Increased Mortality Rates Associated with Staphylococcus aureus and Influenza Co-infection, Maryland and Iowa, USA(1)

We retrospectively analyzed data for 195 respiratory infection patients who had positive Staphyloccocus aureus cultures and who were hospitalized in 2 hospitals in Iowa and Maryland, USA, during 2003-2009. Odds for death for patients who also had influenza-positive test results were >4 times higher than for those who had negative influenza test results.

Infection prevention strategies for procedures performed outside operating rooms: A conceptual integrated model

No comprehensive guidelines or classification exist for infection prevention strategies for medical procedures performed outside operating rooms. We reviewed the available literature and used our clinical experience to develop a progressive, 5-tiered classification of procedures, encompassing clean, aseptic, sterile-superficial, sterile-invasive, and surgical-like procedures to address this need. We provide a description of these categories, along with relevant examples. We fully acknowledge the limitations of our work, which is intended as a starting point for future efforts and not to be definitive.

Association of Evidence-Based Care Processes With Mortality in Staphylococcus aureus Bacteremia at Veterans Health Administration Hospitals, 2003-2014

IMPORTANCE

Staphylococcus aureus bacteremia is common and frequently associated with poor outcomes. Evidence indicates that specific care processes are associated with improved outcomes for patients with S aureus bacteremia, including appropriate antibiotic prescribing, use of echocardiography to identify endocarditis, and consultation with infectious diseases (ID) specialists. Whether use of these care processes has increased in routine care for S aureus bacteremia or whether use of these processes has led to large-scale improvements in survival is unknown.

OBJECTIVE

To examine the association of evidence-based care processes in routine care for S aureus bacteremia with mortality.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective observational cohort study examined all patients admitted to Veterans Health Administration (VHA) acute care hospitals who had a first episode of S aureus bacteremia from January 1, 2003, through December 31, 2014.

EXPOSURES

Use of appropriate antibiotic therapy, echocardiography, and ID consultation.

MAIN OUTCOMES AND MEASURES

Thirty-day all-cause mortality.

RESULTS

Analyses included 36 868 patients in 124 hospitals (mean [SD] age, 66.4 [12.5] years; 36 036 [97.7%] male), including 19 325 (52.4%) with infection due to methicillin-resistant S aureus and 17 543 (47.6%) with infection due to methicillin-susceptible S aureus. Risk-adjusted mortality decreased from 23.5% (95% CI, 23.3%-23.8%) in 2003 to 18.2% (95% CI, 17.9%-18.5%) in 2014. Rates of appropriate antibiotic prescribing increased from 2467 (66.4%) to 1991 (78.9%), echocardiography from 1256 (33.8%) to 1837 (72.8%), and ID consultation from 1390 (37.4%) to 1717 (68.0%). After adjustment for patient characteristics, cohort year, and other care processes, receipt of care processes was associated with lower mortality, with adjusted odds ratios of 0.74 (95% CI, 0.68-0.79) for appropriate antibiotics, 0.73 (95% CI, 0.68-0.78) for echocardiography, and 0.61 (95% CI, 0.56-0.65) for ID consultation. Mortality decreased progressively as the number of care processes that a patient received increased (adjusted odds ratio for all 3 processes compared with none, 0.33; 95% CI, 0.30-0.36). An estimated 57.3% (95% CI, 48.4%-69.9%) of the decrease in mortality between 2003 and 2014 could be attributed to increased use of these evidence-based care processes.

CONCLUSIONS AND RELEVANCE

Mortality associated with S aureus bacteremia decreased significantly in VHA hospitals, and a substantial portion of the decreasing mortality may have been attributable to increased use of evidence-based care processes. The experience in VHA hospitals demonstrates that increasing application of these care processes may improve survival among patients with S aureus bacteremia in routine health care settings.

Descriptive Epidemiology and Case-Control Study of Patients Colonized With Vancomycin-Resistant Enterococcus and Methicillin-ResistantStaphylococcus aureus

Background.

Patients colonized or infected with vancomycin-resistant enterococcus and methicillin-resistantStaphylococcus aureusmay be at risk of acquiring vancomycin-resistantS. aureusif the vanA gene is transferred from vancomycin-resistant enterococcus to methicillin-resistantS. aureus..

Objective.

