A five-year quasi-experimental study to evaluate the impact of empiric antibiotic order sets on antibiotic use metrics among hospitalized adult patients.

OBJECTIVE: Evaluation of adult antibiotic order sets (AOSs) on antibiotic stewardship metrics has been limited. The primary outcome was to evaluate the standardized antimicrobial administration ratio (SAAR). Secondary outcomes included antibiotic days of therapy (DOT) per 1,000 patient days (PD); selected antibiotic use; AOS utilization; Clostridioides difficile infection (CDI) cases; and clinicians' perceptions of the AOS via a survey following the final study phase. DESIGN: This 5-year, single-center, quasi-experimental study comprised 5 phases from 2017 to 2022 over 10-month periods between August 1 and May 31. SETTING: The study was conducted in a 752-bed tertiary care, academic medical center. INTERVENTION: Our institution implemented AOSs in the electronic medical record (EMR) for common infections among hospitalized adults. RESULTS: For the primary outcome, a statistically significant decreases in SAAR were detected from phase 1 to phase 5 (1.0 vs 0.90; P < .001). A statistically significant decreases were detected in DOT per 1,000 PD (4,884 vs 3,939; P = .001), fluoroquinolone orders (407 vs 175; P < .001), carbapenem orders (147 vs 106; P = .024), and clindamycin orders (113 vs 73; P = .01). No statistically significant change in mean vancomycin orders was detected (991 vs 902; P = .221). A statistically significant decrease in CDI cases was also detected (7.8, vs 2.4; P = .002) but may have been attributable to changes in CDI case diagnosis. Clinicians indicated that the AOSs were easy to use overall and that they helped them select the appropriate antibiotics. CONCLUSIONS: Implementing AOS into the EMR was associated with a statistically significant reduction in SAAR, antibiotic DOT per 1,000 PD, selected antibiotic orders, and CDI cases.

Daptomycin Plus Oxacillin for Persistent Methicillin-Susceptible Staphylococcus aureus Bacteremia.

BACKGROUND: The preferred antibiotic salvage regimen for persistent methicillin-susceptible Staphylococcus aureus bacteremia (MSSAB) is unclear. Ertapenem with cefazolin or an antistaphylococcal penicillin has been primarily described, but identifying alternative carbapenem-sparing options may support antibiotic stewardship efforts and decrease the risk of antibiotic-associated Clostridioides difficile infection. OBJECTIVE: We sought to evaluate the effectiveness and safety of daptomycin plus oxacillin (D/O) for persistent MSSAB. METHODS: This was a single-center, retrospective cohort of patients with persistent MSSAB who received D/O between January 1, 2014, and January 1, 2023. Adult patients were included if they had blood cultures positive for MSSA ≥72 hours and received D/O combination for ≥48 hours. Patients were excluded if they were pregnant, incarcerated, or received another antibiotic considered to have excellent activity against MSSA. The primary outcome was time to MSSA bacteremia clearance post-daptomycin initiation. Secondary outcomes included microbiological cure, hospital length of stay, 90-day all-cause mortality, MSSA bacteremia-related mortality, 90-day readmission for MSSAB, and incidence of antibiotic-associated adverse effects. Time to MSSAB clearance post-D/O initiation was plotted using Kaplan-Meier estimation. RESULTS: Seven unique patient encounters were identified including 4 with endocarditis. Despite a median MSSA bacteremia duration of 7.8 days, median clearance was 2 days post-daptomycin initiation. All achieved microbiological cure, and no adverse effects were reported. Ninety-day all-cause mortality, MSSAB-related mortality, and 90-day readmission for MSSAB occurred in 28.6%, 14.3%, and 14.3% of patients, respectively. CONCLUSIONS AND RELEVANCE: D/O was an effective, well-tolerated salvage regimen in this cohort and may represent a carbapenem-sparing option for persistent MSSAB.

Impact of a Pharmacist-Conducted Preoperative Beta-Lactam Allergy Assessment on Perioperative Cefazolin Prescribing.

