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Overview of decisions regarding necessity of antimicrobial therapy.

Overview of decisions regarding necessity of antimicrobial therapy.

Table 1. 
Comparison of Unnecessary and Necessary Antimicrobial Therapy Regimens*
Comparison of Unnecessary and Necessary Antimicrobial Therapy Regimens*
Table 2. 
Reasons for Unnecessary Days of Therapy for All Antimicrobials and the Subset of Agents With Antianaerobic Activity
Reasons for Unnecessary Days of Therapy for All Antimicrobials and the Subset of Agents With Antianaerobic Activity
Table 3. 
Clinical Scenarios Associated With Unnecessary Antimicrobial Therapy
Clinical Scenarios Associated With Unnecessary Antimicrobial Therapy
Table 4. 
Total and Unnecessary Antimicrobial Days of Therapy by Agent
Total and Unnecessary Antimicrobial Days of Therapy by Agent
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2.
Castle  MWilfert  CMCate  TROsterhout  S Antibiotic use at Duke University Medical Center. JAMA. 1977;2372819- 2822Article
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Kunin  CMTupasi  TCraig  WA Use of antibiotics: a brief exposition of the problem and some tentative solutions. Ann Intern Med. 1973;79555- 560Article
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Scheckler  WEBennett  JV Antibiotic usage in seven community hospitals. JAMA. 1970;213264- 267Article
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Kunin  CM The responsibility of the infectious disease community for the optimal use of antimicrobial agents. J Infect Dis. 1985;151388- 398Article
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Schwartz  BBell  DMHughes  JM Preventing the emergence of antimicrobial resistance: a call for action by clinicians, public health officials, and patients. JAMA. 1997;278944- 945Article
7.
McGowan  JE Do intensive antibiotic control programs prevent the spread of antibiotic resistance? Infect Control Hosp Epidemiol. 1994;15478- 483Article
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Goldmann  DAWeinstein  RAWenzel  RP  et al.  Strategies to prevent and control the emergence and spread of antimicrobial-resistant microorganisms in hospitals: a challenge to hospital leadership. JAMA. 1996;275234- 240Article
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Dunagan  WCWoodward  RSMedoff  G  et al.  Antibiotic misuse in two clinical situations: positive blood cultures and administration of aminoglycosides. Rev Infect Dis. 1991;13405- 412Article
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Lee  KRLeggiadro  RJBurch  KJ Drug use evaluation of antibiotics in a pediatric teaching hospital. Infect Control Hosp Epidemiol. 1994;15710- 712Article
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Donskey  CJChowdhry  TKHecker  MT  et al.  Effect of antibiotic therapy on the density of vancomycin-resistant enterococci in the stool of colonized patients. N Engl J Med. 2000;3431925- 1932Article
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Louie  TJ Preservation of colonization resistance parameters during empiric therapy with aztreonam in the febrile neutropenic patient. Rev Infect Dis. 1985;7(suppl 4)S747- S761Article
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Samonis  GGikas  AAnaissie  EJ  et al.  Prospective evaluation of effects of broad-spectrum antibiotics on gastrointestinal yeast colonization of humans. Antimicrob Agents Chemother. 1993;3751- 53Article
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Vollaard  EJClasener  HAL Colonization resistance. Antimicrob Agents Chemother. 1994;38409- 414Article
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Wilson  KH The microecology of Clostridium difficileClin Infect Dis. 1993;16(suppl 4)S214- S218Article
