An Evaluation of Antimicrobial Prophylaxis for Transrectal Prostate Biopsies; a Potential Stewardship Target

BACKGROUND

Transrectal prostate biopsy (TRBP) is a common procedure used to obtain a prostate biopsy. Although generally safe, complications may occur including infection. Pre-procedural antimicrobial prophylaxis is recommended to minimize risk of subsequent infection.

METHODS

This study is a retrospective chart review via the computerized patient record system from January 1, 2018 through February 28, 2022. The study included patients who underwent a TRPB at the Western New York, Syracuse, or Albany Stratton Veterans Affairs Healthcare Systems.

RESULTS

This study included a total of 932 patients who underwent TRPB. Post-operative infection occurred in 3.2% (n=30) of patients within 14 days of the TRPB. Of the 30 patients who developed an infection, 30% (n=9) resulted in bacteremia. For the 932 patients evaluated, 24 different antibiotic regimens were used, none of which followed guideline recommendations. None of the regimens were found to have an impact on rates of subsequent infection.

CONCLUSIONS

Results of this study suggest a need for guideline adherence. There was no benefit to using the guideline-discordant regimens as they were not associated with a decreased risk of infection, and in many cases exposed patients to unnecessarily broad and prolonged antibiotic regimens.

FUNDING

This study was completed without external funding.

Identifying racial disparities in the management of heart failure with reduced ejection fraction

OBJECTIVE(S)

Heart failure (HF) is chronic and progressive. Individuals with a left ventricular ejection fraction (LVEF or EF) < 40% are classified as having heart failure with reduced ejection fraction (HFrEF). Black patients have the highest incidence of HF and are more likely to suffer serious consequences from the disease. Identifying and addressing racial disparities in care is vital to ensuring health equity. The primary objective was to determine the association of race with 1-year heart HF admission rates for white and black patients, when adjusted for EF and age. The secondary objective was to determine the proportion of patients not on guideline-directed medication therapy (GDMT).

DESIGN

This study was a retrospective chart review conducted between 10/22/2021 and 11/22/2022 of Veteran patients with HFrEF who were identified via the VA Heart Failure Dashboard. Only White and Black patients were included. A multivariable logistic regression was used to determine odds of admission due to HF. Pharmacotherapy was analyzed to identify gaps in GDMT and if racial disparities existed.

SETTING AND PARTICIPANTS

Veterans within the Veterans Affairs Western New York Healthcare System.

OUTCOME MEASURES

One-year HF admission rates for white and black patients, when adjusted for EF and age. Proportion of patients not on GDMT.

RESULTS

Of the 345 patients with HF originally identified, 172 were included; 22% were admitted within one year. Black patients were 2.9 times more likely to be admitted. (P = 0.031). A median of two drugs (interquartile range [IQR] 1-3) could be added and one dose could be optimized (IQR 1-4) to reach GDMT goals. No differences were found in the prescribing of GDMT or in proportion of patients not on GDMT at recommended doses between white and black patients.

CONCLUSION

Black patients were more likely to be admitted for HF than white patients. Pharmacists can play an important role in identifying the need for optimizing GDMT. Future studies could focus on pharmacist-led prospective interventions with an aim to close the gap in racial disparities.

Impact of doxycycline on Clostridioides difficile infection in patients hospitalized with community-acquired pneumonia

BACKGROUND

Antibiotic use is a significant risk factor associated with Clostridioides difficile (C difficile) infection (CDI). Community-acquired pneumonia (CAP) is a common infection leading to hospital admission and the use of antibiotics that are highly associated with CDI. It has been proposed that doxycycline, a tetracycline antibiotic, may be protective against CDI.

METHODS

A retrospective analysis was conducted in hospitalized patients in Veterans Affairs Hospitals across the United States to determine if doxycycline was associated with a decreased risk of CDI. The primary outcome was the development of CDI within 30 days of initiation of doxycycline or azithromycin, as part of a standard pneumonia regimen.

RESULTS

Approximately 156,107 hospitalized patients who received care at a Veterans Affairs Hospital and were diagnosed with CAP during the study timeframe were included. A 17% decreased risk of CDI was identified with doxycycline compared to azithromycin when used with ceftriaxone for the treatment of pneumonia (P = .03). In patients who had a prior history of CDI, doxycycline decreased the incidence of CDI by 45% (odds ratio 0.55; P = .02).

CONCLUSIONS

Doxycycline is associated with a lower risk of CDI compared to azithromycin when used for atypical coverage in CAP. Thus, patients who are at such risk may benefit from doxycycline as a first-line agent for atypical coverage, rather than the use of a macrolide antibiotic, if Legionella is not of concern.

Increased Myocardial Infarction Risk Following Herpes Zoster Infection

Background

Myocardial infarction (MI) has been reported as a postinfection sequela of herpes zoster, but with limited data on incidence after zoster and protective effect of the zoster vaccine. This study investigates the risk of developing an MI 30 days postzoster, determines patient-specific risk factors, and investigates the impact of herpes zoster vaccination.

Methods

This retrospective cohort study included patients who received care at a Veterans Affairs facility between 2015 and 2020. Time to MI was determined from either 30 days post-zoster infection (zoster cohort) or a primary care appointment (control cohort).

Results

This study assessed a total of 2 165 584 patients. MI within 30 days occurred in 0.34% (n = 244) of the zoster cohort and 0.28% (n = 5782) of the control cohort (P = .0016). Patients with a documented herpes zoster infection during the study period were 1.35 times more likely to develop an MI within the first 30 days postinfection compared to the control cohort. Patients who received the recombinant zoster vaccine were less likely to have an MI postinfection (odds ratio, 0.82 [95% confidence interval, .74-.92]; P = .0003).

Conclusions

Herpes zoster infection was associated with an increased risk of MI within the first 30 days postinfection. History of prior MI, male sex, age ≥50 years, history of heart failure, peripheral vascular disease, human immunodeficiency virus, prior cerebrovascular accident, and renal disease increased odds of MI 30 days postinfection with herpes zoster. Herpes zoster vaccination decreased the odds of developing an MI in patients aged ≥50 years.

Increased Stroke Risk Following Herpes Zoster Infection and Protection With Zoster Vaccine

BACKGROUND

Studies evaluating stroke following varicella zoster virus (VZV) infection are limited, and the utility of zoster vaccination against this phenomenon is unclear. This study aimed to determine the risk of stroke 30 days following zoster infection and to evaluate the impact of zoster vaccinations on the risk of stroke in VZV-infected patients.

METHODS

This retrospective case-control study was conducted from January 2010 to January 2020 utilizing nationwide patient data retrieved from the Veterans Affairs' Corporate Data Warehouse.

RESULTS

A total of 2 165 505 patients ≥18 years of age who received care at a Veterans Affairs facility were included in the study, of whom 71 911 had a history of zoster infection. Zoster patients were found to have 1.9 times increased likelihood of developing a stroke within 30 days following infection (odds ratio [OR], 1.93 [95% confidence interval {CI}, 1.57-2.4]; P < .0001). A decreased risk of stroke was seen in patients who received the recombinant zoster vaccine (OR, 0.57 [95% CI, .46-.72]; P < .0001) or the live zoster vaccine (OR, 0.77 [95% CI, .65-.91]; P = .002).

CONCLUSIONS

Patients had a significantly higher risk of stroke within the first month following recent herpes zoster infection. Receipt of at least 1 zoster vaccination was found to mitigate this increased risk. Vaccination may therefore be viewed as a protective tool against the risk of neurologic postinfection sequelae.

Risk Factors Associated with Mortality in Hospitalized Patients with Laboratory Confirmed SARS-CoV-2 Infection During the Period of Omicron (B.1.1.529) Variant Predominance

Background

SARS-CoV-2 Omicron variant has a high transmission rate. In December 2021, Omicron became the dominant variant and quickly accounted for majority of infections in the United States. Drug shortages have led to prioritization of patients for COVID-19 treatment based on risk factors for severe disease.

Methods

A retrospective analysis of hospitalized patients with COVID-19 infection at Veteran Affairs Healthcare System across the United States. The primary outcome was 14-day all-cause mortality after the first documented positive SARS-CoV-2 laboratory test. Odds ratios were generated from a multivariate logistic regression of significant factors.

