LAUSR

OBJECTIVES This study reports on the activity of aztreonam-avibactam against a collection of Klebsiella pneumoniae collected in 2016 and 2017. METHODS Non-duplicate isolates of K. pneumoniae were collected from four regions (Africa/Middle East, n=785; Asia-Pacific, n=1433; Europe, n=4236; Latin America, n=1499) and five culture sources (blood, n=902; intra-abdominal, n=992; urinary tract, n=2148; skin and skin structure, n=1409; lower respiratory tract, n=2502). Minimum inhibitory concentrations (MICs) were determined at the central laboratory using Clinical Laboratory Standards Institute broth microdilution methodology. Susceptibility was determined using European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. RESULTS For all culture sources, against all K. pneumoniae, the highest rates of susceptibility were seen for amikacin (>84%), ceftazidime-avibactam (>94%), colistin (>92%), and meropenem (>83%) and >99.9% of isolates were inhibited by an aztreonam-avibactam MIC of ≤4mg/L. Among meropenem-resistant (MEM-R, n=583) and meropenem-resistant metallo-β-lactamase negative (MEM-R-MBLN, n=469) isolates susceptibility was highest to ceftazidime-avibactam (79.9%, 99.4%, respectively) and colistin (67.2%, 62.7%, respectively). All MEM-R-MBLN isolates from blood, intra-abdominal, urinary tract and skin and skin structure sources, and all but one isolate from respiratory sources, were inhibited by an aztreonam-avibactam MIC of ≤2mg/L. Against the meropenem-resistant metallo-β-lactamase positive (MEM-R-MBLP, n=114) isolates susceptibility to colistin was between 75.0% (urinary tract isolates) and 93.3% (lower respiratory tract isolates). All MEM-R-MBLP isolates were inhibited by an aztreonam-avibactam MIC of ≤0.5mg/L. CONCLUSIONS Aztreonam-avibactam is active against K. pneumoniae isolates from a range of culture sources across Africa/Middle East, Asia-Pacific, Europe, and Latin America. Aztreonam-avibactam also has activity against MEM-R-MBLN and MEM-R-MBLP isolates.