Principles of Antimicrobial Use in Older Adults

Epidemiology and Outcomes of Vancomycin-Resistant Enterococcus Infections in the U.S. Military Health System

INTRODUCTION

Vancomycin-resistant enterococci (VRE) are classified by the Centers for Diseases Control and Prevention as a serious antibiotic resistance threat. Our study aims to characterize the epidemiology, associated conditions, and outcomes of VRE infections among hospitalized patients in the U.S. military health system (MHS).

MATERIALS AND METHODS

We performed a retrospective cohort study of patients with VRE infection using the MHS database. Cases included all patients admitted to a military treatment facility for ≥2 days from October 2008 to September 2015 with a clinical culture growing Enterococcus faecalis, Enterococcus faecium, or Enterococcus species (unspecified), reported as resistant to vancomycin. Co-morbid conditions and procedures associated with VRE infection were identified by multivariable conditional logistic regression. Patient case-mix adjusted outcomes including in-hospital mortality, length of stay, and hospitalization cost were evaluated by high-dimensional propensity score adjustment.

RESULTS

During the seven-year study period and among 1,161,335 hospitalized patients within the MHS, we identified 577 (0.05%) patients with VRE infection. A majority of VRE infections were urinary tract infections (57.7%), followed by bloodstream (24.7%), other site/device-related (12.9%), respiratory (2.9%), and wound infections (1.8%). Risk factors for VRE infection included invasive gastrointestinal, pulmonary, and urologic procedures, indwelling devices, and exposure to 4th generation cephalosporins, but not to glycopeptides. Patients hospitalized with VRE infection had significantly higher hospitalization costs (attributable difference [AD] $135,534, P<0.001), prolonged hospital stays (AD 20.44 days, P<0.001, and higher in-hospital mortality (case-mix adjusted odds ratio 5.77; 95% confidence interval 4.59-7.25).

CONCLUSIONS

VRE infections carry a considerable burden for hospitalized patients given their impact on length of stay, hospitalization costs, and in-hospital mortality. Active surveillance and infection control efforts should target those identified as high-risk for VRE infection. Antimicrobial stewardship programs should focus on limiting exposure to 4th generation cephalosporins.

Can Sepsis Be Detected in the Nursing Home Prior to the Need for Hospital Transfer?

OBJECTIVES

To determine whether and to what extent simple screening tools might identify nursing home (NH) residents who are at high risk of becoming septic.

DESIGN

Retrospective chart audit of all residents who had been hospitalized and returned to participating NHs during the study period.

SETTING AND PARTICIPANTS

A total of 236 NH residents, 59 of whom returned from hospitals with a diagnosis of sepsis and 177 who had nonsepsis discharge diagnoses, from 31 community NHs that are typical of US nursing homes overall.

MEASURES

NH documentation of vital signs, mental status change, and medical provider visits 0-12 and 13-72 hours prior to the hospitalization. The specificity and sensitivity of 5 screening tools were evaluated for their ability to detect residents with incipient sepsis during 0-12 and 13-72 hours prior to hospitalization: The Systemic Inflammatory Response Syndrome criteria, the quick Sequential Organ Failure Assessment (SOFA), the 100-100-100 Early Detection Tool, and temperature thresholds of 99.0°F and 100.2°F. In addition, to validate the hospital diagnosis of sepsis, hospital discharge records in the NHs were audited to calculate SOFA scores.

RESULTS

Documentation of 1 or more vital signs was absent in 26%-34% of cases. Among persons with complete vital sign documentation, during the 12 hours prior to hospitalization, the most sensitive screening tools were the 100-100-100 Criteria (79%) and an oral temperature >99.0°F (51%); and the most specific tools being a temperature >100.2°F (93%), the quick SOFA (88%), the Systemic Inflammatory Response Syndrome criteria (86%), and a temperature >99.0°F (85%). Many SOFA data points were missing from the record; in spite of this, 65% of cases met criteria for sepsis.

CONCLUSIONS

NHs need better systems to monitor NH residents whose status is changing, and to present that information to medical providers in real time, either through rapid medical response programs or telemetry.