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Kernodle  DSKaiser  AB Postoperative infections and antimicrobial prophylaxis. Mandell  GLBennett  JEDolin  Reds.Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 5th ed. New York, NY Churchill Livingstone2000;3177- 3191
17.
Garner  JSJarvis  WREmori  TG  et al.  CDC definitions for nosocomial infections. Olmsted  RNed.APIC Infection Control and Applied Epidemiology: Principles and Practice. St Louis, Mo Mosby1996;A1- A20
18.
American Thoracic Society, Hospital-acquired pneumonia in adults: diagnosis, assessment of severity, initial antimicrobial therapy, and preventative strategies: a consensus statement. Am J Respir Crit Care Med. 1996;1531711- 1725Article
19.
Gross  PABarrett  TLDellinger  EP  et al.  Quality standards for the treatment of bacteremia. Clin Infect Dis. 1994;18428- 430Article
20.
Mermel  LAFarr  BMSherertz  RJ  et al.  Guidelines for the management of intravascular catheter-related infections. Clin Infect Dis. 2001;321249- 1272Article
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Gonzales  RBartlett  JGBesser  RE  et al.  Principles of appropriate antibiotic use for treatment of acute respiratory tract infections in adults: background, specific aims, and methods. Ann Intern Med. 2001;134479- 486Article
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Bartlett  JGDowell  SFMandell  LAFile  TMMusher  DMFine  MJ Practice guidelines for the management of community-acquired pneumonia in adults. Clin Infect Dis. 2000;31347- 382Article
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Wormser  GPNadelman  RBDattwyler  RJ  et al.  Practice guidelines for the treatment of lyme disease. Clin Infect Dis. 2000;31(suppl 1)1- 14Article
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US Public Health Services/Infectious Diseases Society of America Prevention of Opportunistic Infections Working Group, 1999 USPHS/IDSA guidelines for the prevention of opportunistic infections in persons infected with human immunodeficiency virus. Clin Infect Dis. 2000;30(suppl 1)S29- S65Article
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Warren  JWAbrutyn  EHebel  JRJohnson  JRSchaeffer  AJStamm  WE Guidelines for antimicrobial treatment of uncomplicated bacterial cystitis and acute pyelonephritis in women. Clin Infect Dis. 1999;29745- 758Article
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Corcoran  MELim  JYChole  RA Prophylaxis for oral surgery and fractures of the facial skeleton. Johnson  JTYu  VLeds.Infectious Diseases and Antimicrobial Therapy of the Ears, Nose and Throat. Philadelphia, Pa WB Saunders Co1997;619- 622
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Steigbigel  NH Macrolides and clindamycin. Mandell  GLBennett  JEDolin  Reds.Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 5th ed. New York, NY Churchill Livingstone2000;366- 382
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Sobel  JDKaye  D Urinary tract infections. Mandell  GLBennett  JEDolin  Reds.Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 5th ed. New York, NY Churchill Livingstone2000;773- 805
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Nicolle  LE Urinary tract infections in long-term-care facility residents. Clin Infect Dis. 2000;31757- 761Article
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Singh  NRogers  PAtwood  CWWagener  MMYu  VL Short course empiric antibiotic therapy for patients with pulmonary infiltrates in the intensive care unit: a proposed solution for indiscriminate antibiotic prescription. Am J Respir Crit Care Med. 2000;162505- 511Article
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Original Investigation
April 28, 2003