Our goal was to identify risk factors for cocolonization or coinfection (CC/CI) with vancomycin-resistant enterococcus and methicillin-resistantS. aureus.

Design.

We conducted a descriptive, epidemiologic study of all patients with CC/CI identified from January 1998 to May 2003 and a nested case-control study of a cohort of patients hospitalized in the burn and wound unit.

Setting.

We conducted our study in a 813-bed tertiary care university teaching hospital.

Population.

The study population consisted of patients found to have CC/CI during the study period.

Methods.

Descriptive epidemiologic data were collected from hospital records of all patients identified as having CC/CI. A subset of patients hospitalized in the burn and wound unit were included in a case-control study.

Results.

CC/CI was detected in 71% of the patients during a single hospital stay. The burn and wound unit, which does active surveillance for both organisms, and the general medicine unit, which does not do active surveillance for either organism, cared for more than one-half of these patients. Among patients being cared for in the burn and wound unit, having exposure to 2 or more invasive devices (central venous catheters, indwelling urinary catheters, and enteral feeding tubes) and renal insufficiency were independent risk factors for CC/CI.

Conclusions.

Patients with CC/CI are the population at greatest risk for vancomycin-resistantS. aureuscolonization or infection. The number of invasive devices to which patients are exposed and, thus, possibly the patients' underlying severity of illness, as well as renal insufficiency, appear to be risk factors for CC/CI.

Epidemiology of Methicillin-ResistantStaphylococcus aureusand Vancomycin-ResistantEnterococcusin a Rural State

Background.

Most data on methicillin-resistantStaphylococcus aureus(MRSA) and vancomycin-resistant Enterococcus (VRE) isolates come from large tertiary care centers. Infection control personnel need to understand the epidemiology of MRSA and VRE across the continuum of care, including small rural hospitals, to develop effective control strategies.

Objective.

To describe the epidemiology of MRSA and VRE in Iowa.

Setting.

Fifteen hospitals in Iowa.

Methods.

Between July 1998 and June 2001, a total of 1,968S. aureusisolates and 1,845Enterococcusisolates from patients infected with these pathogens were examined. Multivariate models were developed to evaluate patient and institutional risk factors for MRSA infection and VRE infection.

Results.

The proportion ofS. aureusisolates resistant to methicillin was 31%, and the proportion ofEnterococcusisolates resistant to vancomycin was 6%. Independent risk factors for MRSA infection included residence in a long-term care facility, age of more than 60 years, hospitalization in a hospital with less than 200 short-term care beds, and acquiring the infection in the hospital. Independent risk factors for VRE infection included use of a central venous catheter, residence in a long-term care facility, acquisition of infection in the hospital, and hospitalization in a hospital with more than 200 short-term care beds.

Conclusions.

In Iowa, the epidemiology of MRSA differ from those of VRE. MRSA has become established in small rural hospitals. Effective MRSA control strategies may require inclusion of all hospitals in a state or region.

Antimicrobial Use Control Measures to Prevent and Control Antimicrobial Resistance in US Hospitals

Objective.

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.

Design.

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

Methods.

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.

Results.

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.

Conclusions.

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.

Determining the Clinical Significance of Coagulase-Negative Staphylococci Isolated From Blood Cultures

Background and Objective:

Coagulase-negative staphylococci are both an important cause of nosocomial bloodstream infections and the most common contaminants of blood cultures. Judging the clinical significance of coagulase-negative staphylococci is vital but often difficult and can have a profound impact on an institution's bloodstream infection rates. Our objective was to develop an algorithm to assist in determining the clinical significance of coagulase-negative staphylococci.

Design:

A single experienced reviewer examined the medical records of 960 consecutive patients with positive blood cultures in a tertiary-care referral teaching hospital. Four hundred five of the cultures contained coagulase-negative staphylococci. A determination of clinical significance was made and the performances of various published algorithms that contained readily available clinical and laboratory data were compared.

Results:

Eighty-nine (22%) of the episodes were considered significant, whereas 316 were contaminants. Patients with bacteremia were significantly more likely to be neutropenic and exhibit signs of sepsis syndrome. The algorithm with the best combined sensitivity (62%) and specificity (91%) for determining the clinical significance of coagulase-negative staphylococci was defined as at least two blood cultures positive for coagulase-negative staphylococci within 5 days, or one positive blood culture plus clinical evidence of infection, which includes abnormal white blood cell count and temperature or blood pressure.

