143. Modification of Linezolid Restriction Criteria Reduces ICU Gram-positive Antibiotic Consumption

Background

Antibiotic time out (ATO) policies have been proposed by the Centers for Disease Control and Prevention to limit unnecessary use of antibiotics. Critically ill patients are often treated empirically with MRSA-active agents for a prolonged duration. The objective of this study was to assess the impact of an ATO policy by targeting empiric gram-positive coverage.

Methods

Before this intervention, linezolid required pre-approval by the antimicrobial stewardship program or infectious diseases (ID) consult service before dispensing, and no automatic ATO policy was in place for any agent. In 2018, restriction of linezolid was modified to allow 72 hours of empiric use in the intensive care unit (ICU). This retrospective, single-center, pre- post-intervention study looked at eight ICUs at our institution from two equal periods. Adults (age ≥ 18 years) were included who received an IV gram-positive antibiotic (IVGP-AB), specifically linezolid or vancomycin, used for empiric therapy and were admitted to the ICU. The primary outcome was antimicrobial consumption of IVGP-AB defined as days of therapy (DOT) per patient. Secondary outcomes included in-hospital length of stay (LOS), ICU LOS, in-hospital mortality, 30-day readmission, and incidence of acute kidney injury (AKI).

Figure 1. Flowchart of patient inclusion into the study

Results

2718 patients met criteria for inclusion in the study. 1091 patients were included in the pre-intervention group and 1627 patients were included in the post-intervention group. Baseline characteristics between the two groups were similar, with ID consults being higher in the pre-intervention group. Total mean DOT of IVGP-AB in pre- and- post-intervention groups was 4.97 days vs. 4.36 days, p< 0.01. Secondary outcomes of in-hospital LOS, ICU LOS, and in-hospital mortality did not vary significantly between groups. Thirty-day readmission was lower in the post-intervention group (12.9% vs. 3.9%, p< 0.01). AKI did not differ significantly between groups, however the need for renal replacement therapy was higher in the pre-intervention group (1.2% vs. 0.2%, p< 0.01).

Conclusion

This study assessed the impact of an ATO policy allowing 72 hours of empiric linezolid in the ICU. We found a statistically significant reduction in days of therapy of IVGP-AB without increases in LOS, mortality, readmission, and AKI.

Disclosures

All Authors: No reported disclosures

1575. Predictors of Negative Clinical Outcomes among Patients treated with Meropenem-Vaborbactam for Serious Gram-Negative Bacterial Infections: Impact of Delayed Appropriate Antibiotic Selection

Background

Numerous number of studies have found a positive correlation between delayed appropriate antibiotic therapy and negative clinical outcomes (NCO) in Gram-negative bacterial infections (GNBI). The combination of meropenem with vaborbactam (MVB) received Food and Drug Administration approval for the treatment of complicated urinary tract infections and acute pyelonephritis caused by susceptible organisms in August 2017. We sought to determine the impact of delayed appropriate therapy with MVB on NCO among patients with GNBI.

Methods

Multi-center, retrospective cohort study from October 2017 to March 2020. We included adult patients treated with MVB for >72 hours. We excluded patients who received alternative appropriate antibiotics for GNB prior to MVB and patients with unknown dates for index culture. NCO were defined as 30-day mortality and/or microbiological recurrence. All outcomes were measured from MVB start date. Classification and regression tree analysis (CART) was used to identify the time breakpoint (BP) that delineates the risk of NCO. Multivariable logistic regression analysis (MLR) was used to examine the independent association between the CART-derived-BP and NCO. Variables were retained in the model if P< 0.2 and removed in a backward stepwise approach.

Results

A total of 86 patients were included from 13 institutions in the United States: median(IQR) age 55 (37-67) years, 67% male, and 48% Caucasian. Median(IQR) APACHE II and Charlson Comorbidity index scores were 18(11-26) and 4(2-6), respectively. Common sources of infection were respiratory (37%) and intra-abdominal (21%). The most common pathogens were carbapenem-resistant Enterobacterales (83%). CART-derived BP between early and delayed treatment was 48 hours, where NCO was increased (36% vs.7%; P=0.04). Delayed MVB initiation was independently associated with NCO in the MLR (aOR=7.4, P=0.02).

Results of Regression Analysis of Variables Associated With Negative Clinical Outcomes and Delayed Appropriate Therapy with Meropenem-vaborbactam

Conclusion

Our results suggest that delaying appropriate antibiotic therapy with MVB for >48 hours significantly increases the risk of NCO in patients with GNBI. Clinicians must ensure timely administration of MVB to assure best outcomes in patients with GNBI.