Unnecessary Use of Antimicrobials in Hospitalized PatientsCurrent Patterns of Misuse With an Emphasis on the Antianaerobic Spectrum of Activity

Author Affiliations

From the Division of Infectious Diseases (Dr Hecker) and Department of Pharmacy (Drs Patel and Lehmann), MetroHealth Medical Center, and Center for Quality Improvement Research (Dr Aron) and Infectious Diseases Section (Dr Donskey), Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio. Drs Hecker, Aron, Patel, and Lehmann have no relevant financial interest in this article. Dr Donskey has received research grant support from Ortho-McNeil Pharmaceutical (Raritan, NJ).

Arch Intern Med. 2003;163(8):972-978. doi:10.1001/archinte.163.8.972
Abstract

Background  Unnecessary use of antimicrobials contributes to the emergence and dissemination of antimicrobial-resistant nosocomial pathogens in part through elimination of normal anaerobic bacterial flora that inhibit overgrowth of pathogenic microorganisms.

Methods  A prospective observational study was conducted in a 650-bed, university-affiliated hospital. All adult nonintensive care inpatients for whom new antimicrobials were prescribed during a 2-week period were monitored throughout their hospitalization. We examined how often antimicrobials, in particular those with antianaerobic activity, were used unnecessarily. The reasons for unnecessary therapy were assessed and common patterns of unnecessary use were identified.

Results  A total of 1941 antimicrobial days of therapy were prescribed for 129 patients. A total of 576 (30%) of the 1941 days of therapy were deemed unnecessary. The most common reasons for unnecessary therapy included administration of antimicrobials for longer than recommended durations (192 days of therapy), administration of antimicrobials for noninfectious or nonbacterial syndromes (187 days of therapy), and treatment of colonizing or contaminating microorganisms (94 days of therapy). Antianaerobic agents accounted for 203 (35%) of the 576 unnecessary antimicrobial days of therapy, and these agents were also frequently prescribed (98 days of therapy) when equally efficacious alternative regimens with minimal antianaerobic activity were available.

Conclusions  In our institution, hospitalized patients frequently received unnecessary antimicrobial therapy, and antianaerobic agents were often prescribed when this spectrum of activity was not indicated.

SEVERAL STUDIES14 performed in the 1970s demonstrated that antimicrobials were often used inappropriately in the hospital setting, and between 14% and 43% of all courses of antimicrobial therapy were deemed unnecessary because there was no evidence of infection. Since overuse of antimicrobials has contributed to the emergence and dissemination of antimicrobial-resistant nosocomial pathogens, many organizations and experts in infectious diseases have called for increased efforts to limit overuse of antimicrobials in the hospital setting.58 Recent studies9,10 examining overuse of antimicrobials in hospitals have focused on specific patient populations or specific indications for therapy. Current data regarding patterns of unnecessary antimicrobial use in adult hospitalized patients with a variety of medical and surgical conditions are needed to identify types of misuse that might be amenable to intervention.

One mechanism by which antimicrobials promote transmission of nosocomial pathogens is through elimination of competing normal bacterial flora, with subsequent overgrowth of pathogenic microorganisms.8,1115 We have demonstrated that therapy with antibiotics that eliminate normal anaerobic intestinal flora results in overgrowth of vancomycin-resistant enterococci (VRE) in stool samples of colonized patients, whereas therapy with antibiotics with minimal activity against anaerobes does not.11 Patients with high-density stool colonization were more likely to contaminate environmental surfaces with VRE than those with low-density colonization.11 We have also demonstrated that antianaerobic antibiotics promote overgrowth of antimicrobial-resistant gram-negative bacilli in stool samples of mice and patients (Claudia K. Hoyen, MD, Nicole J. Pultz, BS, David L. Paterson, MD, D.C.A., C.J.D., unpublished data, 2002; Anita Bhalla, MD, Nicole J. Pultz, BS, Amy J. Ray, MD, Claudia K. Hoyen, MD, Elizabeth C. Eckstein, RN, C.J.D., unpublished data, 2002). Other investigators have demonstrated that antianaerobic antibiotics promote acquisition and overgrowth of Candida species in stool samples,12,13 with subsequent increased frequency of Candida species colonization at other sites.12 These findings suggest that decreasing the use of antianaerobic antibiotics will limit the density of intestinal colonization with nosocomial pathogens and may reduce the spread of these organisms. We are unaware, however, of previous studies that have examined the utility of minimizing use of antianaerobic agents or that have determined how often such agents are used unnecessarily. Our objectives were to prospectively study unnecessary antimicrobial use in a tertiary care medical center and to test the hypothesis that agents with antianaerobic activity are often used when this spectrum of activity is not required.

