Vancomycin-resistant Enterococcus faecium endocarditis in a premature infant successfully treated with linezolid

A Case of Enterococcal Patent Ductus Arteriosus-associated Endarteritis in a Preterm Neonate

INTRODUCTION

The persistent patency of the ductus arteriosus frequently occurs in premature neonates and can cause infective endocarditis (IE) or ductal endarteritis (DE) during sepsis. Even though neonatal IE and DE are believed to be a rare eventuality, their incidence has been increasing in the last decades due to the improved survival of even more preterm babies, favored by highly invasive procedures and therapies. In parallel, antimicrobial resistance is another rising problem in neonatal intensive care units, which frequently compels to treat infections with broad-spectrum or last generation antibiotics.

CASE PRESENTATION

We report the case of a preterm neonate affected by patent ductus arteriosus-associated DE that followed an episode of sepsis caused by a high-level aminoglycoside-resistant enterococcus. The neonate was successfully treated with the synergistic combination of ampicillin and cefotaxime.

DISCUSSION

IE and patent ductus arteriosus-associated DE are rising inside neonatal intensive care units and neonatologists should be aware of these conditions. Enterococcal IE and patent ductus arteriosus-associated DE sustained by high-level aminoglycoside-resistant strains can be successfully treated with the synergistic combination of ampicillin and cefotaxime even in preterm neonates.

Therapeutic Options and Outcomes for the Treatment of Children with Gram-Positive Bacteria with Resistances of Concern: A Systematic Review

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant coagulase-negative Staphylococci (MR-CoNS), and vancomycin-resistant Enterococci (VRE) are increasing worldwide and represent a threat for the limited treatment options in pediatric patients and neonates compared to adults. Recommendations in pediatrics are mainly extrapolated from adults' studies.

METHODS

A literature search for the treatment of these pathogens in children (<18 years old) was conducted in Embase, MEDLINE, and Cochrane Library. Studies reporting data on single-patient-level outcomes related to a specific antibiotic treatment for multidrug resistant (MDR) Gram-positive bacterial infection in children were included. Studies reporting data from adults and children were included if single-pediatric-level information could be identified (PROSPERO registration: CRD42022383867).

RESULTS

The search identified 11,740 studies (since January 2000), of which 48 fulfilled both the inclusion and the exclusion criteria and were included in the analysis: 29 for MRSA, 20 for VRE, and seven for MR-CoNS. Most studies were retrospective studies. Vancomycin was mainly used as a comparator, while linezolid and daptomycin were the most studied antimicrobials showing good efficacy.

CONCLUSIONS

Linezolid showed a safety and efficacy profile in a neonatal setting; daptomycin is increasingly used for MRSA, but the evidence is scarce for VRE.

Optimizing therapy for vancomycin-resistant enterococcal bacteremia in children

PURPOSE OF REVIEW

Uncertainties exist regarding the optimal treatment for vancomycin-resistant enterococcal (VRE) bloodstream infections, particularly in settings in which ampicillin cannot be used.

RECENT FINDINGS

Quinupristin-dalfopristin, linezolid, and daptomycin, all approved between 1999 and 2003, represent the mainstays of therapy for VRE bacteremia, although only linezolid has been specifically approved by the United States Food and Drug Administration for this indication. The main objective of this review is to compare the relative efficacies, dosing strategies, and side-effect profiles of quinupristin-dalfopristin, linezolid, and daptomycin for VRE bacteremia in the pediatric population. A brief description of recently approved broad-spectrum Gram-positive agents that may have a role in the management of VRE bacteremia in upcoming years is also provided.

SUMMARY

Linezolid, despite its bacteriostatic activity against VRE, may be the most versatile of the available drugs. It has activity against both Enterococcus faecalis and E. faecium, can be administered orally, and resistance appears to be less of a concern with linezolid compared with the other agents. Additionally, the results of two recent meta-analyses demonstrate more favorable outcomes with linezolid compared with daptomycin for the treatment of VRE bacteremia. The clinical pharmacokinetics of linezolid have been well described in children. The most notable concern with linezolid, however, is toxicities associated with prolonged use. Until more prospective data are available, we favor linezolid as first-line therapy for the treatment of VRE bacteremia in children.

