mortality in patients with SAB: presence of an ultimately or rapidly fatal underlying disease, acute severity of illness at onset and inappropriate empirical therapy; methicillin resistance was not an independent predictor of mortality.

CONCLUSIONS

Methicillin resistance was not an independent predictor of mortality in patients with SAB. Presence of a fatal underlying disease, acute severity of illness at onset and inappropriate therapy were the main prognosis factors in patients with SAB.

Impact of Prior Antiplatelet Therapy on Risk of Embolism in Infective Endocarditis

BACKGROUND

Embolism is a dreaded complication of infective endocarditis (IE). Currently, antimicrobial therapy is the only medical intervention proven to decrease the risk of embolism associated with IE. We hypothesized that, because platelet aggregation is operative in the pathogenesis of vegetation formation, embolism associated with IE should occur less frequently among patients who have received prior, continuous daily antiplatelet therapy for noninfectious reasons.

METHODS

We studied a retrospective cohort of adult patients with a diagnosis of IE who presented to the Mayo Clinic (Rochester, MN) during 1980-1998. The cohort was divided into 2 groups on the basis of whether they had received continuous daily antiplatelet therapy for at least 6 months prior to the time of hospitalization for IE. Antiplatelet therapy included aspirin, dipyridamole, clopidogrel, ticlopidine, or any of combination of these agents. The primary end point was a symptomatic embolic event that occurred prior to or during hospitalization. Multivariable logistic regression was used to assess the impact of continuous daily antiplatelet therapy on risk of symptomatic emboli associated with IE.

RESULTS

One hundred forty-seven (24.5%) of 600 patients experienced a symptomatic embolic event; the most common embolic manifestation was stroke (in 48.2% of patients). Embolic events occurred significantly less often among those who had received prior, continuous daily antiplatelet therapy (12.0% of patients who had received therapy vs. 27.8% patients who had not receive therapy; P<.001). After adjustment for several covariates known to influence both risk of embolism and propensity for antiplatelet use, the adjusted odds ratio for a symptomatic embolic event was 0.36 (95% confidence interval, 0.19-0.68; P=.002) for patients receiving continuous daily antiplatelet therapy.

CONCLUSIONS

The risk of symptomatic emboli associated with IE was reduced in patients who received continuous daily antiplatelet therapy before onset of IE.

Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group

BACKGROUND

The purpose of this statement is to update the recommendations by the American Heart Association (AHA) for the prevention of infective endocarditis that were last published in 1997.

METHODS AND RESULTS

A writing group was appointed by the AHA for their expertise in prevention and treatment of infective endocarditis, with liaison members representing the American Dental Association, the Infectious Diseases Society of America, and the American Academy of Pediatrics. The writing group reviewed input from national and international experts on infective endocarditis. The recommendations in this document reflect analyses of relevant literature regarding procedure-related bacteremia and infective endocarditis, in vitro susceptibility data of the most common microorganisms that cause infective endocarditis, results of prophylactic studies in animal models of experimental endocarditis, and retrospective and prospective studies of prevention of infective endocarditis. MEDLINE database searches from 1950 to 2006 were done for English-language papers using the following search terms: endocarditis, infective endocarditis, prophylaxis, prevention, antibiotic, antimicrobial, pathogens, organisms, dental, gastrointestinal, genitourinary, streptococcus, enterococcus, staphylococcus, respiratory, dental surgery, pathogenesis, vaccine, immunization, and bacteremia. The reference lists of the identified papers were also searched. We also searched the AHA online library. The American College of Cardiology/AHA classification of recommendations and levels of evidence for practice guidelines were used. The paper was subsequently reviewed by outside experts not affiliated with the writing group and by the AHA Science Advisory and Coordinating Committee.