METHODS
SETTING

MetroHealth Medical Center is a 650-bed tertiary care hospital in Cleveland, Ohio. The hospital has training programs for residents in internal medicine, family practice, obstetrics and gynecology, and several surgical subspecialties. The Department of Pharmacy provides a pharmacokinetics monitoring service for patients receiving vancomycin or aminoglycosides, and pharmacists are assigned to many of the hospital wards to make antimicrobial recommendations regarding appropriate dosing, potential medication interactions, and potential allergic reactions. A pocket-sized card containing information on antimicrobial dosing, antimicrobial costs, recommendations for empiric therapy, and the hospital's antibiogram is distributed annually to physicians.

STUDY DESIGN

We prospectively examined the necessity of oral and parenteral antimicrobial agents administered to adult inpatients for whom new antimicrobials were prescribed during a 2-week period in August 2001. Study patients were identified through daily review of pharmacy records. The patients were located in 6 medical wards, 3 surgical wards, 1 rehabilitation ward, 1 subacute skilled nursing ward, and 1 obstetric-gynecologic ward. Patients located in intensive care units at the time the new antimicrobials were prescribed were excluded from the study. Information regarding demographics, admitting service and ward, indication for antimicrobial therapy (prophylaxis vs treatment), clinical syndrome being treated, laboratory data, vital signs, radiologic tests, and complications of therapy was obtained through medical record review and recorded on a standardized data collection form. Patients' medical records were reviewed daily during antimicrobial therapy and once again 4 to 6 weeks after completion of therapy to assess whether additional complications associated with therapy had occurred. Patients who were transferred to hospital units other than those listed herein, including intensive care units, were followed up in their new units.

Within 24 hours of the initiation of therapy, one of the study investigators (M.T.H. or C.J.D.) determined whether the antimicrobial regimen was necessary or unnecessary. An antimicrobial regimen was defined as unnecessary if no antimicrobial therapy was indicated for the clinical condition being treated. If an antimicrobial regimen was necessary, additional assessments were made regarding whether all of the components of the regimen were necessary. Components of a regimen were classified as unnecessary if redundant antimicrobials (2 agents with the same spectrum of activity in the absence of an indication for combination therapy) were prescribed, one antimicrobial in a regimen supplied a spectrum of activity that was not indicated, a component of a regimen was continued after culture results demonstrated that it was unnecessary (adjustment of therapy not made in a timely manner), and if the duration of therapy was longer than necessary. Therapy was defined as longer than necessary if the length of therapy exceeded standard recommendations for treatment duration or if the use of empiric antibiotics was continued despite negative evaluations for infectious syndromes and/or a noninfectious condition was demonstrated to be responsible for the clinical syndrome.

The determination of the necessity of a prescribed antimicrobial was based on standard guidelines or principles for diagnosis and treatment of infectious diseases.1630 Standard recommendations for antimicrobial prophylaxis for surgical procedures were used.16 Hospital-acquired infections were defined by the Centers for Disease Control and Prevention criteria.17 Treatment guidelines for hospital-acquired infections were based on Infectious Diseases Society of America (IDSA) and American Thoracic Society (ATS) practice guidelines when available.1820 Diagnostic criteria and treatment guidelines for community-acquired infections were based on IDSA practice guidelines when available.2125 If IDSA or ATS guidelines were not available, diagnostic and treatment recommendations from current textbooks of infectious diseases, other subspecialty textbooks, or published articles were used.2633

We defined antianaerobic antibiotics as agents with potent in vitro activity against anaerobes present in the intestinal tract and/or that have been demonstrated to markedly inhibit intestinal anaerobes in humans.11 Such agents available on the hospital formulary included metronidazole, clindamycin, piperacillin-tazobactam, ceftriaxone, cefotetan, cefoxitin, ampicillin-sulbactam, amoxicillin–clavulanic acid, meropenem, imipenem-cilastatin, and gatifloxacin.

