Eravacycline, the first four years: health outcomes and tolerability data for 19 hospitals in 5 U.S. regions from 2018 to 2022

IMPORTANCE

The rise of multidrug-resistant (MDR) pathogens, especially MDR Gram-negatives, poses a significant challenge to clinicians and public health. These resilient bacteria have rendered many traditional antibiotics ineffective, underscoring the urgency for innovative therapeutic solutions. Eravacycline, a broad-spectrum fluorocycline tetracycline antibiotic approved by the FDA in 2018, emerges as a promising candidate, exhibiting potential against a diverse array of MDR bacteria, including Gram-negative, Gram-positive, anaerobic strains, and Mycobacterium. However, comprehensive data on its real-world application remain scarce. This retrospective cohort study, one of the largest of its kind, delves into the utilization of eravacycline across various infectious conditions in the USA during its initial 4 years post-FDA approval. Through assessing clinical, microbiological, and tolerability outcomes, the research offers pivotal insights into eravacycline's efficacy in addressing the pressing global challenge of MDR bacterial infections.

Risk Factors for Carbapenem-Resistant Enterobacterales Clinical Treatment Failure

The Centers for Disease Control and Prevention (CDC) categorized carbapenem-resistant Enterobacterales (CRE) infections as an "urgent" health care threat requiring public attention and research. Certain patients with CRE infections may be at higher risk for poor clinical outcomes than others. Evidence on risk or protective factors for CRE infections are warranted in order to determine the most at-risk populations, especially with newer beta-lactam/beta-lactamase inhibitor (BL/BLI) antibiotics available to treat CRE. We aimed to identify specific variables involved in CRE treatment that are associated with clinical failure (either 30-day mortality, 30-day microbiologic recurrence, or clinical worsening/failure to improve throughout antibiotic treatment). We conducted a retrospective, observational cohort study of hospitalized patients with CRE infection sampled from 2010 to 2020 at two medical systems in Detroit, Michigan. Patients were included if they were ≥18 years old and culture positive for an organism in the Enterobacterales order causing clinical infection with in vitro resistance by Clinical and Laboratory Standards Institute (CLSI) breakpoints to at least one carbapenem. Overall, there were 140 confirmed CRE infections of which 39% had clinical failure. The most common infection sources were respiratory (38%), urinary (20%), intra-abdominal (16%), and primary bacteremia (14%). A multivariable logistic regression model was developed to identify statistically significant associated predictors with clinical failure, and they included Sequential Organ Failure Assessment (SOFA) score (adjusted odds ratio [aOR], 1.18; 95% confidence interval [CI], 1.06 to 1.32), chronic dialysis (aOR, 5.86; 95% CI, 1.51-22.7), and Klebsiella pneumoniae in index culture (aOR, 3.09; 95% CI, 1.28 to 7.47). Further research on CRE infections is needed to identify best practices to promote treatment success. IMPORTANCE This work compares carbapenem-resistant Enterobacterales (CRE) infections using patient, clinical, and treatment variables to understand which characteristics are associated with the highest risk of clinical failure. Knowing which risk factors are associated with CRE infection failure can provide clinicians better prognostic and targeted interventions. Research can also further investigate why certain risk factors cause more clinical failure and can help develop treatment strategies to mitigate associated risk factors.

Nephrotoxicity of Vancomycin in Combination With Beta-Lactam Agents: Ceftolozane-Tazobactam vs Piperacillin-Tazobactam

BACKGROUND

Vancomycin (VAN)-associated acute kidney injury (AKI) is increased when VAN is combined with certain beta-lactams (BLs) such as piperacillin-tazobactam (TZP) but has not been evaluated with ceftolozane-tazobactam (C/T). Our aim was to investigate the AKI incidence of VAN in combination with C/T (VAN/C/T) compared with VAN in combination to TZP (VAN-TZP).

METHODS

We conducted a multicenter, observational, comparative study across the United States. The primary analysis was a composite outcome of AKI and risk, injury, failure, loss, end stage renal disease; Acute Kidney Injury Network; or VAN-induced nephrotoxicity according to the consensus guidelines. Multivariable logistic regression analysis was conducted to adjust for confounding variables and stratified Kaplan-Meir analysis to assess the time to nephrotoxicity between the 2 groups.

RESULTS

We included VAN/C/T (n = 90) and VAN-TZP (n = 284) at an enrollment ratio of 3:1. The primary outcome occurred in 12.2% vs 25.0% in the VAN-C/T and VAN-TZP groups, respectively (P = .011). After adjusting for confounding variables, VAN-TZP was associated with increased odds of AKI compared with VAN-C/T; with an adjusted odds ratio of 3.308 (95% confidence interval, 1.560-6.993). Results of the stratified Kaplan-Meir analysis with log-rank time-to-nephrotoxicity analysis indicate that time to AKI was significantly shorter among patients who received VAN-TZP (P = .004). Cox proportional hazards analysis demonstrated that TZP was consistent with the primary analysis (P = .001).

CONCLUSIONS

Collectively, our results suggest that the AKI is not likely to be related to tazobactam but rather to piperacillin, which is a component in VAN-TZP but not in VAN-C/T.

679. Traditional vs. Alternative Agents in Patients with Lower Respiratory Tract Infections Caused by Carbapenem-Resistant Pseudomonas aeruginosa Susceptible to Traditional Agents

Background

Comparative effectiveness studies to guide treatment decisions for infections caused by carbapenem-resistant P. aeruginosa (CRPA) susceptible to traditional agents (non-carbapenem β-lactams and fluoroquinolones) are unavailable. This study aims to compare clinical outcomes between patients treated with traditional and alternative treatment regimens for lower respiratory tract infection (LRTI) caused by CRPA that remain susceptible to traditional agents.

Methods

Multi-center, retrospective cohort from January 2016 to December 2019. We included adults with CRPA (resistant to ≥ 1 carbapenem; meropenem or imipenem) that were susceptible to ≥1 traditional agent (piperacillin-tazobactam, cefepime, ceftazidime, ciprofloxacin, or aztreonam) by CLSI breakpoints isolated from an LRTI sample. All other antibiotics were considered alternative agents. We excluded patients with known colonization, cystic fibrosis, or who expired ≤24 hours after antibiotic receipt. Primary outcome was 30-day mortality and secondary outcomes included 30-day readmission and 30-day recurrence.

Results

In total, 87 patients, ‘traditional’ treatment (n=53) and ‘alternative’ treatment (n=34), were included from 2 institutions in Detroit, MI, USA: median(IQR) age 59(20) years, 64.4% male, and 59.8% African American. Median(IQR) APACHE II and Charlson Comorbidity index scores were 24(10) and 4(5), respectively. Most patients received traditional therapy (n=53), most commonly with cefepime (60.4%) or piperacillin-tazobactam (41.5%). While 34(39.0%) were treated with alternative agents, most commonly ceftolozane-tazobactam (64.7%) or an aminoglycoside (29.4%) alone or in combination. Thirty-day mortality was not significantly different between traditional and alternative therapy groups (22.6% and 11.8%), respectively. There was no significant difference between 30-day recurrence (17.0% and 20.6%) or 30-day readmission (22.6% and 17.6%) between groups.

Conclusion

Clinical outcomes did not differ significantly between patients receiving traditional vs. alternative agents for LRTI caused by CRPA susceptible to traditional agents. Traditional agents may be considered for these infections. Further comparative studies are needed to guide treatment decisions for CRPA.

Disclosures

All Authors: No reported disclosures.

633. Eravacycline Use in Immunocompromised Patients: Multicenter Evaluation of Clinical and Safety Endpoints

Background

Infections caused by multidrug-resistant (MDR) bacteria are an increasingly common public health threat associated with worse outcomes in immunocompromised patients. Eravacycline (ERV) has potent in-vitro activity against MDR Gram-negative and Gram-positive bacteria and has demonstrated non-inferiority to meropenem in the phase III IGNITE4 trial; however, the trial excluded immunocompromised patients. We aimed to evaluate clinical and safety endpoints of immunocompromised patients receiving ERV as definitive therapy.

Methods

Multicenter, retrospective, observational study conducted from October 2018 to April 2022. Adult hospitalized immunocompromised patients treated with ERV for ≥72 hours were included. Immunocompromised patients were defined as having any of the following: chemo or radiation therapy < 30 days of hospital admission, HIV/AIDS with CD4 < 200, chronic steroids ( >40 mg prednisone or equivalent. The primary outcome was 30-day survival. Secondary outcomes were lack of 30-day infection recurrence and drug-related safety events.