CONCLUSIONS

The major changes in the updated recommendations include the following: (1) The Committee concluded that only an extremely small number of cases of infective endocarditis might be prevented by antibiotic prophylaxis for dental procedures even if such prophylactic therapy were 100% effective. (2) Infective endocarditis prophylaxis for dental procedures is reasonable only for patients with underlying cardiac conditions associated with the highest risk of adverse outcome from infective endocarditis. (3) For patients with these underlying cardiac conditions, prophylaxis is reasonable for all dental procedures that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa. (4) Prophylaxis is not recommended based solely on an increased lifetime risk of acquisition of infective endocarditis. (5) Administration of antibiotics solely to prevent endocarditis is not recommended for patients who undergo a genitourinary or gastrointestinal tract procedure. These changes are intended to define more clearly when infective endocarditis prophylaxis is or is not recommended and to provide more uniform and consistent global recommendations.

Bacteriemias por Staphylococcus aureus sensible a meticilina: epidemiología y factores pronósticos. Estudio prospectivo 2000-2003

BACKGROUND

Staphylococcus aureus bacteremia continues to be a major problem in hospitals due to its high prevalence, severity and treatment difficulties. This study aimed to evaluate epidemiological and clinical features, risk factors and influence of antibiotic choice in outcome and mortality in patients with methicillin susceptible S. aureus bacteremia (SAMSB).

PATIENTS AND METHODS

A prospective, observational study of inpatients with SAMSB (2000-3).

RESULTS

A total of 131 with SAMSB were included (mean age 56 years; 58% > or = 60 year-old); 56.5% were due to nosocomial bacteremia; 46% of all patients had an underlying condition (diabetes mellitus being the most frequent [28%]); a risk factor for bacteraemia was identified in 98% (intravenous catheter: 72%). Mortality rate was 16% (21/131). Comparative analysis according to nosocomial or community acquisition showed that the former was more frequent in Surgical Wards, patients with intravenous or urinary catheters, traumatic patients, dialysis and ICU patients. Initial severity and mortality were highest in community-acquired SAMSB. In multivariate analysis, risk factors associated with higher mortality were: presence of an ultimately or rapidly fatal underlying disease, acute severity of illness at onset and inadequate empirical treatment.

CONCLUSIONS

SAMSB is a clinically severe infection that occurs in patients with baseline disease, especially diabetics, that is almost always related to predisposing risk factors (mainly intravenous catheters). In the presence of a serious baseline disease, the initial critical clinical condition and inadequate empirical treatment are the main prognostic factors associated to greater mortality.

Emerging Options for Treatment of Invasive, Multidrug-ResistantStaphylococcus aureusInfections

Limited established treatment options exist for the treatment of serious, invasive infections caused by multidrug-resistant Staphylococcus aureus, most notably nosocomially acquired methicillin-resistant S. aureus (MRSA). Although vancomycin represents the gold standard for therapy of such invasive infections, reports of increasing in vitro resistance to vancomycin, combined with reports of clinical failures (with this and other antistaphylococcal agents), underscore the need for alternative therapies. Older agents with favorable in vitro activity available in both oral and intravenous dose forms include trimethoprim-sulfamethoxazole and clindamycin. Limited clinical data exist to support their routine use as initial therapy in the treatment of invasive disease. However, these and other options (e.g., tetracyclines) are being reexplored in the setting of increasing concern over MRSA acquired in the community setting. Newer treatment options for MRSA include linezolid, quinupristin-dalfopristin, daptomycin, and tigecycline. With the exception of linezolid, these newer agents require intravenous administration. Combination therapy may be considered in select invasive diseases refractory to standard monotherapies. These diseases include infections such as endocarditis, meningitis, and prosthetic device infections. Additional alternatives to vancomycin are under clinical investigation. Those in later stages of development include oritavancin, dalbavancin, telavancin, and ceftobiprole.