Conclusion:

Use of this algorithm could potentially reduce misclassification of nosocomial bloodstream infections and inappropriate use of vancomycin for positive blood cultures likely to represent contamination (Infect Control Hosp Epidemiol2005;26:559-566).

Variation in the Use of Procedures to Monitor Antimicrobial Resistance in U.S. Hospitals

Background:

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.

Objective:

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.

Methods:

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.

Results:

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).

Conclusion:

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.

Risk Factors for Groin Wound Infection After Femoral Artery Catheterization A Case-Control Study

Objective.

Groin wound infection (GWI) after femoral artery catheterization is unusual. However, several reports of GWI associated with the use of a Perclose device appear in the surgical literature.

Design.

A case-control study.

Setting.

We pooled 23 cases and 83 controls from a university hospital and a community medical center.

Patients.

A case was defined as a patient who developed a GWI after a femoral artery catheterization. At the university hospital, 3 controls were randomly selected from the at-risk population and matched to each case by time of procedure only (within 2 weeks). At the community medical center, 4 controls were selected and matched to each case by time of procedure (within 2 weeks), sex, and age (within 5 years).

Results.

We considered several covariates, including age, sex, body mass index, medical conditions, Perclose use, hematoma formation, and antithrombotic therapy. In a multivariate model, only hematoma formation (odds ratio, 68.8; 95% confidence interval, 12.1-391.4) and glycoprotein IIb/IIIa platelet inhibitor therapy (odds ratio, 6.1; 95% confidence interval, 1.1-33.6) were statistically significant predictors of GWI; Perclose use (odds ratio, 0.9; 95% confidence interval, 0.2-3.7) was not a statistically significant predictor of GWI. However, most of the hematomas (15/17) formed after procedures during which a Perclose device was used.

Conclusion.

Perclose use did not have any additional effect on GWI risk beyond the effect that hematoma formation had.

Importance of Control Group Selection for Evaluating Antimicrobial Use as a Risk Factor for Methicillin-ResistantStaphylococcus AureusBacteremia

Objective:

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

Methods:

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-susceptibleS. 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.

Results:

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 andP= .015, respectively). However, all measures of fluoroquinolone use were similar for case-patients and for control-patients who did not have nosocomial bloodstream infection.

Conclusions:

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)

Association between microbial characteristics and poor outcomes among patients with methicillin-resistant Staphylococcus aureus pneumonia: a retrospective cohort study

Background

Methicillin-resistant S. aureus (MRSA) pneumonia is associated with poor clinical outcomes. This study examined the association between microbial characteristics and poor outcomes among patients with methicillin-resistant Staphylococcus aureus pneumonia.

Findings

This retrospective cohort study included 75 patients with MRSA pneumonia who were admitted to two large tertiary care medical centers during 2003–2010. Multivariable models were created using Cox proportional hazards regression and ordinal logistic regression to identify predictors of mortality or increased length of stay (LOS). None of the microbial characteristics (PFGE type, agr dysfunction, SCCmec type, and detection of PVL, ACME, and TSST-1) were significantly associated with 30-day mortality or post-infection hospital length of stay, after adjusting for gender, age, previous hospital admission within 12 months, previous MRSA infection or colonization, positive influenza test, Charlson Comorbidity Index score, and treatment (linezolid or vancomycin).

Conclusion

Large prospective studies are needed to examine the impact of microbial characteristics on the risk of death and other adverse outcomes among patients with MRSA pneumonia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13756-015-0092-1) contains supplementary material, which is available to authorized users.

Novel Staphylococcus aureus Secreted Protein Alters Keratinocyte Proliferation and Elicits a Proinflammatory Response In Vitro and In Vivo

Staphylococcus aureus is a leading cause of surgical site infections that results in increased hospital stays due to the development of chronic wounds. Little is known about factors involved in S. aureus' ability to prevent wounds from healing. We discovered a novel secreted protein produced by a surgical site isolate of S. aureus that prevents keratinocyte proliferation. The protein has a molecular weight of 15.7 kDa and an isoelectric point of 8.9. The cloned and purified protein has cytotoxic and proinflammatory properties, as shown in vitro and in vivo. Potent biological effects on keratinocytes and rabbit skin suggest that this protein may play an important role in preventing re-epithelialization. Its lack of homology to known exotoxins suggests that this protein is novel, and this observation is likely to open a new field of research in S. aureus exotoxins. Due to its cytotoxic activities, we call this new protein ε-cytotoxin.