Results

Overall, 75 immunocompromised patients treated with ERV were included from 17 United States medical centers. Median (IQR) age was 62 (53-70) and 61.6% were male. Hospital length of stay was 28 (13-42) days and 67% were admitted to the intensive care unit. SOFA and APACHE II scores were 3.5 (1-7) and 16 (11-20), respectively. Common infection sources were intra-abdominal (26%) and lower respiratory tract (18%); 24% were bacteremic. Most patients had cultured Enterobacterales (58.7%) and Enterococci (37%) spp. infections. Of those, 21.3% were CRE and 19% were VRE. Infectious diseases consult was obtained in 91.8% of cases. Time elapsed from index culture collection to ERV initiation was 4 (2-8) days and duration of ERV therapy was 7 (4-12) days. In total, 81.3% of immunocompromised patients achieved 30-day survival and 90.7% did not have 30-day infection recurrence. Probable drug-related adverse events occurred in 5.3% of patients (GI 4%, rash 1%).

Conclusion

A majority of immunocompromised patients receiving ERV as definitive therapy achieved 30-day survival and did not experience infection recurrence. ERV use in immunocompromised subpopulations will benefit from studies tailored to their specific characteristics.

Disclosures

Kimberly C. Claeys, PharmD, BioFire Diagnostics: Honoraria Bruce M. Jones, Pharm.D., FIDSA, BCPS, AbbVie: Advisor/Consultant|AbbVie: Honoraria|La Jolla: Honoraria|Melinta: Advisor/Consultant|Paratek: Honoraria|Regeneron: Honoraria.

1422. A Multi-Center Evaluation of Omadacycline for Multi-Drug Resistant Infections

Background

Multi-drug resistant (MDR) pathogens are a continuously evolving threat for which there are limited effective treatment modalities. Omadacycline (OMC) is a novel oral and intravenously administered aminomethylcycline with potent in-vitro activity against MDR gram-negative and gram-positive pathogens. Post-marketing data investigating its potential place in the antibiotic armamentarium is limited. This study aimed at describing the clinical success and tolerability of patients receiving OMC for various infections.

Methods

This was a multicenter, retrospective, observational study conducted from January 2020 to March 30, 2022. We included all patients ≥ 18 years of age that received OMC for any infection not related to Mycobacterium spp. for ≥72 hours. The primary outcome was clinical success at 30 days, defined as survival, the absence of persistence or re-emergence of infection during or after therapy, and the absence of escalation or alteration of OMC. Incidence of adverse effects while on OMC and reasons for OMC utilization were also analyzed.

Results

This analysis included 19 patients from 10 distinct academic centers. The median age was 50 years (IQR, 37-63), 58% were male, 63% were Caucasian, and the median APACHE II, Charlson and SOFA scores were 10 (IQR 5-12.5), 4 (IQR 2-6.3), and 1 (IQR 0 – 2.25), respectively. Most patients had a bone and joint (8/19, 42.1%) or intra-abdominal infections (4/19, 21.1%), all with positive cultures. Eight patients (44.1%) had a polymicrobial infection and 4 (22.2%) had bacteremia. The most common pathogens encountered were Carbapenem-resistant A. baumannii (5/19, 27.8%), E. coli (5/19, 27.8%), Vancomycin-resistant Enterococcus spp. (4/19, 22.2%), and K. pneumoniae (3/19, 16.7%). Clinical success was observed in 14 patients (74%) and 7 (36.8%) received combination therapy. Adverse drug reactions were reported in 3 patients (15.8%) and of those patients, none discontinued therapy. Reasons for prescribing OMC were mostly attributed to oral availability (12/14, 85.7%) and resistance to other agents (7/14, 50%).

Conclusion

OMC demonstrated clinical effectiveness and safety against a large number of MDR pathogens. More robust, prospective, comparative studies are needed to confirm our preliminary findings.

Disclosures

P. Brandon Bookstaver, PharmD, Spero Therapeutics: Advisor/Consultant.

Clinical Outcomes of Eravacycline in Patients Treated Predominately for Carbapenem-Resistant Acinetobacter baumannii

Forty-six patients were treated with eravacycline (ERV) for Acinetobacter baumannii infections, where 69.5% of isolates were carbapenem resistant (CRAB). Infections were primarily pulmonary (58.3%), and most patients received combination therapy (84.4%). The median (IQR) ERV duration was 6.9 days (5.1 to 11.1). Thirty-day mortality was 23.9% in the cohort and 21.9% in CRAB patients. One patient experienced an ERV-possible adverse event. IMPORTANCE Acinetobacter baumannii, particularly when carbapenem resistant (CRAB), is one of the most challenging pathogens in the health care setting. This is complicated by the fact that there is no consensus guideline regarding management of A. baumannii infections. However, the recent Infectious Diseases Society of America guidelines for treatment of resistant Gram-negative infections provided expert recommendations for CRAB management. The panel suggest using minocycline among tetracycline derivatives rather than eravacycline (ERV) until sufficient clinical data are available. Therefore, we present the largest multicenter real-world cohort in patients treated with ERV for A. baumannii, where the majority of isolates were CRAB (69.5%). Our analysis demonstrate that patients treated with ERV-based regimens achieved a 30-day mortality of 23.9% and had a low incidence of ERV-possible adverse events (2.1%). This study is important as it fills the gap in the literature regarding the use of a novel tetracycline (i.e., ERV) in the treatment of this challenging health care infection.

Clinical Characteristics Associated with Bacterial Bloodstream Coinfection in COVID-19

INTRODUCTION

Inappropriate antibiotic use in COVID-19 is often due to treatment of presumed bacterial coinfection. Predictive factors to distinguish COVID-19 from COVID-19 with bacterial coinfection or bloodstream infection are limited.

METHODS

We conducted a retrospective cohort study of 595 COVID-19 patients admitted between March 8, 2020, and April 4, 2020, to describe factors associated with a bacterial bloodstream coinfection (BSI). The primary outcome was any characteristic associated with BSI in COVID-19, with secondary outcomes including 30-day mortality and days of antibiotic therapy (DOT) by antibiotic consumption (DOT/1000 patient-days). Variables of interest were compared between true BSI (n = 25) and all other COVID-19 cases (n = 570). A secondary comparison was performed between positive blood cultures with true BSI (n = 25) and contaminants (n = 33) on antibiotic use.

RESULTS

Fever (> 38 °C) (as a COVID-19 symptom) was not different between true BSI (n = 25) and all other COVID-19 patients (n = 570) (p = 0.93), although it was different as a reason for emergency department (ED) admission (p = 0.01). Neurological symptoms (ED reason or COVID-19 symptom) were significantly higher in the true BSI group (p < 0.01, p < 0.01) and were independently associated with true BSI (ED reason: OR = 3.27, p < 0.01; COVID-19 symptom: OR = 2.69, p = 0.03) on multivariate logistic regression. High (15-19.9 × 109/L) white blood cell (WBC) count at admission was also higher in the true BSI group (p < 0.01) and was independently associated with true BSI (OR = 2.56, p = 0.06) though was not statistically significant. Thirty-day mortality was higher among true BSI (p < 0.01). Antibiotic consumption (DOT/1000 patient-days) between true BSI and contaminants was not different (p = 0.34). True bloodstream coinfection was 4.2% (25/595) over the 28-day period.

CONCLUSION

True BSI in COVID-19 was associated with neurological symptoms and nonsignificant higher WBC, and led to overall higher 30-day mortality and worse patient outcomes.

Real-World, Multicenter Case Series of Patients Treated with Oral Omadacycline for Resistant Gram-Negative Pathogens

INTRODUCTION

Antibiotic-resistant Gram-negative bacteria have been associated with substantial morbidity and mortality and have limited treatment options available. Omadacycline (OMC) is an aminomethylcycline antibiotic that has been shown to exhibit broad in vitro activity against antibiotic-resistant Gram-negative bacteria. Given the lack of real-world data, the primary objective of our report was to describe early experience with OMC for the treatment of resistant Gram-negative infections.

METHODS

This was a real-world, multicenter, observational cases series/pilot study conducted in the USA. Inclusion criteria included any adult patient aged ≥ 18 years who received OMC for ≥ 72 h either in the inpatient and/or outpatient setting. Clinical success was defined as a composite of 90-day survival from initiation of OMC, lack of alteration in treatment/addition of other antibiotic due to concerns of OMC failure, and lack of microbiologic recurrence within 30 days from the end of therapy.

RESULTS

Oral OMC was used in nine cases primarily for multidrug-resistant (MDR)/extensively drug-resistant (XDR) Gram-negative bacterial infections (55.6% XDR and/or carbapenem-resistant Acinetobacter baumannii [CRAB]). The majority of infections were of bone/joint (55.6%) origin, followed by intra-abdominal (33.3%) origin. Clinical success occurred in 66.7% of cases, with 80.0% success each in infections of bone/joint origin or those caused by CRAB. One patient experienced an adverse effect that was not treatment limiting while on therapy (gastrointestinal).

CONCLUSION

The use of oral OMC in MDR/XDR Gram-negative infections exhibited a relatively high success rate with minimal adverse effects. Real-world studies with larger case numbers are needed to confirm our initial findings.