The bactericidal effects of anti-MRSA agents with rifampicin and sulfamethoxazole-trimethoprim against intracellular phagocytized MRSA

We experienced therapeutic failure with vancomycin in patients with serious methicillin-resistant Staphylococcus aureus (MRSA) infections, in some of whom the bacteria were found to be alive in the leukocytes. We therefore evaluated the antimicrobial activity of several anti-MRSA agents (vancomycin, linezolid, quinupristin/dalfopristin, arbekacin) and co-administered agents (rifampicin, sulfamethoxazole-trimethoprim) against clinically isolated MRSA in phagocytized human polymorphonuclear leukocytes. After allowing the leukocytes to phagocytize the bacteria, the mixture was separated into leukocytes and supernatant, to which MRSA agents were added, and incubated for 24 h. After incubation, the leukocytes were crushed and the intracellular MRSA was cultured quantitatively. Vancomycin resulted in a less than 1% survival ratio of extracellular MRSA, but it was one of the highest ratios of intracellular MRSA with 33.8% compared with other agents. The survival ratios of intracellular MRSA with vancomycin plus rifampicin and with vancomycin plus rifampicin plus sulfamethoxazole-trimethoprim were 0.78% and 1.02%, respectively, which is significantly lower than that of vancomycin. For linezolid, quinupristin/dalfopristin, and arbekacin, there were no significant differences in the survival ratios between monotherapy and combination therapy against either extracellular or intracellular MRSA. The results suggest that the concomitant use of rifampicin or rifampicin plus sulfamethoxazole/trimethoprim with vancomycin is effective for MRSA phagocytized in leukocytes when vancomycin monotherapy is not sufficiently effective. Combination therapy showed no difference in efficacy in the case of linezolid, quinupristin/dalfopristin, and arbekacin.

Case report: infective endocarditis caused by Brevundimonas vesicularis

Background

There are few reports in the literature of invasive infection caused by Brevundimonas vesicularis in patients without immunosuppression or other predisposing factors. The choice of antimicrobial therapy for bacteremia caused by the pathogen requires more case experience to be determined.

Case presentation

The case of a 40-year-old previously healthy man with subacute endocarditis proposed to be contributed from an occult dental abscess is described. The infection was found to be caused by B. vesicularis on blood culture results. The patient recovered without sequelae after treatment with ceftriaxone followed by subsequent ciprofloxacin therapy owing to an allergic reaction to ceftriaxone and treatment failure with ampicillin/sulbactam.

Conclusion

To our knowledge, this is the first report of B. vesicularis as a cause of infective endocarditis. According to an overview of the literature and our experience, we suggest that third-generation cephalosporins, piperacillin/tazobactam, and ciprofloxacin are effective in treating invasive B. vesicularis infections, while the efficacy of ampicillin-sulbactam needs further evaluation.

Comparison of BACTEC PLUS blood culture media to BacT/Alert FA blood culture media for detection of bacterial pathogens in samples containing therapeutic levels of antibiotics

Blood culture bottles with antimicrobial removal systems are recommended for patients who develop fever while on antibiotics. This study compared the ability of Becton Dickinson (Sparks, MD) BACTEC PLUS bottles and bioMerieux (Durham, NC) BacT/Alert FA bottles to effectively remove vancomycin, cefoxitin, ceftriaxone, cefepime, piperacillin-tazobactam, ampicillin, oxacillin, gentamicin, and a combination of gentamicin/penicillin, thus allowing bacterial pathogens to grow. Each bottle was spiked with 10 ml of human blood, antibiotic, and strains of organisms susceptible to the antibiotic evaluated. The organisms used were type strains and clinical isolates of Staphylococcus aureus (methicillin susceptible and resistant), Streptococcus pneumoniae, a viridans streptococcus, Enterococcus faecalis, Enterococcus faecium, Streptococcus agalactiae, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Testing was completed in triplicate, using 10 to 100 CFU/ml of organisms with various concentrations of each antibiotic. Two rounds of testing were completed per antibiotic/organism combination. Bottles were mixed and loaded onto their respective instruments as per the manufacturer's instructions. Antimicrobial removal was evaluated on the basis of time to detection of organism growth, for up to 5 days of incubation. Overall, the BacT/Alert FA system recovered 25.1% of strains from test bottles and 96.9% of strains from growth control bottles (no antibiotic added), and the BACTEC PLUS system recovered 95.1% of strains from test bottles and 100% of strains from growth control bottles. Both systems performed well in the detection of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa in the presence of gentamicin. In the presence of ceftriaxone, neither system was able to recover Streptococcus pneumoniae. The ability to remove vancomycin and cefoxitin was also determined by measuring antibiotic levels remaining in bottles after 1 h of incubation. The results demonstrated remaining levels of 72 to 90% of vancomycin and 71 to 72% of cefoxitin in the BacT/Alert system. For the BACTEC system, remaining levels were 0 to 30% of vancomycin and 0% of cefoxitin. Under these simulated conditions, the BACTEC PLUS system was superior to the BacT/Alert FA system in recovering gram-positive and gram-negative bacterial pathogens in the presence of beta-lactam antibiotics, gentamicin/penicillin, and vancomycin.

