Microbiological Eradication Research Articles

Optimization of Linezolid Dosing Regimens for Treatment of Vancomycin-Resistant Enterococci Infection.

BackgroundLinezolid, an oxazolidinone antibiotic, is recommended for vancomycin-resistant enterococci (VRE). However, 100% free-drug concentration above the minimum inhibitory concentration (fT>MIC) and an area under the curve of free drug to MIC ratio (fAUC24/MIC) >100 were associated with favorable clinical outcome with less emerging resistance. A plasma trough concentration (Ctrough) of linezolid ≥9 µg/mL was also related to hematologic toxicity. Thus, linezolid dose optimization is needed for VRE treatment. The study aimed to determine the in vitro linezolid activity against clinical VRE isolates and linezolid dosing regimens in critically ill patients who met the target pharmacokinetics/pharmacodynamics (PK/PD) for VRE treatment.Materials and MethodsEnterococcal isolates from enterococcal-infected patients were obtained between 2014 and 2018 at Phramongkutklao Hospital. We used Monte Carlo simulation to calculate the probability of target attainment, and the cumulative fraction of response (CFR) of the free area under the curve to MIC ratio (fAUIC24) was used to calculate the fAUC24/MIC 80 - 100 and fT/MIC >85 - 100% of the interval time of administration for clinical response and microbiological eradication as well as the Ctrough ≥9 µg/mL for the probability of hematologic toxicity.ResultsFor linezolid MIC determination, the MIC median (MIC50), MIC for 90% growth (MIC90), and range for linezolid were 1.5 µg/mL, 2 µg/mL, and 0.72 - 2 µg/mL, respectively. A dosing regimen of 1,200 mg either once daily or as a divided dose every 12 h gave target attainments of fAUC24/MICs >80 and >100, which exceeded 90% for MICs ≤1 and ≤1 µg/mL, respectively, with a rate of hematologic toxicity <15%. If the expected fT>MICs were >85% and 100%, a 1,200-mg divided dose every 12 h could cover VRE isolates having linezolid MICs ≤1 µg/mL and ≤0.75 µg/mL. Even 600 mg every 8 h and 1,200 mg as a continuous infusion gave a higher target attainment of fAUC24/MIC and a fT>MIC and the target CFR, but those regimens gave Ctrough ≥9 µg/mL rates of 40.7% and 99.6%.ConclusionThe current dosing of 1,200 mg/day might be optimal treatment for infection by VRE isolates with documented MICs ≤1 µg/mL. For treatment of VRE with a MIC of 2 µg/mL or to achieve the target CFR, the use of linezolid with other antibiotic combinations might help achieve the PK/PD target, provide better clinical outcome, and prevent resistance.

Efficacy and safety of tigecycline for complicated urinary tract infection: a systematic review.

BackgroundFacing the global threat of emerging resistance to antibiotics, tigecycline, a novel glycylcycline antibiotic, is developed to against multidrug-resistant pathogens, but not recommended for the treatment of complicated urinary tract infection (cUTI). We performed a summary of the literatures to characterize and evaluate the efficacy and safety of tigecycline in patients with cUTI.MethodsWe searched PubMed, EMBASE, Cochrane and Clinical Trials using appropriate syntax to retrieve potential articles up to Jan 2020. General information, pathogen, medication regimen, comorbidities of patients from eligible literatures were recorded. Univariate logistic regression analysis was used to detect the potential factors associated with clinical cure.ResultsNineteen articles comprising 31 cases were included. The subpopulation with transplantation (25.8% of the patients) was the most common comorbidity, and cUTIs were mainly caused by Klebsiella pneumoniae (K. pneumoniae) (48.28%) in our research. Tigecycline 100 mg per day as monotherapy was most common. Clinical cure was reported as majority (77.4%), and microbiological eradication cases accounted for the most (65.2%) among the clinical cure cases. Univariate analysis showed that K. pneumoniae caused cUTI and tigecycline as a single treatment have significant meaning to clinical outcomes (P=0.044 and P=0.034, respectively).ConclusionsClinical and microbiological outcomes of tigecycline treatment revealed high rate of successful response. Tigecycline monotherapy may have a role in the treatment of cUTI except that caused by the pathogen K. pneumoniae. Further randomized controlled trials was still needed to evaluate tigecycline monotherapy for cUTI.

1578. Treatments for complicated urinary tract infections (cUTI) caused by multidrug resistant (MDR) Gram-negative (GN) pathogens- a systematic review and network meta-analysis (NMA)

BackgroundAntimicrobial resistance is a major and growing threat to global public health. Cefiderocol (CFDC) is a new siderophore-cephalosporin with a wide activity spectrum covering all aerobic GN pathogens including all WHO critical priority pathogens, that was recently approved by FDA for the treatment of GN cUTI in susceptible organisms. We aim to understand the relative efficacy and safety of current treatment options for cUTI caused by MDR GN pathogens.MethodsWe conducted a systematic review to identify all relevant trials that investigated the efficacy and safety of antimicrobial regimens, for the treatment of GN pathogens in cUTI. Outcomes of interest included clinical cure and microbiological eradication (ME) at time of cure (TOC) and sustained follow up (SFU), and safety. Evidence networks were constructed using data for outcomes of interest and analyses were conducted in a frequentist framework using NMA methods outlined by the NICE decision support unit using the netmeta package in R.ResultsA total of 5 studies, 6 interventions and 2,349 randomised patients were included in the final analysis. Interventions included CFDC, imipenem-cilastatin (IPM-CIL), ceftazidime-avibactam (CAZ/AVI), doripenem (DOR), levofloxacin and ceftolozane-tazobactam (CEF/TAZ). Trials included predominantly Enterobacterales, and Pseudomonas aeruginosa and very few Acinetobacter baumannii. The patient population presented some clinical differences across trials, which were not adjusted for the NMA. Overall, there were numerical differences (especially in endpoints at SFU favouring CFDC), but all treatments showed similar efficacy and safety, with exception of higher ME rate at TOC for CFDC vs IPM, Table 1, also observed at SFU, consistent with the data from the individual clinical trial.Table 1- Results for microbiological eradicationTable 1- Results for microbiological eradication ConclusionThis NMA, showed superiority of CFDC vs IPM-CIL in ME at TOC and SFU and similar efficacy and safety vs all other comparators, with numeric differences favouring CFDC for outcomes at SFU. These traditional methodologies for NMA, are only valid within a similar pathogens pool and population across the trials, and may not reflect the full value of breadth of coverage that new therapeutic options bring for the treatment of MDR GN pathogens.DisclosuresTim Reason, PhD, Shionogi (Consultant) Karan Gill, MSc, Shionogi BV (Employee) Christopher Longshaw, PhD, Shionogi B.V. (Employee) Rachael McCool, PhD, York Health Economics Consortium (Employee, YHEC was commissioned by Shionogi to conduct the systematic review) Katy Wilson, PhD, York Health Economics Consortium (Employee, Shionogi commissioned YHEC to conduct the systematic review) Sara Lopes, PharmD, Shionogi BV (Employee)