Multicenter Cohort Study of Ceftaroline versus Daptomycin for Treatment of Methicillin-Resistant Staphylococcus aureus Bloodstream Infection

Background

Observational data suggest ceftaroline may be effective for methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI), but comparative data with standard of care are limited. This analysis compares the outcomes of MRSA BSI treated with ceftaroline or daptomycin.

Methods

Multicenter, retrospective, observational cohort study of adult patients with MRSA BSI from 2010 to 2017. Patients treated with ≥72 hours of ceftaroline or daptomycin were included. Those clearing BSI before study drug and those with a pneumonia source were excluded. The primary outcome was composite treatment failure, defined as 30-day mortality, BSI duration ≥7 days on study drug, and 60-day MRSA BSI recurrence. Inverse probability of treatment weighted risk difference in composite failure between daptomycin and ceftaroline groups was computed and 15% noninferiority margin applied.

Results

Two hundred seventy patients were included; 83 ceftaroline and 187 daptomycin. Ceftaroline was noninferior to daptomycin with respect to composite failure (39% daptomycin, 32.5% ceftaroline; weighted risk difference, 7.0% [95% confidence interval, –5.0% to 19.0%]). No differences between treatment groups was observed for 30-day mortality or other secondary efficacy outcomes. Creatine phosphokinase elevation was significantly more common among daptomycin patients (5.3% vs 0%, P = .034). Rash was significantly more common among ceftaroline patients (10.8 vs 1.1%, P = .001).

Conclusions

No difference in treatment failure or mortality was observed between MRSA BSI treated with ceftaroline or daptomycin. These data support future study of ceftaroline as a primary MRSA BSI treatment and current use of ceftaroline when an alternative to vancomycin and daptomycin is required.

Early Multicenter Experience With Imipenem-Cilastatin-Relebactam for Multidrug-Resistant Gram-Negative Infections

A multicenter case series of 21 patients were treated with imipenem-cilastatin-relebactam. There were mixed infection sources, with pulmonary infections (11/21,52%) composing the majority. The primary pathogen was Pseudomonas aeruginosa (16/21, 76%), and 15/16 (94%) isolates were multidrug-resistant. Thirty-day survival occurred in 14/21 (67%) patients. Two patients experienced adverse effects.

Vancomycin Area Under the Curve to Predict Timely Clinical Response in the Treatment of Methicillin-resistant Staphylococcus aureus Complicated Skin and Soft Tissue Infections

INTRODUCTION

Although recent guidelines have recommended monitoring vancomycin (VAN) area under the curve (AUC)/minimum inhibitory concentration (MIC) to ensure clinical efficacy and minimize toxicity in methicillin-resistant Staphylococcus aureus (MRSA) for various infections, there are no recommendations regarding complicated skin and soft tissue infections (cSSTIs). We aimed to evaluate the association between VAN AUC and clinical outcomes in MRSA cSSTIs.

METHODS

This was a retrospective cohort study of adult patients treated with ≥72 hours of VAN for MRSA cSSTI from 2008 to 2013 at Detroit Medical Center. The primary outcome was timely clinical success (TCS) defined as (1) resolution of signs and symptoms of infection within 72 hours, (2) stabilization and/or reduction in lesion size, (3) alternative agents not required due to VAN failure or toxicity as elected by the prescribing clinician. Classification and regression tree (CART) analysis was performed to determine the AUC associated with TCS in the cohort. Multivariable logistic regression was used to evaluate the association between VAN-AUC and the primary outcome.

RESULTS

A total of 154 patients were included in this analysis. CART identifed an AUC ≥435 mg*hr/L for TCS. Overall, 60.9% of patients experienced TCS; 69.7% in the target-AUC group versus 52.5% in the below-target AUC group, (P = .013). Target-AUC attainment was independently associated with increased odds of TCS (adjusted odds ratio [aOR], 2.208; 95% confidence interval [CI], 1.047-4.659).

CONCLUSIONS

In adults treated with VAN for MRSA cSSTI, target-AUC attainment was independently associated with improved clinical outcomes and maybe most warranted for patients at high risk of VAN failure or VAN-associated toxicity.

686. Comparing Treatments of Methicillin-Resistant Staphylococcus aureus Infective Endocarditis by People Who Inject Drugs

Background

People who inject drugs (PWID) are at high risk for infective endocarditis (IE) with high-mortality pathogens such as methicillin-resistant Staphylococcus aureus (MRSA). Stigma against PWID may cause differences in treatment and outcomes between these patients infected with MRSA IE.

Methods

Single center retrospective cohort study from August 2006 to February 2021 that includes adult patients diagnosed with IE. Primary outcomes included 90-day all-cause mortality, 60-day MRSA recurrence, 60-day readmission, and hospital length of stay (LOS). Statistical analysis was performed by chi-square, t-test, and Mann-Whitney-U as appropriate.

Results

A total of 214 patients were diagnosed with MRSA IE; 89 PWID and 125 non-PWID. The mean (SD) age was 47.4±12.4 years (PWID) vs 59.3 ±16.0 years (non-PWID) (p&lt; 0.001). Patients were primarily male (56%), but differed in terms of race 34% African-American (AA) (PWID) vs 66% AA (non-PWID) (p&lt; 0001). Mean APACHE II scores differed between groups: 16(±9.9) (PWID) vs 19(±8.1) (non-PWID) (p&lt; 0.008). Among patients who cleared bacteremia, mean (SD) duration was 5.7(±3.9) days and was not significant between groups (p&lt; 0.64). Valve-type was 93% native and 7% prosthetic and not different between groups (p&lt; 0.16). Infectious Diseases consult did not differ at 96% overall (p&lt; 0.31), but pursuit of source control nearly reached significance at 27% for PWID vs 41% non-PWID (p&lt; 0.06). Similarly, use of combination therapy daptomycin and ceftaroline was nearly significant: 21% (PWID) vs 12% (non-PWID) (p&lt; 0.09). Odds ratio of PWID and combination therapy remained non-significant after regression: 0.39(0.14-1.1,p&lt; 0.07). Primary 90-day mortality was lower in PWID vs non-PWID (15% vs 30%) respectively (p&lt; 0.01), but did not differ in 60-day MRSA recurrence (p&lt; 1.0) at 9%, 60-day readmission (p&lt; 1.0) at 33%, or median LOS (IQR) (p&lt; 0.46) at 15 (10-24) days overall.

Conclusion

While PWID are significantly younger, less critically ill, and have lower mortality compared to non-PWID, they have similar LOS, MRSA recurrence, and readmission rates. Analyses suggest a potential difference in the pursuit of source control and combination therapy among PWID, however more studies may be needed to achieve significance.

Disclosures

Michael J. Rybak, PharmD, MPH, PhD, Paratek Pharmaceuticals (Research Grant or Support)

1082. Real-World Experience with Omadacycline for Nontuberculous Mycobacterial Infections: A Multicenter Evaluation

Background

Nontuberculous mycobacteria (NTM) are resistant to numerous antibiotics and lead to significant morbidity and mortality. Omadacycline (OMC) is an aminomethylcycline antibiotic that is Food and Drug Administration-approved for acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia. Furthermore, OMC has shown in vitro activity against NTM. Given that real-world evidence is lacking, our primary objective was to evaluate the clinical success and tolerability of OMC when used for a variety of NTM infections.

Methods

This was a multicenter, retrospective, observational study conducted from January 2020 to June 2021. We included all patients ≥ 18 years of age that received OMC of any indication for Mycobacterium spp. The primary outcome was clinical success, defined as a lack of all-cause mortality, lack of persistence or re-emergence of infection during or after therapy, and lack of alteration of OMC. Incidence of adverse effects potentially attributable to OMC and reasons for OMC utilization were also analyzed.

Results

A total of 31 patients were included from 12 geographically distinct academic health systems (median age: 57 (IQR, 45-63) years; 45% male; 81% Caucasian). The majority of isolated pathogens were Mycobacterium abscessus complex (84%) and of those with subspeciation performed (54%), the majority (86%) were subsp. abscessus. The primary infections were of pulmonary origin (67%) and the median (IQR) duration of OMC therapy was 5.3 (3.2-9.4) months. Most isolates did not have OMC susceptibility conducted (87%), while the majority did for tigecycline (90%). Clinical success was reported in 81% of the population. Most patients were on combination antimicrobial therapy, and 39% of patients reported an adverse effect while on OMC (58% gastrointestinal distress). The majority of patients were prescribed OMC due to ease of administration (61%) and antimicrobial resistance to previous antibiotics (42%).

Conclusion

OMC may be a potential option for the therapy of NTM infections. Prospective, randomized clinical trials are needed to confirm our preliminary findings.

Disclosures

Julie V. Philley, MD, Paratek Pharmaceuticals (Advisor or Review Panel member)Paratek Pharmaceuticals, Inc. (Consultant) Michael P. Veve, Pharm.D., Cumberland (Grant/Research Support)Paratek Pharmaceuticals (Research Grant or Support) Michael J. Rybak, PharmD, MPH, PhD, Paratek Pharmaceuticals (Research Grant or Support)

Real-world, Multicenter Experience With Meropenem-Vaborbactam for Gram-Negative Bacterial Infections Including Carbapenem-Resistant Enterobacterales and Pseudomonas aeruginosa

Background

We aimed to describe the clinical characteristics and outcomes of patients treated with meropenem-vaborbactam (MEV) for a variety of gram-negative infections (GNIs), primarily including carbapenem-resistant Enterobacterales (CRE).