Background: Cefazolin is guideline recommended for perioperative prophylaxis in orthopedic surgery. Despite its unique R1 side chain, cefazolin is often avoided in patients with beta-lactam allergy with concern for cross reactivity. Objectives: The primary outcome was the percentage of patients who received cefazolin perioperatively. Secondary outcomes included the percentage of patients with a beta-lactam allergy clarified following the telephone interview and clinical outcomes including acute kidney injury, surgical site infection, Clostridioides difficile infection, and re-admission at 30 and 90 days. Methods: This single-center, quasi-experimental study evaluated a pilot program in which a pharmacist phoned patients > 18 years of age with a scheduled orthopedic surgery and a documented beta-lactam allergy to assess their allergy preoperatively. Recommendations to use cefazolin were based on an algorithm. Patients were divided into pre- and post-intervention cohorts. Results: A total of 832 patients were screened for inclusion with 135 and 66 patients included in the pre- and post-intervention cohorts. No significant difference was identified in the primary outcome. In the post-intervention cohort, 62% had a beta-lactam reaction updated in the electronic medical record. Those with a beta-lactam allergy delabeled or made less severe were numerically more likely to receive cefazolin than those with an unchanged reaction or a reaction made more severe (95.2% vs 68% vs 65%). There were no differences in clinical outcomes between groups. Conclusion: A pharmacist-conducted preoperative beta-lactam allergy interview in adult patients undergoing elective orthopedic surgery improved beta-lactam allergy documentation but, did not result in increased utilization of cefazolin.

Real-world evaluation of linezolid-associated serotonin toxicity with and without concurrent serotonergic agents.

BACKGROUND: The risk of linezolid-associated serotonin toxicity remains unclear. This study sought to evaluate the incidence of serotonin toxicity among hospitalized patients who received linezolid with or without concurrent serotonergic agents (SAs). Secondary outcomes were to assess the dose, agent selection and number of SAs. METHODS: A single-centre, retrospective cohort study of hospitalized patients aged ≥18 years who received at least one dose of linezolid with or without SAs between 1 January 2014 and 30 June 2021 was performed. Patients were excluded if they were aged <18 years, had linezolid ordered but not administered, were pregnant or were incarcerated. Up to five concurrent SAs were assessed, and dose category was classed as low, moderate or high (dose <33%, 33-66% or >66% of maximum daily dose, respectively). Serotonin toxicity was identified by searching patients' electronic medical records. If identified, the Sternbach criteria and Hunter criteria were applied. RESULTS: Of 2022 patients screened, 1743 were included in this study. Mean age, weight and linezolid duration were 58.5 years, 90.7 kg and 3.8 days, respectively. Approximately 67% (1168/1743) of patients received linezolid with at least one SA, and several patients received multiple SAs. Most patients (53.8%; 616/1144) received moderate- and/or high-dose SAs. Only two patients (0.11%) were identified as possible cases of serotonin toxicity based on the electronic medical record search. However, the incidence of serotonin toxicity was 0.06% (1/1743) based on the Sternbach criteria and 0% (0/1743) based on the Hunter criteria. CONCLUSIONS: Serotonin toxicity among hospitalized patients who received linezolid with or without SAs was exceedingly rare, even among those who received multiple and high-dose SAs.

Single-Dose Antibiotic Prophylaxis with Ertapenem Increases Compliance with Recommendations for Surgical Antibiotic Prophylaxis in Elective Colorectal Surgery: A Retrospective, Single-Center Analysis.