Results

This study included 12,936 COVID-19 inpatients during a period of Omicron predominance. Age ≥ 65 years is a predictor of 14-day mortality among the vaccinated and unvaccinated population (OR 4.05, CI 3.06-5.45, P ≤ .0001). Triple vaccinated patients demonstrated a 52% decreased risk of death with COVID-19 infection (OR 0.48, CI 0.37-0.61, P ≤ .0001). Patients who were double vaccinated had a 39% decreased risk of death with COVID-19 infection (OR 0.61, CI 0.46-0.80, P = .003).

Conclusion

Advanced age ≥ 65 is the greatest risk factor for mortality in hospitalized COVID-19 patients. COVID-19 vaccination, especially booster doses, was associated with a decreased risk of 14-day mortality compared to double vaccinated or non-vaccinated patients. Results of this study suggest that advanced age should be considered first for prioritization of COVID-19 treatments for Omicron.

Outcomes of multiple sclerosis patients admitted with COVID-19 in a large veteran cohort

Background

Given concerns over immune function, the decision whether to continue disease modifying therapy (DMT) in multiple sclerosis (MS) patients during the COVID-19 pandemic has been challenging, complicated by the risk of MS disease progression in the absence of treatment.

Methods

This retrospective analysis of patients treated for COVID-19 infection at veteran affairs healthcare systems across the United States, investigated 30-day all-cause mortality after first positive COVID-19 in patients with and without MS. We examined mortality risk impact of disease modifying therapy for MS, accounting for other relevant factors known to be associated with COVID-19 mortality. Patients were propensity score matched in a 1:20 fashion based on MS diagnosis.

Results

49,737 COVID-19 inpatient cases were identified, of which 258 were diagnosed with MS. In the propensity score matched cohort, MS patients taking DMT (excluding those receiving anti-CD20 antibodies) had a lower odds of 30 day mortality (OR: 0.18 [95%CI: 0.00988-0.94] p=0.041). Similarly, in the unmatched cohort, patients on DMT had a lower risk of death (OR: 0.16 [95%CI: 0.01-0.82] p=0.023). There was no statistically significant difference in mortality between those with and without MS. In the propensity matched cohort, age over 65, heart failure, chronic kidney disease (CKD), and diabetes increased the risk of mortality while vaccination reduced the risk of mortality.

Conclusion

Veteran patients with MS hospitalized for COVID-19 were less likely to die when taking DMTs (excluding those receiving anti-CD20 antibodies), accounting for other relevant factors. Results suggest that, in relation to the COVID-19 pandemic, not only is it safe to continue most DMTs in people with MS, but it may be beneficial given the decreased risk of COVID-19 mortality and decreased risk of MS disease progression.

Admissions and Mortality Related to Urinary Tract Infections in Male Veterans with Dementia

Objective To examine mortality and hospital readmission rates in male veterans with dementia diagnosed with urinary tract infection (UTI) compared with patients without dementia. Design Retrospective cohort study. Setting Veterans Healthcare Systems (VA). Participants Male inpatients with a diagnosis of UTI who were treated at any VA Healthcare Center from January 1, 2009, to December 31, 2018. Interventions None. Main Outcome Measures Mortality and hospital readmission for patients with and without dementia at 30, 60, and 90 days from UTI diagnosis. Results 262,515 veterans admitted with UTI were analyzed, and 58,940 (22.5%) had dementia. The mean age for veterans with dementia was 80.0 +/- 9.7 years. Veterans with dementia experienced less mortality than patients without dementia at 30 days (8.3% vs 8.5%; P < 0.001), but more mortality at 60-day (4.9% vs 4.7%; P < 0.001) and 90-day (3.6% vs 3.3%; P < 0.001) intervals. Death was 20% less likely at 30 days in patients with dementia. Veterans with dementia were readmitted more than those without dementia at 30-day (18.4% vs 16.0%), 60-day (4.5% vs 2.8%), and 90-day (3.4% vs 2.5%) intervals; P < 0.0001. Conclusion Though patients with dementia are at an increased risk for death long-term, risk of death is less than those without dementia shortly following UTI diagnosis. This highlights the possibility that veterans with dementia may be hospitalized and diagnosed with UTIs when in actuality they have asymptomatic bacteriuria. Patients with dementia and UTI therefore represent an important group of geriatric patients that could benefit from the oversight of a senior care pharmacist to help prevent unnecessary treatment of asymptomatic bacteriuria.

Open-source maximum a posteriori-bayesian dosing AdDS to current therapeutic drug monitoring: Adapting to the era of individualized therapy

Recent updates in the therapeutic drug monitoring (TDM) guidelines for vancomycin have rekindled interest in maximum a posteriori-Bayesian (MAP-Bayesian) estimation of patient-specific pharmacokinetic parameters. To create a versatile infrastructure for MAP-Bayesian dosing of vancomycin or other drugs, a freely available, R-based software package, Advanced Dosing Solutions (AdDS), was created to facilitate clinical implementation of these improved TDM methods. The objective of this study was to utilize AdDS for pre- and post-processing of data in order to streamline the therapeutic management of vancomycin in healthy and obese veterans. Patients from a local Veteran Affairs hospital were utilized to compare the process of full re-estimation versus Bayesian updating of priors on healthy adult and obese patient populations for use with AdDS. Twenty-four healthy veterans were utilized to train (14/24) and test (10/24) the base pharmacokinetic model of vancomycin while comparing the effects of updated and fully re-estimated priors. This process was repeated with a total of 18 obese veterans for both training (11/18) and testing (7/18). Comparison of MAP objective function between the original and re-estimated models for healthy adults indicated that 78.6% of the subjects in the training and 70.0% of the subjects in the testing datasets had similar or improved predictions by the re-estimated model. For obese veterans, 81.8% of subjects in the training dataset and 85.7% of subjects in the testing dataset had similar or improved predictions. Re-estimation of model parameters provided more significant improvements in objective function compared with Bayesian updating, which may be a useful strategy in cases where sufficient samples and subjects are available. The generation of bespoke regimens based on patient-specific clearance and minimal sampling may improve patient care by addressing fundamental pharmacokinetic differences in healthy and obese veteran populations.

Smoking status related to Covid-19 mortality and disease severity in a veteran population

INTRODUCTION

Cigarette smoking is associated with development of significant comorbidities. Patients with underlying comorbidities have been found to have worse outcomes associated with Coronavirus Disease 2019 (Covid-19). This study evaluated 30-day mortality in Covid-19 positive patients based on smoking status.

METHODS

This retrospective study of veterans nationwide examined Covid-19 positive inpatients between March 2020 and January 2021. Bivariate analysis compared patients based on smoking history. Propensity score matching adjusted for age, gender, race, ethnicity, Charlson comorbidity index (0-5 and 6-19) and dexamethasone use was performed. A multivariable logistic regression with backwards elimination and Cox Proportional Hazards Ratio was utilized to determine odds of 30-day mortality.

RESULTS

The study cohort consisted of 25,958 unique Covid-19 positive inpatients. There was a total of 2,995 current smokers, 12,169 former smokers, and 8,392 non-smokers. Death was experienced by 13.5% (n = 3503) of the cohort within 30 days. Former smokers (OR 1.15; 95% CI, 1.05-1.27) (HR 1.13; 95% CI, 1.03-1.23) had higher risk of 30-day mortality compared with non-smokers. Former smokers had a higher risk of death compared to current smokers (HR 1.16 95% CI 1.02-1.33). The odds of death for current vs. non-smokers did not significantly differ.

CONCLUSION

Compared to veteran non-smokers with Covid-19, former, but not current smokers with Covid-19 had a significantly higher risk of 30-day mortality.

Sputum susceptibilities in a nationwide veteran cohort

BACKGROUND

Respiratory infections are one of the most common causes of morbidity and mortality. This study examined antimicrobial susceptibility of common respiratory isolates from veterans.

METHODS

Sputum culture data from the Veteran Health Administration were obtained retrospectively between January 2009 and 2019. Cumulative antibiograms were constructed for bacterial isolate susceptibility.

