Clinical practice guidelines and recommended practices to control use of antibiotics have been published, but the effect of these practices on antimicrobial resistance (AMR) rates in hospitals is unknown. The objective of this study was to examine relationships between antimicrobial use control strategies and AMR rates in a national sample of US hospitals.

Cross-sectional, stratified study of a nationally representative sample of US hospitals.

A survey instrument was sent to the person responsible for infection control at a sample of 670 US hospitals. The outcome was current prevalences of 4 epidemiologically important, drug-resistant pathogens, considered concurrently: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci, ceftazidime-resistant Klebsiella species, and quinolone (ciprofloxacin)-resistant Escherichia coli Five independent variables regarding hospital practices were selected from the survey: the extent to which hospitals (1) implement practices recommended in clinical practice guidelines and ensure best practices for antimicrobial use, (2) disseminate information on clinical practice guidelines for antimicrobial use, (3) use antimicrobial-related information technology, (4) use decision support tools, and (5) communicate to prescribers about antimicrobial use. Control variables included the hospitals' number of beds, teaching status, Veterans Affairs status, geographic region, and number of long-term care beds; and the presence of an intensive care unit, a burn unit, or transplant services. A generalized estimating equation modeled all resistance rates simultaneously to identify overall predictors of AMR levels at the facility.

Completed survey instruments were returned by 448 hospitals (67%). Four antimicrobial control measures were associated with higher prevalence of AMR. Implementation of recommended practices for antimicrobial use (P< .01) and optimization of the duration of empirical antibiotic prophylaxis (P<.01) were associated with a lower prevalence of AMR. Use of restrictive formularies (P = .05) and dissemination of clinical practice guideline information (P<.01) were associated with higher prevalence of AMR. Number of beds and Veterans Affairs status were also associated with higher AMR rates overall.

Implementation of guideline-recommended practices to control antimicrobial use and optimize the duration of empirical therapy appears to help control AMR rates in US hospitals. A longitudinal study would confirm the results of this cross-sectional study. These results highlight the need for systems interventions and reengineering to ensure more-consistent application of guideline-recommended measures for antimicrobial use.

We investigated the importance of control group selection during an evaluation of antimicrobial use as a risk factor for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia at our institution.

We performed a case-control study. A case was defined as any patient admitted between January 1997 and May 2001 who developed nosocomial MRSA bacteremia. We used two control groups; control group I consisted of patients with nosocomial methicillin-susceptible S. aureus (MSSA) bacteremia and control group II included only patients without bacteremia. We matched control-patients to case-patients using age, gender, time at risk, and hospital ward. Data collected on all patients included demographics, comorbidities, antibiotic use, time at risk, length of stay, severity of illness, and outcome.

We evaluated 63 patients (21 in each group). The three groups were well matched regarding age, gender, underlying diseases, and severity of illness. Patients in the MRSA group were more likely to have received a fluoroquinolone and had a higher mean number of days of fluoroquinolone use than did patients in the MSSA group (P = .027 and P = .015, respectively). However, all measures of fluoroquinolone use were similar for case-patients and for control-patients who did not have nosocomial bloodstream infection.

Control group selection is important in evaluating antimicrobial use as a risk factor for MRSA bacteremia. Using control-patients infected with MSSA, rather than uninfected control-patients, may overestimate the association between antimicrobial use and MRSA infection. (Infect Control Hosp Epidemiol 2005;26:634-637)

Antimicrobial resistance is a growing clinical and public health crisis. Experts have recommended measures to monitor antimicrobial resistance; however, little is known regarding their use.

We describe the use of procedures to detect and report antimicrobial resistance in U.S. hospitals and the organizational and epidemiologic factors associated with their use.

In 2001, we surveyed laboratory directors (n = 108) from a random national sample of hospitals. We studied five procedures to monitor antimicrobial resistance: (1) disseminating antibiograms to physicians at least annually, (2) notifying physicians of antimicrobial-resistant infections, (3) reporting susceptibility results within 24 hours, (4) using automated testing procedures, and (5) offering molecular typing. Explanatory variables included organizational characteristics and patterns of antimicrobial resistance for oxacillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, quinolone-resistant Escherichia coli, and extended-spectrum beta-lactamase-producing Klebsiella species. Generalized estimating equations accounting for the correlation among outcomes at the facility level were used to identify predictors of the five outcomes.

Use of the procedures ranged from 85% (automated testing) to 33% (offering molecular typing) and was related to teaching hospital status (OR, 3.1; CI95, 1.5–6.5), participation of laboratory directors on the infection control committee (OR, 1.7; CI95, 1.1–2.8), and having at least one antimicrobial-resistant pathogen with a prevalence greater than 10% (OR, 2.2; CI95, 1.4–3.3).

U.S. hospitals underutilize procedures to monitor the spread of antimicrobial resistance. Use of these procedures varies and is related to organizational and epidemiologic factors. Further efforts are needed to increase their use by hospitals.