DATA ANALYSIS

Data were analyzed using SPSS statistical software version 10.0 (SPSS Inc, Chicago, Ill). Bivariate analyses were performed to compare necessary and unnecessary treatment regimens. Continuous data were analyzed using unpaired t tests. Categorical data were assessed using the Pearson χ2 test. The costs of the unnecessary antimicrobial therapies were based on average wholesale prices. The antimicrobial costs of the entire course of therapy were calculated, including agents administered during hospitalization and after discharge. The hospital's institutional review board approved the study protocol.

RESULTS

One hundred twenty-nine patients received 153 antimicrobial regimens during the study period (range, 1-3 regimens per patient). Figure 1 summarizes our findings regarding the necessity of antimicrobial therapy. Of 1941 total antimicrobial days of therapy, 576 (30%) were deemed unnecessary. A total of 255 (44%) of the 576 unnecessary days of therapy were attributable to 36 unnecessary antimicrobial regimens. Analysis of the 117 regimens that were necessary revealed that an additional 321 days of therapy were unnecessary. Antianaerobic agents accounted for 203 (35%) of the 576 unnecessary antimicrobial days of therapy. Overall, 75 (58%) of the 129 study patients received at least 1 day of unnecessary antimicrobial therapy, and 44 (34%) received 1 or more days of unnecessary antianaerobic therapy.

Table 1 provides a comparison of the characteristics of patients receiving necessary vs unnecessary regimens. Treatment regimens were unnecessary more frequently than prophylaxis regimens (27% vs 14%), but the difference was not statistically significant (P = .10). Overall, regimens prescribed by internal medicine or family practice physicians were significantly more likely to be unnecessary than those prescribed by surgery or obstetrics-gynecology physicians (30 [32%] of 95 vs 6 [10%] of 58, P = .003). When prophylaxis regimens were excluded from the analysis, the difference between these groups remained significant (P = .047).

Table 2 summarizes the reasons for the unnecessary days of therapy for all antimicrobials and for the subset of agents with antianaerobic activity. The most common reasons for unnecessary therapy included administration of antimicrobials for longer than recommended durations (192 days of therapy), administration of antimicrobials for noninfectious or nonbacterial syndromes (187 days of therapy), and treatment of colonizing or contaminating microorganisms (94 days of therapy). The reasons for unnecessary antianaerobic therapy were similar to the reasons for all unnecessary therapy.

In addition to the 203 days of unnecessary antianaerobic therapy given in Table 2, 98 days of necessary antimicrobial therapy contained antianaerobic activity when an equally efficacious alternative regimen with minimal antianaerobic activity was available. The most common syndromes for which antianaerobic antibiotics were prescribed when the antianaerobic spectrum of activity was not necessary included uncomplicated skin or soft tissue infections (6 patients), urinary tract infections (3 patients), and uncomplicated acute upper or lower respiratory tract infections (5 patients).

Table 3 lists clinical scenarios associated with all of the unnecessary antimicrobial regimens and some of the regimens in which only part of the regimen was unnecessary. Specific examples are provided to illustrate both cases in which standard guidelines were applied and cases in which determinations were based on standard principles of infectious diseases. The most common scenario treated with unnecessary antimicrobials was asymptomatic bacteriuria, 01brenda funguria, or pyuria.

The total average wholesale price of all unnecessary antimicrobials prescribed for the study patients was $14 599.98, corresponding to an estimated yearly average wholesale price of $350 399.52. Table 4 lists the total and unnecessary antimicrobial days of therapy by agent and the costs of the unnecessary doses administered. Ciprofloxacin was the agent that was most often prescribed unnecessarily. An additional $3828 in excess antimicrobial costs were estimated for 23 courses of necessary therapy in which a less expensive but equally effective agent was available or a change from intravenous to oral formulation was not made in a timely manner.