RESULTS

Sputum and bronchial cultures from approximately 10,345 veterans were included each year. Haemophilus influenzae has maintained high levels of susceptibility to third generation cephalosporins from 2009 (99.7%) to 2018 (97.2%). Third generation cephalosporin susceptibilities amongst Klebsiella pneumoniae have trended upward from 2009 to 2018 as well (79.1% vs 86.4%). In Pseudomonas aeruginosa isolates, there has been an increase in susceptibility rates to cefepime from 2009 to 2018 (79.6%, to 86.6%), gentamicin (81.5% to 89.1%), and piperacillin/tazobactam (86.5% to 90%). Fluoroquinolone susceptibilities amongst Escherichia coli have remained low but stable between 2009 and 2018. Third generation cephalosporin susceptibilities for S. pneumoniae improved slightly from 92.2% to 95% between 2009 and 2018 while susceptibility to azithromycin trended down slightly from 56.8% in 2009 to 51.7% in 2018 for S. pneumoniae.

DISCUSSION

The antibiogram of sputum isolates from the VA Healthcare System were examined to determine changes in patterns of resistance over a decade of use.

CONCLUSIONS

This large-scale study investigated nationwide sputum culture susceptibility trends. Avoidance of macrolides for empiric treatment of community acquired pneumonia and avoidance of fluoroquinolones for empiric treatment of hospital acquired or ventilator associated pneumonia may be warranted based on susceptibility trends.

Societal factors contributing to infections caused by Chlamydia trachomatis and Neisseria gonorrhoeae in a veteran population

BACKGROUND

Veterans have a higher incidence of sexually transmitted infections (STIs) compared to the general population. The objective of this study is to evaluate the association of societal factors on the risk of chlamydia or gonorrhea.

METHODS

This retrospective cohort study evaluated data from Veteran Health Administration. Patients tested for chlamydia or gonorrhea between January 2009 and January 2019 were included. Descriptive statistics and regression were used to evaluate societal factors.

RESULTS

A total of 1,232,173 tests for chlamydia or gonorrhea were performed. There were 51,987 (4.2%) positive cases with 74.18% for chlamydia and 24.96% for gonorrhea. In 13.6% of veterans with reported military sexual trauma, there was no difference in risk of positivity (p = 0.39). Veterans with a history of combat had lower odds of testing positive (OR, 0.94; 95% CI, 0.91-0.97). Tests in veterans who were married had a 24% less chance of positivity (OR, 0.76; 95% CI, 0.74-0.79) compared to tests in divorced veterans. Positive number of cases increased each year.

CONCLUSION

Sexually transmitted infections are a growing concern. Gender, age, ethnicity, marital status, and race are societal identifiers which influence likelihood of STI acquisition.

Antimicrobial susceptibility trends for urinary isolates in the veteran population

BACKGROUND

Guidance on empiric treatment for urinary tract infections (UTIs) is lacking for the male population which comprises much of the Veteran population in the United States. This study evaluated susceptibility trends in antimicrobials used for treatment of UTIs in the inpatient and outpatient Veteran population nationwide.

METHODS

Urine culture data was retrospectively obtained from Corporate Data Warehouse. All urine cultures from Veteran Health Administration patients 18 years of age or older who were treated at any VA health care center in the years 2009 and 2018 were eligible. Antibiograms were constructed for bacterial isolate susceptibility.

RESULTS

In 2009 and 2018 isolates from 54,788 and 58,983 Veterans were analyzed, respectively. Escherichia coli was the most common bacteria isolated. For ceftriaxone, E coli susceptibilities were relatively high but trended downward from 2009 to 2018. Common urinary pathogen susceptibilities remained low for fluoroquinolones and trimethoprim-sulfamethoxazole.

DISCUSSION

Empiric therapy for Veterans with UTIs should be based on local susceptibility patterns as previously recommended first-line agents have fallen out of favor due to increasing resistance rates.

CONCLUSIONS

Both inpatient and outpatient stewardship is needed to ensure appropriate treatment, as viable treatment options for UTIs are becoming increasingly limited.

Risk Factors for Mortality in an Older Veteran Population With infective Endocarditis

OBJECTIVE

To determine 30-day and 1-year mortality in patients treated for infective endocarditis (IE) in a VA population. The secondary objective was to identify risk factors for increased risk of mortality in veterans diagnosed with IE.

DESIGN

A retrospective cohort study.

SETTING

Veterans Affairs Western New York Healthcare System PARTICIPANTS: Patients who had a diagnosis of IE between the years 2005 and 2016. Patients were identified via International Classification of Diseases (ICD) codes.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Factors for death and survival were compared using a bivariate analysis. Significant factors were built into a multivariate logistic regression analysis to determine risk factors for death at 30 days and 1 year.

RESULTS

Between 2005 and 2016, there were 153 patients with IE. All-cause mortality at 30 days was 14% versus 39% at 1 year. Patients were more likely to die at 1 year with higher Pitt Bacteremia Scores, older age, and lower number of minor criteria according to Duke Criteria. Comorbidities were similar between groups.

CONCLUSIONS

Older patients with higher Pitt Bacteremia Scores and lower numbers of minor criteria are more likely to experience mortality at one year. Given the high rates of death at one year, close monitoring, even after completion of therapy may be necessary in older patients. Senior care pharmacists are in a unique position to monitor these patients.

Determining the Utility of Methicillin-Resistant Staphylococcus aureus Nares Screening in Antimicrobial Stewardship

BACKGROUND

Treatment of suspected methicillin-resistant Staphylococcus aureus (MRSA) is a cornerstone of many antibiotic regimens; however, there is associated toxicity. The Department of Veterans Affairs (VA) hospitals screen each patient for MRSA nares colonization on admission and transfer. The objective was to determine the negative predictive value (NPV) of MRSA screening in the determination of subsequent positive clinical culture for MRSA. High NPVs with MRSA nares screening may be used as a stewardship tool.

METHODS

This was a retrospective cohort study across VA medical centers nationwide from 1 January 2007 to 1 January 2018. Data from patients with MRSA nares screening were obtained from the VA Corporate Data Warehouse. Subsequent clinical cultures within 7 days of the nares swab were evaluated for the presence of MRSA. Sensitivity, specificity, positive predictive values, and NPVs were calculated for the entire cohort as well as subgroups for specific culture sites.

RESULTS

This cohort yielded 561 325 clinical cultures from a variety of anatomical sites. The sensitivity and specificity for positive MRSA clinical culture were 67.4% and 81.2%, respectively. The NPV of MRSA nares screening for ruling out MRSA infection was 96.5%. The NPV for bloodstream infections was 96.5%, for intraabdominal cultures it was 98.6%, for respiratory cultures it was 96.1%, for wound cultures it was 93.1%, and for cultures from the urinary system it was 99.2%.

CONCLUSION

Given the high NPVs, MRSA nares screening may be a powerful stewardship tool for deescalation and avoidance of empirical anti-MRSA therapy.

Clinical Course and Outcome of COVID-19 Acute Respiratory Distress Syndrome: Data From a National Repository

BACKGROUND

Mortality attributable to coronavirus disease-19 (COVID-19) 2 infection occurs mainly through the development of viral pneumonia-induced acute respiratory distress syndrome (ARDS).

RESEARCH QUESTION

The objective of the study is to delineate the clinical profile, predictors of disease progression, and 30-day mortality from ARDS using the Veterans Affairs Corporate Data Warehouse.

STUDY DESIGN AND METHODS

Analysis of a historical cohort of 7,816 hospitalized patients with confirmed COVID-19 infection between January 1, 2020, and August 1, 2020. Main outcomes were progression to ARDS and 30-day mortality from ARDS, respectively.

RESULTS

The cohort was comprised predominantly of men (94.5%) with a median age of 69 years (interquartile range [IQR] 60-74 years). 2,184 (28%) were admitted to the intensive care unit and 643 (29.4%) were diagnosed with ARDS. The median Charlson Index was 3 (IQR 1-5). Independent predictors of progression to ARDS were body mass index (BMI) ≥40 kg/m², diabetes, lymphocyte counts <700 × 109/L, LDH >450 U/L, ferritin >862 ng/ml, C-reactive protein >11 mg/dL, and D-dimer >1.5 ug/ml. In contrast, the use of an anticoagulant lowered the risk of developing ARDS (OR 0.66 [95% CI 0.49-0.89]. Crude 30-day mortality rate from ARDS was 41% (95% CI 38%-45%). Risk of death from ARDS was significantly higher in those who developed acute renal failure and septic shock. Use of an anticoagulant was associated with 2-fold reduction in mortality. Survival benefit was observed in patients who received corticosteroids and/or remdesivir but there was no advantage of combination therapy over either agent alone.