Background: Compliance with guideline recommendations for surgical antibiotic prophylaxis (SAP) in colorectal surgery, particularly redosing, has been suboptimal at many institutions including ours. This study aimed to evaluate if single-dose antibiotic prophylaxis with ertapenem improves compliance with guideline recommendations for SAP versus multiple-dose antibiotic prophylaxis in elective colorectal surgery. Methods: A retrospective, cohort study of the use of ertapenem compared with standard of care antibiotic agents was performed in adult patients undergoing elective colorectal surgery at an academic medical center between January 2020 and February 2022. The primary outcome was compliance with guideline-recommended SAP for colorectal surgery. The secondary outcome was surgical site infections (SSIs) within 30 days after surgery. Results: A total of 135 patients were included in this study. Fifty-eight patients received single-dose antibiotic prophylaxis with ertapenem and 77 patients received multiple-dose antibiotic prophylaxis. Cefazolin plus metronidazole was the most common multiple-dose regimen (65 of 77). Single-dose antibiotic prophylaxis with ertapenem increased overall SAP compliance (96.6% vs. 64.9%; p < 0.001) as well as compliance with antibiotic administration within the recommended time period before incision (96.6% vs. 84.4%; p = 0.022), compliance with intra-operative antibiotic redosing when warranted (100% vs. 83.1%; p < 0.001), and compliance with guideline-recommended dosing (100% vs. 92.2%; p = 0.037). Surgical site infection rates were not statistically different between the groups (12.1% vs. 19.4%; p = 0.248). Conclusions: Single-dose antibiotic prophylaxis with ertapenem increased compliance with guideline-recommended SAP for elective colorectal surgeries. No statistically significant difference was observed in SSI rates regardless of the antibiotic regimen used.

Vancomycin plus ceftaroline for persistent methicillin-resistant Staphylococcus aureus bacteremia.

STUDY OBJECTIVE: The preferred antibiotic salvage regimen for persistent methicillin-resistant Staphylococcus aureus bacteremia (MRSAB) is unclear. We sought to evaluate the effectiveness and safety of vancomycin plus ceftaroline for persistent MRSAB. The primary outcome was time to MRSAB clearance post-ceftaroline initiation. Secondary outcomes included microbiological cure, hospital length of stay, 90-day readmission for MRSAB, 90-day all-cause mortality, MRSAB-related mortality, and incidence of antibiotic-associated adverse effects. DESIGN: Single-center, retrospective cohort study between January 1, 2016, and December 31, 2021. SETTING: State University of New York Upstate University Hospital, a 748-bed tertiary care, academic medical center in Syracuse, NY. PATIENTS: Adult patients were included if they had blood cultures positive for MRSA ≥72 h, received vancomycin monotherapy initially, and received vancomycin plus ceftaroline for ≥24 h. Patients were excluded if they received other anti-MRSA antibiotics, were pregnant, or were incarcerated. Of the 178 patients identified, 30 unique patients were evaluated. MEASUREMENTS AND MAIN RESULTS: Patients were medically complex with a median Pitt bacteremia score of 3, 63.3% (19/30) were admitted to the intensive care unit, and 66.7% (20/30) had infective endocarditis. Vancomycin-associated acute kidney injury was observed in 10% (3/30) of patients, which resulted in dose adjustments. No patients experienced ceftaroline-associated neutropenia or Clostridioides difficile infection, but 6.7% (2/30) developed a rash attributed to ceftaroline. Median time to MRSAB clearance post-ceftaroline initiation was 2.6 days. Microbiologic cure occurred in nearly all patients 96.7% (29/30). Median hospital length of stay was 19.5 days, and 6.7% (2/30) of patients had 90-day readmission for MRSAB. 90-day all-cause mortality and MRSAB-related mortality occurred in 26.7% (8/30) and 13.3% (4/30) of patients, respectively. CONCLUSIONS: Vancomycin plus ceftaroline may represent an effective and well-tolerated salvage regimen option for persistent MRSAB.

Accuracy of 4 Free Online Dosing Calculators in Predicting the Vancomycin Area Under the Concentration-Time Curve Calculated Using a 2-Point Pharmacokinetic Approach.