Disclosures

Kevin W. Garey, PharMD, MS, FASHP, Merck & Co. (Grant/Research Support, Scientific Research Study Investigator) Michael J. Rybak, PharmD, MPH, PhD, Paratek (Grant/Research Support)

1576. Re-Evaluation of cefepime or piperacillin-tazobactam to Decrease Use of Carbapenems in ESBL-Producing Enterobacterales BloodStream Infections (REDUCE-BSI)

Background

The ideal therapy for treatment of bloodstream infections (BSI) due to ESBL-producing organisms is widely debated. Although prior studies have demonstrated efficacy of non-carbapenems (CBPNs) for ESBL infections, results from the MERINO study group found increased mortality associated with piperacillin/tazobactam (PT) when compared with meropenem for treatment of ESBL BSI. The goal of this study was to investigate patient outcomes associated with the use of CBPN-sparing therapies (PT and cefepime (CEF)) for ESBL BSI. The primary outcome was in-hospital mortality between non-CBPN (PT and CEF) and CBPN groups. Secondary outcomes included clinical cure, microbiologic cure, infection recurrence, and development of resistance.

Methods

This was a retrospective observational study of patients admitted to the hospital from May 2016 - May 2019 with a positive blood culture for an ESBL-producing organism. Patients receiving meropenem, ertapenem, PT, or CEF were included. Patients were excluded if < 18 years old, receiving antibiotics for < 24 hours, treated for a polymicrobial BSI, or receiving concomitant antibiotic therapy for another gram-negative (non-ESBL) infection.

Results

One hundred and fourteen patients were analyzed; 74 (65%) patients received CBPN therapy compared with 40 (35%) patients that received a non-CBPN (CEF N=30, PT N=10). There were no statistically significant differences in baseline characteristics between groups. The overall in-hospital mortality rate was 6% (N=7). Eight percent of patients (N=6) in the CBPN arm died compared to 3% (N=1) of patients in the non-CBPN arm, P = 0.42. No difference in mortality was detected between groups when evaluating subgroups with Pitt bacteremia score ≥4 (N=25), requiring ICU admission (N=50), non-genitourinary source (N=50), or by causative organism (N=76 E. coli; N=38 Klebsiella spp.). There was no difference between groups for secondary outcomes.

Conclusion

CEF and PT are reasonable options for the treatment of ESBL BSI and did not result in increased mortality or decreased clinical efficacy when compared to CBPNs in this cohort.

Disclosures

All Authors: No reported disclosures

A Comparative Randomized Prospective Clinical Study on Modified Erich Arch Bar with Conventional Erich Arch Bar for Maxillomandibular Fixation

Introduction

Erich arch bar used for maxillomandibular fixation (MMF) since decades has several disadvantages such as risks of injury, additional operating room time, and gingival trauma. To overcome these downsides, modified Erich arch bar was introduced; however, there is not much available literature, indicating the efficacy of modified Erich arch bar over that of conventional arch bar wire. Therefore, the present study focuses on comparing efficiency of modified arch bar with conventional arch bar.

Materials and Methods

This comparative randomized study was conducted on 32 patients that required MMF and were divided into Group A patients who received intermaxillary fixation (IMF) with modified Erich arch bars and Group B patients with conventional Erich arch bars. The parameters recorded were average surgical time required, wire prick injuries, IMF stability, occlusal stability, screw loosening, oral hygiene status, and vitality response of the teeth. The variables were statistically analyzed using Student's t-test and Wilcoxon signed-rank test.

Results

The wire prick injury, intraoperative time noted in Group A was significantly reduced in comparison to Group B (P < 0.0001). Debris indices were significantly good in Group A in comparison to Group B (P < 0.0001). Nonvitality response of tooth was significantly more in Group B than in Group A patients (P < 0.05).

Discussion

The efficiency of modified Erich arch bar group was superior to the conventional arch bar with very limited restrictions.

Real-world Multicenter Analysis of Clinical Outcomes and Safety of Meropenem-Vaborbactam in Patients Treated for Serious Gram-Negative Bacterial Infections

Fourty patients were treated with meropenem-vaborbactam (MEV) for serious Gram-negative bacterial (GNB) infections. Carbapenem-resistant Enterobacteriaceae (CRE) comprised 80.0% of all GNB infections. Clinical success occurred in 70.0% of patients. Mortality and recurrence at 30 days were 7.5% and 12.5%, respectively. One patient experienced a probable rash due to MEV.