CONCLUSIONS

Among those hospitalized for COVID-19, nearly 1 in 10 progressed to ARDS. Septic shock, and acute renal failure are the leading causes of death in these patients. Treatment with either remdesivir and corticosteroids reduced the risk of mortality from ARDS. All hospitalized patients with COVID-19 should be placed at a minimum on prophylactic doses of anticoagulation.

Combatting the Rising Tide of Antimicrobial Resistance: Pharmacokinetic/Pharmacodynamic Dosing Strategies for Maximal Precision

OBJECTIVE

Antimicrobial pharmacokinetics/pharmacodynamics (PK/PD) principles and PK/PD models have been essential in characterizing the mechanism of antibiotic bacterial killing and determining the most optimal dosing regimen that maximizes clinical outcomes. This review summarized the fundamentals of antimicrobial PK/PD and the various types of PK/PD experiments that shaped the utilization and dosing strategies of antibiotics today.

METHODS

Multiple databases - including PubMed, Scopus, and EMBASE - were searched for published articles that involved PK/PD modelling and precision dosing. Data from in vitro, in vivo and mechanistic PK/PD models were reviewed as a basis for compiling studies that guide dosing regimens used in clinical trials.

RESULTS

Literature regarding the utilization of exposure-response analyses, mathematical modelling and simulations that were summarized are able to provide a better understanding of antibiotic pharmacodynamics that influence translational drug development. Optimal pharmacokinetic sampling of antibiotics from patients can lead to personalized dosing regimens that attain target concentrations while minimizing toxicity. Thus the development of a fully integrated mechanistic model based on systems pharmacology can continually adapt to data generated from clinical responses, which can provide the framework for individualized dosing regimens.

CONCLUSIONS

The promise of what PK/PD can provide through precision dosing for antibiotics has not been fully realized in the clinical setting. Antimicrobial resistance, which has emerged as a significant public health threat, has forced clinicians to empirically utilize therapies. Future research focused on implementation and translation of PK/PD-based approaches integrating novel approaches that combine knowledge of combination therapies, systems pharmacology and resistance mechanisms are necessary. To fully realize maximally precise therapeutics, optimal PK/PD strategies are critical to maximize antimicrobial efficacy against extremely-drug-resistant organisms, while minimizing toxicity.

Comparison of in-hospital mortality risk prediction models from COVID-19

OBJECTIVE

Our objective is to compare the predictive accuracy of four recently established outcome models of patients hospitalized with coronavirus disease 2019 (COVID-19) published between January 1st and May 1st 2020.

METHODS

We used data obtained from the Veterans Affairs Corporate Data Warehouse (CDW) between January 1st, 2020, and May 1st 2020 as an external validation cohort. The outcome measure was hospital mortality. Areas under the ROC (AUC) curves were used to evaluate discrimination of the four predictive models. The Hosmer-Lemeshow (HL) goodness-of-fit test and calibration curves assessed applicability of the models to individual cases.

RESULTS

During the study period, 1634 unique patients were identified. The mean age of the study cohort was 68.8±13.4 years. Hypertension, hyperlipidemia, and heart disease were the most common comorbidities. The crude hospital mortality was 29% (95% confidence interval [CI] 0.27-0.31). Evaluation of the predictive models showed an AUC range from 0.63 (95% CI 0.60-0.66) to 0.72 (95% CI 0.69-0.74) indicating fair to poor discrimination across all models. There were no significant differences among the AUC values of the four prognostic systems. All models calibrated poorly by either overestimated or underestimated hospital mortality.

CONCLUSIONS

All the four prognostic models examined in this study portend high-risk bias. The performance of these scores needs to be interpreted with caution in hospitalized patients with COVID-19.

An Evaluation of Antimicrobial Prophylaxis for Dental Procedures at a Veterans Healthcare System; A Role for Senior Care Pharmacists?

OBJECTIVE: The primary objective of this study was to determine the prevalence of appropriate use of antibiotics before a dental procedure.<br/> DESIGN: Retrospective cohort study.<br/> SETTING: Veterans Healthcare Systems.<br/> PARTICIPANTS: Veterans who filled outpatient prescriptions for antimicrobial dental prophylaxis at the Veterans Administration Western New York Healthcare System from December 1, 2017, through October 1, 2019.<br/> INTERVENTIONS: None.<br/> MAIN OUTCOME MEASURES: Use of antibiotic dental prophylaxis was deemed appropriate if in accordance with guideline recommendations. Descriptive statistics were used to summarize data.<br/> RESULTS: A total of 130 veterans receiving antibiotics for dental prophylaxis were included in this evaluation. Of those who were included, only 16.9% received appropriate antibiotic dental prophylaxis. Patients with a prosthetic joint were significantly more likely to be inappropriately prescribed antibiotics for dental prophylaxis. Approximately 87% of patients who were inappropriately prescribed antibiotic prophylaxis had prosthetic joints (P < .0001).<br/> CONCLUSION: Most antibiotics for dental prophylaxis are prescribed inappropriately. The large amount of inappropriately used antibiotics in this study highlights the need for dental stewardship in our veteran population. Antibiotics for dental prophylaxis therefore represent an important stewardship target in the outpatient setting. This may be an ideal opportunity for senior care pharmacists to intervene upon.

Outpatient antimicrobial stewardship: Targets for urinary tract infections

BACKGROUND

Urinary tract infections (UTIs) are common. Outpatient antimicrobial stewardship programs are emerging and a focused approach to UTIs is needed to help guide programs.

METHODS

Data were collected by retrospective chart review of outpatients using encounters from January 2005 to March 2018. Antibiotic therapy was indicated if at least one UTI symptom was present. Antibiotic therapy was appropriate if consistent with guidelines and culture results. Factors that differed significantly (P <.05) between the comparator groups were built into a multivariable logistic regression model to determine factors associated with inappropriate prescribing.

RESULTS

A total of 607 outpatients were included, of which approximately 68% were treated inappropriately. Inappropriate regimens consisted of 50.9% (n = 309) incorrect durations, 35.1% (n = 213) incorrect choice of antibiotic, and 12.4% (n = 75) incorrect doses. Ten percent of patients developed a reinfection within 30 days. Recurrence of UTI with the same pathogen within 30 days occurred in 5.1%. Catheter use and advanced age are both risk factors for recurrence and inappropriate treatment.

CONCLUSIONS

Outpatient antibiotic prescribing for UTIs is suboptimal. Stewardship programs should focus on patients with catheters and of advanced age as they are often inappropriately treated.

Outpatient antimicrobial stewardship: Optimizing patient care via pharmacist led microbiology review

BACKGROUND

Cultures are often taken in the outpatient setting but results are not acted upon, leading to unnecessary re-presentations to the health care setting.

METHODS

This study was a prospective study with interventions made between January 1, 2018, and January 1, 2019. Cultures were reviewed to ensure appropriate antimicrobial coverage. The objective was to compare outcomes with accepted versus rejected interventions. Descriptive statistics were used to summarize data.

RESULTS

A total of 7,360 antibiotic orders were reviewed by the infectious diseases pharmacists. Pharmacists intervened on 20.1% (n = 194) of encounters with related cultures. Interventions were most frequent in the emergency department (42%). Ciprofloxacin required the most interventions (26%), followed by third-generation cephalosporins (22%). The intervention acceptance rate was 76%, which was associated with decreased rates of 30-day treatment failure (5% vs 28%, P < .001) and 30-day admission (0.7% vs 11%, P = .001), when interventions were accepted rather than rejected.

DISCUSSION

Approximately 20% of patients required intervention. Culture review services may be beneficial in a variety of outpatient settings. Outpatient stewardship literature is limited, and our study found a decrease in admission and treatment failure.

CONCLUSIONS

Microbiology review and intervention positively impacted care for outpatients. Intervention was associated with significantly decreased rates of treatment failure and admission when interventions were accepted.