Antibiothérapie du sujet âgé : On peut toujours mieux faire

Antimicrobials are among the most prescribed drugs and their prescription increases with age, due to frailty and accrued risk factors for acquiring infections. Antimicrobial prescription in elderly patients must not only account for the risk of toxicity due to drug overexposure, but also of treatment failure or promotion of antimicrobial resistance due to under-dosage. This paper reviews the main antimicrobial, pharmacokinetic and pharmacodynamic variations induced by aging, comorbidities and polypharmacy, and how to take them into account to optimize antimicrobial prescription in elders.

Challenges with Diagnosing and Managing Sepsis in Older Adults

Sepsis in older adults has many challenges that affect rate of septic diagnosis, treatment, and monitoring parameters. Numerous age-related changes and comorbidities contribute to increased risk of infections in older adults, but also atypical symptomatology that delays diagnosis. Due to various pharmacokinetic/pharmacodynamic changes in the older adult, medications are absorbed, metabolized, and eliminated at different rates as compared to younger adults, which increases risk of adverse drug reactions due to use of drug therapy needed for sepsis management. This review provides information to aid in diagnosis and offers recommendations for monitoring and treating sepsis in the older adult population.

The impact of drug interactions and polypharmacy on antimicrobial therapy in the elderly

Infectious diseases are more prevalent in older people than in younger adults, and represent a major healthcare issue in older populations. Indeed, infections in the elderly are often associated with higher morbidity and mortality, and may present atypically. Additionally, older patients are generally treated with polypharmacy regimens, which increase the likelihood of drug-drug interactions when the prescription of an antimicrobial agent is needed. A progressive impairment in the functional reserve of multiple organs may affect either pharmacokinetics or pharmacodynamics during aging. Changes in body composition occurring with advancing age, reduced liver mass and perfusion, and reduced renal excretion may affect either pharmacokinetics or pharmacodynamics. These issues need to be taken into account when prescribing antimicrobial agents to older complex patients taking multiple drugs. Interventions aimed at improving the appropriateness and safety of antimicrobial prescriptions have been proposed. Educational interventions targeting physicians may improve antimicrobial prescriptions. Antimicrobial stewardship programmes have been found to reduce the length of hospital stay and improve safety in hospitalized patients, and their use in long-term care facilities is worth testing. Computerized prescription and decision support systems, as well as interventions aimed at improving antimicrobial agents dosage in relation to kidney function, may also help to reduce the burden of interactions and inherent costs.

Rational use of medicines: prescribing indicators at different levels of health care

This multicenter study aimed to investigate prescribing patterns of drugs at different levels of health care delivery in university-affiliated outpatient clinics located in eight cities in the South and Midwest of Brazil. All prescriptions collected were analyzed for various items, including WHO prescribing indicators. A total of 2,411 prescriptions were analyzed, and 469 drugs were identified. The number of drugs prescribed per encounter, the frequency of polypharmacy, and the percentage of encounters with at least one injection or antibiotic prescribed were higher in centers providing primary health care services, compared to those where this type of care is not provided. Most drugs (86.1%) were prescribed by generic name. In centers with primary health care services, drug availability was higher, drugs included in the National and Municipal Lists of Essential Medicines were more frequently prescribed, and patients were given more instructions. However, warnings and non-pharmacological measures were less frequently recommended. This study reveals trends in drug prescribing at different levels of health care delivery in university-affiliated outpatient clinics and indicates possible areas for improvement in prescribing practices.

Trends in antibiotic prescribing in adults in Dutch general practice

Background

Antibiotic consumption is associated with adverse drug events (ADE) and increasing antibiotic resistance. Detailed information of antibiotic prescribing in different age categories is scarce, but necessary to develop strategies for prudent antibiotic use. The aim of this study was to determine the antibiotic prescriptions of different antibiotic classes in general practice in relation to age.

Methodology

Retrospective study of 22 rural and urban general practices from the Dutch Registration Network Family Practices (RNH). Antibiotic prescribing data were extracted from the RNH database from 2000–2009. Trends over time in antibiotic prescriptions were assessed with multivariate logistic regression including interaction terms with age. Registered ADEs as a result of antibiotic prescriptions were also analyzed.