Methods

This is a real-world, multicenter, retrospective cohort within the United States between 2017 and 2020. Adult patients who received MEV for ≥72 hours were eligible for inclusion. The primary outcome was 30-day mortality. Classification and regression tree analysis (CART) was used to identify the time breakpoint (BP) that delineated the risk of negative clinical outcomes (NCOs) and was examined by multivariable logistic regression analysis (MLR).

Results

Overall, 126 patients were evaluated from 13 medical centers in 10 states. The most common infection sources were respiratory tract (38.1%) and intra-abdominal (19.0%) origin, while the most common isolated pathogens were CRE (78.6%). Thirty-day mortality and recurrence occurred in 18.3% and 11.9%, respectively. Adverse events occurred in 4 patients: nephrotoxicity (n = 2), hepatoxicity (n = 1), and rash (n = 1). CART-BP between early and delayed treatment was 48 hours (P = .04). MEV initiation within 48 hours was independently associated with reduced NCO following analysis by MLR (adusted odds ratio, 0.277; 95% CI, 0.081–0.941).

Conclusions

Our results support current evidence establishing positive clinical and safety outcomes of MEV in GNIs, including CRE. We suggest that delaying appropriate therapy for CRE significantly increases the risk of NCOs.

Standardized Treatment and Assessment Pathway Improves Mortality in Adults With Methicillin-resistant Staphylococcus aureus Bacteremia: STAPH Study

Background

Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) management remains challenging for clinicians. Numerous in vitro studies report synergy when vancomycin (VAN) and daptomycin (DAP) are combined with beta-lactams (BLs), which has led to clinical implementation of these combinations. While shorter durations of bacteremia have often been reported, there has been no significant impact on mortality.

Methods

The Detroit Medical Center (DMC) developed and implemented a clinical pathway algorithm for MRSA BSI treatment in 2016 that included the early use of BL combination therapy with standard of care (VAN or DAP) and a mandatory Infectious Diseases consultation. This was a retrospective, quasi-experimental study at the DMC between 2013 and 2020. Multivariable logistic regression was used to assess the independent association between pathway implementation and 30-day mortality while adjusting for confounding variables.

Results

Overall, 813 adult patients treated for MRSA BSI were evaluated. Compared with prepathway (PRE) patients (n = 379), those treated postpathway (POST; n = 434) had a significant reduction in 30-day and 90-day mortality: 9.7% in POST vs 15.6% in PRE (P = .011) and 12.2% in POST vs 19.0% in PRE (P = .007), respectively.

The incidence of acute kidney injury (AKI) was higher in the PRE compared with the POST group: 9.6% vs 7.2% (P = .282), respectively. After adjusting for confounding variables including Infectious Diseases consult, POST was independently associated with a reduction in 30-day mortality (adjusted odds ratio [aOR], 0.608; 95% CI, 0.375–0.986).

Conclusions

Implementation of an MRSA BSI treatment pathway with early use of BL reduced mortality with no increased rate of AKI. Further prospective evaluation of this pathway approach is warranted.

Daptomycin Plus β-Lactam Combination Therapy for Methicillin-resistant Staphylococcus aureus Bloodstream Infections: A Retrospective, Comparative Cohort Study

BACKGROUND

Mounting evidence suggests the addition of a β-lactam (BL) to daptomycin (DAP) results in synergistic in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA) and bolsters the innate immune response to infection. This study's objective was to provide clinical translation to these experimental data and determine if DAP+BL combination therapy results in improved clinical outcomes compared with treatment with DAP alone in patients with MRSA bloodstream infections (BSIs).

METHODS

This was a retrospective, comparative cohort study conducted at 2 academic medical centers between 2008 and 2018. Adults with MRSA BSI treated with DAP for ≥72 hours and initiated ≤5 days of culture collection were included. Patients who received a BL for ≥24 hours and initiated ≤24 hours of DAP comprised the DAP+BL group. The primary outcome was composite clinical failure (60-day all-cause mortality and/or 60-day recurrence). Analyses were adjusted for confounding using inverse probability of treatment weighting (IPTW).

RESULTS

A total of 229 patients were included (72 DAP+BL and 157 DAP). In unadjusted and IPTW-adjusted analyses, DAP+BL was associated with significantly reduced odds of clinical failure (odds ratio [OR], 0.362; 95% confidence interval [CI], .164-.801; adjusted OR, 0.386; 95% CI, .175-.853). Adjusted analyses restricted to prespecified subgroups based on infection complexity and baseline health status were consistent with the main analysis.

CONCLUSIONS

The addition of a BL to DAP was associated with improved clinical outcomes in patients with MRSA BSI. This study provides support to ongoing and future studies evaluating the impact of combination therapy for invasive MRSA infections.Patients treated with daptomycin plus a β-lactam for MRSA bloodstream infection had lower odds of composite clinical failure defined as 60-day all-cause mortality and/or 60-day recurrence compared with patients treated with daptomycin monotherapy after adjusting for confounding variables using inverse probability of treatment weighting.

Preliminary, Real-world, Multicenter Experience With Omadacycline for Mycobacterium abscessus Infections

Twelve patients were treated with omadacycline (OMC) as part of a multidrug regimen for Mycobacterium abscessus. The majority of infections were of pulmonary origin (7/12; 58.3%). The median (interquartile range) duration of OMC was 6.2 (4.2-11.0) months. Clinical success occurred in 9/12 (75.0%) patients. Three patients experienced a possible adverse effect while on therapy.

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 &gt;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&lt; 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 &gt;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)

1290. Real-World Experience with Omadacycline for Nontuberculous Mycobacterial and Gram-Negative Infections: A Multicenter Evaluation

Background

Omadacycline (OMC) is an aminomethylcycline antibiotic in the tetracycline class that has been Food and Drug Administration-approved for acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia. OMC has been shown to have potent in vitro activity against a broad-spectrum of Gram-positive and Gram-negative organisms, as well as Nontuberculous Mycobacteria (NTM). Due to it’s unique activity and availability as an oral agent, off-label use of OMC has been increasing. We evaluated the real-world effectiveness and safety of OMC for a variety of infections.

Methods

This was a multicenter, retrospective, observational study that was conducted from January 2020 to June 2020. We included all patients ≥ 18 years of age that received OMC for ≥ 72 hours for any indication and/or pathogen. The primary outcome was clinical success, defined as a lack of 30-day (non-NTM) or 90-day (NTM) mortality or microbiologic recurrence and absence of therapy escalation or alteration. Reasons for OMC utilization and incidence of potential adverse effects attributable to OMC were also analyzed.

Results

A total of 18 patients were included from six geographically distinct academic health systems (median age: 56 (IQR, 49-60.5) years; 61% male; 72% Caucasian). The majority of OMC use was in NTM (61%; 100% Mycobacterium abscessus) and in Acinetobacter baumannii (22%) for bone/joint (39%) and respiratory tract (33%) infections. OMC was used primarily in the outpatient setting alone (83%) and most isolates did not have OMC susceptibility conducted (89%). Clinical success was reported in 83% of the total population (71% non-NTM and 91% NTM). The majority of patients were prescribed OMC due to antimicrobial resistance to previous antibiotic(s) (61%) and/or due to OMC’s availability as an oral agent (44%). Three patients experienced side effects while on therapy (serum creatinine elevation, AST/ALT increase, and gastrointestinal distress).

Conclusion

OMC appears to be effective and well-tolerated for a variety of infections caused by various pathogens, including M. abscessus and A. baumannii.

Disclosures

Michael J. Rybak, PharmD, MPH, PhD, Paratek (Grant/Research Support)

1577. Real-World, Multicenter Experience with Eravacycline for Various Infections

Background

Eravacycline (ERV) is Food and Drug Administration approved in patients for the treatment of adults complicated intra-abdominal infections in 2018. Real-world data regarding the indications for ERV use are is limited. We evaluated the clinical/safety outcomes of patients treated with ERV in FDA and non-FDA approved indications.

Methods

Multicenter, retrospective, observational study from September 2018 to June 2020. Adult patients treated with ERV for ³ 72 hours were included. The primary outcome was 30-day survival. Secondary outcomes included a lack of 30-day infection-recurrence, resolution of signs/symptoms of infection and safety. All outcomes were measured from ERV start date.

