Adam L. Hersh

National trends in ambulatory visits and antibiotic prescribing for skin and soft-tissue infections.

BACKGROUND Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as a common cause of skin and soft-tissue infections (SSTIs) in the United States. It is unknown whether this development has affected the national rate of visits to primary care practices and emergency departments (EDs) and whether changes in antibiotic prescribing have occurred. METHODS We examined visits by patients with SSTIs to physician offices, hospital outpatient departments, and EDs using the National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey from 1997 to 2005. We estimated annual visit rates for all SSTIs and a subset classified as abscess/cellulitis. For abscess/cellulitis visits, we examined trends in characteristics of patients and clinical settings and in antibiotic prescribing. RESULTS Overall rate of visits for SSTIs increased from 32.1 to 48.1 visits per 1000 population (50%; P = .003 for trend), reaching 14.2 million by 2005. More than 95% of this change was attributable to visits for abscess/cellulitis, which increased from 17.3 to 32.5 visits per 1000 population (88% increase; P < .001 for trend). The largest relative increases occurred in EDs (especially in high safety-net-status EDs and in the South), among black patients, and among patients younger than 18 years. Use of antibiotics recommended for CA-MRSA increased from 7% to 28% of visits (P < .001) during the study period. Independent predictors of treatment with these antibiotics included being younger than 45 years, living in the South, and an ED setting. CONCLUSIONS The incidence of SSTIs has rapidly increased nationwide in the CA-MRSA era and appears to disproportionately affect certain populations. Although physicians are beginning to modify antibiotic prescribing practices, opportunities for improvement exist, targeting physicians caring for patients who are at high risk.

Prevalence of Inappropriate Antibiotic Prescriptions Among US Ambulatory Care Visits, 2010-2011

IMPORTANCE The National Action Plan for Combating Antibiotic-Resistant Bacteria set a goal of reducing inappropriate outpatient antibiotic use by 50% by 2020, but the extent of inappropriate outpatient antibiotic use is unknown. OBJECTIVE To estimate the rates of outpatient oral antibiotic prescribing by age and diagnosis, and the estimated portions of antibiotic use that may be inappropriate in adults and children in the United States. DESIGN, SETTING, AND PARTICIPANTS Using the 2010-2011 National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey, annual numbers and population-adjusted rates with 95% confidence intervals of ambulatory visits with oral antibiotic prescriptions by age, region, and diagnosis in the United States were estimated. EXPOSURES Ambulatory care visits. MAIN OUTCOMES AND MEASURES Based on national guidelines and regional variation in prescribing, diagnosis-specific prevalence and rates of total and appropriate antibiotic prescriptions were determined. These rates were combined to calculate an estimate of the appropriate annual rate of antibiotic prescriptions per 1000 population. RESULTS Of the 184,032 sampled visits, 12.6% of visits (95% CI, 12.0%-13.3%) resulted in antibiotic prescriptions. Sinusitis was the single diagnosis associated with the most antibiotic prescriptions per 1000 population (56 antibiotic prescriptions [95% CI, 48-64]), followed by suppurative otitis media (47 antibiotic prescriptions [95% CI, 41-54]), and pharyngitis (43 antibiotic prescriptions [95% CI, 38-49]). Collectively, acute respiratory conditions per 1000 population led to 221 antibiotic prescriptions (95% CI, 198-245) annually, but only 111 antibiotic prescriptions were estimated to be appropriate for these conditions. Per 1000 population, among all conditions and ages combined in 2010-2011, an estimated 506 antibiotic prescriptions (95% CI, 458-554) were written annually, and, of these, 353 antibiotic prescriptions were estimated to be appropriate antibiotic prescriptions. CONCLUSIONS AND RELEVANCE In the United States in 2010-2011, there was an estimated annual antibiotic prescription rate per 1000 population of 506, but only an estimated 353 antibiotic prescriptions were likely appropriate, supporting the need for establishing a goal for outpatient antibiotic stewardship.