Principal Findings

In total 658,940 patients years were analyzed. In 11.5% (n = 75,796) of the patient years at least one antibiotic was prescribed. Antibiotic prescriptions increased for all age categories during 2000–2009, but the increase in elderly patients (>80 years) was most prominent. In 2000 9% of the patients >80 years was prescribed at least one antibiotic to 22% in 2009 (P<0.001). Elderly patients had more ADEs with antibiotics and co-medication was identified as the only independent determinant for ADEs.

Conclusion/Discussion

The rate of antibiotic prescribing for patients who made a visit to the GP is increasing in the Netherlands with the most evident increase in the elderly patients. This may lead to more ADEs, which might lead to higher consumption of health care and more antibiotic resistance.

Severe sepsis and septic shock in the elderly: An overview

The incidence of severe sepsis and septic shock is increasing in the older population leading to increased admissions to the intensive care units (ICUs). The elderly are predisposed to sepsis due to co-existing co-morbidities, repeated and prolonged hospitalizations, reduced immunity, functional limitations and above all due to the effects of aging itself. A lower threshold and a higher index of suspicion is required to diagnose sepsis in this patient population because the initial clinical picture may be ambiguous, and aging increases the risk of a sudden deterioration in sepsis to severe sepsis and septic shock. Management is largely based on standard international guidelines with a few modifications. Age itself is an independent risk factor for death in patients with severe sepsis, however, many patients respond well to timely and appropriate interventions. The treatment should not be limited or deferred in elderly patients with severe sepsis only on the grounds of physician prejudice, but patient and family preferences should also be taken into account as the outcomes are not dismal. Future investigations in the management of sepsis should not only target good functional recovery but also ensure social independence and quality of life after ICU discharge.

Severe sepsis and septic shock in the elderly: An overview

The incidence of severe sepsis and septic shock is increasing in the older population leading to increased admissions to the intensive care units (ICUs). The elderly are predisposed to sepsis due to co-existing co-morbidities, repeated and prolonged hospitalizations, reduced immunity, functional limitations and above all due to the effects of aging itself. A lower threshold and a higher index of suspicion is required to diagnose sepsis in this patient population because the initial clinical picture may be ambiguous, and aging increases the risk of a sudden deterioration in sepsis to severe sepsis and septic shock. Management is largely based on standard international guidelines with a few modifications. Age itself is an independent risk factor for death in patients with severe sepsis, however, many patients respond well to timely and appropriate interventions. The treatment should not be limited or deferred in elderly patients with severe sepsis only on the grounds of physician prejudice, but patient and family preferences should also be taken into account as the outcomes are not dismal. Future investigations in the management of sepsis should not only target good functional recovery but also ensure social independence and quality of life after ICU discharge.