Impact of Beta-lactam Allergy on Treatment of Outpatient Infections

PURPOSE

The most commonly reported medication allergies in the United States involve beta-lactam antibiotics, creating an important consideration for prescribers when choosing optimal treatment of infections. Currently, few data exist on outpatient prescribing patterns in response to patients with a beta-lactam allergy. This study sought to evaluate the appropriateness of outpatient antibiotic therapy in patients with documented beta-lactam allergies within a Veterans Affairs health care system to evaluate areas of improvement in prescribing practices.

METHODS

Patients receiving outpatient oral antibiotics were prospectively identified through real-time electronic alerts from June 2017 through February 2018. Prescriptions were then reviewed retrospectively to identify appropriateness of antibiotic, drug choice, dose, and duration based on current guideline recommendations. Data were compared between patients with a listed beta-lactam allergy and patients without a beta-lactam allergy to determine the impact on prescribing patterns and outcomes. Baseline characteristics were compared by using descriptive statistics. Significant risk factors for inappropriate prescribing were identified through a multivariable analysis.

FINDINGS

The cohort included 1844 antibiotic prescriptions (documented beta-lactam allergy, 221; no beta-lactam allergy, 1623). Appropriate drug, dose, and duration for antibiotics prescribed in patients reporting a beta-lactam allergy versus nonallergic patients were 44.3% versus 53.0% (P = 0.02), 91.4% versus 86.2% (P = 0.03), and 75.1% versus 76.2% (P = 0.83), respectively. Patients with a reported beta-lactam allergy were 31% less likely to receive the correct drug for indication empirically (95% CI, 0.52-0.92) in the multivariable regression model when adjusted for fluoroquinolone use. In addition, patients reporting a beta-lactam allergy were 2.2 times (95% CI, 1.6-3.0) more likely to receive a fluoroquinolone antibiotic. Antibiotics were considered overall inappropriate based on at least one aspect of therapy in 79.6% of patients reporting a beta-lactam allergy and in 71% of nonallergic patients.

IMPLICATIONS

Antibiotic therapy in patients with a documented beta-lactam allergy was less likely to be appropriate overall, suggesting an area of improvement for prescribing habits. Future interventions should focus on prescriber education regarding first-line and alternative treatments for patients with beta-lactam allergies to ensure that optimal treatment is being provided.

1113. Outpatient Antimicrobial Stewardship: Targets for Urinary Tract Infections

Background

Methods

Results

Conclusion

Disclosures

1422. Evaluation of Diabetic Foot Infections and Osteomyelitis in a Veteran Population: Targets for Improved Outcomes

Background

Diabetic foot infections (DFI) complicated with osteomyelitis are a difficult infection to treat often resulting in poor outcomes. DFIs often require amputations, including serial amputations due to inadequate initial intervention and infection progression. This study examines various diagnostic and treatment strategies aimed to improve outcomes.

Methods

This retrospective cohort study included patients greater than or equal to 18 years of age with a DFI as identified via ICD 9 and ICD 10 codes from January 2005 to December 2018. Outcomes were analyzed to measure the impact of baseline characteristics on outcomes. The severity of infection was defined by PEDIS score (perfusion, extent, depth, infection, and sensation). Descriptive statistics were used to report differences.

Results

One hundred and thirty patients were included, 72% with osteomyelitis. The median PEDIS score was 3 (interquartile range 2–3). Magnetic resonance imaging was used to evaluate 38% of the population. Osteomyelitis patients who had an MRI performed were noted to have a higher rate of appropriate treatment and cure (56%) when compared with a similar group of patients who did not receive an MRI (25%) (P = 0.005). Comparing prolonged (> 4 weeks) therapy to short therapy, there was a significantly higher proportion of cures noted (62.71% vs. 36.62%, P < 0.0001). Failure was associated with less than 4 weeks of therapy (66.7%, P = 0.03) and presence of residual inflammation/infection after amputation (58.3%, P < 0.0001). Route of antibiotic had no impact on failure rates. However, patients with an initial drug-bug mismatch were more likely to fail. Sixty-six percent of patients with decreased ankle brachial index failed (P = 0.02).

Conclusion

Diabetic foot infections have serious consequences. Over a third of patients required further amputation or additional antibiotic therapy. Risk of failure was associated with short durations of therapy, poor perfusion, and residual inflammation after amputation. However, a higher rate of cures was noted with use of an MRI and prolonged therapy in patients. Stewardship initiatives may wish to focus on ensuring prolonged treatment courses and appropriate surgical intervention rather than on route of antibiotic therapy as there was no difference in failure rates.

Disclosures

All authors: No reported disclosures.

1466. Alkaline Urine: A Cause for Urinary Tract Infection Recurrence

Background

Urinary tract infections (UTIs) are one of the most common indications for antibiotics in both the inpatient and outpatient setting. The purpose of this study was to examine the impact of urinary pH on recurrence of UTIs. A recent review article stated imaging should be considered for patients with a urinary pH of 7 or higher. This study examines the impact of pH on outcomes of patients with UTI to determine whether pH plays a role in recurrent infection and representations to the healthcare facility.

Methods

This was a retrospective chart review via the computerized patient record system. Patients over the age of 18 years who presented to the healthcare facility between January 1, 2005 to January 1, 2019 for treatment of UTIs were included in this study. Alkaline urine was defined as a urinary pH greater than or equal to 7, while acidic urine was defined as a urinary pH less than 7. Urease splitting organisms included Proteus spp., Providencia spp., and Morganella spp. Outcomes included recurrence and re-presentation to the healthcare facility within 30 days.

Results

A total of 793 patients were included in this study, of which 21.3% had alkaline urine. Patients with alkaline urine were more likely to have recurrence of UTI (8.3% vs. 4.3%). Patients with a catheter were more likely to have alkaline urine (30% vs 18%; P = 0.0005). As expected, alkaline urine was associated with a higher frequency of urease splitting organisms (19% in alkaline urine vs. 3% in acidic urine). Renal calculi were found in 3.6% of patients with alkaline urine; however, only 34.3% of patients with alkaline urine had imaging completed. The use of drugs which can alkalinize the urine did not differ significantly between groups.

Conclusion

Patients with an alkaline urinary pH were more likely to experience recurrence and readmission within 30 days. Imaging was performed in a minority of patients which may represent a potential target for stewardship programs. Alkaline urine may be a marker for urease splitting organisms and calculi formation. More widespread imaging may be able to detect stones, allowing for potential urologic intervention, preventing subsequent antibiotic courses and repeated healthcare presentations.

Disclosures

All authors: No reported disclosures.

2068. Outpatient Antimicrobial Stewardship: Optimizing Patient Care Via Pharmacist Led Culture Review

Background

Antimicrobial stewardship programs are well established in the inpatient setting; however, progress has lagged in the outpatient setting. With a growing need for outpatient stewardship, data are needed to guide the development of new services to improve patient care. Many times, cultures are taken in the outpatient setting but results are not acted upon, leading to unnecessary re-presentations to the healthcare setting.

Methods

This study was a prospective chart review via the computerized patient record system with interventions made as needed between January 1, 2018 and January 1, 2019. Infectious Diseases received alerts when oral antibiotics for outpatient use were ordered. Cultures were reviewed daily to ensure drug-bug match and timely interventions. The primary objective of this study was to compare outcomes in patients with accepted interventions vs. rejected interventions: 30-day re-presentation rates, 30-day admission rates, and 30-day treatment failure. Descriptive statistics were used to summarize data.

Results

A total of 7,360 antibiotic orders were reviewed in real time by Infectious Diseases. Of which, 965 encounters with cultures were included in the culture review service. Pharmacists intervened on 20.1% (n = 194) of patient encounters. The majority of antibiotic prescriptions that required intervention were from the emergency department (42%) and primary care (39%), with the remaining 19% being from various outpatient specialty clinics. The most common antibiotics prescribed for patients requiring intervention were ciprofloxacin (26%), third-generation cephalosporins (22%), and sulfamethoxazole/trimethoprim (18%). The most common indication for use was urinary tract infection. The intervention acceptance rate was 76%. Intervention significantly decreased rates of 30-day treatment failure (5% vs. 28%, P < 0.0001) and 30-day admission (0.7% vs. 11%, P = 0.0005) when interventions were accepted rather than rejected.

