The Emperor's New Clothes: PRospective Observational Evaluation of the Association Between Initial VancomycIn Exposure and Failure Rates Among ADult HospitalizEd Patients With Methicillin-resistant Staphylococcus aureus Bloodstream Infections (PROVIDE).

BACKGROUND: Vancomycin is the most commonly administered antibiotic in hospitalized patients, but optimal exposure targets remain controversial. To clarify the therapeutic exposure range, this study evaluated the association between vancomycin exposure and outcomes in patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. METHODS: This was a prospective, multicenter (n = 14), observational study of 265 hospitalized adults with MRSA bacteremia treated with vancomycin. The primary outcome was treatment failure (TF), defined as 30-day mortality or persistent bacteremia ≥7 days. Secondary outcomes included acute kidney injury (AKI). The study was powered to compare TF between patients who achieved or did not achieve day 2 area under the curve to minimum inhibitory concentration (AUC/MIC) thresholds previously found to be associated with lower incidences of TF. The thresholds, analyzed separately as co-primary endpoints, were AUC/MIC by broth microdilution ≥650 and AUC/MIC by Etest ≥320. RESULTS: Treatment failure and AKI occurred in 18% and 26% of patients, respectively. Achievement of the prespecified day 2 AUC/MIC thresholds was not associated with less TF. Alternative day 2 AUC/MIC thresholds associated with lower TF risks were not identified. A relationship between the day 2 AUC and AKI was observed. Patients with day 2 AUC ≤515 experienced the best global outcomes (no TF and no AKI). CONCLUSIONS: Higher vancomycin exposures did not confer a lower TF risk but were associated with more AKI. The findings suggest that vancomycin dosing should be guided by the AUC and day 2 AUCs should be ≤515. As few patients had day 2 AUCs <400, further study is needed to define the lower bound of the therapeutic range.

Phase I Study To Evaluate the Pharmacokinetics, Safety, and Tolerability of Two Dosing Regimens of Oral Fosfomycin Tromethamine in Healthy Adult Participants.

The pharmacokinetics (PK), safety, and tolerability of two repeated dosing regimens of oral fosfomycin tromethamine were evaluated in 18 healthy adult subjects. Subjects received 3 g every other day (QOD) for 3 doses and then every day (QD) for 7 doses, or vice versa, in a phase I, randomized, open-label, two-period-crossover study. Serial blood (n = 11) and urine (n = 4 collection intervals) samples were collected before and up to 24 h after dosing on days 1 and 5, along with predose concentrations on days 3 and 7. PK parameters were similar between days 1 and 5 within and between dosing regimens. The mean (± standard deviation [SD]) PK parameters for fosfomycin in plasma on day 5 during the respective QOD and QD dosing regimens were as follows: maximum concentration of drug in serum (Cmax) = 24.4 ± 6.2 versus 23.8 ± 5.6 µg/ml, time to Cmax (Tmax) = 2.2 ± 0.7 versus 2.0 ± 0.4 h, apparent volume of distribution (V/F) = 141 ± 67.9 versus 147 ± 67.6 liters, apparent clearance (CL/F) = 21.4 ± 8.0 versus 20.4 ± 5.3 liters/h, renal clearance (CLR) = 7.5 ± 4.1 versus 7.3 ± 3.5 liters/h, area under the concentration-time curve from 0 to 24 h (AUC0-24) = 151.6 ± 35.6 versus 156.6 ± 42.5 µg · h/ml, and elimination half-life (t1/2) = 4.5 ± 1.1 versus 5.0 ± 1.7 h. Urine concentrations peaked at approximately 600 µg/ml through the 0- to 8-h urine collection intervals but displayed significant interindividual variability. Roughly 35 to 40% of the 3-g dose was excreted in the urine by 24 h postdose. No new safety concerns were identified during this study. The proportion of diarrhea-free days during the study was significantly lower with the QD regimen than with the QOD regimen (61% versus 77%; P < 0.0001). Further studies to establish the clinical benefit/risk ratio for repeated dosing regimens of oral fosfomycin tromethamine are warranted. (This trial is registered at ClinicalTrials.gov under registration no. NCT02570074.).

Feasibility of Core Antimicrobial Stewardship Interventions in Community Hospitals.

Importance: The feasibility of core Infectious Diseases Society of America-recommended antimicrobial stewardship interventions in community hospitals is unknown. Objective: To determine the feasibility and results of implementing 2 core stewardship intervention strategies in community hospitals. Design, Setting, and Participants: Three-stage, multicenter, prospective nonrandomized clinical trial with crossover design. The setting was 4 community hospitals in North Carolina (median bed size, 305; range, 102-425). Participants were all patients receiving targeted study antibacterial agents or alternative, nonstudy antibacterial agents. The study dates were October 2014 through October 2015. All statistical analyses were completed as of October 2016. Interventions: Two antimicrobial stewardship strategies targeted vancomycin hydrochloride, piperacillin-tazobactam, and the antipseudomonal carbapenems on formulary at the study hospitals: (1) modified preauthorization (PA), in which the prescriber had to receive pharmacist approval for continued use of the antibiotic after the first dose, and (2) postprescription audit and review (PPR), in which the pharmacist would engage the prescriber about antibiotic appropriateness after 72 hours of therapy. Two hospitals performed modified PA for 6 months, then PPR for 6 months after a 1-month washout. The other 2 hospitals performed the reverse. Main Outcomes and Measures: The primary outcome was the feasibility of implementing the interventions, determined by (1) approval by hospital administration and committees at each study hospital; (2) completion of pharmacist training; (3) initiation and implementation as determined by number, type, and outcomes of interventions performed; and (4) time required for interventions. Secondary outcomes included antimicrobial use (days of therapy) compared with matched historical periods and length of hospitalization. Results: A total of 2692 patients (median age, 65 years; interquartile range, 53-76 years) underwent a study intervention; 1413 (52.5%) were female, 1323 (49.1%) were white, and 1047 (38.9%) were African American. Intervention approvals took a median of 95 days (range, 56-119 days); during these discussions, strict PA was deemed not feasible. Instead, the modified PA intervention was used throughout the study. Pharmacists performed 1456 modified PA interventions (median per hospital, 350 [range, 129-628]) and 1236 PPR interventions (median per hospital, 298 [range, 273-366]). Study antimicrobials were determined to be inappropriate 2 times as often during the PPR period (41.0% [435 of 1060] vs 20.4% [253 of 1243]; P < .001). Pharmacists recommended dose change more often during the modified PA intervention (15.9% [232 of 1456] vs 9.6% [119 of 1236]; P < .001) and de-escalation during PPR (29.1% [360 of 1236] vs 13.0% [190 of 1456]; P < .001). The median time dedicated to the stewardship interventions varied by hospital (range of median hours per week, 5-19). Overall antibiotic use decreased during PPR compared with historical controls (mean [SD] days of therapy per 1000 patient-days, 925.2 [109.8] vs 965.3 [109.4]; mean difference, -40.1; 95% CI, -71.7 to -8.6), but not during modified PA (mean [SD] days of therapy per 1000 patient-days, 931.0 [102.0] vs 926.6 [89.7]; mean difference, 4.4; 95% CI, -55.8 to 64.7). Conclusions and Relevance: Strict PA was not feasible in the study hospitals. In contrast, PPR was a feasible and effective strategy for antimicrobial stewardship in settings with limited resources and expertise. Trial Registration: ClinicalTrials.gov identifier: NCT02212808.