BACKGROUND: Free online adaptive vancomycin dosing calculators are available to estimate area under the concentration-time curve (AUC), but the accuracy of predicting vancomycin AUC using these calculators compared with using a 2-point pharmacokinetic approach has not been described. OBJECTIVE: To evaluate the accuracy of calculator-predicted AUC (cpAUC) using 4 free online calculators compared with reference AUC (rAUC), and to assess pharmacists' impressions of the ease of use. METHODS: Vancomycin AUC was estimated using (1) the reference method via the Sawchuk-Zaske method and linear-logarithmic trapezoidal rule using 2 steady-state postdistributional vancomycin serum concentrations and (2) 4 free online vancomycin dosing calculators including ClinCalc, VancoPK, TDMx, and DMC. Accuracy was calculated by dividing cpAUC by rAUC. Ease of cpAUC estimation was determined by using a 10-point Likert scale. RESULTS: All 4 calculators had a median cpAUC accuracy ranging from 89% to 110%. Concordance between cpAUC and rAUC determinations of AUC <400 and > 600 mg·h/L occurred 63.3% to 71.4% and 74.5% to 78.6% of the time, respectively. Pharmacist investigators agreed that ClinCalc and VancoPK calculators were easiest to use. CONCLUSION AND RELEVANCE: cpAUC accuracy varied among the 4 calculators, but all consistently identified patients with an rAUC <400 mg·h/L and an rAUC > 600 mg·h/L at comparable frequencies. All 4 calculators demonstrated some imprecision based on their wide 95% CIs and potential inaccuracies in predicting an rAUC <400 mg·h/L or an rAUC > 600 mg·h/L. Clin Calc and VancoPK were most user friendly based on our pharmacists' impressions.

Does a Positive Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Screen Predict the Risk for MRSA Skin and Soft Tissue Infection?

BACKGROUND: Skin and soft tissue infections (SSTIs) are often caused by gram-positive bacteria that colonize the skin. Given the overuse of antibiotics, SSTIs are increasingly caused by resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Guidance on the utility of MRSA nasal screening for MRSA SSTI is limited. OBJECTIVE: To determine whether MRSA nasal screening predicts the risk of MRSA SSTIs. METHODS: This was a single-center, retrospective cohort study of adult patients with an SSTI diagnosis that had MRSA nasal screening and wound cultures obtained within 48 hours of starting antibiotics. Sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios were calculated using VassarStats. Pretest and posttest probabilities were estimated with Microsoft Excel. RESULTS: A total of 884 patient encounters were reviewed between December 1, 2018, and October 31, 2021, and 300 patient encounters were included. The prevalence of MRSA SSTI was 18.3%. The MRSA nasal colonization had a sensitivity of 63.6%, specificity of 93.9%, positive predictive value of 70.0% (95% CI = 55.2%-81.7%), negative predictive value of 92.0% (95% CI = 87.7%-94.9%), positive likelihood ratio of 10.39 (95% CI = 6.12-17.65), negative likelihood ratio of 0.39 (95% CI = 0.27-0.55), positive posttest probability of 70.0%, and negative posttest probability of 8.0%. CONCLUSIONS: Given the high positive likelihood ratio, a positive MRSA nasal screen was associated with a large increase in the probability of MRSA SSTI at our institution, and a negative MRSA nasal screen was associated with a small but potentially significant decrease in the probability of MRSA SSTI.

Plasma and cerebrospinal fluid concentrations of cefiderocol during successful treatment of carbapenem-resistant Acinetobacter baumannii meningitis.

BACKGROUND: To date, no real-world data are available to describe cefiderocol use in carbapenem-resistant Acinetobacter baumannii (CRAB) meningitis. Furthermore, cefiderocol pharmacokinetic (PK) data to support CNS penetration in human subjects are limited. These gaps pose a significant concern for clinicians who are faced with treating such infections when considering cefiderocol use. OBJECTIVES: To describe cefiderocol CSF and plasma PK and pharmacodynamic (PD) data from two different dosing regimens [2 g IV q6h (regimen 1) and 2 g IV q8h (regimen 2)] during treatment of CRAB meningitis. PATIENTS AND METHODS: A 61-year-old woman with CRAB meningitis was treated with cefiderocol and intraventricular gentamicin. Steady-state plasma and CSF cefiderocol concentrations were evaluated on Day 19 (regimen 1) and Day 24 (regimen 2) during the cefiderocol treatment course. RESULTS: CSF AUC was 146.49 and 118.28 mg·h/L, as determined by the linear-log trapezoidal method for regimens 1 and 2, respectively. Penetration into CSF estimated as the AUCCSF/AUCfree plasma ratio was 68% and 60% for regimens 1 and 2, respectively. Estimated free plasma and CSF concentrations exceeded the MIC of the isolate for 100% of the dosing interval. Microbiological and clinical cure were achieved, and no cefiderocol-associated adverse effects were observed. CONCLUSIONS: Cefiderocol, when given as 2 g q8h and 2 g q6h, attained CSF concentrations that exceeded the organism-specific MIC and the CLSI susceptible breakpoint (≤4 mg/L) for 100% of the dosing interval.

