Antimicrobial susceptibility and distribution of extended-spectrum β-lactamases, AmpC β-lactamases and carbapenemases among Proteus, Providencia and Morganella isolated from global hospitalised patients with intra-abdominal and urinary tract infections: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART), 2008–2011
Jui-Hsuan Yang, Wang‐Huei Sheng, Po‐Ren Hsueh
Abstract
OBJECTIVES: The increasing trend of β-lactam resistance among Enterobacteriaceae is a worldwide problem. This study investigated isolates of the tribe Proteeae (Proteus, Providencia and Morganella) causing intra-abdominal and urinary tract infections from the worldwide Study for Monitoring Antimicrobial Resistance Trends (SMART) collected from 2008-2011. METHODS: Antimicrobial susceptibility testing was performed on isolates with an ertapenem minimum inhibitory concentration >0.5mg/L or those phenotypically producing extended-spectrum β-lactamases (ESBLs). ESBLs, AmpC β-lactamases and carbapenemases were detected by multiplex PCR. RESULTS: A total of 142 isolates, including Proteus mirabilis (n=121), Proteus vulgaris (n=3), Providencia stuartii (n=5), Providencia rettgeri (n=6) and Morganella morganii (n=7), were analysed. Proteus mirabilis was generally susceptible to ertapenem (∼90%) compared with imipenem (≤25%). The most common ESBLs were CTX-M types (n=64), followed by TEM (n=27) and SHV (n=7). CTX-M-1, CTX-M-2 and CTX-M-15 were the dominant CTX-M-type ESBLs in P. mirabilis isolates. CMY (n=14), which included CMY-2 (n=6), was the most common AmpC β-lactamase, followed by DHA (n=6) and FOX (n=4). NDM (n=7), which included NDM-1 (n=4), was the most common carbapenemase, followed by KPC (n=2). Isolates from hospital-associated infections had more complicated β-lactamase combinations than isolates from community-acquired infections. CONCLUSION: The global emergence and spread of β-lactamase-producing Proteeae isolates are major issues in tackling antimicrobial resistance. Continuous monitoring of antimicrobial resistance trends and developing further resistance surveillance are necessary.