Enterococcal endocarditis revisited

The Enterococcus species is the third main cause of infective endocarditis (IE) worldwide, and it is gaining relevance, especially among healthcare-associated cases. Patients with enterococcal IE are older and have more comorbidities than other types of IE. Classical treatment options are limited due to the emergence of high-level aminoglycosides resistance (HLAR), vancomycin resistance and multidrug resistance in some cases. Besides, few new antimicrobial alternatives have shown real efficacy, despite some of them being recommended by major guidelines (including linezolid and daptomycin). Ampicillin plus ceftriaxone 2 g iv./12 h is a good option for Enterococcus faecalis IE caused by HLAR strains, but randomized clinical trials are essential to demonstrate its efficacy for non-HLAR EFIE and to compare it with ampicillin plus short-course gentamicin. The main mechanisms of resistance and treatment options are also reviewed for other enterococcal species.

Linezolid: A New Antibiotic for Newborns and Children?

Staphylococcus aureus remains one of the most common and troublesome microorganisms causing disease in humans, despite the development of effective antibiotics. Linezolid is a member of a new class of synthetic antibiotics called oxazolidinones, introduced into therapy due to the increasing resistance of Gram-positive pathogens to traditional antibiotics. Information about the pharmacokinetics and tolerability profile of linezolid in the pediatric population mostly derive from adult studies and especially in the neonatal field relatively few data are available. Here we summarize linezolid's characteristics and report data available in the literature regarding linezolid use in newborns and children. For this purpose, a Medline search was performed between 1990 and 2006 involving the term "linezolid" combined with the terms "newborn", "infant", "child", "pediatrics". Additional information was obtained from Reactions Weekly.

Enterococcal endocarditis: can we win the war?

Treatment of enterococcal infections has long been recognized as an important clinical challenge, particularly in the setting of infective endocarditis (IE). Furthermore, the increase prevalence of isolates exhibiting multidrug resistance (MDR) to traditional anti-enterococcal antibiotics such as ampicillin, vancomycin and aminoglycosides (high-level resistance) poses immense therapeutic dilemmas in hospitals around the world. Unlike IE caused by most isolates of Enterococcus faecalis, which still retain susceptibility to ampicillin and vancomycin, the emergence and dissemination of a hospital-associated genetic clade of multidrug resistant Enterococcus faecium, markedly limits the therapeutic options. The best treatment of IE MDR enterococcal endocarditis is unknown and the paucity of antibiotics with bactericidal activity against these organisms is a cause of serious concern. Although it appears that we are winning the war against E. faecalis, the battle rages on against isolates of multidrug-resistant E. faecium.

Clinical experience with linezolid in infants and children

The worldwide spread of multidrug-resistant organisms has required the development of new antimicrobials. Linezolid, the first oxazolidinone, has a broad spectrum of activity against Gram-positive bacteria, including resistant strains. Although approved by the Food and Drug Administration in 2002, the clinical experience with linezolid in the paediatric population is still limited, also given the fact that in most European countries the paediatric use of linezolid is off-label. In this paper we summarize the actual evidence on both licensed and off-label clinical uses of linezolid in children, including efficacy, safety and tolerability issues. Taking into account the potential bias in comparing heterogeneous clinical trials and reports, the available literature data suggest that linezolid is a safe and effective agent for the treatment of serious Gram-positive bacterial infections in neonates and children. At present, linezolid is reserved for those children who are intolerant to or fail conventional agents. A linezolid-containing regimen can be a valuable option for treating multidrug-resistant and extensively drug-resistant tuberculosis in children as well as disseminated non-tuberculous mycobacterial infections. Given the rare occurrence of serious side effects, careful monitoring of haematological parameters, possible drug interactions and neurological manifestations is recommended in linezolid-treated children, especially in case of prolonged treatments. Appropriate linezolid dosage and hospital infection control measures are essential to avoid the spread of linezolid resistance. Further studies are needed to establish novel paediatric indications for linezolid use and to assess the tolerability of long-term treatments.