1316. Pharmacokinetic/Pharmacodynamic Analyses of Cefiderocol in Critically Ill Patients

BackgroundCefiderocol (CFDC), a novel siderophore cephalosporin, has demonstrated potent antibacterial activity against a wide range of Gram-negative bacteria including carbapenem-resistant strains. We aimed to evaluate relationships between drug exposure and outcomes in critically ill patients.MethodsSparse pharmacokinetic (PK) samples at steady state from critically ill patients with pneumonia, bloodstream infection/sepsis, or complicated urinary tract infection receiving CFDC in two Phase 3 studies were analyzed. Percent time of dosing interval of free drug concentration exceeding the minimum inhibitory concentration (MIC) in plasma and epithelial lining fluid (ELF) (%fT>MIC and %fT>MIC,ELF, respectively) were determined for 60 (CREDIBLE-CR; NCT02714595) and 97 patients (APEKS-NP; NCT03032380), using a 3-compartment population PK model. The %fT>MIC,ELF was calculated for 125 pneumonia patients based on an intrapulmonary PK model. Relationships between %fT>MIC, %fT>MIC,ELF and clinical and microbiological outcomes at test of cure (TOC), or mortality at Day 28 were assessed.ResultsThe median (90th percentile) MICs of Gram-negative pathogens in the PK/pharmacodynamic (PD) analyses were 0.25 (4) µg/mL (CREDIBLE-CR) and 0.25 (2) µg/mL (APEKS-NP), respectively. Individual plasma %fT>MIC was 100% in ≥95% of patients in each study, and estimated %fT>MIC,ELF was 100% in 89.3% (25/28 pneumonia patients; CREDIBLE-CR) and 97.9% (95/97 pneumonia patients; APEKS-NP). Clinical cure rates and survival rates in patients with 100% fT>MIC or %fT>MIC,ELF were similar between the two studies (Table). No PK/PD relationships between %fT>MIC, %fT>MIC,ELF and clinical cure, microbiological eradication, or survival were identified in either study because high %fT>MIC or %fT>MIC,ELF was achieved in all patients.Table. Clinical cure and survival rates in patients with 100% fT>MIC or %fT>MIC,ELF in CREDIBLE-CR and APEKS-NP studies ConclusionPK/PD relationship was not identified between CFDC plasma or ELF exposure and clinical or microbiological outcomes, or mortality as high %fT>MIC and %fT>MIC,ELF were achieved, suggesting the recommended dosing regimen of 2 g q8h or renally adjusted dosage (including augmented renal clearance), infused over 3 hours, provides sufficient exposure to CFDC in critically ill patients.DisclosuresTakayuki Katsube, PhD, Shionogi & Co., Ltd. (Employee) Nao Kawaguchi, BPharm, Shionogi & Co., Ltd. (Employee) Yuko Matsunaga, MD, Shionogi Inc. (Employee) Mari Ariyasu, BPharm, Shionogi & Co., Ltd. (Employee) Tsutae Den Nagata, MD, Shionogi & Co., Ltd. (Employee) Simon Portsmouth, MD, Shionogi Inc. (Employee) David Paterson, Accelerate (Speaker’s Bureau)BioMerieux (Speaker’s Bureau)BioMerieux (Advisor or Review Panel member)Entasis (Advisor or Review Panel member)Merck (Advisor or Review Panel member)Merck (Grant/Research Support)Merck (Speaker’s Bureau)Pfizer (Speaker’s Bureau)Shionogi & Co., Ltd. (Grant/Research Support)VenatoRx (Advisor or Review Panel member) Michael J. Satlin, MD, MS, Achaogen (Consultant)Allergan (Grant/Research Support)Merck (Grant/Research Support)Shionogi Inc. (Consultant) Roger Echols, MD, Shionogi Inc. (Consultant) Toshihiro Wajima, PhD, Shionogi & Co., Ltd. (Employee)

1271. Efficacy and Safety of Cefiderocol and Best Available Therapy in Patients with Serious Infections Caused by Carbapenem-Resistant Gram-Negative Infections: Results of the Pathogen-Focused Phase 3 CREDIBLE-CR Study