Conclusion

Culture review service positively impacted outcomes for patients in the outpatient setting. For those antibiotic orders that required intervention, the intervention significantly decreased rates of 30-day treatment failure and 30-day admission when interventions were accepted.

Disclosures

All authors: No reported disclosures.

571. Determining the Utility of Methicillin-Resistant Staphylococcus aureus Nares Screening in Antimicrobial Stewardship

Background

Treatment of suspected Methicillin-resistant Staphylococcus aureus (MRSA) is a cornerstone of many antibiotic regimens; however, some anti-MRSA antibiotics are associated with toxicity. The Veterans Affairs (VA) screens each patient on admission for MRSA nares colonization. The objective of this study was to determine whether MRSA nares screening can be used as a stewardship tool for de-escalation as well as avoidance of anti-MRSA therapy.

Methods

This was a retrospective cohort study across VA medical centers nationwide from January 1, 2007 to January 1, 2018. Data from patients with MRSA nares screening were obtained from the Corporate Data Warehouse. Subsequent clinical cultures within 7 days of the nares swab were evaluated for the presence of MRSA. Sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) were calculated for the entire cohort, as well as subgroups for specific culture sites. Cultures were considered to be from a sterile site if they were from a fluid/aspirate, bone, tissue, or blood taken from the periphery. NPVs and PPVs were calculated for each of these sterile sites.

Results

A total of 447,579 clinical cultures were included in the final analysis. The NPV of MRSA nares screening for ruling out MRSA was 95.7% for all cultures submitted. The sensitivity and specificity for positive clinical cultures were 67.4% and 83%, respectively. The NPV for bloodstream infections (n = 64,128) was 96.2% for intra-abdominal cultures (n = 8,071) was 97.9%, for respiratory cultures (n = 75,242) was 95.3%, for wound cultures (n = 95,832) was 90.4%, and for renal cultures (n = 164,330) was 99.1%. NPVs for sterile sites are as follows: intra-abdominal (n = 7,426) was 98.1%, respiratory (n = 15,583) was 95.2%, wound (n = 51,793) was 91%.

Conclusion

MRSA nares screening has a high NPV and specificity for ruling out potential MRSA infections at a variety of culture sites including bloodstream, intra-abdominal, respiratory, renal, and wounds. MRSA nares screening is a powerful stewardship tool for de-escalation and avoidance of empirical anti-MRSA therapy.

Disclosures

All authors: No reported disclosures.

Antibiotic stewardship targets in the outpatient setting

BACKGROUND

Outpatient prescriptions comprise 60% of antibiotic use. This study prospectively identified inappropriate antibiotic use enabling a focused approach to outpatient antimicrobial stewardship.

METHODS

Outpatients at the Veterans Affairs Western New York Healthcare System were identified via an electronic antibiotic alert from June 2017 to September 2017. Descriptive statistics and multivariable logistic regression identified stewardship targets.

RESULTS

Of the 1,063 patients, 40% of antibiotic prescriptions were not indicated. Urinary tract infections (21%), bronchitis (20%), skin structure infections (17%), and sinusitis (10%) were common causes of inappropriate antibiotic use. Azithromycin (37%) was prescribed unnecessarily most often, followed by ciprofloxacin (16%), amoxicillin/clavulanate (13%), and cephalexin (12%). The correct drug was chosen in 52%, dose in 81%, and duration in 75% of patients. When the antibiotic was indicated, the correct drug was 2.9 times more likely to be prescribed and 2 times more likely to have the correct duration and receive care in the emergency room.

DISCUSSION

Focusing on 4 drugs; amoxicillin/clavulanate, azithromycin, ciprofloxacin, and cephalexin accounted for 80% of unnecessary drug use. This study provides a guide to concentrate efforts during implementation of an outpatient stewardship program.

CONCLUSIONS

Poor antibiotic prescribing was found in the outpatient setting. This study identifies areas for improvement via stewardship.

Evaluation of Antibiotic Prescribing in a Veterans Affairs Outpatient Setting: Identification of Stewardship Targets

OBJECTIVE: To evaluate antibiotic prescribing practices for geriatric outpatients in a Veterans Affairs (VA) health care system.<br/> DESIGN: This is a single-center, observational, prospective cohort study.<br/> SETTING: Veterans Affairs Healthcare System.<br/> PATIENTS: Outpatients treated with oral antibiotics between June and September 2017.<br/> INTERVENTIONS: None.<br/> MAIN OUTCOME MEASURE(S): Appropriate therapy was assessed based on clinical practice guidelines. Multivariable logistic regression was used to identify predictors of appropriate treatment.<br/> RESULTS: This study yielded 1,063 prescriptions for analysis. No significant difference was observed for antibiotic indicated (60%), correct drug (50%), or correct duration (75%). Patients older than 65 years of age were more likely to receive an inappropriate dose (86% vs. 76%; P < 0.002). In the multivariable analysis, patients with chronic obstructive pulmonary disease (COPD) were more than 1.4 times likely to be treated appropriately (95% confidence interval 1.03-1.9) versus those without COPD. Older patients were not more likely to be re-treated or admitted within 30 days.<br/> CONCLUSION: Antibiotics are often inappropriately used in the outpatient setting; but not more frequently in elderly patients. Older adults were more likely to be prescribed an antibiotic at an inappropriate dose. Opportunities exist for stewardship teams to provide value in the outpatient setting to ensure appropriate antibiotic prescribing with a focus on dosing.

Successful cure of daptomycin-non-susceptible, vancomycin-intermediate Staphylococcus aureus prosthetic aortic valve endocarditis directed by synergistic in vitro time-kill study

Infectious complications following surgical valve replacements are extremely difficult to treat, often requiring prolonged antimicrobials therapy with or without surgery. Vancomycin-intermediate Staphylococcus aureus is an infrequent pathogen, with an estimated prevalence of less than 0.3%, but presents even greater challenges. We report a case of successful cure of daptomycin-non-susceptible and vancomycin-intermediate Staphylococcus aureus prosthetic valve endocarditis using an eight-week course of combination antimicrobial therapy. Using time-kill study, the combination of daptomycin plus ceftaroline and rifampin resulted in a greater than 4 log reduction of bacterial growth at 24 hours. This antimicrobial combination was used for a total of eight weeks with a successful outcome.

Outpatient Antimicrobial Stewardship: Targets for Community-acquired Pneumonia

PURPOSE

Community-acquired pneumonia (CAP) is one of the leading causes of death in the United States. The primary objective of this study was to determine the prevalence of appropriate diagnosis and treatment of outpatients treated for CAP. Knowledge of problems with CAP treatment can be helpful in developing stewardship initiatives to improve care of outpatients with CAP.

METHODS

Included in this study were patients 18 years and older who received antibiotic therapy for the treatment of CAP in the outpatient setting. Outpatients were identified by International Classification of Diseases, Ninth Revision (ICD-9) and International Classification of Diseases, Tenth Revision (ICD-10) codes for CAP in the Veterans Affairs Western New York Healthcare System between January 2008 and January 2018. Appropriate treatment was evaluated using CAP guidelines. Factors associated with an inappropriate regimen were determined via multivariable analyses.

FINDINGS

This study included 518 outpatients, of whom 66% were appropriately diagnosed with CAP. Of the 341 appropriately diagnosed patients, only 31% received an antibiotic regimen consistent with guidelines. Regarding inappropriate regimens, 76.7% contained an incorrect drug based on patient comorbidities, and 39.4% consisted of an inappropriate duration, which was most often attributable to prolonged length of therapy >7 days. The odds of being prescribed an inappropriate regimen if a patient was considered to be at risk for drug-resistant Streptococcus pneumoniae (DRSP) was 4.2 (95% CI, 2.4-7.4). The population at risk for DRSP was more likely to present to the health care system again within 30 days compared with low-risk patients (19.4% vs 8.7%, P = 0.005).

IMPLICATIONS

Improvement in prescribing is needed for CAP. An outpatient stewardship program that targets patients with risk factors for DRSP would improve adherence to guidelines.

Identification of risk factors for failure in patients with skin and soft tissue infections

PURPOSE

The purpose was to determine significant predictors of treatment failure of skin and soft tissue infections (SSTI) in the inpatient and outpatient setting.

