Optimized Charge/Hydrophobicity Balance of Antimicrobial Peptides Against Polymicrobial Abdominal Infections

Antimicrobial peptides (AMPs) potentially serve as ideal antimicrobial agents for the treatment of polymicrobial abdominal infections due to their broad-spectrum antimicrobial activity and excellent biocompatibility. However, the balance of chain length, positive charges, and hydrophobicity on the antimicrobial activity of AMPs are still far from being optimal. Herein, a series of AMPs ([KX]n -NH2 , X = Ile, Leu or Phe, n = 3, 4, 5, or 6) with varied charges and hydrophobicity for the treatment of polymicrobial abdominal infections are designed. Specifically, [KI]4 -NH2 peptide exhibits the best in vitro antimicrobial activity against Gram-positive and -negative bacteria, as well as fungal strains. Based on the good cell biocompatibility, [KI]4 -NH2 peptide is found to have negligible in vivo toxicity at the dosage of up to 28 mg kg-1 . Furthermore, great in vivo therapeutic efficacy of [KI]4 -NH2 peptide against S. typhimurium is demonstrated in the mice abdominal infection model. The design of short sequence of antimicrobial peptides with a charge/hydrophobicity balanced structures provides a simple and efficient strategy for potential clinical applications of antimicrobial peptide-based biomaterials in a variety of bacterial infection diseases.

Barriers to Adherence to Antimicrobial Stewardship Postprescription Review and Feedback For Broad-Spectrum Antimicrobial Agents: A Nested Case-Control Study

Background

Postprescription review and feedback (PPRF) is one of the most common strategies in antimicrobial stewardship program (ASP) intervention. However, disagreements between the prescribers and ASP personnel can occur. The aim of the present study was to identify the factors associated with nonadherence to PPRF intervention.

Methods

The present retrospective nested case-control study was performed at a tertiary care center, which has been conducting a once-weekly PPRF for carbapenems and piperacillin/tazobactam since 2014. Nonadherence to ASP recommendations was defined as the failure of the primary care team to modify or stop antimicrobial therapy 72 hours after the issuance of PPRF recommendations. Factors associated with nonadherence to PPRF intervention were identified using multivariate logistic regression analysis.

Results

In total, 2466 instances of PPRF in 1714 cases between April 2014 and September 2019 were found. The nonadherence rate was 5.9%, and 44 cases were found in which carbapenems or piperacillin/tazobactam continued to be used against PPRF recommendations. Factors associated with nonadherence to PPRF recommendations were a previous history of hospitalization within 90 days (adjusted odds ratio [aOR], 2.62; 95% confidence interval [CI], 1.18-5.81) and a rapidly fatal McCabe score at the time of PPRF intervention (aOR, 2.87; 95% CI, 1.18-6.98). A review of the narrative comments in the electronic medical records indicated that common reasons for nonadherence were "the patient was sick" (n = 12; 27.3%) and "the antimicrobial seemed to be clinically effective" (n = 9; 20.5%).

Conclusions

Nonadherence to PPRF recommendations was relatively uncommon at the study institution. However, patients with a severe disease condition frequently continued to receive broad-spectrum antimicrobials against PPRF recommendations. Understanding physicians' cognitive process in nonadherence to ASP recommendations and ASP interventions targeting medical subspecialties caring for severely ill patients is needed to improve ASP.

Efficacy of a Postprescription Review of Broad-Spectrum Antimicrobial Agents With Feedback: A 4-Year Experience of Antimicrobial Stewardship at a Tertiary Care Center

Background

An inpatient antimicrobial stewardship program is vital for judicious antimicrobial use. We began a hospital-wide, postprescription review with feedback (PPRF) in 2014; the present study evaluated its impact on antimicrobial consumption and clinical outcomes over 4 years.

Methods

Once-weekly PPRF for carbapenems and piperacillin/tazobactam was implemented. We tracked the data on each antimicrobial use as days of therapy (DOT) per 1000 patient-days (PD). Changes in the incidence of drug-resistant organisms, in-hospital mortality, and length of hospital stay per month were analyzed by an interrupted time series.

Results

Carbapenem use continued to decline in the preintervention and intervention periods (−0.73 and −0.003 DOT/1000 PD, respectively), and although monthly average use remained low in the intervention period (8.3 DOT/1000 PD), more importantly, the postintervention change in the slope diminished significantly. Piperacillin/tazobactam use showed a steeper decline in the intervention period, but the change in the slope was not statistically significant (change in slope: −0.20 DOT/1000 PD per month [P = .16]). Postintervention use of narrower-spectrum antimicrobials including ampicillin/sulbactam (change in slope: +0.58 DOT/1000 PD per month [P < .001]) increased. 

The antimicrobial cost and the monthly average length of hospital stay also declined (−37.4 USD/1000 PD per month [P < .001] and −0.04 days per month [P < .001], respectively), whereas few postintervention changes in the incidence of drug-resistant organisms were observed.