BackgroundThe CREDIBLE-CR study assessed the efficacy and safety of cefiderocol (CFDC), a novel siderophore cephalosporin, in the treatment of serious infections due to carbapenem-resistant (CR) Gram-negative (GN) bacteria.MethodsCREDIBLE-CR was an open-label, prospective, randomized 2:1, Phase 3 study (NCT02714595) in patients with nosocomial pneumonia (NP), bloodstream infections/sepsis (BSI/Sepsis), or complicated urinary tract infections (cUTI) with evidence of CR GN pathogens. Adults received intravenous CFDC 2 g, q8h, 3-h infusion or best available therapy (BAT; up to 3 drugs) for 7–14 days (extendable to 21 days). The primary endpoint at test of cure in the CR microbiological intent-to-treat (CR-MITT) population was clinical cure (NP, BSI/Sepsis) or microbiological eradication (cUTI). Secondary endpoints were clinical and microbiological outcomes, all-cause mortality (ACM) and safety. Only descriptive statistics were pre-specified.ResultsA total of 101 patients received CFDC and 49 received BAT (CR-MITT: CFDC n=80, BAT n=38): 50% had pneumonia, 31.4% BSI/Sepsis, and 18.6% cUTI (Table 1). Most frequent CR pathogens were Acinetobacter baumannii (45.8%), Klebsiella pneumoniae (37.3%), and Pseudomonas aeruginosa (23.7%). CFDC monotherapy was given to 83% of patients, while BAT monotherapy to 29% of patients. Primary outcome in the CFDC and BAT arms was achieved in 50.0% and 52.6% in NP, 43.5% and 42.9% in BSI/Sepsis, and 52.9% and 20.0% in cUTI patients (Figure). CFDC was highly efficacious vs CREs and NDM-producing pathogens. Day 28 ACM was 24.8% (25/101) with CFDC and 18.4% (9/49) with BAT. Rescue therapy was given more frequently in the BAT than CFDC arm. Mortality results by pathogen showed an imbalance in Acinetobacter spp. infections (Table 2) with a higher rate in the CFDC arm than BAT arm. ICU and shock at randomization were more frequent in the CFDC arm than in the BAT arm in Acinetobacter spp. infections (Table 2). No safety concerns related to CFDC emerged.Table 1. Baseline demographics and characteristics (CR-MITT population) Figure. CREDIBLE-CR study primary efficacy endpoints and secondary outcomes at test-of-cure visit in CR-MITT population. Table 2. All-cause mortality by baseline pathogen inpatients with or without Acinetobacter spp. infection (safety population) ConclusionEfficacy of CFDC was demonstrated in this descriptive pathogen-focused study, including CREs, metallo-NDM producers and CR non-fermenters. Baseline imbalances of ICU and shock in the subset of infections with Acinetobacter spp. may have contributed to the mortality difference between CFDC and BAT arms.DisclosuresMatteo Bassetti, MD, Shionogi Inc. (Advisor or Review Panel member) Roger Echols, MD, Shionogi Inc. (Consultant) Yuko Matsunaga, MD, Shionogi Inc. (Employee) Simon Portsmouth, MD, Shionogi Inc. (Employee) Mari Ariyasu, BPharm, Shionogi & Co., Ltd. (Employee) Kiichiro Toyoizumi, PhD, Shionogi & Co., Ltd. (Employee) Tsutae Den Nagata, MD, Shionogi & Co., Ltd. (Employee)

1619. Meta-analysis of Randomized Control Trials Evaluating New Beta-Lactamase Combination Antibiotics

BackgroundCeftolozane/ Tazobactam (C/T), Ceftazidime/ Avibactam (C/A), Meropenem/ Vaborbactam (M/V) and Imipenem/ Relebactam (I/R) are new combination beta-lactam/ beta-lactamase inhibitor antibiotics primarily used to treat multidrug-resistant (MDR) Gram-negative infections. This study synthesized outcomes of comparative observational studies and randomized control trials (RCTs) that evaluated clinical success of these antibiotics compared to other therapies.MethodsPubMed, EMBASE, and Google Scholar were searched from January 1st, 2013 through October 1st, 2019 for comparative observational studies and RCTs of C/T, C/A, M/V and I/R in patients with pneumonia, complicated intra-abdominal and urinary tract infections. Study and patient demographics were collected along with clinical and microbiological success rates. Meta-regression analysis was used to determine the pooled effectiveness of C/T, C/A, M/V, and I/R. Heterogeneity and publication bias were assessed via I2 values and funnel plots, respectively.ResultsLiterature search returned 1,645 results. After exclusion criteria, 21 publications representing 6,246 patients were retained: 16 RCTs (8 C/A, 3 C/T, 3 I/R, 2 M/V) and 5 comparative observational studies (3 C/A, 2 C/T). Pooled risk ratios for clinical success showed that all four antibiotics were non-inferior to comparator antibiotics (0.99 (95% CI (0.97-1.01)). Eleven of the sixteen RCTs evaluated microbiological success; pooled risk ratio was 1.08 (95% CI 1.04-1.13), indicating that older therapies were more successful at microbiological eradication than newer antibiotics. Only 6 of the included studies (3 RCTs and 2 observational studies) focused on patients with MDR infections. Limiting the analysis to MDR RCTs did not change the overall conclusions.ConclusionAlthough older therapies had slightly higher microbiologic clearance, pooled clinical success rates for C/A, C/T, M/V, and I/R were non-inferior to older therapies, including in studies focused on patients with MDR infections. Additional studies are needed to further evaluate these drugs’ effectiveness for treatment of MDR infections.Disclosures All Authors: No reported disclosures

LB-4. Cefepime-Enmetazobactam Demonstrates Superiority to Piperacillin-Tazobactam in a Subgroup of Patients with Complicated Urinary Tract Infections/Acute Pyelonephritis Caused by Extended Spectrum β-Lactamase-Producing Enterobacterales