Validation of Methicillin-Resistant Staphylococcus aureus (MRSA) Risk Factors in Predicting MRSA Community-Acquired Pneumonia at an Academic Medical Center.

Background: The 2019 Infectious Diseases Society of America community-acquired pneumonia (CAP) guidelines recommend antimethicillin- resistant Staphylococcus aureus (MRSA) therapy in patients with CAP based on previously identified risk factors for MRSA with an emphasis on local epidemiology and institutional validation of risk. Thus, we sought to assess the ability of guideline-recognized risk factors to predict MRSA CAP at our institution. Methods: This was a single-center, retrospective cohort study from January 2016 to March 2020. Patients were included if they were >18 years old, diagnosed with CAP, and had a MRSA nasal screen and respiratory culture obtained on admission. Patients were excluded if CAP diagnosis was not met, respiratory cultures were not obtained within 48 hours of antibiotic initiation, or they had cystic fibrosis. Sensitivity, specificity, negative predictive value, positive predictive value, and likelihood ratios (LR) were calculated using Vasser Stats 2019. Pre/post-test odds and pre/post-test probabilities were calculated using Excel 2019. Results: Of 705 screened patients, 221 were included. MRSA prevalence in CAP patients at our institution was 3.6%. History of MRSA isolated from a respiratory specimen had high specificity (98%), high positive LR of 20 (95% CI 5.3-74.8), and high post-test probability of 42.8%. Receipt of IV antibiotics during hospitalization within the past 90 days had a positive LR of 1.9 (95% CI 0.74-4.84). A positive MRSA nasal screen on admission had a positive LR of 6.9 (95% CI 4.0-12.1), negative LR 0.28 (95% CI 0.08-0.93), positive post-test probability of 20.7%, and negative post-test probability of 1.04%. Conclusion: Our study utilized institutional data to validate guideline recognized risk factors for MRSA CAP specifically at our institution. Risk factors including history of MRSA isolated from a respiratory specimen, and positive post-admission MRSA nasal screen were validated as significant risk factors; receipt of IV antibiotics during hospitalization within the past 90 days was not shown to be a risk factor for MRSA CAP based on our institutional data. Validated risk factors may help providers discern which patients with CAP at our institution would benefit most from empiric MRSA treatment.

Evaluation of ß-lactam therapeutic drug monitoring among US health systems with postgraduate year 2 infectious diseases pharmacy residency programs.

PURPOSE: While some guidelines recognize the need for ß-lactam therapeutic drug monitoring (TDM), there is still a paucity of data regarding the prevalence of and barriers to performing ß-lactam TDM in the United States. We sought to estimate the prevalence of ß-lactam TDM, describe monitoring practices, and identify actual and perceived barriers to implementation among health systems in the US. METHODS: A multicenter, cross-sectional, 40-item electronic survey was distributed to all postgraduate year 2 (PGY2) infectious diseases (ID) pharmacy residency program directors (RPDs) listed in the American Society of Health-System Pharmacists pharmacy residency directory. The primary outcome was the percentage of institutions with established ß-lactam TDM. Secondary outcomes included assessing ß-lactam TDM methods and identifying potential barriers to implementation. RESULTS: The survey was distributed to 126 PGY2 ID RPDs, with a response rate of 31.7% (40 of 126). Only 8% of respondents (3 of 39) performed ß-lactam TDM. Patient populations, therapeutic targets, and frequency and timing of obtaining repeat ß-lactam concentration measurements varied among institutions. The greatest barrier to implementation was lack of access to testing with a rapid turnaround time. Institutions were unlikely to implement ß-lactam TDM within the next year but were significantly more inclined to do so within 5 years (P < 0.001). CONCLUSION: ß-lactam TDM was infrequently performed at the surveyed US health systems. Lack of access to serum concentration testing with rapid turnaround and lack of US-specific guidelines appear to be considerable barriers to implementing ß-lactam TDM. Among institutions that have implemented ß-lactam TDM, there is considerable variation in monitoring approaches.