Results

Overall, 108 patients were included from 12 geographically-distinct medical centers across the United States. The median(IQR) age was 60(52-67) years and 60% were male. Median(IQR) APACHE II and Charlson Comorbidity scores were 15(11-21) and 3 (2-6), respectively. The most common sources of infection were intra-abdominal (32%), and respiratory (24%). Common pathogens included Acinetobacter baumannii (19%), Klebsiella pneumoniae and Enterococcus faecium (16%). Infectious diseases consultation was obtained in 98%, and surgical interventions in 51% of cases. Patients often received active therapy prior to ERV(40%). Median(IQR) ERV therapy duration was 7.7(4.4-14.0) days. Among cases with documented cultures, ERV was initiated within a median(IQR) of 4.8(2.5-9.9) days. Combination therapy ³ 48 hours was given in 45%. The primary endpoint was achieved in 79%(85/108). Of patients who died(n=23), 57% were on monotherapy, 39% were critically ill, 39% had intra-abdominal as a source, and 30% had positive blood cultures. For secondary outcomes, 94%(102/108) lacked 30-day infection-recurrence and 74%(80/108) resolved signs/symptoms of infection. ERV was selected primarily for consolidation of the regimen(40%). Eight patients experienced a probable ERV-related adverse event, mainly gastrointestinal(87.5%) and none experienced clostridium difficile.

Conclusion

30-day survival was achieved in the majority of patients treated with ERV. Studies with longer follow-up are required to confirm these findings.

Disclosures

Madeline King, PharmD, Tetraphase (Speaker’s Bureau) Bruce M. Jones, PharmD, BCPS, ALK-Abello (Research Grant or Support)Allergan/Abbvie (Speaker’s Bureau) Michael J. Rybak, PharmD, MPH, PhD, Paratek (Grant/Research Support)

A comparison of daptomycin alone and in combination with ceftaroline fosamil for methicillin-resistant Staphylococcus aureus bacteremia complicated by septic pulmonary emboli

The use of daptomycin (DAP) in septic pulmonary emboli (SPE) remains controversial. We analyzed 29 cases of MRSA bacteremia complicated by SPE treated with DAP (n = 14) or DAP-ceftaroline fosamil (CPT; n = 15). Initial treatment with DAP monotherapy was found to have a success rate comparable with DAP-CPT (71% vs. 80%; p = 0.68).

Evaluation of the INCREMENT-CPE, Pitt Bacteremia and qPitt Scores in Patients with Carbapenem-Resistant Enterobacteriaceae Infections Treated with Ceftazidime-Avibactam

BACKGROUND

The aim of this study was to evaluate the predictive performance of the INCREMENT-CPE (ICS), Pitt bacteremia score (PBS) and qPitt for mortality among patients treated with ceftazidime-avibactam for carbapenem-resistant Enterobacteriaceae (CRE) infections.

METHODS

Retrospective, multicenter, cohort study of patients with CRE infections treated with ceftazidime-avibactam between 2015 and 2019. The primary outcome was 30-day all-cause mortality. Predictive performance was determined by assessing discrimination, calibration and precision.

RESULTS

In total, 109 patients were included. Thirty-day mortality occurred in 18 (16.5%) patients. There were no significant differences in discrimination of the three scores [area under the curve (AUC) ICS 0.7039, 95% CI 0.5848-0.8230, PBS 0.6893, 95% CI 0.5709-0.8076, and qPitt 0.6847, 95% CI 0.5671-0.8023; P > 0.05 all pairwise comparisons]. All scores showed adequate calibration and precision. When dichotomized at the optimal cut-points of 11, 3, and 2 for the ICS, PBS, and qPitt, respectively, all scores had NPV > 90% at the expense of low PPV. Patients in the high-risk groups had a relative risk for mortality of 3.184 (95% CI 1.35-8.930), 3.068 (95% CI 1.094-8.606), and 2.850 (95% CI 1.016-7.994) for the dichotomized ICS, PBS, and qPitt, scores respectively. Treatment-related variables (early active antibiotic therapy, combination antibiotics and renal ceftazidime-avibactam dose adjustment) were not associated with mortality after controlling for the risk scores.

CONCLUSIONS

In patients treated with ceftazidime-avibactam for CRE infections, mortality risk scores demonstrated variable performance. Modifications to scoring systems to more accurately predict outcomes in the era of novel antibiotics are warranted.

Monotherapy with Vancomycin or Daptomycin versus Combination Therapy with β-Lactams in the Treatment of Methicillin-Resistant Staphylococcus Aureus Bloodstream Infections: A Retrospective Cohort Analysis

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI) are associated with high morbidity and mortality. More in vitro, in vivo, and clinical data suggest that vancomycin (VAN) or daptomycin (DAP) combination therapy with β-lactams (BL) improves outcomes of MRSA infections. We hypothesize that BL combination with VAN or DAP would reduce the odds of clinical failure compared to VAN or DAP monotherapy.

METHODS

A retrospective cohort study of adult patients ≥ 18 years treated with VAN or DAP for MRSA BSI from 2006 to 2019 at Detroit Medical Center. Combination therapy (CT) was defined as VAN or DAP plus any BL for ≥ 24 h within 72 h of index culture. Monotherapy (MT) was defined as ≥ 72 h VAN or DAP within 72 h of index culture and no BL for ≥ 24 h up to 7 days following VAN/DAP initiation. Primary outcome was composite endpoint of clinical failure defined as: (1) 30-day mortality, (2) 60-day recurrence, or (3) persistent bacteremia (PB). PB was defined as bacteremia > 5 days. Multivariable logistic regression was used to evaluate the association between CT and the primary outcome.

RESULTS

Overall, 597 patients were included in this analysis, 153 in the MT group and 444 in the CT group. CT was independently associated with reduced odds of clinical failure (adjusted odds ratio, 0.523; 95% confidence interval, 0.348-0.787). The composite endpoint was driven by 60-day recurrence and PB but not 30-day mortality. There were no difference in adverse events including nephrotoxicity between the two study arms.

CONCLUSIONS

In hospitalized adults with MRSA BSI, CT with any BL was independently associated with improved clinical outcomes and may ultimately be selected as preferred therapy.

Sequential intravenous-to-oral outpatient antibiotic therapy for MRSA bacteraemia: one step closer

Background

Published guidelines call for prolonged courses of intravenous (iv) antibiotics for the treatment of MRSA bloodstream infection (BSI) to ensure eradication of deep foci and decrease relapse risk. Sequential iv-to-oral antibiotic therapy has been successfully applied to other serious infections but has not been evaluated for MRSA BSI.

Objectives

To compare outcomes in adults completing MRSA BSI therapy with oral versus parenteral antibiotics in the outpatient setting [oral outpatient antibiotic therapy (OOAT) versus outpatient parenteral antibiotic therapy (OPAT)].

Methods

This was a single-centre, retrospective, cohort study between 2008 and 2018. The primary outcome was 90 day clinical failure (MRSA BSI recurrence, deep-seated MRSA infection or all-cause mortality). Analyses were adjusted for confounding using inverse probability of treatment weighting (IPTW).

Results

A total of 492 patients were included (70 OOAT, 422 OPAT). In general, OOAT patients had characteristics consistent with a lower risk of poor outcomes; however, after IPTW key prognostic factors were balanced. In IPTW-adjusted analysis, there was non-significant reduction in the rate of 90 day clinical failure in the OOAT group compared with the OPAT group [adjusted HR (aHR) 0.379, 95% CI 0.131-1.101]. In analyses restricted to pre-specified subgroups defined by index infection complexity and comorbidity burden, findings were consistent with the main analysis. Furthermore, OOAT patients had a significantly reduced rate of 90 day hospital readmission (aHR 0.603, 95% CI 0.388-0.937).

Conclusions

We provide preliminary evidence that selected patients with MRSA BSI may have at least equivalent clinical outcomes with OOAT versus OPAT and provide support to ongoing and future studies evaluating oral antibiotics for MRSA BSI.

Early Experience With Eravacycline for Complicated Infections

Eravacycline (ERV) was used in 35 patients for various infections. The most common pathogen was Klebsiella pneumoniae, and 30-day survival was 74%. Absence of 30-day recurrence and resolution of signs and symptoms of infection were 91% and 57%, respectively. ERV was well-tolerated, with adverse events leading to drug discontinuation in one patient.

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.

A Multicenter Evaluation of Vancomycin-Associated Acute Kidney Injury in Hospitalized Patients with Acute Bacterial Skin and Skin Structure Infections

Background

We sought to determine the real-world incidence of and risk factors for vancomycin-associated acute kidney injury (V-AKI) in hospitalized adults with acute bacterial skin and skin structure infections (ABSSSI).

Methods

Retrospective, observational, cohort study at ten U.S. medical centers between 2015 and 2019. Hospitalized patients treated with vancomycin (≥ 72 h) for ABSSSI and ≥ one baseline AKI risk factor were eligible. Patients with end-stage kidney disease, on renal replacement therapy or AKI at baseline, were excluded. The primary outcome was V-AKI by the vancomycin guidelines criteria.

