To assess the prevalence of antibiotic-resistant gram-negative bacteria (R-GNB) among patients without recent hospitalization and to examine the influence of outpatient antibiotic exposure on the risk of acquiring R-GNB in this population.

2-year retrospective cohort study.

Regional Veterans Affairs healthcare system.

Outpatients at 13 community-based clinics.

We examined the rate of acquisition of R-GNB within 90 days following an outpatient visit from 2018 to 2019. We used clinical and administrative databases to determine and summarize prescriptions for systemic antibiotics, associated infectious diagnoses, and subsequent R-GNB acquisition among patients without recent hospitalizations. We also calculated the odds ratio of R-GNB acquisition following antibiotic exposure.

During the 2-year study period, 7,215 patients had outpatient visits with microbiological cultures obtained within 90 days. Of these patients, 206 (2.9%) acquired an R-GNB. Among patients receiving antibiotics at the visit, 4.6% acquired a R-GNB compared to 2.7% among patients who did not receive antibiotics, yielding an unadjusted odds ratio of 1.75 (95% confidence interval, 1.18–2.52) for a R-GNB following an outpatient visit with versus without an antibiotic exposure. Regardless of R-GNB occurrence, >50% of antibiotic prescriptions were issued at visits without an infectious disease diagnosis or issued without documentation of an in-person or telehealth clinical encounter.

Although the rate of R-GNBs was low (2.9%), the 1.75-fold increased odds of acquiring a R-GNB following an outpatient antibiotic highlights the importance of antimicrobial stewardship efforts in outpatient settings. Specific opportunities include reducing antibiotics prescribed without an infectious diagnosis or a clinical visit.

We examined the impact of microbiological results from respiratory samples on choice of antibiotic therapy in patients treated for hospital-acquired pneumonia (HAP) or ventilator-associated pneumonia (VAP).

Four-year retrospective study.

Veterans’ Health Administration (VHA).

VHA patients hospitalized with HAP or VAP and with respiratory cultures between October 1, 2014, and September 30, 2018.

We compared patients with positive and negative respiratory culture results, assessing changes in antibiotic class and Antibiotic Spectrum Index (ASI) from the day of sample collection (day 0) through day 7.

Between October 1, 2014, and September 30, 2018, we identified 5,086 patients with HAP/VAP: 2,952 with positive culture results and 2,134 with negative culture results. All-cause 30-day mortality was 21% for both groups. The mean time from respiratory sample receipt in the laboratory to final respiratory culture result was longer for those with positive (2.9 ± 1.3 days) compared to negative results (2.5 ± 1.3 days; P < .001). The most common pathogens were Staphylococcus aureus and Pseudomonas aeruginosa. Vancomycin and β-lactam/β-lactamase inhibitors were the most commonly prescribed agents. The decrease in the median ASI from 13 to 8 between days 0 and 6 was similar among patients with positive and negative respiratory cultures. Patients with negative cultures were more likely to be off antibiotics from day 3 onward.

The results of respiratory cultures had only a small influence on antibiotics used during the treatment of HAP/VAP. The decrease in ASI for both groups suggests the integration of antibiotic stewardship principles, including de-escalation, into the care of patients with HAP/VAP.

We introduced a long-term care facility (LTCF) infectious disease (ID) consultation service (LID service) that provides on-site consultations to residents of a Veterans Affairs (VA) LTCF. We determined the impact of the LID service on antimicrobial use and Clostridium difficile infections at the LTCF.

A 160-bed VA LTCF.

Systemic antimicrobial use and positive C. difficile tests at the LTCF were compared for the 36 months before and the 18 months after the initiation of the ID consultation service through segmented regression analysis of an interrupted time series.

Relative to that in the preintervention period, total systemic antibiotic administration decreased by 30% (P<.001), with significant reductions in both oral (32%; P<.001) and intravenous (25%; P = .008) agents. The greatest reductions were seen for tetracyclines (64%; P<.001), clindamycin (61%; P<.001), sulfamethoxazole/trimethoprim (38%; P<.001), fluoroquinolones (38%; P<.001), and β lactam/β-lactamase inhibitor combinations (28%; P<.001). The rate of positive C. difficile tests at the LTCF declined in the postintervention period relative to preintervention rates (P = .04).

Implementation of an LTCF ID service led to a significant reduction in total antimicrobial use. Bringing providers with ID expertise to the LTCF represents a new and effective means to achieve antimicrobial stewardship.