METHODS

A retrospective chart review of patients treated between January 1, 2005 to July 1, 2016 with ICD-9 or ICD-10 code of cellulitis or abscess. The primary outcome was failure defined as an additional prescription or subsequent hospital admission within 30 days of treatment. Risk factors for failure were identified through multivariate logistic regression.

RESULTS

A total of 541 patients were included. Seventeen percent failed treatment. In the outpatient group, 24% failed treatment compared to 9% for inpatients. Overweight/obesity (body mass index (BMI) > 25 kg/m²) was identified in 80%, with 15% having a BMI >40 kg/m². BMI, heart failure, and outpatient treatment were determined to be significant predictors of failure. The unit odds ratio for failure with BMI was 1.04 (95% [Cl] = 1.01 to 1.1, p = 0.0042). Heart failure increased odds by 2.48 (95% [Cl] = 1.3 to 4.7, p = 0.0056). Outpatients were more likely to fail with an odds ratio of 3.36.

CONCLUSION

Patients with an elevated BMI and heart failure were found to have increased odds of failure with treatment for SSTIs. However, inpatients had considerably less risk of failure than outpatients. These risk factors are important to note when making the decision whether to admit a patient who presents with SSTI in the emergency department. Thoughtful strategies are needed with this at-risk population to prevent subsequent admission.

Decreased mortality in patients prescribed vancomycin after implementation of antimicrobial stewardship program

BACKGROUND

The impact of an antimicrobial stewardship program (ASP) on 30-day mortality rates was evaluated in patients prescribed vancomycin in a Veterans Affairs hospital.

METHODS

A retrospective chart review of patients receiving a minimum of 48 hours of vancomycin during October 2006-July 2014. A multivariate logistic regression analysis was used to determine predictors of mortality. Interventions of the ASP consist of appropriate antibiotic selection, dosing, microbiology, and treatment duration.

RESULTS

Death occurred in 12.4% of 453 patients. Of the 56 deaths, 64.3% occurred during prestewardship versus 35.7% during stewardship (P = .021). Increased mortality was associated with pre-ASP (odds ratio [OR], 2.17; 95% confidence interval [CI], 1.13-4.27), age (unit OR, 1.08; 95% CI, 1.05-1.12), nephrotoxicity (OR, 3.24; 95% CI, 1.27-8.01), and hypotension (OR, 3.28; 95% CI, 1.42-7.44). Patients treated in the intensive care unit were associated with increased mortality. Patients in the stewardship group experienced lower rates of mortality, which may be caused by interventions initiated by the stewardship team, including minimizing nephrotoxicity and individualized chart review.

CONCLUSIONS

Mortality in patients treated with vancomycin was decreased after antimicrobial stewardship was implemented. As anticipated, older age, hypotension, nephrotoxicity, and intensive care unit admission were associated with an increased incidence of mortality.

A combination of ceftaroline and daptomycin has synergistic and bactericidal activity in vitro against daptomycin nonsusceptible methicillin-resistant Staphylococcus aureus (MRSA)

There is an urgent need to optimize therapeutic options in patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia who have failed conventional therapy. Two clinical isolates were obtained from a 68-year-old male with persistent MRSA bacteremia before and after the development of daptomycin nonsusceptibility. The pharmacodynamic activity of monotherapies and combinations of ceftaroline, daptomycin, cefoxitin, nafcillin and vancomycin were evaluated in time-kill experiments versus 108 CFU/mL of the pre- and post-daptomycin nonsusceptible MRSA isolates. Cefoxitin, nafcillin and vancomycin alone or in combination with ceftaroline failed to generate prolonged bactericidal activity against the post-daptomycin nonsusceptible isolate whereas a ceftaroline-daptomycin combination resulted in 6, 24 and 48 h log10(CFU/mL) reductions of 3.90, 4.40 and 6.32. Population analysis profiles revealed a daptomycin heteroresistant subpopulation of the pre-daptomycin nonsusceptible MRSA isolate that expanded by >10,000× on daptomycin agar containing 2-16 mg/L in the post-daptomycin nonsusceptible isolate. Daptomycin and ceftaroline combinations may be promising against persistent MRSA bacteremia.

Successful treatment of multidrug-resistant Pseudomonas aeruginosa pubic symphysis osteomyelitis with ceftolozane/tazobactam

New antibiotic options are needed for the treatment of multidrug-resistant (MDR) Pseudomonas infections. We present a case of a man aged 64 years with a bladder fistula due to radiation, ultimately causing osteomyelitis of the pubic symphysis. Repeated antibiotic courses, without correcting the fistula, resulted in infection with MDR Pseudomonas aeruginosa. He was successfully treated for his osteomyelitis through cystectomy, aggressive debridement and a prolonged course of antimicrobials directed at the MDR Pseudomonas isolate.

Daptomycin Use After Vancomycin-Induced Neutropenia in a Patient with Left-Sided Endocarditis

Objective:

To report a positive outcome in a patient treated with daptomycin for left-sided endocarditis associated with methicillin-resistant Staphylococcus aureus (MRSA) subsequent to vancomycin-induced neutropenia.

Case Summary:

A 55-year-old African American male was diagnosed with left-sided endocarditis, brain abscesses, and septic arthritis due to community-acquired MRSA. He began treatment with intravenous vancomycin to achieve a trough concentration of 15–20 μg/mL and oral rifampin 600 mg/day. A repair and resection of the mitral valve was completed on day 15 of hospitalization. Vancomycin was discontinued on day 36 secondary to drug-induced neutropenia (absolute neutrophil count nadir 162 cells/μL). Intravenous therapy with daptomycin 6 mg/kg every 24 hours was then initiated and the neutropenia resolved. The patient was discharged from the hospital on day 56.

Discussion:

Upon discontinuation of vancomycin, treatment options were limited to a small number of alternatives. Documented clinical experience and relevant studies are limited regarding the use of quinupristin/dalfopristin (Q/D), linezolid, trimethoprim/sulfamethoxazole (TMP/SMX), and daptomycin for the treatment of MRSA left-sided endocarditis. Daptomycin was selected because of its bactericidal qualities and its recent approval for this indication. The prognostic outlook for use of daptomycin in this treatment was uncertain; however, Q/D, linezolid, and TMP/SMX posed greater risks of failure.

Conclusions:

Treatment of MRSA left-sided endocarditis in patients intolerant to vancomycin is challenging. The positive outcome in our patient is likely attributable to aggressive vancomycin dosing and extended duration of treatment prior to the initiation of daptomycin. The use of daptomycin in this case enabled successful management of left-sided endocarditis.

Male veterans with complicated urinary tract infections: Influence of a patient-centered antimicrobial stewardship program

BACKGROUND

The influence of antimicrobial stewardship programs (ASPs) on outcomes in male veterans treated for complicated urinary tract infection has not been determined.

METHODS

This was a retrospective cohort study encompassing the study period January 1, 2005-October 31, 2014, which was conducted at a 150-bed Veterans Affairs Healthcare System facility in Buffalo, NY. Male veterans admitted for treatment of complicated urinary tract infection were identified using ICD-9-CM codes. Outcomes before and after implementation of a patient-centered ASP, including duration of antibiotic therapy, length of hospitalization, readmission within 30 days, and Clostridium difficile infection were compared. Interventions resulting from the ASP were categorized.

RESULTS

Of the 1,268 patients screened, 241 met criteria for inclusion in the study (n = 118 and n = 123 in the pre-ASP and ASP group, respectively). Duration of antibiotic therapy was significantly shorter in the ASP group (10.32 days vs 11.96 days; P < .0001), as was length of hospitalization (5.76 days vs 6.76 days; P = .015). There was no difference in 30-day readmission. A total of 170 interventions were identified that resulted from the ASP (1.39 interventions per patient).

CONCLUSIONS

ASPs may be useful to improve clinical outcomes in men with complicated urinary tract infection. Implementation of an ASP was associated with significant decreases in duration of antibiotic therapy and length of hospitalization, without adversely affecting 30-day readmission rates.

Native valve Proteus mirabilis endocarditis: successful treatment of a rare entity formulated by in vitro synergy antibiotic testing

Infective endocarditis caused by Proteus mirabilis is a rare and poorly reported disease, with no well-defined effective antibiotic regimen. Here, we present a case of P. mirabilis aortic valve endocarditis. We reviewed prior cases and treatment regimens, and devised effective treatment, which was guided by in vitro sensitivity and synergy testing on the pathogen. Our patient survived without complications or the need for a surgical intervention.