BackgroundThere is a critical need for carbapenem-sparing therapies for infections caused by extended spectrum β-lactamase (ESBL)-producing Enterobacterales. Enmetazobactam is a novel ESBL inhibitor combined with the cephalosporin cefepime. Treatment outcomes of cefepime-enmetazobactam (FPE) versus piperacillin-tazobactam (PTZ) were assessed in subgroups of patients with ESBL-producing baseline uropathogens (ESBL-BU) in the ALLIUM phase 3 trial of complicated urinary tract infections (cUTI)/acute pyelonephritis (AP).Methods1034 cUTI/AP patients randomized 1:1 in a double-blind, multicenter trial received either 2 g cefepime/0.5 g enmetazobactam or 4 g piperacillin/0.5 g tazobactam q8h by 2h infusion for 7 to 14 days. Enterobacterales with MICs ≥1 µg/ml to ceftazidime, ceftriaxone, cefepime, meropenem, or FPE were genotyped for β-lactamases. In addition to the primary analysis (by stratified Newcombe) of overall success (combination of clinical cure and microbiological eradication) in the microbiological modified intent to treat population (mMITT) at test-of-cure (TOC), subgroup analyses were performed on patients with ESBL-BU non-resistant to FPE (MIC≤8 µg/ml) and PTZ (MIC≤64 µg/ml) and a subgroup (mMITT+R) that also included the ESBL-BU resistant to either agent (FPE MIC ≥16 µg/ml or PTZ MIC≥128 µg/ml).ResultsIn mMITT, FPE (273/345, 79.1%) demonstrated superiority to PTZ (196/333, 58.9%) at TOC (difference, 21.2%; 95% CI: 14.3, 27.9). The prevalence rate of ESBL-BU was 20.9% (142/678), with 99.3% (141/142) expressing a CTX-M-type (-1, -3, -9, -14, -15, -27, -55, -91, -169) and 3.5% (5/142) co-expressing AmpC (CMY-2/-59). FPE (56/76, 73.7%) demonstrated superiority to PTZ (34/66, 51.5%) in this subgroup at TOC (difference 30.2%; 95% CI: 13.4, 45.1; Table). In mMITT+R, the ESBL-BU prevalence rate was 22.3% (172/771), with 6.4% (11/172) co-expressing AmpC (CMY-2/-4/-59/-99), 4.7% (8/172) co-expressing a metallo-β-lactamase (VIM-1, NDM-1), and 2.3% (4/172) co-expressing OXA-48. Superiority of FPE (67/91, 73.6%) compared to PTZ (41/81, 50.6%) was also observed at TOC despite inclusion of ESBL-BU resistant to either agent (difference 30.0%; 95% CI: 14.9, 43.3).Table ConclusionFPE may represent a new empiric carbapenem-sparing option in settings where ESBL are endemic.Disclosures Adam Belley, PHD, Allecra Therapeutics SAS (Consultant) Philip Barth, MD, Allecra Therapeutics SAS (Consultant) Shikhar Kashyap, n/a, Allecra Therapeutics SAS (Consultant)Allecra Therapeutics SAS (Consultant) Omar Lahlou, PhD, Allecra Therapeutics SAS (Employee) Paola Motta, PhD, Allecra Therapeutics SAS (Employee) Patrick Velicitat, MD, Allecra Therapeutics SAS (Employee)

LB-3. Oral Tebipenem Pivoxil Hydrobromide is Non-inferior to IV Ertapenem in Complicated Urinary Tract Infection (cUTI) and Acute Pyelonephritis (AP) – Results from the Pivotal ADAPT-PO Study

BackgroundTebipenem pivoxil hydrobromide (TBP-PI-HBr) is an orally bioavailable prodrug that is rapidly converted in plasma to the carbapenem, tebipenem. Tebipenem has in vitro activity against select multidrug-resistant Gram-negative pathogens, including fluoroquinolone-resistant and extended-spectrum ß-lactamase (ESBL)-producing Enterobacterales. TBP-PI-HBr is being developed in the United States as the first oral carbapenem for treatment of cUTI and AP.MethodsADAPT-PO was a global, double-blind, Phase 3 study to evaluate the efficacy and safety of oral TBP-PI-HBr vs. IV ertapenem in hospitalized adult patients with cUTI or AP. The primary endpoint was overall response (composite clinical cure and microbiologic eradication) at the test-of-cure (TOC) visit (Day 19 ± 2) in the micro-ITT population. Patients (N=1372) were randomized 1:1 to receive TBP-PI-HBr 600 mg PO q8h plus placebo IV q24h or ertapenem 1 g IV q24h plus oral placebo q8h for 7–10 days (or up to 14 days in patients with bacteremia).ResultsOral TBP-PI-HBr met the primary objective of non-inferiority compared with IV ertapenem with an overall response rate of 58.8% (264/449) vs. 61.6% (258/419), respectively (treatment difference -3.3%; 95% CI: -9.7, 3.2; -12.5% NI margin). Clinical cure rates at TOC were > 93% in both treatment groups. Microbiological response rates for target uropathogens were comparable across treatment groups.TBP-PI-HBr was well tolerated. Treatment-emergent adverse events (TEAEs) were observed in 25.7% TBP-PI-HBr and 25.6% ertapenem patients. Most TEAEs were mild; premature discontinuation of study drug was uncommon (< 1%). The most frequent TEAEs were diarrhea (5.0%) and headache (3.8%). No C. difficile-associated TEAEs were observed in the TBP-PI-HBr group; 3 cases occurred in the ertapenem group. Serious adverse events were infrequent (1.3% vs. 1.7%), with no deaths.ConclusionResults from this pivotal Phase 3 study provide the first head-to-head demonstration of non-inferiority of an oral (TBP-PI-HBr) antibacterial agent to an IV (ertapenem) agent in patients with cUTI and AP, with a comparable tolerability profile. If approved in the U.S., TBP-PI-HBr would provide a new oral therapeutic option — and the first oral carbapenem — for patients with serious Gram-negative infections.Disclosures Lori A. Muir, n/a, Spero Therapeutics (Employee)Spero Therapeutics (Employee, Shareholder) Susannah M. Walpole, PhD, Spero Therapeutics, Inc. (Employee) Hanna Kwak, n/a, Spero Therapeutics (Employee) Anne-Marie Phelan, n/a, Spero Therapeutics (Employee)Spero Therapeutics (Employee, Shareholder) Gary E. Moore, BS/MS, Spero Therapeutics (Consultant) Akash Jain, PhD, Spero Therapeutics (Employee) Tim Keutzer, BA, Spero Therapeutics, Inc (Employee) Aaron Dane, MSc, Da Volterra (Consultant)Spero theraputics (Consultant) Aaron Dane, MSc, Spero theraputics (Consultant) David Melnick, MD, Spero Therapeutics (Employee)Spero Therapeutics (Employee) Angela K. Talley, MD, Spero Therapeutics (Employee, Shareholder)

1285. Outcomes in Patients with Gram-Negative Bacteremia from Phase 2 and Phase 3 Clinical Trials of Cefiderocol, a Novel Siderophore Cephalosporin