Elderly patients with community-acquired pneumonia: optimal treatment strategies

Community-acquired pneumonia (CAP) is a common infectious disease that still causes substantial morbidity and mortality. Elderly people are frequently affected, and several issues related to care of this condition in the elderly have to be considered. This article reviews current recommendations of guidelines with a special focus on aspects of the care of elderly patients with CAP. The most common pathogen in CAP is still Streptococcus pneumoniae, followed by other pathogens such as Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella species. Antimicrobial resistance is an increasing problem, especially with regard to macrolide-resistant S. pneumoniae and fluoroquinolone-resistant strains. With regard to β-lactam antibacterials, resistance by H. influenzae and Moraxella catarrhalis is important, as is the emergence of multidrug-resistant Staphylococcus aureus. The main management decisions should be guided by the severity of disease, which can be assessed by validated clinical risk scores such as CURB-65, a tool for measuring the severity of pneumonia based on assessment of confusion, serum urea, respiratory rate and blood pressure in patients aged ≥65 years. For the treatment of low-risk pneumonia, an aminopenicillin such as amoxicillin with or without a β-lactamase inhibitor is frequently recommended. Monotherapy with macrolides is also possible, although macrolide resistance is of concern. When predisposing factors for special pathogens are present, a β-lactam antibacterial combined with a β-lactamase inhibitor, or the combination of a β-lactam antibacterial, a β-lactamase inhibitor and a macrolide, may be warranted. If possible, patients who have undergone previous antibacterial therapy should receive drug classes not previously used. For hospitalized patients with non-severe pneumonia, a common recommendation is empirical antibacterial therapy with an aminopenicillin in combination with a β-lactamase inhibitor, or with fluoroquinolone monotherapy. With proven Legionella pneumonia, a combination of β-lactams with a fluoroquinolone or a macrolide is beneficial. In severe pneumonia, ureidopenicillins with β-lactamase inhibitors, broad-spectrum cephalosporins, macrolides and fluoroquinolones are used. A combination of a broad-spectrum β-lactam antibacterial (e.g. cefotaxime or ceftriaxone), piperacillin/tazobactam and a macrolide is mostly recommended. In patients with a predisposition for Pseudomonas aeruginosa, a combination of piperacillin/tazobactam, cefepime, imipenem or meropenem and levofloxacin or ciprofloxacin is frequently used. Treatment duration of more than 7 days is not generally recommended, except for proven infections with P. aeruginosa, for which 15 days of treatment appears to be appropriate. Further care issues in all hospitalized patients are timely administration of antibacterials, oxygen supply in case of hypoxaemia, and fluid management and dose adjustments according to kidney function. The management of elderly patients with CAP is a challenge. Shifts in antimicrobial resistance and the availability of new antibacterials will change future clinical practice. Studies investigating new methods to detect pathogens, determine the optimal antimicrobial regimen and clarify the duration of treatment may assist in further optimizing the management of elderly patients with CAP.

Indications for antimicrobial prescribing in European nursing homes: results from a point prevalence survey

PURPOSE

In light of the emerging problem with multiresistant microorganisms in nursing homes (NHs), the European Surveillance of Antimicrobial Consumption NH subproject was set up to measure and describe antimicrobial use across Europe. The aim of this paper was to investigate the indications for antimicrobial use and hence identify targets for quality improvement.

METHODS

Data were obtained from a point prevalence survey conducted in 323 NHs across 21 European countries. A resident questionnaire had to be completed for each resident receiving an antimicrobial, collecting data such as compound name and indication for antimicrobial prescribing. Four main indications for antimicrobial use were recorded: nasal decolonisation of methicillin-resistant Staphylococcus aureus (MRSA) carriage with mupirocin, prophylactic, empirical, and microbiologically documented treatments. The latter three treatment types were further subdivided according to the targeted infections.

RESULTS

In total, 1966 residents were treated with 2046 antimicrobials. Empirical treatments were most common (54.4% of all antimicrobial therapies; prevalence: 3.39 per 100 eligible residents), followed by prophylactic (28.8%; prevalence: 1.87%) and microbiologically documented (16.1%; prevalence: 1.01%) regimes. MRSA decolonisation with nasal mupirocin (0.7%; prevalence: 0.02%) was uncommon. Antimicrobials were most frequently prescribed for the prevention or treatment of urinary (49.5%; prevalence: 3.23%) and respiratory (31.8%; prevalence: 1.81%) tract infections. A very high proportion of uroprophylaxis was reported (25.6% of all prescribed antimicrobials; prevalence: 1.67%).

CONCLUSIONS

The indications for antimicrobial prescribing varied markedly between countries. We identified uroprophylaxis as a possible target for quality improvement.