Impact of Antimicrobial Stewardship on Outcomes in Hospitalized Veterans With Pneumonia

PURPOSE

The purpose of this study was to evaluate the impact of an antimicrobial stewardship program (ASP) on outcomes for inpatients with pneumonia, including length of stay, treatment duration, and 30-day readmission rates.

METHODS

A retrospective chart review comparing outcomes of veterans admitted with pneumonia before (2005-2006) and after (2013-2014) implementation of an ASP was conducted; pneumonia was defined according to International Classification of Diseases, Ninth Revision (ICD-9) codes. Infectious diseases physicians and pharmacist in the ASP provided appropriate recommendations to the primary medicine teams. Bivariate analysis of baseline characteristics and comorbid conditions were performed between the time frames. Least squares regression was used to analyze length of stay, time of IV to PO conversions, and duration of antibiotics. Multivariate logistic regressions were used to determine odds of 30-day readmission and odds of Clostridium difficile infections between time periods.

FINDINGS

There were 86 patients in the pre-ASP period and 88 patients in the ASP period. Mean length of stay decreased from 8.1 to 6.6 days (P = 0.02), total duration of antibiotic therapy decreased from 12 to 8.5 days (P < 0.0001), and time of IV to PO antibiotic conversions decreased from 5.3 to 3.9 days (P = 0.0003), before ASP and during ASP, respectively. The odds ratio of 30-day readmission before ASP was 2.78 and 0.36 during the ASP (P = 0.05). The odds ratios of Clostridium difficile infections before ASP was 2.08 and 0.48 during the ASP (P = 0.37).

IMPLICATIONS

The ASP interventions were associated with shorter durations of therapy, shorter lengths of stay, and lower rates of readmission and Clostridium difficile infections within 30 days. Limitations of this study are retrospective cohort design, small study population, limited study population diversity, and non-concurrent cohort times periods.

Impact of an Antimicrobial Stewardship Program on Patient Safety in Veterans Prescribed Vancomycin

PURPOSE

This study aimed to determine the safety impact of an antimicrobial stewardship program (ASP) on vancomycin-associated nephrotoxicity and to examine risk factors contributing to the development of toxicity.

METHODS

This was a retrospective chart review of data from 453 veterans receiving vancomycin in the VA Western New York Healthcare System between October 2006 and July 2014. Nephrotoxicity was defined as an increase in serum creatinine of ≥ 0.5 mg/dL or by 50% of baseline for 2 consecutive days.

FINDINGS

Patients receiving vancomycin after the implementation of the ASP were less likely to develop nephrotoxicity (odds ratio [OR] = 2.06; 95% CI, 1.02-4.28). Nephrotoxicity occurred in 6.84% of patients from the pre-ASP cohort and in 3.75% of patients after the implementation of the ASP. Predictors of nephrotoxicity included hospital service (surgical service, OR = 2.29; 95% CI, 1.13-4.64), elevated maximum trough concentration (unit OR = 1.15; 95% CI, 1.10-1.20), and concurrent piperacillin/tazobactam therapy (OR = 3.21; 95% CI, 1.43-7.96). The number of vancomycin trough concentration measurements per patient did not vary between the pre-ASP and ASP groups.

IMPLICATIONS

ASPs represent an important aspect of a patient-safety initiative in order to reduce vancomycin-associated nephrotoxicity. Concurrent piperacillin/tazobactam therapy, surgical service, and elevated maximum trough concentration were risk factors for nephrotoxicity.

Outcomes and Pharmacoeconomic Analysis of a Home Intravenous Antibiotic Infusion Program in Veterans

PURPOSE

The use of outpatient parenteral antibiotic therapy (OPAT) programs has become more frequent because of benefits in costs with equivalent clinical outcomes compared with inpatient care. The purpose of this study was to evaluate the outcomes of our program. A modified pharmacoeconomic analysis was performed to compare costs of our program with hospital or rehabilitation facility care.

METHODS

This was a retrospective chart review of 96 courses of OPAT between April 1, 2011, and July 31, 2013. Clinical failures were defined as readmission or death due to worsening infection or readmission secondary to adverse drug event (ADE) to antibiotic therapy. This does not include those patients readmitted for reasons not associated with OPAT therapy, including comorbidities or elective procedures. Baseline characteristics and program-specific data were analyzed. Statistically significant variables were built into a multivariate logistic regression model to determine predictors of failure. A pharmacoeconomic analysis was performed with the use of billing records.

FINDINGS

Of the total episodes evaluated, 17 (17.71%) clinically failed therapy, and 79 (82.29%) were considered a success. In the multivariate analysis, number of laboratory draws (P = 0.02) and occurrence of drug reaction were significant in the final model, P = 0.02 and P = 0.001, respectively. The presence an adverse drug reaction increases the odds of failure (OR = 10.10; 95% CI, 2.69-44.90). Compared with inpatient or rehabilitation care, the cost savings was $6,932,552.03 or $2,649,870.68, respectively.

IMPLICATIONS

In our study, patients tolerated OPAT well, with a low number of failures due to ADE. The clinical outcomes and cost savings of our program indicate that OPAT can be a viable alternative to long-term inpatient antimicrobial therapy.

Effectiveness and safety of nitrofurantoin in outpatient male veterans

OBJECTIVES

The aim of the study was to assess both the safety and the effectiveness of nitrofurantoin in male veterans treated for urinary tract infections (UTIs) with varying degrees of renal impairment in the outpatient setting. Nitrofurantoin is an important oral option for treating UTIs given increasing resistance to commonly used agents. Nitrofurantoin is currently contraindicated in patients with a creatinine clearance (CrCl) of < 60 ml/min, but the reason for this threshold has not been well documented.

METHODS

Data were collected through a retrospective chart review from January 2004 to July 2013 of men who had received nitrofurantoin. Bivariate analyses followed by multivariate analyses were performed between patients experiencing clinical cure and those who did not, to determine factors significantly impacting effectiveness.

RESULTS

The Gram stain of the organism causing the UTI and CrCl were significant factors impacting effectiveness. For every 1 ml/min increase in CrCl, the odds of clinical cure increased by 1.3%. Patients with Gram-negative UTIs predictably had 80% cure rates with CrCl around 60 ml/min. Patients with Gram-positive UTIs required higher CrCl, nearing 100 ml/min, to establish an 80% cure rate. Adverse effects did not vary with CrCl.

CONCLUSIONS

The odds of clinical cure varied with CrCl and with the type of organism causing the UTI, while adverse events did not differ based on renal function. A minimum CrCl of 60 ml/min is suggested for men to achieve an 80% cure rate for UTIs with the most common urinary pathogens.

Vancomycin Nephrotoxicity

Vancomycin earned notoriety for its tendency to cause nephrotoxicity shortly after it was introduced into practice, though the impurities responsible for historically significant rates of nephrotoxicity are of minimal concern today. Increasing usage of vancomycin has provided evidence that the drug itself can be nephrotoxic, but the exact mechanism by which this occurs has not been determined. Various studies have identified risk factors associated with development of vancomycin-associated nephrotoxicity, including total daily dose > 4 grams, trough levels > 20 mg/L, therapy exceeding 6 days, concurrent use of other nephrotoxic agents, preexisting renal disease, obesity, hypotensive episodes, and increasing severity of illness. Preventative strategies beyond risk assessment and therapeutic drug monitoring have shown little promise. Most cases of nephrotoxicity are reversible with discontinuation of vancomycin, but permanent renal damage can occur. This article is intended to serve as a practical review of vancomycin-associated nephrotoxicity, including historical context, risk factors, and common methods to evaluate and define renal dysfunction.

Corticosteroid use is associated with a reduced incidence of Clostridium difficile-associated diarrhea: a retrospective cohort study

The impact of corticosteroid use on the incidence of Clostridium difficile-associated diarrhea (CDAD) was examined retrospectively in 532 patients receiving antibiotic treatment for respiratory infections. As determined by logistic regression, corticosteroids were associated with a decreased incidence of CDAD (Odds Ratio 0.12, 95% Confidence Interval 0.006-0.95).