Cardiobacterium hominis endocarditis: Two cases and a review of the literature

Cardiobacterium hominis, a member of the HACEK group (Haemophilus parainfluenzae, Haemophilus aphrophilus, and Haemophilus paraphrophilus, Actinobacillus actinomycetemcomitans, C. hominis, Eikenella corrodens, and Kingella species), is a rare cause of endocarditis. There are 61 reported cases of C. hominis infective endocarditis in the English-language literature, 15 of which involved prosthetic valve endocarditis. There is one reported case of C. hominis after upper endoscopy and none reported after colonoscopy. Presented here are two cases of C. hominis prosthetic valve endocarditis following colonoscopy and a review of the microbiological and clinical features of C. hominis endocarditis. Patients with C. hominis infection have a long duration of symptoms preceding diagnosis (138+/-128 days). The most common symptoms were fever (74%), fatigue/malaise (53%), weight loss/anorexia (40%), night sweats (24%), and arthralgia/myalgia (21%). The most common risk factors were pre-existing cardiac disease (61%), the presence of a prosthetic valve (28%), and history of rheumatic fever (20%). Of the 61 cases reviewed here, the aortic valve was infected in 24 (39%) and the mitral valve in 19 (31%) patients. The average duration of blood culture incubation before growth was detected was 6.3 days (range, 2-21 days). Complications were congestive heart failure (40%), central nervous system (CNS) emboli (21%), arrhythmia (16%), and mycotic aneurysm (9%). C. hominis is almost always susceptible to beta-lactam antibiotics. Ceftriaxone is recommended by the recently published American Heart Association guidelines. The prognosis of C. hominis native valve and prosthetic valve endocarditis is favorable. The cure rate among 60 patients reviewed was 93% (56/60). For prosthetic valve endocarditis, the cure rate was 16/17 (94%). Valve replacement was required in 27 (45%) cases.

Monotherapy versus combination therapy

The science of antibiotic therapy for infectious diseases continues to evolve. In many instances where empiric coverage is necessary, treatment with more than one agent is considered prudent. If an etiology is identified, antibiotics are modified based on culture and susceptibility data. Even when the organism is known, more than one antibiotic may be needed. Decisions about antibiotics should be made after assessments of pertinent clinical information, laboratory and microbiology information, ease of administration, patient compliance, potential adverse effects, cost, and available evidence supporting various treatment options. Clinicians also need to consider synergy and local resistance patterns in selecting therapeutic options. In this article, the authors outline monotherapy and combination therapy options for several common infectious diseases.

A dangerous dilemma: management of infectious intracranial aneurysms complicating endocarditis

A 41-year-old right-handed man with bicuspid aortic valve and a 3-month history of chronic fever and weight loss presented with sudden onset of severe headache. Computerised tomography of the head revealed a right basal ganglia haemorrhage. Further investigation documented Streptococcus mitis bacteraemia, a fusiform right middle cerebral artery aneurysm, and an abscess at the base of the anterior leaflet of the mitral valve. The patient subsequently died when repeat aneurysmal haemorrhage resulted in cerebral herniation and brain death while on antibiotic therapy. Infectious intracranial aneurysms (IIAs) are uncommon but severe complications of bacterial endocarditis. Several case series have been published evaluating the management of IIAs, but no randomised controlled trials exist to guide treatment decisions. Improved diagnostic techniques, microvascular neurosurgical approaches, and endovascular therapies hold the promise of improved outcomes in the future. This difficult case is used to show an approach towards the management of IIAs complicating bacterial endocarditis based on a review of the published work.