Empiric antibiotic selection strategies for healthcare-associated pneumonia, intra-abdominal infections, and catheter-associated bacteremia

Initial selection and early deployment of appropriate/adequate empiric antimicrobial therapy is critical to minimize the significant morbidity and mortality associated with hospital- or healthcare-associated infections (HAIs). Initial empiric therapy that inadequately covers the pathogen(s) causing a serious HAI has been associated with increased mortality, longer hospital stay, and elevated healthcare costs. Moreover, subsequent modification of initial inadequate therapy, later in the disease process when culture results become available, may not remedy the impact of the initial choice. Because of this, it is important that initial empiric therapy covers the most likely pathogens associated with infection in a particular patient, even if this initial regimen turns out to be unnecessarily broad, based on subsequent culture results. The current paradigm for management of serious HAIs is to initiate empiric therapy with a broad-spectrum regimen covering likely pathogens, based on local surveillance and susceptibility data, and presence of risk factors for involvement of a resistant microorganism. Subsequent modification (de-escalation) of the initial regimen becomes possible later, when culture results are available and clinical status can be better assessed, 2 to 4 days after initiation of empiric therapy. When possible, de-escalation and other steps to modify antimicrobial exposure are important for minimizing risk of antimicrobial resistance development. This article examines the general process for selection of initial empiric antibiotic therapy for patients with HAIs, illustrated through 3 case studies dealing with healthcare-associated pneumonia, complicated intra-abdominal infection, and catheter-associated bacteremia, respectively.

Safety and clinical outcomes among older adults receiving daptomycin therapy: Insights from a patient registry

BACKGROUND

Serious gram-positive bacterial infections are an important cause of morbidity and mortality among older adults and can present significant challenges to clinicians. Data evaluating the safety and effectiveness of newer agents in this population are limited.

OBJECTIVE

Daptomycin is a lipopeptide with activity against resistant gram-positive organisms. To better understand the overall safety and effectiveness of daptomycin in older adults (≥66 years of age), the authors reviewed the data that were collected as part of an ongoing registry maintained by Cubist Pharmaceuticals, Inc. (Lexington, Massachusetts), the manufacturer of daptomycin.

METHODS

The Cubicin Outcomes Registry and Experience (CORE) is a multicenter, retrospective registry designed to collect postmarketing clinical data on patients who received daptomycin. The CORE data collected from 58 institutions across the United States between January 1, 2005, and December 31, 2007, were analyzed to better understand the overall safety profile of daptomycin and the clinical outcomes of older adults who were treated with this agent. Patients were considered to be nonevaluable if the medical record did not contain sufficient information to determine response at the end of therapy. Nonevaluable patients were excluded from the clinical outcome analysis but included in the safety analysis.

RESULTS

The registry contained 1073 patients aged ≥66 years who received daptomycin; 23.8% (255/1073) were ≥81 years of age. Overall, 18.1% (194/1073) of patients experienced 324 adverse events, and 6.2% (67/1073) of patients experienced 97 adverse events that were considered possibly related to treatment with daptomycin. The most frequently reported adverse events that were considered possibly treatment related included creatine phosphokinase (CPK) elevations, gastrointestinal disorders, and skin rashes. Among the 67 patients who experienced ≥1 adverse event that was possibly related to daptomycin, 30 discontinued therapy due to the adverse event (13 due to CPK elevation). Overall, 78.7% (844/1073) of patients were considered evaluable for clinical outcomes. The clinical success rate for all evaluable patients was 90.2% (761/844). The success rate for evaluable patients ≥81 years of age (88.6% [171/193]) was comparable to that of the overall population.

CONCLUSION

Experience with daptomycin in this group of older adults suggests good tolerability and clinical outcomes that are consistent with the results of other studies published to date.

Bacteremia in the elderly

Bacteremia is an increasingly significant health problem among the elderly. Older adults may present with atypical manifestations of bacteremia. In addition, there are age-related differences in etiologic agents and corresponding resistance patterns. Important factors to consider when prescribing antibiotics for older adults with bacteremia include the severity and source of infection, antimicrobial susceptibility of the organism and renal function. The association between increasing age and poor outcomes in patients with bacteremia is well established. Despite the current paucity of data, the understanding of the natural history of bacteremia in the elderly should not be limited to mortality but should also focus on functional status, cognitive function and the eventual need for long-term care. Appropriate management of bacteremia in the elderly requires timely administration of broad-spectrum antibiotics in addition to managing key geriatric issues. Further studies are required to assess the impact of using broader outcomes other than mortality when addressing bacteremia in the elderly.