Distribution of Extended-Spectrum β-Lactamases, AmpC β-Lactamases, and Carbapenemases among Enterobacteriaceae Isolates Causing Intra-Abdominal Infections in the Asia-Pacific Region: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART)

Abstract

ABSTRACTThe increasing trend of β-lactam resistance amongEnterobacteriaceaeis a worldwide threat.Enterobacteriaceaeisolates causing intra-abdominal infections (IAI) from the Study for Monitoring Antimicrobial Resistance Trends (SMART) collected in 2008 and 2009 from the Asia-Pacific region were investigated. Detection of extended-spectrum β-lactamases (ESBLs), AmpC β-lactamases, and carbapenemases was performed by multiplex PCR. A total of 699Enterobacteriaceaeisolates with positive genotypic results, includedEscherichia coli(n= 443),Klebsiella pneumoniae(n= 187),Enterobacter cloacae(n= 45),Klebsiella oxytoca(n= 9),Citrobacter freundii(n= 5),Proteus mirabilis(n= 3),Enterobacter aerogenes(n= 2),Morganella morganii(n= 2), and one each ofEnterobacter asburiae,Proteus vulgaris, andProvidencia rettgeriwere analyzed. Nearly 20% of these β-lactamase-producingEnterobacteriaceaeisolates were from community-associated IAI. CTX-M (588 isolates, including 428 [72.8%] with CTX-M-15) was the most common ESBL, followed by SHV (n= 59) and TEM (n= 4). CMY (n= 110, including 102 [92.7%] with CMY-2) was the most common AmpC β-lactamase, followed by DHA (n= 46) and ACT/MIR (n= 40). NDM (n= 65, including 62 [95.4%] with NDM-1) was the most common carbapenemase, followed by IMP (n= 7) and OXA (n= 7). Isolates from hospital-associated IAI had more complicated β-lactamase combinations than isolates from the community. Carbapenemases were all exclusively detected inEnterobacteriaceaeisolates from India, except that IMP β-lactamases were also detected in Philippines and Australia. CTX-M β-lactamases were the predominant ESBLs produced byEnterobacteriaceaecausing IAI in the Asia-Pacific region. Emergence of CTX-M-15-, CMY-2-, and NDM-1-producingEnterobacteriaceaeisolates is of major concern and highlights the need for further surveillance in this area.