Impact of an antimicrobial stewardship initiative on time to administration of empirical antibiotic therapy in hospitalized patients with bacteremia

PURPOSE

The impact of an antimicrobial stewardship initiative on time to first antibiotic dose and clinical outcomes in bacteremic patients was evaluated.

METHODS

A single-center, retrospective study was conducted for adult inpatients who received antibiotics before and after implementation of a rapid administration of antimicrobials by an infectious diseases specialist (RAIDS) protocol. Patients admitted to an inpatient service from June to October 2011 (pre-RAIDS protocol) and from December 2011 to February 2012 (post-RAIDS protocol) were eligible for inclusion if (1) they were age 18 years or older, (2) their infection occurred two or more days after hospital admission, and (3) they had a blood culture growing an organism other than common skin contaminants (i.e., coagulase-negative staphylococci, Bacillus species). The primary outcome was the time to the first antibiotic dose (TFAD), defined as the time that elapsed from a positive blood culture result to administration of the first empirical antimicrobial dose.

RESULTS

A total of 111 bacteremic patients were included in the analysis. Implementation of the RAIDS protocol led to significantly faster antibiotic order entry, verification, and administration of empirical antibiotics in patients with bacteremia. The median TFAD was approximately 8 hours faster in the post-RAIDS group than in the pre-RAIDS group (9:09 hr:min versus 1:23 hr:min, p < 0.001). Patients in the post-RAIDS group had a significant reduction in infection-related mortality (p = 0.047), though all-cause 30-day mortality was similar.

CONCLUSION

Early notification of an infectious diseases pharmacist about positive blood cultures using the RAIDS protocol led to increased appropriateness of empirical drug selection and a dramatic reduction in the administration of antibiotics and was associated with decreased infection-related mortality.

2425. Clinical and Microbiologic Outcomes Among Patients With Monomicrobial Stenotrophomonas maltophilia Infections

Background

Stenotrophomonas maltophilia is an opportunistic pathogen observed in nosocomial infections. Due to biofilm production and intrinsic resistance to numerous antimicrobials, organism eradication is difficult and morbidity and mortality remain high. Unfortunately, study outcomes are often confounded by co-infecting organisms. Therefore, clinical and microbiologic outcome data for monomicrobial infections is warranted.

Methods

Single-center, retrospective chart review of adult patients receiving treatment for S. maltophilia between January 2012 and October 2016. Polymicrobial infections and cystic fibrosis patients were excluded. Primary endpoint was clinical cure (CC) at end of therapy. Secondary endpoints included microbiological eradication (ME), 28-day mortality, and resistance selection. An exploratory analysis was performed in patients receiving trimethoprim-sulfamethoxazole (TMP/SMX) or levofloxacin (LVX).

Results

Seventy-six patients were included in the analysis. The population was 60 years of age, predominantly female (62%) with median APACHE score of 16. Infection onset occurred 6 days after admission with 71% located in the ICU. Approximately 2/third of ICU patients were intubated. Primary site of infection was the lung (92%). Treatment strategies included TMP/SMX (45 patients) or LVX (31 patients). Overall, CC, ME, and 28-day mortality was observed in 79%, 82%, and 14%, respectively. Adverse events were uncommon with three patients receiving TMP/SMX requiring alternate therapy. Comparative analysis revealed similar baseline characteristics except higher APACHE scores (18 vs. 14; P = 0.03) and frequency of mechanical ventilation in the TMP/SMX group (64% vs. 30%; P = 0.007). CC was similar between TMP/SMX and LVX (82% vs. 74%, respectively (P = 0.4)). ME was observed in 84% and 77%, respectively (P = 0.5). Resistance selection to primary treatment was observed in 29% (2/7) and 86% (6/7), respectively (P = 0.1).

Conclusion

Use of TMP/SMX or LVX for S. maltophilia infections resulted in high CC rates. No differences in primary or secondary outcomes were observed; however, a trend toward resistance selection with LVX was identified. Larger studies assessing outcomes and resistance selection are warranted to further delineate treatment.

Disclosures

K. Klinker, Melinta Therapeutics: Consultant, Speaker honorarium. Nabriva Therapeutics: Scientific Advisor, Consulting fee.

Training a Drug to Do New Tricks: Insights on Stability of Meropenem Administered as a Continuous Infusion

Background

The antibiotic armamentarium used to combat multi-drug resistant organisms (MDROs) include carbapenems. Continuous infusion (CI) dosing is frequently employed to maximize beta-lactam efficacy; however, use of meropenem CI has been limited due to concerns with product instability.