Results

In total, 415 patients were included. V-AKI occurred in 39 (9.4%) patients. Independent risk factors for V-AKI were: chronic alcohol abuse (aOR 4.710, 95% CI 1.929–11.499), no medical insurance (aOR 3.451, 95% CI 1.310–9.090), ICU residence (aOR 4.398, 95% CI 1.676–11.541), Gram-negative coverage (aOR 2.926, 95% CI 1.158–7.392) and vancomycin duration (aOR 1.143, 95% CI 1.037–1.260). Based on infection severity and comorbidities, 34.7% of patients were candidates for oral antibiotics at baseline and 39.3% had non-purulent cellulitis which could have been more appropriately treated with a beta-lactam. Patients with V-AKI had significantly longer hospital lengths of stay (9 vs. 6 days, p = 0.001), higher 30-day readmission rates (30.8 vs. 9.0%, p < 0.001) and increased all-cause 30-day mortality (5.1 vs. 0.3%, p = 0.024)

Conclusions

V-AKI occurred in approximately one in ten ABSSSI patients and may be largely prevented by preferential use of oral antibiotics whenever possible, using beta-lactams for non-purulent cellulitis and limiting durations of vancomycin therapy.

Electronic supplementary material

The online version of this article (10.1007/s40121-019-00278-1) contains supplementary material, which is available to authorized users.

Real-World Experience With Ceftazidime-Avibactam for Multidrug-Resistant Gram-Negative Bacterial Infections

Background

We conducted this study to describe the clinical characteristics, microbiology, and outcomes of patients treated with ceftazidime-avibactam (CZA) for a range of multidrug-resistant Gram-negative (MDR-GN) infections.

Methods

This is a multicenter, retrospective cohort study conducted at 6 medical centers in the United States between 2015 and 2019. Adult patients who received CZA (≥72 hours) were eligible. The primary outcome was clinical failure defined as a composite of 30-day all-cause mortality, 30-day microbiological failure, and/or failure to resolve or improve signs or symptoms of infection on CZA.

Results

In total, data from 203 patients were evaluated. Carbapenem-resistant Enterobacteriaceae (CRE) and Pseudomonas spp were isolated from 117 (57.6%) and 63 (31.0%) culture specimens, respectively. The most common infection sources were respiratory (37.4%), urinary (19.7%), and intra-abdominal (18.7%). Blood cultures were positive in 22 (10.8%) patients. Clinical failure, 30-day mortality, and 30-day recurrence occurred in 59 (29.1%), 35 (17.2%), and 12 (5.9%) patients, respectively. On therapy, CZA resistance developed in 1 of 62 patients with repeat testing. Primary bacteremia or respiratory tract infection and higher SOFA score were positively associated with clinical failure (adjusted odds ratio [aOR] = 2.270, 95% confidence interval [CI] = 1.115–4.620 and aOR = 1.234, 95% CI = 1.118–1.362, respectively). Receipt of CZA within 48 hours of infection onset was protective (aOR, 0.409; 95% CI, 0.180–0.930). Seventeen (8.4%) patients experienced a potential drug-related adverse effect (10 acute kidney injury, 3 Clostridioides difficile infection, 2 rash, and 1 each gastrointestinal intolerance and neutropenia)

Conclusions

Ceftazidime-avibactam is being used to treat a range of MDR-GN infections including Pseudomonas spp as well as CRE.

Multicenter Study of the Real-World Use of Ceftaroline versus Vancomycin for Acute Bacterial Skin and Skin Structure Infections

The objective of this study was to determine if real-world ceftaroline treatment in adults hospitalized for acute bacterial skin and skin structure infections (ABSSSI) is associated with decreased infection-related length of stay (LOSinf) compared to that with vancomycin. This was a retrospective, multicenter, cohort study from 2012 to 2017. Cox proportional hazard regression, propensity score matching, and inverse probability of treatment weighting (IPTW) were used to determine the independent effect of treatment group on LOSinf The patients were adults hospitalized with ABSSSI and treated with ceftaroline or vancomycin for ≥72 h within 120 h of diagnosis at four academic medical centers and two community hospitals in Arizona, Florida, Michigan, and West Virginia. A total of 724 patients were included (325 ceftaroline treated and 399 vancomycin treated). In general, ceftaroline-treated patients had characteristics consistent with a higher risk of poor outcomes. The unadjusted median LOSinf values were 5 (interquartile range [IQR], 3 to 7) days and 6 (IQR, 4 to 8) days in the vancomycin and ceftaroline groups, respectively (hazard ratio [HR], 0.866; 95% confidence interval [CI], 0.747 to 1.002). The Cox proportional hazard model (adjusted HR [aHR], 0.891; 95% CI, 0.748 to 1.060), propensity score-matched (aHR, 0.955; 95% CI, 0.786 to 1.159), and IPTW (aHR, 0.918; 95% CI, 0.793 to 1.063) analyses demonstrated no significant difference in LOSinf between groups. Patients treated with ceftaroline were significantly more likely to meet criteria for discharge readiness at day 3 in unadjusted and adjusted analyses. Although discharge readiness at day 3 was higher in ceftaroline-treated patients, LOSinf values were similar between treatment groups. Clinical and nonclinical factors were associated with LOSinf.

442. Risk Score for Vancomycin-Associated Acute Kidney Injury in Hospitalized Patients with Acute Bacterial Skin and Skin Structure Infections

Background

Methods

Results

Conclusion

Disclosures

2254. Multicenter Evaluation of Ceftazidime–Avibactam for Multidrug-Resistant Pseudomonas aeruginosa Infections

Background

Ceftazidime–avibactam (CZA) is a novel cephalosporin/β-lactamase inhibitor with activity against carbapenem-resistant Enterobacteriaceae (CRE) and multidrug-resistant (MDR) Pseudomonas aeruginosa (PA). Real-world experience with CZA for CRE infections is accumulating but data on its use for MDR PA infections remains limited.

Methods

Retrospective, multicenter cohort study describing the clinical characteristics and outcomes of patients treated with CZA (≥ 72 hours) for MDR PA infections between 2015 and 2018.

Results

Fifty-one patients were included. The median (IQR) age was 61 (43, 71) years. Most patients had MDR risk factors including recent hospitalization (74.5%), recent antimicrobial exposure (84.3%), and/or previous infection or colonization with an MDR pathogen (58.8%). The median Charlson Comorbidity score was 4 (2, 6) and the median APACHE II score was 20 (12, 29). Infections were predominantly (68.6%) hospital-acquired and 52.9% of patients were in the ICU at infection onset. The common sources were respiratory tract (60.8%), osteoarticular (11.8%) and skin and soft tissue (11.8%). Two patients had positive blood cultures. PA antibiotic susceptibilities were as follows: ceftazidime 52.6% (n = 51), CZA 92.0% (n = 25), ciprofloxacin 10% (n = 30), meropenem 19.6% (n = 46), piperacillin–tazobactam 30.4% (n = 4) and tobramycin 72.9% (n = 48). Most (60.8%) infections were polymicrobial including 15 (29.4) CRE co-infections. CZA was started 97 (50, 170) hours after culture collection and continued for 9 (7, 14) days. Only 8 patients (15.7%) received active antibiotic therapy before CZA. Combination CZA therapy was used 35.3%, most often an aminoglycoside (8/18, 44.4%). Clinical cure or improvement was achieved in 40 patients (78.4%), and 42 (82.4%) were discharged alive. Among patients with repeat cultures (n = 11), CZA resistance development was not detected. Three patients (5.9%) experienced infection recurrence within 30 days of completing therapy.

Conclusion

The use of CZA was associated with high rates of favorable outcomes in complex patients with MDR PA infections. Future studies evaluating long-term outcomes and comparative studies are needed to more precisely define the role of CZA for MDR PA infections.

Disclosures

All authors: No reported disclosures.

A new simplified predictive model for mortality in methicillin-resistant Staphylococcus aureus bacteremia

Adjustment for confounding is important in observational methicillin-resistant Staphylococcus aureus bacteremia (MRSAB) studies due to the wide spectrum of disease severity and baseline health status that patients present with. The objectives of this study were to develop a simplified MRSAB-specific scoring model to estimate the risk of 30-day all-cause mortality and to compare its performance to the APACHE II and Pitt Bacteremia scores. Retrospective, singe-center, cohort study in adults with MRSAB 2008 to 2018. Independent predictors of mortality were identified through multivariable logistic regression. A scoring model was derived using a regression coefficient-based scoring method. Discriminatory ability was assessed using the c statistic. A total of 455 patients were included. Thirty-day mortality was 16.3%. The MRSAB score consisted of six variables: age, respiratory rate, Glasgow Coma scale, renal failure, hospital-acquired MRSAB, and infective endocarditis or lower respiratory tract infection source. The score demonstrated very good discrimination (c statistic 0.8662, 95% CI 0.824-0.909) and was superior to the APACHE II (P = 0.043) and the Pitt bacteremia (P < 0.001) scores. A weighted combination of six independent variables routinely measured in patients with MRSAB can be used to predict, with high discrimination, 30-day all-cause mortality. External validation is required before widespread use.