Of the 36 unnecessary antimicrobial treatment regimens, 9 (25%) were associated with complications or adverse effects that were possibly attributable to the therapy. Six patients experienced minor gastrointestinal adverse effects, such as nausea or diarrhea. One patient was noted to have urinary tract colonization with Candida species after completing antimicrobial therapy. One patient developed bacteremia with a multi–drug-resistant strain of Pseudomonas aeruginosa after receiving ciprofloxacin therapy for asymptomatic bacteriuria. One patient was readmitted to the hospital for 2 days when he developed Clostridium difficile colitis after receiving an unnecessary course of piperacillin-tazobactam.

COMMENT

Considerable efforts have been made in recent years to educate physicians and the public about the importance of minimizing the unnecessary use of antimicrobials.58 Despite these efforts, nearly one third of antimicrobial days of therapy prescribed for hospitalized patients in our institution were not necessary. This proportion of unnecessary use is similar to the findings of other investigators in the 1970s.14 Thirty-five percent of the unnecessary antimicrobial days of therapy consisted of agents with potent activity against anaerobes, and these agents were also frequently prescribed when equally efficacious alternatives with minimal antianaerobic activity were available.

The normal anaerobic intestinal flora provide an important host defense by inhibiting growth of potentially pathogenic microorganisms.11,14 As noted previously, antibiotics that eliminate anaerobes have been shown to promote intestinal overgrowth of nosocomial pathogens.1115 Antianaerobic antibiotics have also been associated with VRE bacteremia.34 Studies are needed to determine whether limiting the use of such agents will be an effective means to decrease rates of transmission and infection with nosocomial pathogens that colonize the intestinal tract. Our data suggest that a control program in our institution that minimized all types of unnecessary antimicrobial use would eliminate approximately 60% of the unnecessary use of the antianaerobic spectrum of activity. Substitution of antianaerobic antibiotics with equally efficacious alternatives with minimal antianaerobic activity would further reduce the unnecessary use of this spectrum of activity.

In addition to promoting transmission and infection with nosocomial pathogens, the overuse of antimicrobials in hospitals may have several other adverse implications for patients and health care systems. The unnecessary antimicrobials prescribed in this study added significantly to the direct costs of medical care (Table 4). Indirect costs related to management of adverse effects or complications associated with unnecessary antimicrobial use were not calculated in this study but may also be significant. For example, we did not calculate the costs of C difficile testing in patients who developed antibiotic-associated diarrhea nor did we calculate hospitalization costs for the patient readmitted with C difficile colitis after an unnecessary antimicrobial regimen. Ancillary costs of administering antimicrobials, such as intravenous catheter placements, intravenous tubing, and nursing time, were also not calculated. Finally, acceptance of high rates of unnecessary antimicrobial use in teaching hospitals will contribute to continued unnecessary antimicrobial use among future generations of physicians.

Forty-four percent of the unnecessary days of therapy were due to treatment regimens that were entirely unnecessary. Several common clinical scenarios accounted for most of these unnecessary treatment regimens (Table 3). For example, asymptomatic bacteriuria in elderly patients or individuals with indwelling bladder catheters was often treated with antimicrobials. Asymptomatic bacteriuria occurs frequently in such patients, and randomized trials have demonstrated that antimicrobial therapy provides no benefit.25,32,35 Several patients with noninfectious or nonbacterial upper and lower respiratory tract syndromes received antibacterial therapy. It is likely that even more patients may have received such unnecessary therapy if our study had been performed during the winter respiratory virus season. Interventions targeting the elimination of antimicrobial therapy for the most common scenarios listed in Table 3 would result in significant reductions in unnecessary antimicrobial use. We agree with the recommendation that all hospitals should review antimicrobial use in their institutions to identify their own local patterns of misuse.8