Hospital Discharge: An Opportune Time for Antimicrobial Stewardship.

BACKGROUND: Approximately 30% of antimicrobials prescribed in the outpatient setting are unnecessary and up to 50% are inappropriate. Despite this, antimicrobial stewardship (AS) efforts mostly focus on the inpatient setting, and limited data describe AS interventions at hospital discharge. Acknowledging the potential value of discharge AS, we used our existing resources to review discharge oral antimicrobial prescriptions. OBJECTIVE: The primary objective of this retrospective, single-center study was to evaluate the impact of an AS program on discharge oral antimicrobial prescriptions. METHODS: Discharge oral antimicrobial prescriptions sent to our hospital-operated outpatient pharmacy, reviewed by an infectious diseases (ID) pharmacist, and recorded into our data collection tool from September 1, 2020, to February 28, 2021, were evaluated retrospectively. The primary outcome was to identify the frequency a drug-related problem (DRP) was identified by an ID pharmacist. Secondary outcomes included DRP characterization, percentage of prescriptions with interventions, intervention acceptance rate, and reduction in antimicrobial days dispensed at discharge when interventions to limit treatment duration were accepted. RESULTS: Of the 803 discharge oral antimicrobial prescriptions reviewed, at least 1 DRP was identified in 43.1% (346/803). The most frequently identified DRPs pertained to treatment duration, drug selection, and dose selection. At least 1 intervention was recommended in 42.8% (344/803) of prescriptions. In total, 438 interventions were made and the acceptance rate was 75.6% (331/438). The most common types of interventions included recommendations for a different duration, a different dose or frequency, and antimicrobial discontinuation. When interventions to reduce treatment duration were accepted, the median (interquartile range) number of antimicrobial days decreased from 8 (5-10) days to 4 (0-5.5) days (P < 0.001). CONCLUSION AND RELEVANCE: An ID pharmacist's review of discharge oral antimicrobial prescriptions sent to our hospital-operated outpatient pharmacy resulted in identification of DRPs and subsequent interventions in a substantial number of prescriptions.

Impact of a pharmacist-facilitated, evidence-based bundle initiative on Staphylococcus aureus bacteremia management.

OBJECTIVE: To evaluate a pharmacist-facilitated evidence-based bundle (EBB) initiative with infectious disease consultation (IDC) for Staphylococcus aureus bacteremia (SAB). METHODS: This was a before-and-after quasi-experimental study of adult patients with SAB before and after the pharmacist-facilitated EBB initiative, which included IDC, timely definitive antibiotics, source control, echocardiography, and repeat blood cultures. RESULTS: Ninety and 111 patients were included in pre- and post-intervention cohorts, respectively. We observed significant increases in adherence to all 5 (4.4% vs 68.5%, P < 0.001) and 4 (10.0% vs 76.6%, P < 0.001) EBB elements. Time to definitive antibiotics (48 vs 16 hours, P < 0.001), time to IDC (43.5 vs 32 hours, P < 0.001), SAB duration (95 vs 66 hours, P = 0.009), persistent SAB (18.9% vs 9.0%, P = 0.041), and length of stay (14 vs 13 days, P = 0.027) also improved. No statistically significant differences for SAB-related readmission or all-cause mortality were observed. CONCLUSIONS: Our pharmacist-facilitated SAB initiative was associated with improved EBB adherence and clinical outcomes.

Cefiderocol: a novel siderophore cephalosporin for multidrug-resistant Gram-negative bacterial infections.