Objective

The primary objective of this study was to quantify meropenem serum concentrations to reflect drug stability when administered as CI over 8- or 12-h exchanges. In addition, a stability experiment was performed to further establish meropenem integrity over 12 h. The secondary objectives were to assess the ability of meropenem to achieve target pharmacokinetic/pharmacodynamic (PK/PD) exposures relative to the minimum inhibitory concentration (MIC) of the pathogen, and to determine clinical cure.

Methods

This was a retrospective, observational study on use of CI meropenem (infused either over 8- or 12- h) at a 1% concentration. The stability experiment was conducted on 1% meropenem at room temperature.

Results

In 22 patients, a median meropenem daily dose of 6 g/day (range 2-6 g/day) resulted in a median serum concentration of 17.8 mg/L (interquartile range, 9.3-27.8 mg/L). In 95% of cases, meropenem delivered as CI resulted in free drug concentrations at or above the MIC of the pathogen for the entire dosing interval. Clinical cure was achieved in 80% of patients included in this review. The stability experiment revealed negligible drug degradation at the end of the 12-h dosing interval.

Conclusions

The data from this study provides compelling evidence for the use of meropenem as CI utilizing either a 12- or 8-h exchange process.

Assessing antimicrobial stewardship initiatives: Clinical evaluation of cefepime or piperacillin/tazobactam in patients with bloodstream infections secondary to AmpC-producing organisms

Management of micro-organisms harbouring AmpC β-lactamases remains challenging. Carbapenems are often considered first-line agents. Due to growing concern regarding carbapenem-resistant Enterobacteriaceae, integrating non-carbapenem treatment strategies is being explored for these pathogens. The primary objective of this study was to evaluate clinical outcomes in patients with bacteraemia secondary to AmpC-producing organisms treated with cefepime or piperacillin/tazobactam (TZP). A retrospective study of adult patients receiving cefepime or TZP for the treatment of AmpC -producing organisms with positive cefoxitin screen (i.e. Citrobacter, Enterobacter or Serratia spp. along with cefoxitin resistance) isolated from blood cultures was conducted. The primary endpoint was clinical cure at end of therapy (EOT). Secondary endpoints included microbiological eradication, frequency of susceptibility changes following treatment, and 7- and 30-day all-cause mortality. Clinical cure at EOT was 87.1%, with 93.2% of patients achieving microbiological eradication. The 7- and 30-day mortality rates were 3.8% and 10.6%, respectively. Organism susceptibility was exceptionally high, with minimum inhibitory concentrations (MICs) of ≤2 μg/mL in 90% of patients treated with cefepime (n = 108). Selection for resistance to third-generation cephalosporins or primary antimicrobial therapy was infrequent at 6.1% (8/132). In conclusion, use of cefepime or TZP for management of AmpC bloodstream infections was associated with clinical and microbiological cure with infrequent selection for resistance.

Use of an Anti-Infective Medication Review Process at Hospital Discharge to Identify Medication Errors and Optimize Therapy

BACKGROUND

Medication reconciliation is a major patient safety concern, and the impact of a structured process to evaluate anti-infective agents at hospital discharge warrants further review.

OBJECTIVE

The aim of this study was to (1) describe a structured, multidisciplinary approach to review anti-infectives at discharge and (2) measure the impact of a stewardship-initiated antimicrobial review process in identifying and preventing anti-infective-related medication errors (MEs) at discharge.

METHODS

A prospective study to evaluate adult patients discharged on anti-infectives was conducted from October 2013 to May 2014. The antimicrobial stewardship program (ASP) classified interventions on anti-infective regimens into predefined ME categories.

RESULTS

Forty-five patients who were discharged on 59 anti-infective prescriptions were included in the study. The most common indications for anti-infective regimens at discharge were pneumonia (22%, n = 10), bacteremia (18%, n = 8), and skin and soft tissue infections (16%, n = 7). An ME was identified in 42% (n = 19/45) of anti-infective regimens. Seventy percentage of ASP team recommendations were accepted which resulted in an avoidance of MEs in 68% (n = 13/19) of patients with an ME prior to discharge.

CONCLUSION

This study describes the outcomes of a stewardship-initiated review process in preventing MEs at discharge. Developing a systematic process for a multidisciplinary ASP team to review all anti-infectives can be a valuable tool in preventing MEs at hospital discharge.

