Background: Multi-drug resistant (MDR) Enterobacteriaceae pose serious challenges for patient treatment and infection control. Using data from the Tigecycline Evaluation and Surveillance Trial (TEST), the epidemiology and susceptibility of MDR Enterobacteriaceae from North America were examined.
Methods: 9,316 Enterobacteriaceae isolates (Escherichia coli, Klebsiella spp., Citrobacter spp., Enterobacter spp., and Serratia spp.) from various specimen sources were collected in Canada and United States (US) from inpatients in 2011-2014. MICs were determined at each site using CLSI broth microdilution method and interpreted according to CLSI guidelines. Isolates were categorized as multi-drug resistant if resistant to ≥3 of the tested drug classes (glycylcyclines, β-lactam/inhibitor, cephems, penems, penicillins [ampicillin], quinolones, tetracyclines, and aminoglycosides).
Results: The overall MDR rate for Enterobacteriaceae in 2011-2014 in North America was 19.1%. MDR rates for selected species are shown below.
The relatively high MDR rate for E. coli was at least in part due to high levofloxacin resistance of 31% in this species. MDR rates for all Enterobacteriaceae for the years 2011-2014 were 19.7%, 20.1%, 18.8%, and 17.5% (p=0.04, Cochran-Armitage test for trend). The overall MDR rate for 2011-2014 was 22.0% in Canada versus 18.6% in the US; 21.5% in ICU wards versus 18.3% in non-ICU wards; and 19.6% in medicine wards versus 18.9% in surgery wards. Susceptibility of MDR pathogens in 2014 was ≤21% to ampicillin, amoxicillin-clavulanate, and ceftriaxone; 50-70% to cefepime, levofloxacin, piperacillin-tazobactam, and minocycline; and >90% to amikacin, meropenem, and tigecycline.
Conclusion: Almost 20% of Enterobacteriaceae were MDR in North America in 2011-2014, although the prevalence appears to be slightly decreasing. MDR rates for Enterobacteriaceae varied by species but overall were fairly similar in US and Canada as well as across types of wards. Treatment of these isolates is challenging with only amikacin, meropenem, and tigecycline inhibiting >90% in 2014.
M. Hackel, IHMA, Inc.: Independent Contractor , Consulting fee
D. Sahm, IHMA, Inc.: Independent Contractor , Consulting fee
H. Leister-Tebbe, Pfizer, Inc.: Employee , Salary