Evaluate the evidence for effects of inpatient antimicrobial stewardship programs (ASPs) on patient, prescribing, and microbial outcomes.

Systematic review.

Search of MEDLINE (2000 through November 2013), Cochrane Library, and reference lists of relevant studies. We included English language studies with patient populations relevant to the United States (ie, infectious conditions and prescriptions required for antimicrobials) that evaluated ASP interventions and reported outcomes of interest. Study characteristics and outcomes data were extracted and reviewed by investigators and trained research personnel.

Few intervention types (eg, audit and feedback, guideline implementation, and decision support) substantially impacted patient outcomes, including mortality, length of stay, readmission, or incidence of Clostridium difficile infection. However, most interventions were not powered adequately to demonstrate impacts on patient outcomes. Most interventions were associated with improved prescribing patterns as measured by decreased antimicrobial use or increased appropriate use. Where reported, ASPs were generally associated with improvements in microbial outcomes, including institutional resistance patterns or resistance in the study population. Few data were provided on harms, sustainability, or key intervention components. Studies were typically of short duration, low in methodological quality, and varied in study design, populations enrolled, hospital setting, ASP intent, intervention composition and implementation, comparison group, and outcomes assessed.

Numerous studies suggest that ASPs can improve prescribing and microbial outcomes. Strength of evidence was low, and most studies were not designed adequately to detect improvements in mortality or other patient outcomes, but obvious adverse effects on patient outcomes were not reported.

Overutilization of antimicrobial therapy places patients at risk for harm and contributes to antimicrobial resistance and escalating healthcare costs. Focusing on redundant or duplicate antimicrobial therapy is 1 recommended strategy to reduce overutilization and its attendant effects on patient safety and hospital costs

This study explored the incidence and economic impact of potentially redundant antimicrobial therapy.

We conducted a retrospective analysis of inpatient administrative data drawn from 505 nonfederal US hospitals. All hospitalized patients discharged between January 1, 2008, and December 31, 2011, were eligible for study inclusion. Potentially redundant antimicrobial therapy was identified from pharmacy records and was defined as patients receiving treatment with overlapping antibiotic spectra for 2 or more consecutive days.

We found evidence of potentially inappropriate, redundant antimicrobial coverage for 23 different antimicrobial combinations in 394 of the 505 (78%) hospitals, representing a total of 32,507 cases. High-frequency redundancies were observed in 3 antianaerobic regimens, accounting for 22,701 (70%) of the cases. Of these, metronidazole and piperacillin-tazobactam accounted for 53% (n = 17,326) of all potentially redundant cases. Days of redundant therapy totaled 148,589, representing greater than $12 million in potentially avoidable healthcare costs.

Our study suggests that there may be pervasive use of redundant antimicrobial therapy within US hospitals. Appropriate use of antimicrobials may reduce the risk of harm to patients and lower healthcare costs.

Appropriate use of antimicrobials for surgical prophylaxis is an important patient safety issue. Antimicrobial levels should be present during the duration of the surgical procedure until incision site closure. For prolonged surgical procedures in which the tissue concentration of the prophylactic antimicrobial may decrease to below the necessary minimum inhibitory concentration, intraoperative redosing of antimicrobials may be crucial

To evaluate compliance of appropriate intraoperative antimicrobial surgical prophylaxis using real-time intraoperative antimicrobial dosing reminders at a large teaching hospital.

A retrospective review of electronic records (March 2009–October 2012) was performed. Patients were included if they were at least 18 years of age and underwent a procedure requiring antimicrobial surgical prophylaxis. Compliance was determined by comparing 3 time intervals: baseline (March 2009–March 2010); intervention period 1 (IP-1; April 1, 2010–April 30, 2012), and intervention period 2 (IP-2; May 1, 2012–October 31, 2012). Interventions included a hospital-wide standardized protocol comprising an automated intraoperative paging system to notify when antimicrobials should be redosed.

A total of 7,461 of 75,230 surgical procedures required intraoperative redosing of antimicrobials and were analyzed. Patient mean age (± standard deviation) was 45 ± 19 years, and 62.6% were female. The most common procedures that required prophylaxis were solid organ transplantation, neurosurgical procedures, and orthopedic procedures. Baseline compliance (n = 2,183) was 15.8%; compliance significantly improved to 65.3% during IP-1 (n = 4,486; P < .001). The compliance rate improved to 76.7% during IP-2 (P > .001 compared with no reminder).

Compliance with redosing of intraoperative antimicrobials was improved with the combined approach of guidelines, education to healthcare providers, and real-time automated paging system.