Impact of an Extended Infusion Β-lactam Strategy on Outcomes in Critically Ill Patients with Pseudomonas Infections

Background

Pseudomonas aeruginosa (PSA) is frequently associated with nosocomial infections resulting in significant morbidity and mortality. High MICs in MDR strains highlights the need to maximize antibiotic exposure with the goal of improving patient outcomes. For β-lactams, optimal efficacy is achieved when free drug concentrations are above the MIC for ~ 40–60% of the dosing interval. Unfortunately, due to significant pharmacokinetic variability in the critically ill, achieving this target with standard intermittent infusions (II) is challenging, resulting in preference for extended (EI) or continuous infusion strategies. Additional data in patients with PSA infections are needed to understand the association between infusion strategy and clinical outcome.

Methods

A single-center, retrospective chart review. Adult patients with positive respiratory or blood cultures for PSA treated with cefepime or piperacillin/tazobactam managed in an ICU from January 2012 to May 2016 were included. Primary endpoint was clinical cure (CC) at end of therapy (EOT) between patients receiving EI or II. Secondary endpoints included microbiologic eradication (ME), 28-day mortality, length of ICU and hospital stay, and effect of baseline kidney function on clinical cure.

Results

Eighty-three patients were included in the analysis. Patient characteristics were well matched except for a higher frequency of malignancy in the EI arm (P = 0.02). CC was achieved in an overwhelming majority of EI patients compared with II (89.2% vs. 69.6%, P = 0.031). Further, patients with normal renal function (CrCL ≥ 60; P = 0.02) or APACHE II ≥ 17 (P = 0.04) receiving II experienced higher failure rates. In multivariate analysis, use of II associated with 4-fold higher incidence of clinical failure (OR 4.5 [1.3–16.3]). For other secondary endpoints, ME was observed in 73% of EI vs. 65% of II (P = 0.44) and 28-day mortality was observed in 13% of patients in both arms (P = 0.94). No significant differences were observed with other secondary variables.

Conclusion

Use of an EI strategy in critically ill patients with PSA infections improves CC. Further, EI benefitted those patients with normal to augmented renal clearance suggesting that improved exposure may play a role in clinical outcomes.

Disclosures

K. Klinker, The Medicines Company: Scientific Advisor, Consulting fee.

Management of skin and soft-tissue infections at a community teaching hospital using a severity-of-illness tool

OBJECTIVES

Skin and soft-tissue infections (SSTIs) encompass a diverse range of infections of varying severity. The Clinical Resource Efficiency Support Team (CREST) scoring system stratifies patients into four classes (I = least severe to IV = most severe) based on the Standardized Early Warning Score (SEWS). The objective of this study was to apply CREST to hospitalized patients with SSTIs in order to quantify disease severity and evaluate appropriateness of antibiotic management.

METHODS

This was a retrospective, hypothesis-generating, single-centre evaluation of hospitalized patients with SSTIs admitted in 2011. Based on CREST classification, the empirical antimicrobial choices were categorized as appropriate, over-treatment or under-treatment.

RESULTS

A total of 369 patients were screened and 200 met the inclusion criteria. The majority of patients were classified as either CREST class I (n = 68) or class II (n = 102). Over-treatment was more common in the less severe classes (88% and 32% in class I and class II, respectively; P < 0.05). Sixty-three percent of class I (n = 43) were over-treated due to both the use of intravenous antibiotics when oral therapy was sufficient and use of unnecessarily broad-spectrum antibiotics. In contrast, 25% (n = 26) of class II were over-treated due to use of unnecessarily broad-spectrum antibiotics. Overall clinical failure rates remained low with only 1%, 4% and 17% of patients unable to achieve initial response in class II, class III and class IV.

CONCLUSIONS

Retrospective application of CREST identified opportunities to improve the management of SSTIs. CREST can be of great value in discriminating less-severe SSTIs, which can be treated on an outpatient basis.

Preparing Students to Enter the Race for Postgraduate Training

PURPOSE

Exposure of pharmacy students to postgraduate training prior to clinical practice is currently endorsed by national professional organizations. To meet this goal, colleges and schools of pharmacy are developing residency preparation programs. In this descriptive report, we review published studies of curricular activities and structured programs from academic institutions across the United States aimed at preparing students for residency training and promoting postgraduate education. Additionally, we discuss our experience developing a residency preparation program at Touro College of Pharmacy (TCOP).