Association of a bundled intervention with surgical site infections among patients undergoing cardiac, hip, or knee surgery

IMPORTANCE

Previous studies suggested that a bundled intervention was associated with lower rates of Staphylococcus aureus surgical site infections (SSIs) among patients having cardiac or orthopedic operations.

OBJECTIVE

To evaluate whether the implementation of an evidence-based bundle is associated with a lower risk of S. aureus SSIs in patients undergoing cardiac operations or hip or knee arthroplasties.

DESIGN, SETTING, AND PARTICIPANTS

Twenty hospitals in 9 US states participated in this pragmatic study; rates of SSIs were collected for a median of 39 months (range, 39-43) during the preintervention period (March 1, 2009, to intervention) and a median of 21 months (range, 14-22) during the intervention period (from intervention start through March 31, 2014).

INTERVENTIONS

Patients whose preoperative nares screens were positive for methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus (MSSA) were asked to apply mupirocin intranasally twice daily for up to 5 days and to bathe daily with chlorhexidine-gluconate (CHG) for up to 5 days before their operations. MRSA carriers received vancomycin and cefazolin or cefuroxime for perioperative prophylaxis; all others received cefazolin or cefuroxime. Patients who were MRSA-negative and MSSA-negative bathed with CHG the night before and morning of their operations. Patients were treated as MRSA-positive if screening results were unknown.

MAIN OUTCOMES AND MEASURES

The primary outcome was complex (deep incisional or organ space) S. aureus SSIs. Monthly SSI counts were analyzed using Poisson regression analysis.

RESULTS

After a 3-month phase-in period, bundle adherence was 83% (39% full adherence; 44% partial adherence). Overall, 101 complex S. aureus SSIs occurred after 28,218 operations during the preintervention period and 29 occurred after 14,316 operations during the intervention period (mean rate per 10,000 operations, 36 for preintervention period vs 21 for intervention period, difference, -15 [95% CI, -35 to -2]; rate ratio [RR], 0.58 [95% CI, 0.37 to 0.92]). The rates of complex S. aureus SSIs decreased for hip or knee arthroplasties (difference per 10,000 operations, -17 [95% CI, -39 to 0]; RR, 0.48 [95% CI, 0.29 to 0.80]) and for cardiac operations (difference per 10,000 operations, -6 [95% CI, -48 to 8]; RR, 0.86 [95% CI, 0.47 to 1.57]).

CONCLUSIONS AND RELEVANCE

In this multicenter study, a bundle comprising S. aureus screening, decolonization, and targeted prophylaxis was associated with a modest, statistically significant decrease in complex S. aureus SSIs.

Comparative effectiveness of beta-lactams versus vancomycin for treatment of methicillin-susceptible Staphylococcus aureus bloodstream infections among 122 hospitals

BACKGROUND

Previous studies indicate that vancomycin is inferior to beta-lactams for treatment of methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream infections. However, it is unclear if this association is true for empiric and definitive therapy. Here, we compared beta-lactams with vancomycin for empiric and definitive therapy of MSSA bloodstream infections among patients admitted to 122 hospitals.

METHODS

This retrospective cohort study included all patients admitted to Veterans Affairs hospitals from 2003 to 2010 who had positive blood cultures for MSSA. Hazard ratios (HR) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression. Empiric therapy was defined as starting treatment 2 days before and up to 4 days after the first MSSA blood culture was collected. Definitive therapy was defined as starting treatment between 4 and 14 days after the first positive blood culture was collected.

RESULTS

Patients who received empiric therapy with a beta-lactam had similar mortality compared with those who received vancomycin (HR, 1.03; 95% CI, .89-1.20) after adjusting for other factors. However, patients who received definitive therapy with a beta-lactam had 35% lower mortality compared with patients who received vancomycin (HR, 0.65; 95% CI, .52-.80) after controlling for other factors. The hazard of mortality decreased further for patients who received cefazolin or antistaphylococcal penicillins compared with vancomycin (HR, 0.57; 95% CI, .46-.71).