Antibiotic resistance in neonatal intensive care unit pathogens: mechanisms, clinical impact, and prevention including antibiotic stewardship

Antimicrobial-resistant pathogens are of increasing concern in the neonatal intensive care unit population. A myriad of resistance mechanisms exist in microorganisms, and management can be complex because broad-spectrum antibiotics are increasingly needed. Control and prevention of antibiotic-resistant organisms (AROs) require an interdisciplinary team with continual surveillance. Judicious use of antibiotics; minimizing exposure to risk factors, when feasible; and effective hand hygiene are crucial interventions to reduce infection and transmission of AROs.

Medical treatment of endocarditis

Infective endocarditis (IE) remains a serious and deadly disease. The incidence, which varies by gender and on the presence of predisposing factors, has not decreased, due in part to the aging population with more healthcare exposures and predisposing risk factors such as prosthetic heart valves and intracardiac devices. The most important aspects of treatment in IE hinge upon early diagnosis, microorganism identification with susceptibility testing, and early initiation of appropriate antibiotic therapy. In addition, echocardiographic imaging is critical for both diagnostic and prognostic purposes. Early evaluation for surgery should be considered. Once a therapeutic strategy is begun, careful attention to the clinical course is necessary to ensure appropriate response to therapy and to identify complications early.

Clinical efficacy and tolerability of linezolid in pediatric patients: a systematic review

BACKGROUND

Linezolid is marketed for the treatment of severe, vancomycin-resistant infections with gram-positive bacteria in adults. Most information regarding the pharmacokinetic profile, efficacy, and tolerability of linezolid is derived from adult studies.

OBJECTIVE

The aim of this review was to summarize evidence regarding the use of linezolid in infants and children, focusing on the drug's clinical efficacy data and tolerability profile.

METHODS

A literature search was conducted of the Cochrane Library, EMBASE, and MEDLINE databases, from their inception through July 20, 2009, using the following terms: linezolid, newborn, infant, child, pediatrics, adolescent, human, clinical trial, and case report. Articles were excluded if they were redundant or not pertinent. (Articles that did not focus on the use of linezolid in children were considered not pertinent.) Bibliographies of all relevant articles were also evaluated.

RESULTS

Forty-seven publications regarding the use of linezolid in children were included in the review: 5 pharmacokinetic studies, 32 case reports, 6 randomized clinical trials (RCTs), 2 uncontrolled trials, 1 subanalysis of 2 published RCTs, and 1 subanalysis of published data about linezolid's tolerability. Pharmacokinetic data on linezolid use in children were derived from studies that enrolled 447 children. Plasma pharmacokinetics of linezolid in pediatric patients were found to be age dependent. Results from 6 vancomycinor cefadroxil-controlled RCTs (including 1480 children) evaluating linezolid treatment in children reported variable clinical cure rates, ranging from 75.0% to 93.2% in children with skin and skin-structure infections and from 77.5% to 90.0% in children with bacteremia or pneumonia. No significant difference in clinical cure rates between the linezolid group and the comparator group was observed in any study. The most frequently reported adverse events were diarrhea (from 3.1% to 16.8%), nausea and/or vomiting (from 2.9% to 11.9%), and thrombocytopenia (from 1.9% to 4.7%). To date, 3 cases of neuropathy have been described in children.

CONCLUSIONS

The reviewed pediatric studies in skin and skin-structure infections, bacteremia, or pneumonia found that linezolid was associated with high clinical cure rates (75.0%-93.2%) that did not differ significantly from those of vancomycin or cefadroxil. RCTs enrolling children with other types of infection (eg, osteomyelitis, endocarditis), as well as long-term studies, are needed to draw definitive conclusions about linezolid's efficacy and tolerability in pediatric patients. Careful monitoring for adverse events and possible linezolid resistance continues to be essential.