Twenty-seven percent of the unnecessary days of therapy were due to continuation of initially necessary therapy for a longer than required duration. Eighty percent of these unnecessary days of therapy were due to continuation of necessary regimens beyond the durations recommended by standard guidelines. Improving adherence to guidelines for treatment duration would therefore be the most effective means to reduce this type of misuse. The remaining 20% of these unnecessary days of therapy occurred when regimens initiated for suspected infections were continued despite identification of a noninfectious origin or failure to identify any source of infection. Reassessment of the need for antimicrobial therapy after a few days of therapy would be required to reduce this type of misuse. Such reassessments of the necessity and appropriateness of antimicrobial therapy have been effective in reducing antimicrobial costs36,37 and antimicrobial resistance and superinfections in an intensive care unit setting.36

For several reasons, our results probably represent an underestimation of the unnecessary days of therapy and the associated costs and complications. First, unnecessary antimicrobial use is common in intensive care units.36 We did not include patients located in intensive care units at the time antimicrobials were initially prescribed. Second, in some situations experts have differing opinions regarding whether antimicrobial therapy is indicated. In such cases, we classified therapy as necessary. Third, standard guidelines for therapy often provide a range of appropriate durations (eg, 4-6 weeks for treatment of osteomyelitis or endocarditis), and we considered antimicrobials to be necessary as long as they fell within these ranges. Clinicians often choose the longer duration of therapy when given such an option (M.T.H., D.C.A., N.P.P., M.K.L., C.J.D., unpublished data, 2002). Fourth, the potential cost savings that might have been realized if less expensive, equally efficacious agents were chosen or if more timely conversions from parenteral to oral formulations had occurred are not shown in Table 4; we estimated additional excess costs of $3828 that were attributable to such factors. Finally, we included only complications that were associated with unnecessary regimens, not those that might have been related to longer than necessary or redundant therapy. Studies that include interventions to limit unnecessary use of antibiotics are needed to provide a more accurate assessment of the effect of unnecessary antimicrobials on clinical and economic outcomes.

Further studies are needed to determine the reasons why physicians prescribe unnecessary antimicrobials for hospitalized patients. Patients' demands for antimicrobials are often cited as a reason for unnecessary prescriptions in the outpatient setting,21 but such demands were unlikely to motivate much of the unnecessary use that we observed (eg, asymptomatic bacteriuria). Possible reasons suggested for excessive antimicrobial use in hospitals include the acutely ill and complex status of patients, diagnostic uncertainty, pressure to keep lengths of stay short, and prescribing by clinically inexperienced physicians, as in teaching hospitals.38 Most of the unnecessary antimicrobials administered during this study did not seem to involve complex decision making for severely ill patients, as might have been seen if we had included patients located in intensive care units at the time antimicrobials were prescribed. Another possible reason for excessive antimicrobial use is that physicians may lack a full appreciation of the frequency with which antimicrobial therapy is associated with adverse effects, not only for the individual patient but also for the broader microbiologic environment. They may, therefore, have a low threshold to give antimicrobials, because they believe that these agents are unlikely to cause harm.

Our study has several limitations. We studied only one teaching hospital during a 2-week period. Although our findings may not be applicable to institutions with intensive antimicrobial control programs, many hospitals lack such programs. Antimicrobial use in teaching hospitals may differ from nonteaching hospitals; however, previous studies have also documented high rates of inappropriate antimicrobial use in nonteaching hospitals.4 Because the categorization of therapy as necessary or unnecessary was based solely on information available in the medical records, some necessary regimens may have been misclassified as unnecessary due to inadequate documentation of the reasons for therapy. However, it is also possible that a greater number of unnecessary regimens might have been identified if we had interviewed and examined patients.

In summary, antimicrobials and their antianaerobic spectrum of activity were frequently used unnecessarily in a tertiary care medical center. We identified several common clinical scenarios associated with unnecessary antimicrobial use that may be amenable to intervention. Further studies are needed to determine if limiting the unnecessary use of antianaerobic antimicrobials will be effective as a control measure for nosocomial pathogens that colonize the intestinal tract.

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Article Information

Corresponding author and reprints: Curtis J. Donskey, MD, Infectious Diseases Section, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, 10701 East Blvd, Cleveland, OH 44106 (e-mail: curtisd123@yahoo.com).