Antibiotic Prescribing in Ambulatory Pediatrics in the United States

BACKGROUND: Antibiotics are commonly prescribed for children with conditions for which they provide no benefit, including viral respiratory infections. Broad-spectrum antibiotic use is increasing, which adds unnecessary cost and promotes the development of antibiotic resistance. OBJECTIVE: To provide a nationally representative analysis of antibiotic prescribing in ambulatory pediatrics according to antibiotic classes and diagnostic categories and identify factors associated with broad-spectrum antibiotic prescribing. PATIENTS AND METHODS: We used the National Ambulatory and National Hospital Ambulatory Medical Care surveys from 2006 to 2008, which are nationally representative samples of ambulatory care visits in the United States. We estimated the percentage of visits for patients younger than 18 years for whom antibiotics were prescribed according to antibiotic classes, those considered broad-spectrum, and diagnostic categories. We used multivariable logistic regression to identify demographic and clinical factors that were independently associated with broad-spectrum antibiotic prescribing. RESULTS: Antibiotics were prescribed during 21% of pediatric ambulatory visits; 50% were broad-spectrum, most commonly macrolides. Respiratory conditions accounted for >70% of visits in which both antibiotics and broad-spectrum antibiotics were prescribed. Twenty-three percent of the visits in which antibiotics were prescribed were for respiratory conditions for which antibiotics are not clearly indicated, which accounts for >10 million visits annually. Factors independently associated with broad-spectrum antibiotic prescribing included respiratory conditions for which antibiotics are not indicated, younger patients, visits in the South, and private insurance. CONCLUSIONS: Broad-spectrum antibiotic prescribing in ambulatory pediatrics is extremely common and frequently inappropriate. These findings can inform the development and implementation of antibiotic stewardship efforts in ambulatory care toward the most important geographic regions, diagnostic conditions, and patient populations.

Antibiotic prescribing for adults in ambulatory care in the USA, 2007–09

OBJECTIVES To determine patterns of ambulatory antibiotic prescribing in US adults, including the use of broad-spectrum versus narrow-spectrum agents, to provide a description of the diagnoses for which antibiotics are prescribed and to identify patient and physician factors associated with broad-spectrum antibiotic prescribing. METHODS We used data for patients aged ≥ 18 years from the National Ambulatory and National Hospital Ambulatory Medical Care Surveys (2007-09). These are nationally representative surveys of patient visits to offices, hospital outpatient departments and emergency departments (EDs) in the USA, collectively referred to as ambulatory visits. We determined the types of antibiotics prescribed, including the use of broad-spectrum versus narrow-spectrum antibiotics, and examined prescribing patterns by diagnoses. We used multivariable logistic regression to identify factors associated with broad-spectrum antibiotic prescribing. RESULTS Antibiotics were prescribed during 101 million (95% CI: 91-111 million) ambulatory visits annually, representing 10% of all visits. Broad-spectrum agents were prescribed during 61% of visits in which antibiotics were prescribed. The most commonly prescribed antibiotics were quinolones (25% of antibiotics), macrolides (20%) and aminopenicillins (12%). Antibiotics were most commonly prescribed for respiratory conditions (41% of antibiotics), skin/mucosal conditions (18%) and urinary tract infections (9%). In multivariable analysis, among patients prescribed antibiotics, broad-spectrum agents were more likely to be prescribed than narrow-spectrum antibiotics for respiratory infections for which antibiotics are rarely indicated (e.g. bronchitis), during visits to EDs and for patients ≥ 60 years. CONCLUSIONS Broad-spectrum agents constitute the majority of antibiotics in ambulatory care. More than 25% of prescriptions are for conditions for which antibiotics are rarely indicated. Antibiotic stewardship interventions targeting respiratory and non-respiratory conditions are needed in ambulatory care.

Current recommended dosing of vancomycin for children with invasive methicillin-resistant Staphylococcus aureus infections is inadequate.

Background: Vancomycin area-under-the-concentration-time-curve (AUC) for 24 hours divided by the minimum inhibitory concentration (MIC) (AUC24/MIC) >400 optimally treats invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in adults. It is unknown whether recommended vancomycin dosing regimens for children achieve this value. Methods: AUC24/MIC was calculated in children using vancomycin doses of 40 and 60 mg/kg/d. AUC24 was calculated as daily dose/vancomycin clearance. Vancomycin clearance in children was estimated by 2 approaches: (1) previously literature-reported vancomycin clearance, and (2) calculated vancomycin clearance using previously derived predictor models and a hypothetical population of healthy children. Representative MIC of hospital MRSA isolates was used (0.5, 1.0, and 2.0 μg/mL). Results: The MIC50/90 for pediatric MRSA isolates in the previous year was 1.0 μg/mL. With a dose of 40 mg/kg/d, both approaches consistently predicted AUC24/MIC <400 when MIC was 1.0 μg/mL. At 60 mg/kg/d, AUC24/MIC >400 was more readily achieved when MIC was 1.0 μg/mL, however, an MIC of 2.0 μg/mL resulted in AUC24/MIC <400 for both dosing regimens. Conclusions: A vancomycin dose of 40 mg/kg/d in children is unlikely to achieve the recommended pharmacodynamic target of AUC24/MIC >400 for invasive MRSA infections even when MIC is 1.0 μg/mL. A starting dose of 60 mg/kg/d should be used in settings where isolates with MIC of 1.0 are common. Alternatives to vancomycin should strongly be considered for patients with MIC ≥2.0 μg/mL.