BackgroundCefiderocol (CFDC) is the first siderophore cephalosporin approved (US and EU) for a broad range of infections caused by Gram-negative (GN) bacteria, including carbapenem-resistant Enterobacterales (ENT) and non-fermenters (NFs). Bacteremia is a serious manifestation of GN infection and understanding how well an antibiotic works to clear the bacteremia is an important part of drug evaluation.MethodsAll completed clinical studies for CFDC development were used to identify patients with GN bacteremia. Information collected included the primary infection site, species identification and antibiotic susceptibility, post randomization blood cultures and clinical and bacteremia outcome. In patients with missing data (blood cultures) clinical response of cure was used to impute microbiological eradication. Indeterminate responses resulted from a combination of missing data and clinical failure, including death prior to test of cure (TOC).ResultsThree clinical studies randomized 900 patients (CFDC 552; comparators 348) of whom 84 (CFDC 52; comparators 32) had GN bacteremia at baseline (Table). Bacteremia rate by study was CREDIBLE-CR 25.3%, APEKS-cUTI 6.2%, APEKS-NP 6.0%. Escherichia coli (29), Klebsiella pneumoniae (23) and Acinetobacter spp (21) were most frequent species. Sources included urinary tract (31), lung (22), unknown (10), IV line (8), intraabdominal (6), or other (7). Persistence of bacteremia at TOC was seen in 2/52 (3.8%) CFDC and 2/32 (6.2%) control patients (Table), usually due to lack of source control. Clinical outcomes varied by study and infection source and were often confounded (indeterminate response). Eradication in patients with ENT at TOC was determined for 27/39 (69%) for CFDC and 16/23 (70%) for controls, and for 9/16 (56%) for CFDC and 10/11 (91%) for controls in patients with NFs, respectively.Table. Clinical and bacteremia microbiological outcomes per patient at TOC. ConclusionPost-treatment negative blood cultures were inconsistently collected, especially in APEKS-NP and -cUTI, however, negative blood cultures on therapy without recurrence was seen in 96% of CFDC patients with sufficient information. A dedicated clinical trial in GN bacteremia (GAME CHANGER; NCT03869437) is ongoing and will better delineate microbiological outcomes.Disclosures David Paterson, Accelerate (Speaker’s Bureau)BioMerieux (Speaker’s Bureau)BioMerieux (Advisor or Review Panel member)Entasis (Advisor or Review Panel member)Merck (Advisor or Review Panel member)Merck (Grant/Research Support)Merck (Speaker’s Bureau)Pfizer (Speaker’s Bureau)Shionogi & Co., Ltd. (Grant/Research Support)VenatoRx (Advisor or Review Panel member) Masahiro Kinoshita, MPharm, Shionogi & Co., Ltd. (Employee) Kiichiro Toyoizumi, PhD, Shionogi & Co., Ltd. (Employee) Yuko Matsunaga, MD, Shionogi Inc. (Employee) Roger Echols, MD, Shionogi Inc. (Consultant)

1257. A phase II Prospective Randomized Study to Assess Ceftolozane-Tazobactam in the Management of Febrile Neutropenia in Patients with Hematological Malignancies

BackgroundDespite the implementation of successful antibiotic stewardship programs, antibiotic resistance continue to emerge particularly against gram-negative bacteria. With the increase use of antibiotics in high risk patients with hematological malignancies, the empiric therapy with standard antibiotic could be inappropriate. New antibiotics may be useful to cover potential resistant pathogens. We evaluated the role of a new cephalosporin /β-lactamase inhibitor ceftolozane-tazobactam (C/T) in comparison to standard of care (SOC) antibiotics in the empiric treatment of febrile neutropenic cancer patients with hematological malignancies.MethodsWe conducted a prospective randomized open label comparative study to evaluate the safety and efficacy of C/T vs SOC antibiotics consisting of cefepime, piperacillin-tazobactam or meropenem when used in combination with gram positive antibacterial agents. Between May 2018 and March 2020, we enrolled 88 febrile neutropenic patients with hematological malignancies who presented to our emergency center. Patients received at least 72 hours of intravenous study drugs and were followed through end of IV therapy and for up to 42 days.ResultsA total of 88 patients were analyzed of whom 42 received C/T and 46 SOC antimicrobial agents. The rate of documented bloodstream infections was similar in both groups (CE-TZ 21% vs SOC 26%, p=0.61). Favorable clinical response at end of IV therapy was significantly better in the C/T arm compared to SOC therapy (88% vs 72%, p=0.039), at test of cure (21 days), and last follow-up (42 days). In patients with documented infections, the rate of microbiological eradication was similar in both groups. Drug-related adverse events that led to drug discontinuation was similar in both groups (7%). Similarly overall mortality was similar in both groups.ConclusionThe empiric use of C/T to cover gram negative organisms in high risk febrile neutropenic patients with hematological malignancies is safe and associated with better clinical outcome than SOC antimicrobial agents. The emergence of resistant pathogens should be further evaluated.Disclosures Issam I. Raad, MD, Citius (Other Financial or Material Support, Ownership interest)Cook Medical (Grant/Research Support)Inventive Protocol (Other Financial or Material Support, Ownership interest)Novel Anti-Infective Technologies (Shareholder, Other Financial or Material Support, Ownership interest)