Elimination of vancomycin-resistant enterococci from a neonatal intensive care unit following an outbreak

A policy of weekly faecal cultures for vancomycin-resistant enterococci (VRE) was instituted following the investigation of an outbreak of VRE in our neonatal intensive care unit in 2005. We found that 11 of 18 patients were infected or colonised during the outbreak, including three cases of bloodstream infection and one case of meningitis. This report describes the utility of the surveillance policy in maintaining a VRE-free environment. The outbreak investigation showed that all VRE isolated were Enterococcus faecium of the vanA type. Pulsed-field gel electrophoresis suggested that the outbreak was caused by a single strain. Control of the outbreak was achieved by enhanced contact isolation precautions, cohorting of patients and staff, improved environmental decontamination and closure of the unit to new admissions. The patients with bloodstream infections and meningitis were treated successfully with linezolid. Approximately one year after the outbreak, weekly surveillance detected two patients with faecal carriage of VRE whose periods of admission overlapped. Early intensive intervention was associated with disappearance of the organism from the neonatal intensive care unit. No further cases of colonisation or disease have occurred in the unit in the two and a half years since then.

Methicillin-resistant Staphylococcus epidermidis (MRSE) endocarditis treated with linezolid

Linezolid is not yet recognized as a standard therapy for infective endocarditis but its use becomes a necessity when infection is due to multidrug-resistant microorganisms. This report describes 1 patient with endocarditis treated with linezolid and 45 similar cases from the medical literature.

Linezolid for the treatment of drug-resistant infections

Multidrug-resistant pathogens have become increasingly common in contemporary healthcare. Specific to Gram-positive pathogens, methicillin-resistant Staphylococcus aureus (MRSA) is of particular concern, as it has been associated with increased hospital length of stay, higher healthcare expenditures and poorer outcomes. To date, linezolid is the first and only oxazolidinone approved by the US FDA for the treatment of infections caused by Gram-positive pathogens, including MRSA. This article will serve as a comprehensive review of linezolid, including an overview of the current market and its in vitro activity, with an in-depth review of its pharmacokinetic and pharmacodynamic profile. Emphasis will be placed on clinical data for the drug, both on- and off-label. The article will conclude with a brief overview of linezolid's pharmacoeconomic implications and safety profile, followed by a commentary and 5-year prospective analysis remarking on the future of the antimicrobial field as it relates to MRSA.

Linezolid therapy for infective endocarditis

Linezolid is not yet recognised as a standard therapy for infective endocarditis. This report describes nine patients with endocarditis treated with linezolid and 33 similar cases from the medical literature. The majority of cases involved multiresistant strains, and the reasons for administering linezolid were refractory disease (60%), intolerance (28%), sequential therapy (12%) and a resistant pathogen (1%). Linezolid was administered for a mean of 37 days, with a successful outcome in 79% of cases. Reversible adverse effects were described in ten cases. The mean follow-up period was 8.5 months. Further data from randomised controlled clinical trials are needed to determine the efficacy and safety of linezolid for treating endocarditis.

Antibiotic-resistant organisms in the neonatal intensive care unit

Neonates, particularly those born prematurely, are at an increased risk of bacterial infection. Empiric treatment with antimicrobials occurs frequently in the neonatal intensive care unit (NICU). Repeated and/or prolonged courses of antibiotic exposure have resulted in an increase in the prevalence of hospital-acquired, antibiotic-resistant organisms such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and multidrug-resistant Gram-negative rods. As bacterial strains become increasingly resistant to standard antimicrobial therapy, measures to control and prevent this problem are essential. Current efforts have focused on monitoring and restricting the use of antimicrobials, proper hand hygiene, evaluation of potential reservoirs of bacterial acquisition and transmission, cohorting and isolation of colonized infants, decolonization strategies, and fostering of effective inter- and intrahospital communication.

Cerebrospinal fluid penetration and bacteriostatic activity of linezolid against Enterococcus faecalis in a child with a ventriculoperitoneal shunt infection

We report a 4-year-old girl with a complicated Enterococcus faecalis ventriculoperitoneal shunt infection who failed vancomycin therapy. We demonstrate linezolid's high CSF penetration and its CSF bacteriostatic activity against E. faecalis. Linezolid may be a good alternative for treatment of ventriculoperitoneal shunt infections in cases of vancomycin-resistant organisms or apparent treatment failures.