Cefiderocol is a novel siderophore cephalosporin that forms a complex with extracellular free ferric iron, which leads to transportation across the outer cell membrane to exert its bactericidal activity through cell wall synthesis inhibition. This pharmacological property has rendered cefiderocol active against several clinically relevant MDR Gram-negative bacteria as evidenced by several in vitro and in vivo studies. Cefiderocol was first approved by the US FDA on 14 November 2019 for the treatment of complicated urinary tract infections. On 28 September 2020, cefiderocol was approved for the treatment of hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia. The FDA-approved indications are based on clinical data from the APEKS-cUTI, APEKS-NP and CREDIBLE-CR trials. In APEKS-cUTI, cefiderocol demonstrated non-inferiority to imipenem/cilastatin for the treatment of complicated urinary tract infection caused by MDR Gram-negative bacteria. In APEKS-NP, cefiderocol demonstrated non-inferiority to meropenem for treatment of nosocomial pneumonia. However, in CREDIBLE-CR, higher all-cause mortality was observed with cefiderocol compared with best available therapy for the treatment of severe infections caused by Gram-negative bacteria, primarily in the subset of patients with Acinetobacter spp. infections. Several case reports/series have demonstrated clinical success with cefiderocol for a variety of severe infections. The purpose of this article is to review available data on the mechanism of action, in vitro and in vivo data, pharmacokinetics, pharmacodynamics, susceptibility testing, efficacy and safety of cefiderocol to address its role in therapy.

Cefiderocol for treatment of an empyema due to extensively drug-resistant Pseudomonas aeruginosa: Clinical observations and susceptibility testing considerations.

Cefiderocol is a novel siderophore cephalosporin antibacterial with activity against carbapenem-resistant Gram-negative bacteria including Pseudomonas aeruginosa. We report a medically complex patient treated with compassionate use cefiderocol for an empyema caused by extensively drug-resistant P. aeruginosa as well as clinical considerations for cefiderocol use based on our findings. We observed a potential discordance in cefiderocol susceptibility testing results depending if disk diffusion or iron-depleted cation-adjusted Mueller Hinton Broth dilution is used. Furthermore, interpretative criteria differ between the Clinical Laboratory Standards Institute and United States Food and Drug Administration for P. aeruginosa, which makes cefiderocol interpretation potentially challenging for clinicians. We may have also observed selective pressure from prior cefiderocol exposure given the respective increases and decreases in MIC values and zone diameters for P. aeruginosa isolates following cefiderocol treatment. Additional data are needed to further describe cefiderocol use, susceptibility testing, and resistance development as real-world clinical use expands.

Cost comparison of AUC:MIC- versus trough-based vancomycin monitoring for MRSA bacteremia.

OBJECTIVES: It is anticipated that the updated vancomycin monitoring guidelines will reconsider area under the concentration-time curve to minimum inhibitory concentration ratio (AUC:MIC)-based monitoring instead of trough-based monitoring for methicillin-resistant Staphylococcus aureus (MRSA) infections. The AUC:MIC can be estimated using 2 steady-state serum concentrations and first-order pharmacokinetic equations or Bayesian modeling. The cost of AUC:MIC-based monitoring compared with trough-based monitoring is unknown and has been cited as a potential barrier to implementing this monitoring method. The objective of this study was to compare the total vancomycin drug and monitoring cost for patients with MRSA bacteremia who received AUC:MIC- or trough-based monitoring. DESIGN: This was a single-center, retrospective cohort study. SETTING AND PARTICIPANTS: This study included patients who were treated for MRSA bacteremia between May 1, 2013 and December 31, 2018, with an 8-month washout period between trough and AUC:MIC-based monitoring at our institution. OUTCOME MEASURES: The primary outcome was the aggregate cost of vancomycin therapy, which included the cost associated with sample collection (i.e., supply cost and nursing time), sample analysis (i.e., assay cost and laboratory technician time), result interpretation (i.e., pharmacist time), and drug cost (i.e., cost of total administered vancomycin dose) during the hospital stay. RESULTS: A total of 52 patients met inclusion criteria with 26 patients in each group. The median (interquartile range) total vancomycin drug and monitoring cost was $338.14 ($235.07-$601.05) for the AUC:MIC-based group compared with $316.79 ($253.36-$520.96) for the trough-based group (P = 0.687). CONCLUSION: Vancomycin monitoring using 2 steady-state serum concentrations and first-order pharmacokinetic equations to calculate AUC:MIC was no more costly than a trough-based approach in patients with MRSA bacteremia at our institution.