1618. Meropenem-vaborbactam vs standard of care for multidrug resistant carbapenem-resistant Enterobacteriaceae

BackgroundAntimicrobial resistance to gram negative organisms is an increasing issue worldwide, particularly with regards to extended-spectrum B-lactamase (ESBL) and carbapenem-resistant Enterobacteriaeceae (CRE) producing organisms. Meropenem/vaborbactam (M-V) is an approved antimicrobial for treatment of some CRE infections. This study compares the outcomes of patients with CRE who were treated with M-V to standard of care (SoC) therapy.Table 1. Results MethodsA retrospective chart analysis was performed which analyzed 25 patients in the M-V group and 25 patients in the SoC group at an 800-bed tertiary care hospital in Southeast Michigan. Patients were matched by type of infection. Variables included basic demographics, infection source, bacterial species, as well as 30-day readmission, ICU admission, and creatinine pre- and post-treatment. The primary outcome of interest was 30-day mortality and clinical outcome (cure/improved/failure). Secondary outcomes included microbiological outcome (eradication/presumed eradication/persistence/presumed persistence) and acute kidney injury (AKI) on therapy. The data was analyzed using SPSS version 14.0.ResultsThe most commonly used antibiotics in the SoC group were ceftazidime-avibactam (64%) and cefepime (32%). In both groups, the most common infection source was intra-abdominal (56%). The most commonly isolated pathogen in each group was Klebsiella pneumoniae (52% in M-V and 48% in SoC). Mortality and re-admission at 30 days did not differ statistically between the two groups. However, patients who received M-V were found to be more likely to achieve clinical cure, although this did not achieve statistical significance. Patients who were treated with SoC were significantly more likely to achieve an improved clinical outcome and presumed microbiological eradication (p=0.001 and 0.01 respectively). Of the 50 patients, only 26 patients (52%) met criteria to analyze for AKI. Patients who received M-V were more likely to have AKI (16% compared to 8%) but this did not reach statistical significance.ConclusionM-V is an important option for care of patients with infections due to MDR gram-negative bacteria. However, further studies are warranted to determine whether its use is associated with reduced mortality and improved clinical outcomes.DisclosuresMarcus Zervos, MD, Melinta Therapeutics (Grant/Research Support)

Tigecycline therapy in pediatric patients with multidrug resistant bacteremia

IntroductionMultidrug resistance among bacteria increases the need for new therapeutic options. Tigecycline is one candidate drug, due to property of a wider anti-bacterial spectrum to multi-drug resistant (MDR) pathogens. However, it has still not been approved for use in pediatric patients. MethodsIn this study the effectiveness and safety of tigecycline in children was assessed retrospectively. ResultsA total of 36 pediatric patients, received tigecycline therapy with a median of 13 days (2–32 days). Tigecycline was used as a combination therapy in all cases. Microbiological eradication was achieved in 27 patients (75%) and clinical response was observed in 30 patients (83%). There were six cases (17%) of relapse. ConclusionOur findings suggest that tigecycline may be an option for children with severe infections due to multidrug resistant bacteria.

Dual-route-administration versus single-route-administration of polymyxin B in VAP caused by MDR Klebsiella pneumoniae: An observational study

Background: Ventilator-associated pneumonia (VAP) in critically ill patients of intensive care units (ICUs) is associated with high rate of mortality and morbidity, and VAP caused by multidrug-resistant (MDR) gram-negative bacteria (GNB) such as, Klebsiella pneumoniae (KP) is a life threatening infectious event. In MDR KP-associated VAP (MDR-KP-VAP) infections, KP is generally found only sensitive to few last-line potential antibiotics including polymyxin B. Intravenous polymyxin B in MDR-KP-VAP treatment is practiced worldwide but, nebulized polymyxin B is a direct-to-infection site therapy. The objective of this study was to evaluate the clinical outcomes of dual-route (intravenous and nebulization) administration of polymyxin B versus single-route (intravenous) administration in MDR-KP-VAP treatment. Methods and materials: This observational study was conducted on 121 mechanically ventilated patients with MDR-KP-VAP infection where KP was resistant to penicillins, cephalosporins, aminoglycosides and fluoroquinolones but, only sensitive to polymyxin B. Polymyxin B intravenously and nebulization was administered to 64 patients in one group (PIVNL group) whereas 57 patients of another group (PIV group) found only intravenous polymyxin B for MDR-KP-VAP treatment. Intravenous levofloxacin was coexisted with polymyxin B therapies in both groups’ patients. Group-wise therapeutic outcomes were compared prospectively. Results: The microbiological eradication rate was higher (92.1%, n = 64) in PIVNL group than the PIV group (70.1%, n = 57) (p value = 0.002). PIV group showed higher secondary bacterial infection rate (19.2%, n = 57) than PIVNL group (6.2%, n = 64) (p value = 0.030), and 30-day mortality rate was also found higher in PIV group patients (15.7%, n = 57) than PIVNL group (7.8%, n = 64) (p value = 0.171). In terms of adverse drug reaction (ADR), polymyxin B-induced bronchospasm events were found (4, 6.2%, n = 64) in PIVNL group whereas nil in PIV group, and nephrotoxicity events were similarly happened in PIVNL (3, 4.6%, n = 64) and PIV group (3, 5.2%, n = 57). Conclusion: The emergence of MDR gram-negative bacterial infections in mechanically ventilated patients is an appalling issue worldwide and to treat with few last-line antibiotics is a do-or-die challenge at this moment. In this study, simultaneous intravenous administration of polymyxin B with its nebulization in MDR-KP-associated VAP patients exhibited better clinical success than with intravenous polymyxin B alone.

Efficacy and Tolerability of Eravacycline in Bacteremic Patients with Complicated Intra-Abdominal Infection: A Pooled Analysis from the IGNITE1 and IGNITE4 Studies.