Management of Community-Associated Methicillin-ResistantStaphylococcus aureusInfections in Children

In recent years, community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as a pathogen in children without established risk factors, and its prevalence in the United States is increasing. Although many CA-MRSA infections are mild, primarily involving the skin and soft tissues, the organism can cause serious, invasive, and life-threatening infections. To provide a comprehensive review of the epidemiology, clinical features, therapy, and prevention of CA-MRSA infections in children, we performed MEDLINE (1966-January 2006) and Cochrane Library searches, and reviewed abstracts for relevance to S. aureus infections. Only articles pertaining to CA-MRSA infections in pediatrics were closely examined. As a genetically distinct pathogen, CA-MRSA is generally susceptible to multiple non-beta-lactam antimicrobials. The optimal treatment for CA-MRSA infections in pediatric patients has not been well studied. Common antibiotics used include clindamycin, trimethoprim-sulfamethoxazole, vancomycin, and rifampin. Rational empiric antimicrobial therapy for infections caused by S. aureus requires consideration of the possibility of methicillin resistance. The local prevalence and susceptibilities of CA-MRSA, severity of infection, and individual risk factors should be considered in selecting treatment.

Enterococcal Infection in Children

From relative obscurity, enterococci have become a leading cause of nosocomial infection. This has been attributed, in part, to the growth in susceptible host populations, increased use of intravascular devices, prolonged hospital stay, and widespread antibiotics use. Furthermore, the facility with which enterococci acquire resistance characteristics coupled with their capacity to survive in the environment renders them uniquely suited as nosocomial opportunists and have resulted in global dissemination of resistant strains. Debate continues as to whether most serious infections arise from a person's indigenous flora or dissemination of virulent clones. Enterococci are normal inhabitants of the human gastrointestinal tract. Classically associated with endocarditis and wound and urinary tract infections, increasingly they are a cause of nosocomial bacteremia. The rise in incidence of serious enterococcal infection has been particularly evident in neonatal, paediatric intensive care, and haematology/oncology units. Spread of resistant phenotypes has posed a difficult therapeutic challenge. We have been rescued, albeit perhaps only temporarily, by the addition of newer agents, such as linezolid, to the therapeutic armamentarium. However, there is no room for complacency. Linezolid resistance already has been reported. Efforts must continue to focus on prevention of the emergence and dissemination of resistance through policies of rational antibiotic use, infection control and education.

[Linezolid, the first oxazolidinone antibiotic]

The spread of multiresistant Staphylococcus and Enterococcus strains required the development of new drugs. Linezolid is the first molecule of a new antibiotic family, oxazolidinones, with an original mechanism of action. In this general review, the authors first present its antibacterial activity, its pharmacokinetic properties, its therapeutic uses in serious Gram-positive infections, pneumonia, skin and soft tissue infections, and also in other indications. They then explain the rules for administration and tolerability.

Endocarditis Due to Vancomycin-Resistant Enterococci: Case Report and Review of the Literature

BACKGROUND

Endocarditis due to vancomycin-resistant enterococci (VRE) is rare, and the literature consists almost exclusively of reports of single cases.

METHODS

We report a case of VRE prosthetic valve endocarditis and review 18 cases of native and prosthetic valve VRE endocarditis reported in the literature.

RESULTS

The majority of cases were due to Enterococcus faecium. Nearly all of these infections were hospital acquired, and the vast majority of patients had significant underlying disease processes, including dialysis and transplantation. More than three-quarters of cases were left-sided, and the aortic valve was most commonly involved. Peripheral stigmata of endocarditis were not reported in any of the cases. Approximately 40% of patients developed cardiac complications. Nearly three-quarters of patients survived, despite the difficulties associated with providing bactericidal antimicrobial therapy, and only 4 patients underwent valve replacement.

CONCLUSIONS

VRE endocarditis is an uncommon nosocomial infection that affects patients with significant comorbid conditions. Most cases are due to E. faecium, and the aortic valve is involved in at least one-half of cases. One-third of patients require surgical treatment. Optimal antimicrobial therapy remains undefined, but an attempt to identify bactericidal combination therapy should be sought.