Hospitalizations for acute bacterial skin and skin structure infection (ABSSSI) are common. Optimizing antibiotic use for ABSSSIs requires an understanding of current management. The objective of this study was to evaluate antibiotic prescribing practices and factors affecting prescribing in a diverse group of hospitals

Multicenter, retrospective cohort study.

Seven community and academic hospitals.

Children and adults hospitalized between June 2010 and May 2012 for cellulitis, wound infection, or cutaneous abscess were eligible. The primary endpoint was a composite of 2 prescribing practices representing potentially avoidable antibiotic exposure: (1) use of antibiotics with a broad spectrum of activity against gram-negative bacteria or (2) treatment duration greater than 10 days.

A total of 533 cases were included: 320 with nonpurulent cellulitis, 44 with wound infection or purulent cellulitis, and 169 with abscess. Of 492 cases with complete prescribing data, the primary endpoint occurred in 394 (80%) cases and varied significantly across hospitals (64%–97%; P < .001). By logistic regression, independent predictors of the primary endpoint included wound infection or purulent cellulitis (odds ratio [OR], 5.12 [95% confidence interval (CI)], 1.46–17.88), head or neck involvement (OR, 2.83 [95% CI, 1.17–6.82]), adult cases (OR, 2.20 [95% CI, 1.18–4.11]), and admission to a community hospital (OR, 1.90 [95% CI, 1.05–3.44]).

Among patients hospitalized for ABSSSI, use of antibiotics with broad gram-negative activity or treatment courses longer than 10 days were common. There may be substantial opportunity to reduce antibiotic exposure through shorter courses of therapy targeting gram-positive bacteria.

Infect Control Hosp Epidemiol 2014;35(10):1241–1250

Determine the prevalence and relatedness of Staphylococcus aureus anterior nares colonization in individuals with community-associated staphylococcal skin and soft-tissue infection (SSTI)

Observational cohort.

US Army soldiers undergoing infantry training.

Trainees who developed SSTI from May 2010 to January 2012.

Participants underwent anterior nares culture at the time of presentation for purulent SSTI. We determined the prevalence of S. aureus nasal colonization and strain relatedness between colonizing and clinical isolates with pulsed-field gel electrophoresis (PFGE).

We enrolled 1,203 SSTI participants, of whom 508 had culture-confirmed S. aureus SSTI. Overall, 70% (357/508) were colonized with S. aureus. Phenotypically, concordant colonization was more common with methicillin-susceptible S. aureus (MSSA; 56%; 122/218) than methicillin-resistant S. aureus (MRSA) SSTI (41%; 118/290; P < .01). With PFGE, 48% (121 of 254) of clinical-colonizing pairs were indistinguishable, and concordant colonization was more common with MRSA (53%; 92/173) than MSSA SSTI (36%; 29/81; P < .01). Restricting analysis to concomitant MRSA-MRSA or MSSA-MSSA pairs, 92% (92/100) of MRSA SSTI were indistinguishable, and 40% (29/72) MSSA SSTI were indistinguishable (P < .01). All 92 MRSA pairs were USA300.

On the phenotypic level, concordant anterior nares colonization with incident staphylococcal SSTI is more common in MSSA than MRSA; however, the opposite is observed when accounting for molecular typing, and MRSA SSTI displays greater concordance. USA300 was responsible for strain concordance with MRSA SSTI. Studies are needed to examine the roles of nasal and extra-nasal carriage, colonization preceding infection, and increased virulence in the pathogenesis of MRSA SSTI.

ClinicalTrials.gov identifier: NCT01105767.

Infect Control Hosp Epidemiol 2014;35(10):1251–1256

To evaluate whether an ecologic inverse association exists between methicillin-susceptible Staphylococcus aureus (MSSA) prevalence and methicillin-resistant S. aureus (MRSA) prevalence in nursing homes.

We conducted a secondary analysis of a prospective cross-sectional study of S. aureus prevalence in 26 nursing homes across Orange County, California, from 2008–2011. Admission prevalence was assessed using bilateral nares swabs collected from all new residents within 3 days of admission until 100 swabs were obtained. Point prevalence was assessed from a representative sample of 100 residents. Swab samples were plated on 5% sheep blood agar and Spectra MRSA chromogenic agar. If MRSA was detected, no further tests were performed. If MRSA was not detected, blood agar was evaluated for MSSA growth. We evaluated the association between MRSA and MSSA admission and point prevalence using correlation and linear regression testing.

We collected 3,806 total swabs. MRSA and MSSA admission prevalence were not correlated (r = −0.40, P = .09). However, MRSA and MSSA point prevalence were negatively correlated regardless of whether MSSA prevalence was measured among all residents sampled (r = −0.67, P = .0002) or among those who did not harbor MRSA (r = −0.41, P = .04). This effect persisted in regression models adjusted for the percentage of residents with diabetes (β = −0.73, P = .04), skin lesions (β = −1.17, P = .002), or invasive devices (β = −1.4, P = .0006).