Accepted for publication July 29, 2002.

This study was supported by a Career Development Award grant to Dr Donskey from the Department of Veterans Affairs, Washington, DC.

References
1.
Maki  DGSchuna  AA A study of antimicrobial misuse in a university hospital. Am J Med Sci. 1978;275271- 281Article
2.
Castle  MWilfert  CMCate  TROsterhout  S Antibiotic use at Duke University Medical Center. JAMA. 1977;2372819- 2822Article
3.
Kunin  CMTupasi  TCraig  WA Use of antibiotics: a brief exposition of the problem and some tentative solutions. Ann Intern Med. 1973;79555- 560Article
4.
Scheckler  WEBennett  JV Antibiotic usage in seven community hospitals. JAMA. 1970;213264- 267Article
5.
Kunin  CM The responsibility of the infectious disease community for the optimal use of antimicrobial agents. J Infect Dis. 1985;151388- 398Article
6.
Schwartz  BBell  DMHughes  JM Preventing the emergence of antimicrobial resistance: a call for action by clinicians, public health officials, and patients. JAMA. 1997;278944- 945Article
7.
McGowan  JE Do intensive antibiotic control programs prevent the spread of antibiotic resistance? Infect Control Hosp Epidemiol. 1994;15478- 483Article
8.
Goldmann  DAWeinstein  RAWenzel  RP  et al.  Strategies to prevent and control the emergence and spread of antimicrobial-resistant microorganisms in hospitals: a challenge to hospital leadership. JAMA. 1996;275234- 240Article
9.
Dunagan  WCWoodward  RSMedoff  G  et al.  Antibiotic misuse in two clinical situations: positive blood cultures and administration of aminoglycosides. Rev Infect Dis. 1991;13405- 412Article
10.
Lee  KRLeggiadro  RJBurch  KJ Drug use evaluation of antibiotics in a pediatric teaching hospital. Infect Control Hosp Epidemiol. 1994;15710- 712Article
11.
Donskey  CJChowdhry  TKHecker  MT  et al.  Effect of antibiotic therapy on the density of vancomycin-resistant enterococci in the stool of colonized patients. N Engl J Med. 2000;3431925- 1932Article
12.
Louie  TJ Preservation of colonization resistance parameters during empiric therapy with aztreonam in the febrile neutropenic patient. Rev Infect Dis. 1985;7(suppl 4)S747- S761Article
13.
Samonis  GGikas  AAnaissie  EJ  et al.  Prospective evaluation of effects of broad-spectrum antibiotics on gastrointestinal yeast colonization of humans. Antimicrob Agents Chemother. 1993;3751- 53Article
14.
Vollaard  EJClasener  HAL Colonization resistance. Antimicrob Agents Chemother. 1994;38409- 414Article
15.
Wilson  KH The microecology of Clostridium difficileClin Infect Dis. 1993;16(suppl 4)S214- S218Article
16.
Kernodle  DSKaiser  AB Postoperative infections and antimicrobial prophylaxis. Mandell  GLBennett  JEDolin  Reds.Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 5th ed. New York, NY Churchill Livingstone2000;3177- 3191
17.
Garner  JSJarvis  WREmori  TG  et al.  CDC definitions for nosocomial infections. Olmsted  RNed.APIC Infection Control and Applied Epidemiology: Principles and Practice. St Louis, Mo Mosby1996;A1- A20
18.
American Thoracic Society, Hospital-acquired pneumonia in adults: diagnosis, assessment of severity, initial antimicrobial therapy, and preventative strategies: a consensus statement. Am J Respir Crit Care Med. 1996;1531711- 1725Article
19.
Gross  PABarrett  TLDellinger  EP  et al.  Quality standards for the treatment of bacteremia. Clin Infect Dis. 1994;18428- 430Article
20.
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