Activity of Ertapenem against Enterobacteriaceae in seven global regions-SMART 2012-2016

Antimicrobial resistance among Enterobacteriaceae has been increasing globally especially due to extended-spectrum-β-lactamases (ESBLs), which typically necessitate the use of carbapenems for treatment of serious infections. Emerging carbapenem-resistant Enterobacteriaceae further complicate therapy. As part of the Study for Monitoring Antimicrobial Resistance Trends (SMART), this analysis examined the recent activity of a key carbapenem (ertapenem) and other important therapeutic options against Enterobacteriaceae. From 2012 to 2016, 224 hospitals in 57 countries collected up to 100 consecutive gram-negative bacilli from intra-abdominal (IAI) and 50 from urinary tract infections (UTI) per year, totaling 106,300 Enterobacteriaceae isolates. Susceptibility was determined using CLSI broth microdilution and breakpoints. Although statistically significant decreasing trends in ertapenem activity against Enterobacteriaceae were found in all regions except Middle East, the actual size of the decreases was < 3 percentage points, and susceptibility in 2015-2016 remained ca. 90% or higher, ranging from 89.5% in Asia to 97.3% in US/Canada. Of the comparators, only amikacin exceeded these results. Ertapenem was active against > 90% of isolates with ESBL phenotype from Latin America, Middle East, South Pacific, and US/Canada, and against > 80% of MDR isolates in all regions except Africa (72.9%), Asia (75.1%), and Europe (78.0%). Only imipenem, amikacin, and colistin exceeded these rates. Ertapenem, which is popular among clinicians due to its convenient once-daily dosing schedule and favorable safety and tolerability profile, remains highly active against Enterobacteriaceae from IAI and UTI, even as ESBLs and other resistance mechanisms limit therapeutic options, but continued susceptibility testing for surveillance and individual patients is important.