Background: Eravacycline is a novel, fully synthetic fluorocycline antibiotic that was evaluated for the treatment of complicated intra-abdominal infections (cIAI) in two phase 3 clinical trials. The objective of this analysis was to evaluate the clinical cure and microbiologic response at the test-of-cure (TOC) visit and the safety of eravacycline in patients with cIAI and baseline bacteremia who received eravacycline versus comparators. Patients and Methods: Pooled data of patients with bacteremia from the Investigating Gram-Negative Infections Treated with Eravacycline (IGNITE) 1 and IGNITE4 studies were analyzed. All patients were randomly assigned in a one-to-one ratio to receive eravacycline 1 mg/kg intravenously every 12 hours, ertapenem 1 g intravensouly every 24 hours (IGNITE1), or meropenem 1 g intravenously every eight hours (IGNITE4) for four to 14 days. Blood and intra-abdominal samples were collected from all patients at baseline. Clinical outcome and microbiologic eradiation at the TOC visit (28 days after randomization) and safety in the microbiologic-intent-to-treat population (micro-ITT) were assessed. Results: Of 415 patients treated with eravacycline and 431 treated with carbapenem comparators, concurrent bacteremia was identified in 32 (7.7%) and 31 (7.2%) patients, respectively. Demographic and baseline characteristics were similar among treatment groups. In the micro-ITT population, the pooled clinical response at the TOC visit for eravacycline was 28 of 32 (87.5%) and was 24 of 31 (77.0%) for comparators among the subgroup with baseline bacteremia (treatment difference 5.9; 95% confidence interval [CI], -6.5 to 17.4). At TOC, microbiologic eradication of pathogens isolated from blood specimens occurred for 34 of 35 (97.1%) pathogens with eravacycline and 35 of 36 (97.2%) pathogens with comparators. The incidence of adverse events was comparable between treated groups and similar to that observed in the non-bacteremic population. Conclusion: Eravacycline demonstrated a similar clinical outcome and microbiologic eradication rate as comparator carbapenems in patients with cIAI and associated secondary bacteremia. Future clinical trials of cIAI should report outcomes of this important clinical cohort (cIAI with concurrent bacteremia) given their high risk for adverse outcomes.

Efficacy and safety of colistin for the treatment of infections caused by multidrug-resistant gram-negative bacilli

BackgroundThe efficacy and safety of colistin for the treatment of infections caused by multidrug-resistant gram-negative bacilli have been poorly investigated in Japanese patients. This study was performed to investigate the efficacy and safety of colistin in Japanese patients by analyzing a considerable number of cases. Furthermore, we evaluated the relationship between the plasma concentration and efficacy and safety of colistin in some cases. MethodsA retrospective cohort study was conducted at Hokkaido University Hospital, analyzing patients treated with colistin (colistimethate sodium) during the period from January 2007 to December 2019. ResultsOverall, 42 cases were enrolled. Favorable clinical response was observed in 25 cases (59.5%), with an all-cause 30-day mortality of 33.3% (14/42 cases). Microbiological eradication was achieved in 18 cases (42.9%). Nephrotoxicity was observed in 20 cases (47.6%) and was mild and reversible in all cases. Plasma trough concentrations of colistin determined in nine patients correlated with changes in serum creatinine concentration (⊿) and creatinine clearance (%). The cutoff value of colistin trough concentration for nephrotoxicity was 2.02 μg/mL. ConclusionOur results showed approximately 60% clinical efficacy of colistin therapy against infections caused by multidrug-resistant gram-negative bacilli in the patients. Further studies with larger populations are needed to elucidate the efficacy and safety of colistin in Japanese patients.

Cefiderocol for compassionate use in the treatment of complicated infections caused by extensively and pan-resistant Acinetobacter baumannii

ObjectiveThis study presents real-life experience with cefiderocol used on a compassionate basis for treatment of three patients with severe infections caused by extensively/pan-drug resistant (XDR/PDR) Acinetobacter baumannii (Ab). MethodsSerum bactericidal activity was determined and considered as a surrogate of cefiderocol susceptibility. ResultsClinical improvement and microbiological eradication of A. baumannii were observed in all three patients, who were affected by extremely complex conditions either for type of infection, adverse effect or resistance profile of A. baumannii. ConclusionCefiderocol for XDR/PDR-Ab infections might be reconsidered, especially in light of the recent disappointing results of the CREDIBLE-CR study.

Efficacy and safety of cefiderocol or best available therapy for the treatment of serious infections caused by carbapenem-resistant Gram-negative bacteria (CREDIBLE-CR): a randomised, open-label, multicentre, pathogen-focused, descriptive, phase 3 trial

New antibiotics are needed for the treatment of patients with life-threatening carbapenem-resistant Gram-negative infections. We assessed the efficacy and safety of cefiderocol versus best available therapy in adults with serious carbapenem-resistant Gram-negative infections. We did a randomised, open-label, multicentre, parallel-group, pathogen-focused, descriptive, phase 3 study in 95 hospitals in 16 countries in North America, South America, Europe, and Asia. We enrolled patients aged 18 years or older admitted to hospital with nosocomial pneumonia, bloodstream infections or sepsis, or complicated urinary tract infections (UTI), and evidence of a carbapenem-resistant Gram-negative pathogen. Participants were randomly assigned (2:1 by interactive web or voice response system) to receive either a 3-h intravenous infusion of cefiderocol 2 g every 8 h or best available therapy (pre-specified by the investigator before randomisation and comprised of a maximum of three drugs) for 7-14 days. For patients with pneumonia or bloodstream infection or sepsis, cefiderocol treatment could be combined with one adjunctive antibiotic (excluding polymyxins, cephalosporins, and carbapenems). The primary endpoint for patients with nosocomial pneumonia or bloodstream infection or sepsis was clinical cure at test of cure (7 days [plus or minus 2] after the end of treatment) in the carbapenem-resistant microbiological intention-to-treat population (ITT; ie, patients with a confirmed carbapenem-resistant Gram-negative pathogen receiving at least one dose of study drug). For patients with complicated UTI, the primary endpoint was microbiological eradication at test of cure in the carbapenem-resistant microbiological ITT population. Safety was evaluated in the safety population, consisting of all patients who received at least one dose of study drug. Mortality was reported through to the end of study visit (28 days [plus or minus 3] after the end of treatment). Summary statistics, including within-arm 95% CIs calculated using the Clopper-Pearson method, were collected for the primary and safety endpoints. This trial is registered with ClinicalTrials.gov (NCT02714595) and EudraCT (2015-004703-23). Between Sept 7, 2016, and April 22, 2019, we randomly assigned 152 patients to treatment, 101 to cefiderocol, 51 to best available therapy. 150 patients received treatment: 101 cefiderocol (85 [85%] received monotherapy) and 49 best available therapy (30 [61%] received combination therapy). In 118 patients in the carbapenem-resistant microbiological ITT population, the most frequent carbapenem-resistant pathogens were Acinetobacter baumannii (in 54 patients [46%]), Klebsiella pneumoniae (in 39 patients [33%]), and Pseudomonas aeruginosa (in 22 patients [19%]). In the same population, for patients with nosocomial pneumonia, clinical cure was achieved by 20 (50%, 95% CI 33·8-66·2) of 40 patients in the cefiderocol group and ten (53%, 28·9-75·6) of 19 patients in the best available therapy group; for patients with bloodstream infection or sepsis, clinical cure was achieved by ten (43%, 23·2-65·5) of 23 patients in the cefiderocol group and six (43%, 17·7-71·1) of 14 patients in the best available therapy group. For patients with complicated UTIs, microbiological eradication was achieved by nine (53%, 27·8-77·0) of 17 patients in the cefiderocol group and one (20%, 0·5-71·6) of five patients in the best available therapy group. In the safety population, treatment-emergent adverse events were noted for 91% (92 patients of 101) of the cefiderocol group and 96% (47 patients of 49) of the best available therapy group. 34 (34%) of 101 patients receiving cefiderocol and nine (18%) of 49 patients receiving best available therapy died by the end of the study; one of these deaths (in the best available therapy group) was considered to be related to the study drug. Cefiderocol had similar clinical and microbiological efficacy to best available therapy in this heterogeneous patient population with infections caused by carbapenem-resistant Gram-negative bacteria. Numerically more deaths occurred in the cefiderocol group, primarily in the patient subset with Acinetobacter spp infections. Collectively, the findings from this study support cefiderocol as an option for the treatment of carbapenem-resistant infections in patients with limited treatment options. Shionogi.