The inverse association between MRSA and MSSA point prevalence and minimal association on admission prevalence suggest MSSA carriage may protect against MRSA acquisition in nursing homes. The minimal association on admission prevalence further suggests competition may occur during nursing home stays.

Infect Control Hosp Epidemiol 2014;35(10):1257–1262

States have established public reporting of hospital-associated (HA) infections—including those of methicillin-resistant Staphylococcus aureus (MRSA)—but do not account for hospital case mix or postdischarge events

Identify facility-level characteristics associated with HA-MRSA infection admissions and create adjusted hospital rankings.

A retrospective cohort study of 2009–2010 California acute care hospitals. We defined HA-MRSA admissions as involving MRSA pneumonia or septicemia events arising during hospitalization or within 30 days after discharge. We used mandatory hospitalization and US Census data sets to generate hospital population characteristics by summarizing across admissions. Facility-level factors associated with hospitals’ proportions of HA-MRSA infection admissions were identified using generalized linear models. Using state methodology, hospitals were categorized into 3 tiers of HA-MRSA infection prevention performance, using raw and adjusted values.

Among 323 hospitals, a median of 16 HA-MRSA infections (range, 0–102) per 10,000 admissions was found. Hospitals serving a greater proportion of patients who had serious comorbidities, were from low-education zip codes, and were discharged to locations other than home were associated with higher HA-MRSA infection risk. Total concordance between all raw and adjusted hospital rankings was 0.45 (95% confidence interval, 0.40–0.51). Among 53 community hospitals in the poor-performance category, more than 20% moved into the average-performance category after adjustment. Similarly, among 71 hospitals in the superior-performance category, half moved into the average-performance category after adjustment.

When adjusting for nonmodifiable facility characteristics and case mix, hospital rankings based on HA-MRSA infections substantially changed. Quality indicators for hospitals require adequate adjustment for patient population characteristics for valid interhospital performance comparisons.

Infect Control Hosp Epidemiol 2014;35(10):1263–1270

To determine the durability of methicillin-resistant Staphylococcus aureus (MRSA)–free status after patients are removed from contact precautions and the association of specific clearance policy variables with survival

Retrospective cohort study from October 2007 to April 2013.

Veteran Affairs Boston Healthcare System.

Patients with a prior history of MRSA who were removed from contact precautions after deemed cleared of their MRSA status by infection prevention.

Active nasal screening results and clinical data from acute, long-term, and outpatient care facilities were evaluated to determine survival of MRSA-free status in a time-to-event analysis.

A total of 351 unique patients were followed for 107,112 patient-days. The median age was 68 years. Overall, 249 (71%) of patients remained MRSA-free, and 102 (29%) reverted to MRSA positive. The median MRSA-free survival was 880 days. Comorbidities, presence of indwelling devices, and the use of systemic antibiotics at the time of clearance screening were not associated with MRSA-free survival. More than 21,000 days of inpatient isolation days were avoided during the study period.

The majority of patients removed from contact precautions remained MRSA-free for more than 2 years. Antibiotic use at the time of clearance was not associated with reductions in MRSA-free survival. These findings can be used to simplify clearance criteria, promote clearance policies, and reduce patient isolation days.

To determine whether hand hygiene adherence is influenced by peer effects and, specifically, whether the presence and proximity of other healthcare workers has a positive effect on hand hygiene adherence

An observational study using a sensor network.

A 20-bed medical intensive care unit at a large university hospital.

Hospital staff assigned to the medical intensive care unit.

We deployed a custom-built, automated, hand hygiene monitoring system that can (1) detect whether a healthcare worker has practiced hand hygiene on entering and exiting a patient’s room and (2) estimate the location of other healthcare workers with respect to each healthcare worker exiting or entering a room.

We identified a total of 47,694 in-room and out-of-room hand hygiene opportunities during the 10-day study period. When a worker was alone (no recent healthcare worker contacts), the observed adherence rate was 20.85% (95% confidence interval [CI], 19.78%–21.92%). In contrast, when other healthcare workers were present, observed adherence was 27.90% (95% CI, 27.48%–28.33%). This absolute increase was statistically significant (P < .01). We also found that adherence increased with the number of nearby healthcare workers but at a decreasing rate. These results were consistent at different times of day, for different measures of social context, and after controlling for possible confounding factors.

The presence and proximity of other healthcare workers is associated with higher hand hygiene rates. Furthermore, our results also indicate that rates increase as the social environment becomes more crowded, but with diminishing marginal returns.

Infect Control Hosp Epidemiol 2014;35(10):1277–1285