Conclusions

In our study, the 4-year PPRF for broad-spectrum antimicrobials coincided with a reduction in the use of targeted antimicrobials and resulted in an improvement in 1 patient-centered outcome, thus conferring the additional benefit of reducing expenditures for antimicrobials.

Early Antimicrobial De-escalation and Stewardship in Adult Hematopoietic Stem Cell Transplantation Recipients: Retrospective Review

BACKGROUND

Antimicrobial stewardship in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients remains underutilized in North America. European guidelines advise de-escalation of broad-spectrum therapy after 72 hours in select patients with neutropenic fever of unknown origin. This is not commonplace in the United States, as current guidelines recommend broad-spectrum therapy until neutrophil engraftment. If de-escalating after at least 5 days of broad-spectrum therapy and defervescence in neutropenic allo-HSCT recipients does not predispose them to recurrent fever or infection, the practice could afford several benefits.

METHODS

The primary end point was rate of recurrent fever. Secondary outcomes included Clostridium difficile-associated infections, length of stay, intensive care unit (ICU) admission incidence, in-hospital mortality rate, need for re-escalation of therapy, rate of positive blood cultures for patients who had recurrent fevers, overall antimicrobial utilization from neutropenic fever onset, and pharmacoeconomic impact.

RESULTS

A total of 120 patients were assessed in 2 groups as cohort 1 (n = 46), which received early de-escalation, and cohort 2 (n = 74), which did not. The primary end point met criteria for noninferiority, as 7 patients (15%) in cohort 1 had recurrent fever within the specified time frame compared with 14 (19%) in cohort 2 (90% CI, -0.0878 to 0.1629, P = .026). Patients in cohort 1 received significantly less gram-positive broad-spectrum antimicrobials, with trends toward lower use of broad-spectrum gram-negative agents and lower associated costs and no differences in length of stay, ICU admission incidence, need for re-escalation of therapy, rate of culture-positive bacteremia after de-escalation or discontinuation of broad-spectrum therapy, or in-hospital mortality rate.

CONCLUSIONS

De-escalating after at least 5 days of broad-spectrum therapy and defervescence did not appear to affect the rate of recurrent fever. This allowed for significant reductions in gram-positive broad-spectrum antimicrobial utilization, with trends toward lower use of broad-spectrum gram-negative agents and associated costs and no difference in clinical outcomes compared with those continuing such therapy until neutrophil engraftment.

Description and validation of a spectrum score method to measure antimicrobial de-escalation in healthcare associated pneumonia from electronic medical records data

BACKGROUND

Comparison of antimicrobial de-escalation rates between healthcare settings is problematic. To objectively and electronically measure de-escalation a method based upon the spectrum of antimicrobial regimens administered (i.e., spectrum score) was developed.

METHODS

A Delphi process was used to develop applicable concepts. Spectrum scores were created for 27 antimicrobials based upon susceptibility for 19 organisms. National VA susceptibility data was used to estimate microbial spectrum. Susceptibility estimates were converted to ordinal scores, and values for organisms with multi-drug resistance potential were weighted more heavily. Organism scores were summed to create antibiotic-specific spectrum scores and extended mathematically to score multi-antimicrobial regimens. Vignettes were created from antimicrobial regimens administered to 300 patients hospitalized with pneumonia. Daily spectrum scores were calculated for each case. Hospitalization day 4 scores were subtracted from day 2 scores (i.e., spectrum score ∆). A positive spectrum score ∆ defined de-escalation. Experts ranked each pneumonia case on a 7-point Likert scale (Likert >4 indicated de-escalation). Spectrum score ∆s were compared to expert review. Findings were used to identify score deficiencies. Next, 40 pairs of cases were modified to include antimicrobial administration routes. Each pair contained almost similar regimens; however, one contained oral (PO) the other only intravenous (IV) antimicrobials on day 4 of therapy. Experts reviewed cases as described. Spectrum score ∆ credits to account for PO conversion were derived from the mean paired differences in Likert Score. De-escalation status was evaluated in 100 vignettes containing antimicrobial route by different experts and compared to the modified method.

RESULTS

Initial sensitivity and specificity of the spectrum score ∆ to detect expert classified de-escalation events was 86.3 and 96.0%, respectively. In paired cases, the mean (± SD) Likert score was 5.0 (1.5) and 4.6 (1.5) for PO and IV (P = 0.002), respectively. To improve de-escalation event detection, two credits were added to spectrum score ∆s based upon the percentage of antimicrobials administered PO on day 4. The final method, exhibited sensitivity and specificity to detect expert classified de-escalation events of 96.2 and 93.6%, respectively.

CONCLUSIONS

The final spectrum score method exhibited excellent agreement with expert judgments of de-escalation events in pneumonia.