Efficacy and Safety of Carbapenems vs New Antibiotics for Treatment of Adult Patients With Complicated Urinary Tract Infections: A Systematic Review and Meta-analysis.

This systematic review and meta-analysis evaluated the clinical efficacy and safety of carbapenems for the treatment of complicated urinary tract infections (cUTIs), with the comparators being new antibiotics evaluated for this indication. We searched 13 electronic databases for published randomized controlled trials (RCTs) and completed and/or ongoing trials. The search terms were developed using the Population, Intervention, Comparison, Outcomes, and Study framework. Pooled efficacy estimates of composite cure (clinical success and microbiological eradication) favored the new antibiotic groups, although this was not statistically significant (risk ratio [RR], 0.91; 95% CI, 0.79–1.04). A pooled estimate examining clinical response alone showed no difference between treatment arms (RR, 1.00; 95% CI, 0.96–1.05), however, new antibiotic treatments were superior to carbapenems for microbiological response (RR, 0.85; 95% CI, 0.79–0.91). New antibiotic treatments demonstrated a superior microbiological response compared with carbapenems in clinical trials of cUTI, despite an absence of carbapenem resistance. However, it is noteworthy that the clinical response and safety profile of new antibiotics were not different from those of carbapenems.

Five-day antibiotic treatment for community-acquired bacterial pneumonia: A systematic review and meta-analysis of randomized controlled trials

ObjectivesThis systematic review and meta-analysis of randomized controlled trials (RCTs) investigated whether the clinical efficacy of a 5-day antibiotic course is comparable to that of a longer (≥7 d) course for treating adults with community-acquired bacterial pneumonia (CABP). MethodsThe PubMed, Web of Science, Cochrane Library, Ovid MEDLINE, and Embase. were searched before January 18, 2020. RCTs comparing the efficacy of a 5-day antibiotic course with a longer course (≥7 d) for CABP treatment were included. Primary outcomes included the clinical response, microbiological response, and risk of adverse events (AEs). ResultsIn this meta-analysis, 7 RCTs were included, and the 5-day antibiotic courses group, and a longer course group comprised 1499 and 1522 patients, respectively. The difference in the overall clinical response rates between the 5-day and longer courses (88.3% vs 88.8%, odds ratio [OR], 0.95, 95% confidence interval [CI], 0.70–1.28, I2 = 19%) was nonsignificant. Additionally, the microbiological eradication rates did not differ significantly between the groups, at 94.8% and 95.8% in the 5-day and longer courses groups, respectively (OR, 0.84, 95% CI, 0.38–1.87, I2 = 0%). Finally, all-cause mortality did not differ between the 2 groups (OR, 0.91, 95% CI, 0.31–2.66, I2 = 0%). ConclusionsFive-day treatment and longer antibiotic courses for CABP yield similar clinical and microbiological responses and exhibit similar safety profiles.

Clinical outcomes of continuous vs intermittent meropenem infusion for the treatment of sepsis: A systematic review and meta-analysis.

The antibiotic meropenem is commonly administered to patients with sepsis and septic shock. The aim of this study was to conduct a meta-analysis to evaluate the clinical efficacy and safety of continuous compared to intermittent meropenem infusion for the treatment of sepsis. Electronic databases such as PubMed, EMBASE, Cochrane Library, and China National Knowledge Infrastructure (CNKI) were researched to collect clinical trials comparing continuous and intermittent infusion of meropenem in patients with sepsis. After data extraction and quality assessment of the included studies, Stata v. 12.0 software (Stata Corporation LLC, College Station, USA) was used for a meta-analysis of mortality, clinical cure, microbiological eradication, and safety. Seven studies with a total of 1,191 participants met the inclusion criteria and were included in the meta-analysis. The meta-analysis showed that continuous meropenem infusion was superior to intermittent infusion in terms of mortality (combined risk ratio (RR) = 0.66, 95% confidence interval (95% CI) = 0.46-0.98, p = 0.03), clinical cure rate (combined RR = 1.15, 95% CI = 1.02-1.30, p = 0.026) and microbiological eradication (combined RR = 1.20, 95% CI = 1.01-1.42, p = 0.04), although it may increase the incidence of some adverse events (AEs). Compared with intermittent dosing, administration of meropenem antibiotics through continuous infusion in patients with sepsis is associated with decreased hospital mortality, increased clinical cure rates and greater microbiological eradication. Further high-quality studies should be conducted to confirm our findings.