CONCLUSIONS

For patients with MSSA bloodstream infections, beta-lactams are superior to vancomycin for definitive therapy but not for empiric treatment. Patients should receive beta-lactams for definitive therapy, specifically antistaphylococcal penicillins or cefazolin.

Wide Variability in the Use of Antimicrobial Lock Therapy and Prophylaxis among Infectious Diseases Consultants

We surveyed infectious diseases physicians to determine their practice patterns with regard to both antimicrobial lock prophylaxis and antimicrobial lock therapy. Antimicrobial lock prophylaxis is relatively uncommon; only 19% of infectious diseases physicians reported using it at least once. Although antimicrobial lock therapy is more commonly used, we found a significant variation in practice patterns.

Diagnosing and Reporting of Central Line–Associated Bloodstream Infections

Background.

The diagnosis of central line-associated bloodstream infections (CLABSIs) is often controversial, and existing guidelines differ in important ways.

Objective.

To determine both the range of practices involved in obtaining blood culture samples and how central line-associated infections are diagnosed and to obtain members' opinions regarding the process of designating bloodstream infections as publicly reportable CLABSIs.

Design.

Electronic and paper 11-question survey of infectious-diseases physician members of the Infectious Diseases Society of America Emerging Infections Network (IDSA EIN).

Participants.

All 1,364 IDSA EIN members were invited to participate.

Results.

692 (51%) members responded; 52% of respondents with adult practices reported that more than half of the blood culture samples for intensive care unit (ICU) patients with central lines were drawn through existing lines. A sizable majority of respondents used time to positivity, differential time to positivity when paired blood cultures are used, and quantitative culture of catheter tips when diagnosing CLABSI or determining the source of that bacteremia. When determining whether a bacteremia met the reportable CLABSI definition, a majority used a decision method that involved clinical judgment.

Conclusions.

Our survey documents a strong preference for drawing 1 set of blood culture samples from a peripheral line and 1 from the central line when evaluating fever in an ICU patient, as recommended by IDSA guidelines and in contrast to current Centers for Disease Control and Prevention recommendations. Our data show substantial variability when infectious-diseases physicians were asked to determine whether bloodstream infections were primary bacteremias, and therefore subject to public reporting by National Healthcare Safety Network guidelines, or secondary bacteremias, which are not reportable.

Evaluation of Postprescription Review and Feedback as a Method of Promoting Rational Antimicrobial Use: A Multicenter Intervention

Objective.

To evaluate the impact of postprescription review of broad-spectrum antimicrobial (study-ABX) agents on rates of antimicrobial use.

Design.

Quasi-experimental before-after study.

Setting.

Five academic medical centers.

Patients.

Adults receiving at least 48 hours of study-ABX.

Methods.

The baseline, intervention, and follow-up periods were 6 months each in 2 units at each of 5 sites. Adults receiving at least 48 hours of study-ABX entered the cohort as case-patients. During the intervention, infectious-diseases physicians reviewed the cases after 48 hours of study-ABX. The provider was contacted with alternative recommendations if antimicrobial use was considered to be unjustified on the basis of predetermined criteria. Acceptance rates were assessed 48 hours later. The primary outcome measure was days of study-ABX per 1,000 study-patient-days in the baseline and intervention periods.

Results.

There were 1,265 patients in the baseline period and 1,163 patients in the intervention period. Study-ABX use decreased significantly during the intervention period at 2 sites: from 574.4 to 533.8 study-ABX days/1,000 patient-days (incidence rate ratio [IRR], 0.93; 95% confidence interval [CI], 0.88-0.97; P = .002) at hospital В and from 615.6 to 514.4 study-ABX days/1,000 patient-days (IRR, 0.83; 95% CI, 0.79-0.88; P < .001) at hospital D. Both had established antimicrobial stewardship programs (ASP). Study-ABX use increased at 2 sites and stayed the same at 1 site. At all institutions combined, 390 of 1,429 (27.3%) study-ABX courses were assessed as unjustified; recommendations to modify or stop therapy were accepted for 260 (66.7%) of these courses.

Conclusions.

Postprescription review of study-ABX decreased antimicrobial utilization in some of the study hospitals and may be more effective when performed as part of an established ASP.