Principles of Judicious Antibiotic Prescribing for Upper Respiratory Tract Infections in Pediatrics

Most upper respiratory tract infections are caused by viruses and require no antibiotics. This clinical report focuses on antibiotic prescribing strategies for bacterial upper respiratory tract infections, including acute otitis media, acute bacterial sinusitis, and streptococcal pharyngitis. The principles for judicious antibiotic prescribing that are outlined focus on applying stringent diagnostic criteria, weighing the benefits and harms of antibiotic therapy, and understanding situations when antibiotics may not be indicated. The principles can be used to amplify messages from recent clinical guidelines for local guideline development and for patient communication; they are broadly applicable to antibiotic prescribing in general.

Improving Antimicrobial Stewardship: The Evolution of Programmatic Strategies and Barriers

OBJECTIVE To describe the prevalence and characteristics of antimicrobial stewardship programs (ASPs) in hospitals across the United States and to describe financial support provided for these programs. DESIGN Electronic and paper 14-question survey of infectious diseases physician members of the Infectious Diseases Society of America Emerging Infections Network (IDSA EIN). PARTICIPANTS All 1,044 IDSA EIN members who care for adult patients were invited to participate. RESULTS Five hundred twenty-two (50%) members responded. Seventy-three percent of respondents reported that their institutions had or were planning an ASP, compared with 50% reporting the same thing in an EIN survey 10 years before. A shift was noted from formulary restriction alone to use of a set of tailored strategies designed to provide information and feedback to prescribers, particularly in community hospitals. Lack of funding and lack of personnel were reported as major barriers to implementing a program. Fifty-two percent of respondents with an ASP reported that infectious diseases physicians do not receive direct compensation for their participation in the ASP, compared with 18% 10 years ago. CONCLUSIONS The percentage of institutions reporting ASPs has increased over the last decade, although small community hospitals were least likely to have these programs. In addition, ASP strategies have shifted dramatically. Lack of funding remains a key barrier for ASPs, and administrators need additional cost savings data in order to support ASPs. Interestingly, while guidelines and editorials regard compensated participation by an infectious diseases physician in these programs as critical, we found that more than half of the respondents reported no direct compensation for ASP activities.

Ambulatory visit rates and antibiotic prescribing for children with pneumonia, 1994-2007

BACKGROUND: The incidence of pediatric hospitalizations for community-acquired pneumonia (CAP) has declined after the widespread use of the heptavalent pneumococcal conjugate vaccine. The national incidence of outpatient visits for CAP, however, is not well established. Although no pediatric CAP treatment guidelines are available, current data support narrow-spectrum antibiotics as the first-line treatment for most patients with CAP. OBJECTIVE: To estimate the incidence rates of outpatient CAP, examine time trends in antibiotics prescribed for CAP, and determine factors associated with broad-spectrum antibiotic prescribing for CAP. PATIENTS AND METHODS: The National Ambulatory and National Hospital Ambulatory Medical Care Surveys (1994–2007) were used to identify children aged 1 to 18 years with CAP using a validated algorithm. We determined age group–specific rates of outpatient CAP and examined trends in antibiotic prescribing for CAP. Data from 2006–2007 were used to study factors associated with broad-spectrum antibiotic prescribing. RESULTS: Overall, annual CAP visit rates ranged from 16.9 to 22.4 per 1000 population, with the highest rates occurring in children aged 1 to 5 years (range: 32.3–49.6 per 1000). Ambulatory CAP visit rates did not change between 1994 and 2007. Antibiotics commonly prescribed for CAP included macrolides (34% of patients overall), cephalosporins (22% overall), and penicillins (14% overall). Cephalosporin use increased significantly between 2000 and 2007 (P = .002). Increasing age, a visit to a nonemergency department office, and obtaining a radiograph or complete blood count were associated with broad-spectrum antibiotic prescribing. CONCLUSIONS: The incidence of pediatric ambulatory CAP visits has not changed significantly between 1994 and 2007, despite the introduction of heptavalent pneumococcal conjugate vaccine in 2000. Broad-spectrum antibiotics, particularly macrolides, were frequently prescribed despite evidence that they provide little benefit over penicillins.