Clinical manifestations and outcome in Staphylococcus aureus endocarditis among injection drug users and nonaddicts: a prospective study of 74 patients

BACKGROUND

Endocarditis is a common complication in Staphylococcus aureus bacteremia (SAB). We compared risk factors, clinical manifestations, and outcome in a large, prospective cohort of patients with S. aureus endocarditis in injection drug users (IDUs) and in nonaddicts.

METHODS

Four hundred and thirty consecutive adult patients with SAB were prospectively followed up for 3 months. Definite or possible endocarditis by modified Duke criteria was found in 74 patients: 20 patients were IDUs and 54 nonaddicts.

RESULTS

Endocarditis was more common in SAB among drug abusers (46%) than in nonaddicts (14%) (odds ratio [OR], 5.12; 95% confidence interval [CI], 2.65-9.91; P < 0.001). IDUs were significantly younger (27 +/- 15 vs 65 +/- 15 years, P < 0.001), had less ultimately or rapidly fatal underlying diseases (0% vs 37%, P < 0.001) or predisposing heart diseases (20% vs 50%, P = 0.03), and their SAB was more often community-acquired (95% vs 39%, P < 0.001). Right-sided endocarditis was observed in 60% of IDUs whereas 93% of nonaddicts had left-sided involvement (P < 0.001). An extracardiac deep infection was found in 85% of IDUs and in 89% of nonaddicts (P = 0.70). Arterial thromboembolic events and severe sepsis were also equally common in both groups. There was no difference in mortality between the groups at 7 days, but at 3 months it was lower among IDUs (10%) compared with nonaddicts (39%) (OR, 5.73; 95% CI, 1.20-27.25; P = 0.02).

CONCLUSION

S. aureus endocarditis in IDUs was associated with as high complication rates including extracardiac deep infections, thromboembolic events, or severe sepsis as in nonaddicts. Injection drug abuse in accordance with younger age and lack of underlying diseases were associated with lower mortality, but after adjusting by age and underlying diseases injection drug abuse was not significantly associated with mortality.

Severe infective endocarditis due to Neisseria sicca: case report and review of literature

We report a case of infective endocarditis (IE) caused by an unusual micro-organism in a previously healthy young man. Our patient presented with meningo-encephalitis and embolic signs due to IE caused by Neisseria sicca. Risk factors for IE due to Neisseria sicca, such as intravenous drug use and pre-existing heart disease were absent. The patient recovered well after mitral valve surgery and antimicrobial therapy. IE due to Neisseria spp. is associated with embolic manifestations and valve destruction. However, no deaths have been reported in patients who are treated with appropriate antimicrobial and surgical therapy.

Brucella endocarditis in prosthetic valves

Human brucellosis is a multiple organ disease that presents with fever and is most often transmitted via contaminated, unpasteurized goat milk and cheese. In chronic cases, focal complications (eg, spondylitis, neurobrucellosis and endocarditis) are frequently seen. Although the disease may be severely debilitating, the mortality rate is low. Fatal cases are often due to endocarditis. Because Brucella endocarditis is a rare complication (2% to 5%), therapeutic considerations are based on single-case experiences only. Therapy includes long-term antibiotic treatment using combinations of various antimicrobial drugs and surgical valve replacement when required. A case of Brucella endocarditis complicated by the infection of two valvular prostheses implanted after involvement of the mitral and aortic valve due to rheumatic fever is described. The patient was successfully treated by a medical and surgical approach. Therapeutic strategies in Brucella endocarditis are discussed in light of the current literature.

Options to preserve fertility before oncological treatment: cryopreservation of ovarian tissue and its clinical application

Chemotherapy and radiotherapy induce premature ovarian failure in many patients treated with these methods for oncological and benign diseases. This paper reviews the risk of developing premature ovarian failure according to the types of treatment as well as the different options to preserve fertility. We focus mainly on the cryopreservation of ovarian tissue procedure and we report here the second world-wide spontaneous pregnancy after cryopreserved ovarian tissue transplantation.