1073. Predictors of Vancomycin Switch or Escalation in Patients With Methicillin-Resistant Staphylococcus aureus Bloodstream Infection

Background

Vancomycin (VAN) is the primary agent for the treatment methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI). VAN is frequently combined with or switched to a second anti-MRSA agent for the treatment of serious BSI because VAN monotherapy has been linked to treatment failures. We aimed to determine the potential risk factors for patients with MRSA BSI who switched or had therapy escalated.

Methods

This was a multicenter, retrospective cohort study of adults (≥18 years) initially treated with VAN (>24 hours) for MRSA BSI between 2006 and 2018. Patients with a respiratory source were excluded. Baseline clinical and infection characteristics were compared between patients who received VAN as the sole anti-MRSA agent and continued on VAN until discharge and patients who switched or had a second anti-MRSA agent added during their admission (switch/escalate group). Multivariable logistic regression was performed to identify independent predictors of therapy switch or escalation.

Results

A total of 195 patients were included (66 VAN and 129 switch/escalate). The mean (SD) age of the study population was 56 (15.5) years, 68.2% were male, and 81.0% were African-American. Most (80%) of patient had community-onset BSI. The median (IQR) Charlson Comorbidity index and Acute Physiology and Chronic Health Evaluation (APACHE) II scores were 3 (1–5) and 14 (8–20), respectively. The major sources of BSI were skin/soft tissue (24.6%), infective endocarditis (24.1%), and bone/joint (23.1%). Median (IQR) time to switch/escalation was 67 (44–97) hours. In multivariable logistic regression analysis, infective endocarditis (aOR 6.2, 95% CI 2.2–16), hospitalization in the past 90 days (aOR 2.0, 95% CI 1.0–4.0), and APACHE II (aOR 1.07, 95% CI 1.01–1.12) were independently associated with switch/escalation.

Conclusion

We have identified a number of baseline clinical and infection characteristics that should be taken into account for clinicians to predict the likelihood of switch or escalation in vancomycin treated patients with MRSA BSI. Further studies evaluating the impact of up front alternative therapies in these higher risk patients are needed.

Disclosures

S. L. Davis, Achaogen: Scientific Advisor, Consulting fee. Allergan: Scientific Advisor, Consulting fee. Melinta: Scientific Advisor, Consulting fee. Nabriva: Scientific Advisor, Consulting fee. Zavante: Scientific Advisor, Consulting fee. M. J. Rybak, Allergan: Consultant, Grant Investigator and Speaker’s Bureau, Research grant and Research support. Achaogen: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Bayer: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Melinta: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Merck: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Theravance: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Sunovian: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Zavante: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. NIAID: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support.

2384. Multidrug-Resistant Gram-Negative Infections Treated With Ceftolozane–Tazobactam: Impact of Delayed Initiation

Background

Methods

Results

Conclusion

Disclosures

1061. Comparison of the Acute Physiology and Chronic Health Evaluation (APACHE) II Score and the Pitt Bacteremia Score to Predict Mortality in Methicillin-Resistant Staphylococcus aureus Bacteremia

Background

Methicillin-resistant Staphylococcus aureus bloodstream infection (MRSA BSI) is associated with high morbidity and mortality. The prediction of outcomes may have a profound impact on clinical decision making and risk stratification. The Acute Physiology and Chronic Health Evaluation (APACHE) II Score and the Pitt Bacteremia Score (PBS) have been repeatedly described as independent predictors of mortality in MRSA BSI. The APACHE II is complex to calculate and many of the variables may not be pertinent to MRSA BSI. The PBS is a simple score using readily assessable variables. The comparative predictive performance of the two models in MRSA BSI has not been evaluated.

Methods

Retrospective, observational, singe-center cohort study in adults with MRSA BSI between 2008 and 2018. Patients who did not receive active therapy ≤72 hours of index culture were excluded. APACHE II and PBS were calculated using the worst physiological values recorded ≤24 hours of blood culture collection. Discriminatory ability for 30-day mortality was assessed using the c-statistic and was compared using the Hanley and McNeil method. The best cut-off point in each scoring system was determined using the Youden Index (J).

Results

A total of 455 patients were included. The median (IQR) PBS and APACHE II were 2 (0, 3) and 18 (11, 23), respectively. All-cause 30-day mortality was 16.3%. The c-statistic (95% CI) for the APACHE II vs. PBS in the overall cohort and stratified by ICU status were: 0.813 (0.763, 0.863) vs. 0.717 (0.653, 0.782), P = 0.0035; ICU 0.729 (0.610, 0.848) vs. 0.570 (0.442, 0.699), P = 0.026; and non-ICU 0.821 (0.761, 0.881) vs. 0.700 (0.614, 0.786),P = 0.0046, respectively. The APACHE II with the maximum J value was 21; sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for 30-day mortality were 81.08%, 72.97%, 36.81%, and 95.21%, respectively. The PBS with the maximum J value was 3; sensitivity, specificity, PPV, and NPV were 66.22%, 72.18%, 31.61%, and 91.67%, respectively.

Conclusion

The APACHE II was superior to the PBS in predicting 30-mortality in patients with MRSA BSI in the overall cohort and stratified by ICU status at BSI onset. Future research to develop a more practical scoring model with high discriminatory power is needed.

Disclosures

M. J. Rybak, Allergan: Consultant, Grant Investigator and Speaker’s Bureau, Research grant and Research support. Achaogen: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Bayer: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Melinta: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Merck: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Theravance: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Sunovian: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Zavante: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. NIAID: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support.

1227. Development of a Clinical Prediction Model for Mortality in Methicillin-Resistant Staphylococcus aureus Bacteremia

Background

Methicillin-resistant Staphylococcus aureus bloodstream infection (MRSA BSI) is associated with high mortality despite advances in medical care. Mortality prediction may have a profound impact on clinical decision making and risk stratification. Widely used scoring systems such as the Acute Physiology and Chronic Health Evaluation (APACHE) II Score and the Pitt Bacteremia Score were derived in the general critical care and Gram-negative BSI populations, respectively and may be less precise in MRSA BSI. We sought to develop a predictive model (PM) for 30-day mortality in patients with MRSA BSI based on characteristics readily assessable at initial evaluation.

Methods

Retrospective, singe-center, cohort study in adults with MRSA BSI 2008 to 2018. Patients who did not receive active therapy within 72 hours of index culture were excluded. Independent baseline demographic, clinical and infection predictors of 30-day mortality were identified through multivariable logistic regression analysis with bootstrap resampling and coefficient shrinkage. The PM was derived using a regression coefficient-based scoring method. PM discriminatory ability was assessed using the c-statistic. The optimal threshold score was determined using the Youden Index (J).

Results

A total of 455 patients were included and 30-day mortality was 16.3%. The PM consisted of five variables and a potential total score of 33. Points were assigned as follows: age (9 points ≥90 years, 6 points 80–89 years, 5 points 70–79 years, 0 points &lt;70 years); Glasgow Coma Scale (8 points ≤9, 5 points 10–13, 0 points ≥14); 7 points infective endocarditis or pneumonia; 5 points serum creatinine ≥ 3.5 dl/L; and four points respiratory rate &lt;10 or &gt;24. The PM c-statistic was 0.860 (95% CI 0.818, 0.902). The PM score with the maximum J value was 13. Thirty-day mortality was 5.2% vs. 44.5% for PM score &lt;13 vs. ≥13 points, respectively (P &lt; 0.001). The sensitivity, specificity, positive predictive value (PV), negative PV, and accuracy using a threshold of 13 points were 77.0%, 81.4%, 44.5%, 94.8%, and 80.7%, respectively.

Conclusion

Our findings demonstrate a weighted combination of five independent variables readily assessable at initial evaluation can be used to predict, with high discrimination, 30-d mortality in MRSA BSI. External validation is required before wide-spread clinical use.

Disclosures

M. J. Rybak, Allergan: Consultant, Grant Investigator and Speaker’s Bureau, Research grant and Research support. Achaogen: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Bayer: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Melinta: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Merck: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support

Theravance: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Sunovian: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Zavante: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. NIAID: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support.

Antimicrobial Stewardship Opportunities in Critically Ill Patients with Gram-Negative Lower Respiratory Tract Infections: A Multicenter Cross-Sectional Analysis

INTRODUCTION

Lower respiratory tract infections (LRTIs) are a major cause of morbidity and death. Because of changes in how LRTIs are defined coupled with the increasing prevalence of drug resistance, there is a gap in knowledge regarding the current burden of antimicrobial use for Centers for Disease Control and Prevention (CDC)-defined LRTIs. We describe the infection characteristics, antibiotic consumption, and clinical and economic outcomes of patients with Gram-negative (GN) LRTIs treated in intensive care units (ICUs).