SUMMARY

A literature search yielded 15 residency preparation programs. While the format, content, and length of programs varied, there were common components such as curriculum vitae critique, mock interviews, and focused sessions on the residency application process. At TCOP, a 5-themed residency preparation workshop series was implemented during the third and fourth academic year. The workshops were modeled after existing programs and included several of the core components. One feature unique to the TCOP program was the addition of multiple mock interviews.

CONCLUSION

The growing focus on residency training has led to increased competition among applicants. To better prepare students for this rigorous application and interview process, development of structured residency preparation programs, similar to TCOP's, should be encouraged.

Administration of a survey to evaluate the attitudes of house staff physicians towards antimicrobial resistance and the antimicrobial stewardship programme at a community teaching hospital

Antimicrobial stewardship programmes (ASPs) are used in numerous institutions in an effort to promote safe and effective antimicrobial use. The objectives of this study were to (i) assess physicians' perceptions, attitudes and knowledge about antimicrobial use, resistance and the ASP at The Brooklyn Hospital Center (TBHC) and (ii) measure physicians' beliefs and attitudes to the current system of prior authorisation of antimicrobials. A 75-item, anonymous, voluntary, traditional paper and pencil survey was distributed to resident physicians at TBHC. Multiple-choice, 5-point Likert scale and knowledge-based questions were utilised. Of the 261 residents, 129 (49%) completed the survey. The respondents significantly believed that antibiotics are overused more frequently nationally vs. locally [117/129 (91%) vs. 91/129 (71%); P=0.0001]. Although 49% (63/129) felt that other providers overprescribe antibiotics, only 26% (34/129) agreed that they themselves were contributing to the current problem (P=0.0003). Fifty-seven percent of respondents agreed that individual patient care is improved by having an antibiotic approval programme; however, 45% of respondents reported that the antibiotic approval programme limits their autonomy in choosing antibiotics. Compared with surgical residents, medical residents were more likely (33% vs. 13%; P=0.02) to feel that the antibiotic approval programme forced them to choose an inappropriate antibiotic. On the antibiotic knowledge assessment segment of the survey, there was no difference in score when stratified by specialty or years of postgraduate training. Based on the survey results, house staff are supportive of antimicrobial stewardship and feel that the ASP is valuable for patient care.

Time-resolved digital holographic microscopy of laser-induced forward transfer process

We develop a method for time-resolved digital holographic microscopy to obtain time-resolved 3-D deformation measurements of laser induced forward transfer (LIFT) processes. We demonstrate nanometer axial resolution and nanosecond temporal resolution of our method which is suitable for measuring dynamic morphological changes in LIFT target materials. Such measurements provide insight into the early dynamics of the LIFT process and a means to examine the effect of laser and material parameters on LIFT process dynamics.

Incidence of Antiretroviral Drug Interactions During Hospital Course

Background: Human immunodeficiency virus (HIV) providers are treating more comorbid conditions with additional pharmacologic agents, resulting in patients with HIV being disproportionately at risk for clinically significant drug–drug interactions (CSDDIs). There is a potential to overlook these interactions and ultimately place patients at risk for drug toxicity, resistance, and virologic failure. Objective: To assess the burden of CSDDIs among patients receiving antiretroviral therapy (ART) within 24 hours of admission and to evaluate the effect of a clinical pharmacist operating through an antiretroviral stewardship (ARVSP) program in identifying and correcting potential drug interactions. Methods: Adult HIV-positive patients receiving ART who were admitted to The Brooklyn Hospital Center from November 2010 through January 2012 were included in the analysis. Drug interactions were categorized according to time frame (ie, within 24 hours of admission vs after 24 hours of admission) and type (ie, contraindicated combinations, dosage modifications, and frequency alterations). The Liverpool HIV drug reference, Micromedex drug database, and the Department of Health and Human Services Guidelines were used as comprehensive tools for identification of antiretroviral drug errors. Results: Eighty-four CSDDIs were identified from 252 admissions among 158 patients receiving ART during the study period. Of the identified CSDDIs, 61 (73%) occurred within 24 hours of admission and 23 (27%) later in the hospital course. Forty-eight drug interactions (57%) represented contraindicated drug combinations. Protease inhibitor–based regimens were associated with the highest percentage of CSDDIs (98%). Of all CSDDIs, the most common interacting drug class was acid-suppressive therapy (63%). Clinical pharmacists identified and intervened in 80% of the CSDDIs that occurred on patient admission with all interventions accepted. Conclusions: CSDDIs are common among patients receiving ART at the time of admission and throughout the hospital course. Interventions including medication review by clinical pharmacists are critical in the prevention of CSDDIs on admission.