Nephrotoxicity Risk and Clinical Effectiveness of Continuous versus Intermittent Infusion Vancomycin Among Patients in an Outpatient Parenteral Antimicrobial Therapy Program.

STUDY OBJECTIVE: To compare rates of nephrotoxicity, time to nephrotoxicity onset, and clinical failure among patients who received continuous infusion (C-I) or intermittent infusion (I-I) vancomycin in an outpatient parenteral antimicrobial therapy (OPAT) program. Nephrotoxicity was defined as an increase in serum creatinine greater than 0.5 mg/dl or a 50% increase from baseline for two consecutive measurements while receiving vancomycin during OPAT. Clinical failure was defined as unplanned readmission, extension of therapy, or change in antibiotics. DESIGN: Single-center propensity score-matched retrospective cohort study. SETTING: OPAT clinic affiliated with two nearby hospitals. PATIENTS: We identified 300 patients who received C-I or I-I vancomycin for at least 1 week in the OPAT program between October 1, 2017, and March 31, 2019. Propensity score matching based on age, sex, and infection was performed to minimize differences in patient characteristics between groups. MEASUREMENTS AND MAIN RESULTS: After propensity score matching and exclusion criteria, 74 patients were included in each cohort. Continuous infusion vancomycin was associated with a 3.22-fold decrease in nephrotoxicity risk (C-I 6.8% [5/74 patients] vs I-I 18.9% [14/74 patients]; odds ratio 3.22, 95% confidence interval 1.10-9.46, p=0.027) and a significantly slower onset to nephrotoxicity compared with I-I (p=0.035). No statistically significant difference in clinical failure rates was observed between the C-I and I-I groups (13.5% [10/74 patients] vs 23.0% [17/74 patients], p=0.147). CONCLUSION: In an OPAT setting, C-I vancomycin was associated with a lower risk of and slower onset to nephrotoxicity than I-I vancomycin; however, no statistically significant difference in clinical failure rates was observed with C-I versus I-I vancomycin.

The Culture of Carbapenem Overconsumption: Where Does It Begin? Results of a Single-Center Survey.

Purpose: The United States has seen an increased consumption of carbapenem antibiotics in recent years. The increased utilization of these agents has potential negative consequences, including the increasing incidence of carbapenem-resistant Enterobacteriaceae. Reasons for the rise in carbapenem use among providers in acute care hospitals are not well elucidated in literature. The objectives of this study were to identify factors that influence empiric carbapenem use among providers in a single academic medical center, and to assess therapeutic knowledge pertaining to carbapenem use. Methods: A cross-sectional, single-center, 9-item electronic research survey was developed independently and validated by an infectious diseases pharmacist and infectious diseases physician. The survey was distributed to email accounts of providers at a single academic medical center. Demographic data, factors affecting carbapenem prescription, and baseline therapeutic knowledge were assessed. Results: Ninety-five of 416 providers responded to the survey (response rate of 22.8%). Respondents were well distributed across all levels of training with primary roles in internal medicine and surgery. The most important factors influencing empiric carbapenem use were suspected pathogens at the site of infection, drug allergies, history of multidrug resistant organisms, severity of illness, type of infection, and local resistance rates. A recommendation from a pharmacist was selected as the most likely factor for deterring carbapenem use. Misconceptions pertaining to penicillin drug allergy and beta-lactam cross reactivity, knowledge of local resistance rates according to the institutional antibiogram, and comparative efficacy data for carbapenems were apparent across all levels of training. Conclusions: Provider misconceptions regarding several factors appear to contribute to unnecessary use of carbapenems. An opportunity exists for hospital pharmacists to improve the prescribing patterns of carbapenems by correcting provider misconceptions through education.