METHODS

This was a retrospective, observational, cross-sectional study of adult patients treated in ICUs at two large academic medical centers in metropolitan Detroit, Michigan, from October 2013 to October 2015. To meet the inclusion criteria, patients must have had CDC-defined LRTI caused by a GN pathogen during ICU stay. Microbiological assessment of available Pseudomonas aeruginosa isolates included minimum inhibitory concentrations for key antimicrobial agents.

RESULTS

Four hundred and seventy-two patients, primarily from the community (346, 73.3%), were treated in medical ICUs (272, 57.6%). Clinically defined pneumonia was common (264, 55.9%). Six hundred and nineteen GN organisms were identified from index respiratory cultures: P. aeruginosa was common (224, 36.2%), with 21.6% of these isolates being multidrug resistant. Cefepime (213, 45.1%) and piperacillin/tazobactam (174, 36.8%) were the most frequent empiric GN therapies. Empiric GN therapy was inappropriate in 44.6% of cases. Lack of in vitro susceptibility (80.1%) was the most common reason for inappropriateness. Patients with inappropriate empiric GN therapy had longer overall stay, which translated to a median total cost of care of $79,800 (interquartile range $48,775 to $129,600) versus $68,000 (interquartile range $38,400 to $116,175), p = 0.013. Clinical failure (31.5% vs 30.0%, p = 0.912) and in-hospital all-cause mortality (26.4% vs 25.9%, p = 0.814) were not different.

CONCLUSION

Drug-resistant pathogens were frequently found and empiric GN therapy was inappropriate in nearly 50% of cases. Inappropriate therapy led to increased lengths of stay and was associated with higher costs of care.

Multidrug-resistant Pseudomonas aeruginosa lower respiratory tract infections in the intensive care unit: Prevalence and risk factors

Intensive care unit (ICU) admission is a risk for multidrug-resistant (MDR) Pseudomonas aeruginosa, but factors specific to critically ill pneumonia patients are not fully characterized. Objective was to determine risk factors associated with MDR P. aeruginosa pneumonia among ICU patients. This was a retrospective case-control study of P. aeruginosa pneumonia in the ICU; cystic fibrosis and colonizers were excluded. Risk factors included comorbid conditions and prior healthcare exposure (anti-pseudomonal antibiotics, hospitalizations, nursing home, P. aeruginosa colonization/infection, mechanical ventilation). Of 200 patients, 47 (23.5%) had MDR P. aeruginosa pneumonia. Independent predictors for MDR were ≥24h antibiotics in the preceding 90days (carbapenems, fluoroquinolones, and piperacillin-tazobactam) (odds ratio, 3.6 [95% CI, 1.6-8.1]) and nursing home residence (2.3 [1.1-4.9]). MDR P. aeruginosa remains prevalent among ICU patients with pneumonia. Given poor outcomes with delayed therapy, patients should be thoroughly assessed for prior anti-pseudomonal antibiotic exposure and nursing home residency.

Multicenter Observational Study of Ceftaroline Fosamil for Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

Novel therapies for methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) are needed in the setting of reduced antibiotic susceptibilities and therapeutic failure. Ceftaroline is a cephalosporin antibiotic with MRSA activity. Although not FDA approved for MRSA BSI, ceftaroline has generated much interest as a potential treatment option. However, detailed descriptions of its use in this setting remain limited. To address this, we conducted a retrospective, multicenter, observational study of adult patients with MRSA BSI treated with at least 72 h of ceftaroline from 2011 to 2015. Safety outcomes were examined in the overall cohort, while efficacy outcomes were examined among patients who had not cleared their BSI prior to ceftaroline initiation. Data were also stratified by ceftaroline monotherapy or combination therapy. Predictors of clinical failure on ceftaroline treatment were also sought. Overall, 211 patients were included in the safety population; Clostridium difficile infection, rash, and neutropenia occurred in 6 patients (2.8%), 7 patients (3.3%), and 3 patients (1.4%), respectively. Clinical success was observed in 86 (68.3%) of the 126 patients included in the efficacy population. The monotherapy and combination therapy subgroups had similar proportions of patients experiencing success (69.7 and 64.9%, respectively). The median BSI durations post-ceftaroline treatment were 2 days (interquartile range, 1 to 4 days) for monotherapy and 3 days (interquartile range, 1.5 to 5 days) for combination therapy. Higher acute physiology and chronic health evaluation II scores and comorbid malignancy independently predicted treatment failure. Ceftaroline appears effective for MRSA BSI as both monotherapy and combination therapy. However, comparative studies are needed to further delineate the role of ceftaroline in MRSA BSI treatment.

Time Is of the Essence: The Impact of Delayed Antibiotic Therapy on Patient Outcomes in Hospital-Onset Enterococcal Bloodstream Infections

BACKGROUND

With increasing prevalence of vancomycin-resistant enterococci (VRE), appropriate antibiotic therapy for enterococcal bloodstream infections (EBSI) can be delayed. Data regarding the impact of delayed therapy on EBSI outcomes are conflicting, and the time delay most strongly associated with poor outcomes has not been defined.

METHODS

This was a single-center, retrospective cohort study of adult, nonneutropenic patients with hospital-onset EBSI from 2010 to 2014. Classification and regression tree (CART) analysis was used to determine the delay in appropriate therapy most predictive of 30-day mortality. Appropriate therapy was defined as antibiotic therapy to which the enterococci and copathogen, where applicable, were susceptible. Outcomes and clinical characteristics were compared between patients receiving early or delayed therapy, defined by CART timepoint. Poisson regression was employed to determine the independent association of delayed therapy on 30-day mortality and predictors of delayed therapy.

RESULTS

Overall, 190 patients were included. A breakpoint in time to appropriate therapy was identified at 48.1 hours, where 30-day mortality was substantially increased (14.6% vs 45.3%; P < .001). Patients receiving appropriate therapy after 48.1 hours also experienced higher in-hospital mortality and longer EBSI duration. After adjustment for severity of illness and comorbidity, delayed therapy ≥48.1 hours was associated with a 3-fold increase in 30-day mortality (risk ratio, 3.16 [95% confidence interval, 1.96-5.09]). Vancomycin resistance was the only independent predictor of delayed therapy.

CONCLUSIONS

In patients with hospital-onset EBSI, receipt of appropriate therapy within the first 48 hours was associated with reduced mortality, underscoring the potential role of rapid diagnostic testing for early identification of VRE.

Comparison of outcomes between patients with single versus multiple positive blood cultures for Enterococcus: Infection versus illusion?

Enterococci represent one of the most common causative pathogens of bloodstream infections (BSIs). There is debate in the literature regarding the clinical importance of single versus multiple positive blood cultures for Enterococci. This single-center retrospective study found that patients with multiple positive blood cultures experienced increased inpatient mortality and a shorter median survival. Additionally, BSIs >6.7 days resulted in approximately 20% increased mortality. These results are preliminary and require further exploration.

Acute Bacterial Skin and Skin Structure Infections Treated with Intravenous Antibiotics in the Emergency Department or Observational Unit: Experience at the Detroit Medical Center

Introduction

Acute bacterial skin and skin structure infections (ABSSSIs) are frequently treated in emergency departments (EDs) or observation units (OUs) initially with intravenous (IV) antibiotics before discharge on oral therapy. This study aims to describe ABSSSI patients discharged directly from EDs/OUs.

Methods

This is a retrospective cohort study of patients with ABSSSIs treated in EDs/OUs of the Detroit Medical Center from 2012 to 2014. Adults with less than 24 h of IV antibiotics without hospital admission were included. Demographics, clinical characteristics, and severity were compared between ED and OU patients. Resource utilization, including tissue and blood cultures, and use of radiographic analysis was also collected. The primary outcome was 96-h ED revisit/hospitalization.

Results

Analysis included 308 patients; 219 ED and 89 OU. OU patients were significantly more likely to be obese, have COPD/asthma, be diagnosed with cellulitis, and meet at least one systemic inflammatory response syndrome (SIRS) criterion. Tissue cultures were obtained in 21.7% of abscesses in the ED; 67.9% were in uncomplicated abscesses. In the OU tissue cultures were obtained in 48.8% of abscesses and 37.5% were uncomplicated cases. Blood cultures were drawn in 18.3% of ED patients and 56.2% of OU patients, not significantly associated with the presence of SIRS criteria. Radiology was used in the diagnosis of ABSSSIs in 33.5% of ED versus 69.5% OU patients (p < 0.001), Plain film radiograph being the most common. Thirty patients revisited the ED or required hospitalization within 96 h, 23 from the ED (p = 0.479). Prior history of ABSSSI (adjusted odds ratio [aOR] = 2.382, 95% confidence interval [CI] 1.264–6.346) and location on torso/buttocks (aOR = 2.355, 95% CI 1.067–5.197) were independent predictors.

Conclusions

The low rate of ED revisit/hospitalization supports the use of OUs for low acuity ABSSSIs requiring initial IV therapy. Resource utilization within EDs/OUs for the management of ABSSSIs needs to be evaluated for unnecessary testing/procures.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-015-0069-7) contains supplementary material, which is available to authorized users.