Does this coughing adolescent or adult patient have pertussis

CONTEXT Pertussis is often overlooked as a cause of chronic cough, especially in adolescents and adults. Several symptoms are classically thought to be suggestive of pertussis, but the diagnostic value of each of them is uncertain. OBJECTIVE To systematically review the evidence regarding the diagnostic value of 3 classically described symptoms of pertussis: paroxysmal cough, posttussive emesis, and inspiratory whoop. DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION We searched MEDLINE (January 1966-April 2010), EMBASE (January 1969 to April 2010), and the bibliographies of pertinent articles to identify relevant English-language studies. Articles were selected that included children older than 5 years, adolescents, or adults and confirmed the diagnosis of pertussis among patients with cough illness (of any duration) with an a priori-defined accepted reference standard. Two authors independently extracted data from articles that met selection criteria and resolved any discrepancies by consensus. DATA SYNTHESIS Five prospective studies met inclusion criteria; 3 were used in the analysis. Presence of posttussive emesis (summary likelihood ratio [LR], 1.8; 95% confidence interval [CI], 1.4-2.2) or inspiratory whoop (summary LR, 1.9; 95% CI, 1.4-2.6) increases the likelihood of pertussis. Absence of paroxysmal cough (summary LR, 0.52; 95% CI, 0.27-1.0) or posttussive emesis (summary LR, 0.58; 95% CI, 0.44-0.77) reduced the likelihood. Absence of inspiratory whoop was less useful (summary LR, 0.78; 95% CI, 0.66-0.93). No studies evaluated combinations of findings. CONCLUSIONS In a nonoutbreak setting, data to determine the diagnostic usefulness of symptoms classically associated with pertussis are limited and of relatively weak quality. The presence or absence of posttussive emesis or inspiratory whoop modestly change the likelihood of pertussis; therefore, clinicians must use their overall clinical impression to decide about additional testing or empirical treatment.

Antibiotic Resistance Patterns of Outpatient Pediatric Urinary Tract Infections

PURPOSE We characterize the current national patterns of antibiotic resistance of outpatient pediatric urinary tract infection. MATERIALS AND METHODS We examined outpatient urinary isolates from patients younger than 18 years in 2009 using The Surveillance Network®, a database with antibiotic susceptibility results and patient demographic data from 195 United States hospitals. We determined the prevalence and antibiotic resistance patterns for the 6 most common uropathogens, ie Escherichia coli, Proteus mirabilis, Klebsiella, Enterobacter, Pseudomonas aeruginosa and Enterococcus. We compared differences in uropathogen prevalence between males and females using chi-square analysis. RESULTS We identified 25,418 outpatient urinary isolates. E. coli was the most common uropathogen overall but the prevalence of E. coli was higher among females (83%) than males (50%, p <0.001). Other common species among males were Enterococcus (17%), P. mirabilis (11%) and Klebsiella (10%). However, these uropathogens each accounted for 5% or less of female isolates (p <0.001). Resistance among E. coli was highest for trimethoprim-sulfamethoxazole (24%) but lower for nitrofurantoin (less than 1%) and cephalothin (15%). Compared to 2002 Surveillance Network data, E. coli resistance rates increased for trimethoprim-sulfamethoxazole (from 23% to 31% in males and from 20% to 23% in females) and ciprofloxacin (from 1% to 10% and from 0.6% to 4%, respectively). CONCLUSIONS E. coli remains the most common pediatric uropathogen. Although widely used, trimethoprim-sulfamethoxazole is a poor empirical choice for pediatric urinary tract infections in many areas due to high resistance rates. First-generation cephalosporins and nitrofurantoin are appropriate narrow-spectrum alternatives given their low resistance rates. Local antibiograms should be used to assist with empirical urinary tract infection treatment.