In vitro activity of eravacycline against 2213 Gram-negative and 2424 Gram-positive bacterial pathogens isolated in Canadian hospital laboratories: CANWARD surveillance study 2014-2015

Treatment of Infections by OXA-48-Producing Enterobacteriaceae

Carbapenemase-producing Enterobacteriaceae (CPE) contribute significantly to the global public health threat of antimicrobial resistance. OXA-48 and its variants are unique carbapenemases with low-level hydrolytic activity toward carbapenems but no intrinsic activity against expanded-spectrum cephalosporins. bla _OXA-48 is typically located on a plasmid but may also be integrated chromosomally, and this gene has progressively disseminated throughout Europe and the Middle East. Despite the inability of OXA-48-like carbapenemases to hydrolyze expanded-spectrum cephalosporins, pooled isolates demonstrate high variable resistance to ceftazidime and cefepime, likely representing high rates of extended-spectrum beta-lactamase (ESBL) coproduction. In vitro data from pooled studies suggest that avibactam is the most potent beta-lactamase inhibitor when combined with ceftazidime, cefepime, aztreonam, meropenem, or imipenem. Resistance to novel avibactam combinations such as imipenem-avibactam or aztreonam-avibactam has not yet been reported in OXA-48 producers, although only a few clinical isolates have been tested. Although combination therapy is thought to improve the chances of clinical cure and survival in CPE infection, successful outcomes were seen in ∼70% of patients with infections caused by OXA-48-producing Enterobacteriaceae treated with ceftazidime-avibactam monotherapy. A carbapenem in combination with either amikacin or colistin has achieved treatment success in a few case reports. Uncertainty remains regarding the best treatment options and strategies for managing these infections. Newly available antibiotics such as ceftazidime-avibactam show promise; however, recent reports of resistance are concerning. Newer choices of antimicrobial agents will likely be required to combat this problem.

Randomized, Double-Blind, Placebo-Controlled Studies of the Safety and Pharmacokinetics of Single and Multiple Ascending Doses of Eravacycline

Eravacycline is a novel, fully synthetic fluorocycline antibiotic with in vitro activity against aerobic and anaerobic Gram-positive and Gram-negative pathogens, including multidrug-resistant (MDR) bacteria. The pharmacokinetics (PK), urinary excretion, and safety/tolerability of intravenous (i.v.) eravacycline were evaluated in single- and multiple-ascending-dose studies.

Eravacycline is a novel, fully synthetic fluorocycline antibiotic with in vitro activity against aerobic and anaerobic Gram-positive and Gram-negative pathogens, including multidrug-resistant (MDR) bacteria. The pharmacokinetics (PK), urinary excretion, and safety/tolerability of intravenous (i.v.) eravacycline were evaluated in single- and multiple-ascending-dose studies. Healthy subjects received single i.v. doses of 0.1 to 3 mg/kg of body weight or 10 days of treatment with 0.5 or 1.5 mg/kg every 24 h (q24h) over 30 min, 1.5 mg/kg q24h over 60 min, or 1 mg/kg q12h over 60 min. After single doses, total exposure (the area under the plasma concentration-time curve [AUC]) and the maximum plasma concentrations (C_max) of eravacycline increased in an approximately dose-proportional manner. After multiple doses, steady state was achieved within 5 to 7 days. Accumulation ranged from approximately 7% to 38% with the q24h dosing regimens and was 45% with 1 mg/kg q12h. Eravacycline was generally well tolerated, with dose-related nausea, infusion site effects, and superficial phlebitis that were mild or moderate occurring. These results provide support for the 1-mg/kg q12h regimen used in clinical studies of eravacycline.

Antimicrobial resistance and treatment: an unmet clinical safety need

INTRODUCTION

Infections due to multidrug-resistant (MDR) bacteria are burdened by high mortality rates. The development of new compounds to face the global threat of resistance is urgently needed. Combination regimens including "old" high-dose antimicrobials are currently limited by the risk of toxicity, resistance selection, and reduced efficacy. Following the Infectious Diseases Society of America call to develop 10 new antibacterials by 2020, new molecules are currently under development or have become available for use in clinical practice.

AREAS COVERED

We have reviewed safety characteristics and tolerability of old antimicrobials that are currently employed in combination regimens as well as new antimicrobials, including beta-lactams/beta-lactamase inhibitors, new cephalosporins, quinolones, and aminoglycosides.

EXPERT OPINION

The availability of new compounds that show in vitro efficacy against MDR represents a unique opportunity to face the threat of resistance and to optimize the current use of antimicrobials, potentially reducing toxicity. Agents that are potentially active against MDR Gram-negatives are ceftozolane/tazobactam, new carbapenems and cephalosporins, the combination of avibactam with ceftazidime, and plazomicin. Further data from clinical trials and post-marketing studies for drugs targeting MDR pathogens are crucial to confirm their efficacy and safety.