Antimicrobial susceptibility profiles of aerobic and facultative Gram-negative bacilli isolated from patients with intra-abdominal infections in the Asia-Pacific region according to currently established susceptibility interpretive criteria

SummaryObjectivesThe Study for Monitoring Antimicrobial Resistance Trends (SMART) was intended to reveal the evolving profiles of antimicrobial resistance among Gram-negative pathogens causing intra-abdominal infections (IAIs) from Asia-Pacific region in 2009.MethodsA total of 3577 aerobic and facultative Gram-negative bacilli associated with IAIs were collected from 32 centers in 12 countries. The in vitro susceptibilities of these isolates to 12 antimicrobial agents were determined using the broth microdilution method. Susceptibility results for selected species of Enterobacteriaceae were also compared using different MIC interpretive criteria recommended by the Clinical and Laboratory Standards Institute in 2009 (M100-S19), in January 2010 (M100-S20), in June 2010 (M100-S20-U) and the European Committee on Antimicrobial Susceptibility Testing in 2010 (EUCAST-2010).ResultsEnterobacteriaceae comprised 89.5% of the isolates of which Escherichia coli was the most common species (56.7%). Enterobacteriaceae showed poor susceptibility to ampicillin-sulbactam in China (25.3%) and India (19%), and to fluoroquinolones in India (23.4%) and China (37.7%). The rates of extended-spectrum β-lactamase (ESBL)-producing E. coli (36.8%) and Klebsiella pneumoniae (26.3%) remained high. The resistance of ESBL-producing K. pneumoniae to carbapenems also increased, especially to ertapenem (9.9%). Using M100-S20 criteria, 19% of ESBL-producing E. coli and 9% of ESBL-producing K. pneumoniae were susceptible to ceftazidime; 5% and 10% were susceptible to cefepime, respectively. Using M100-S20-U guidelines, the susceptibility rates of ESBL-producing K. pneumoniae (88%) and Enterobacter cloacae (69%) to ertapenem were substantially decreased from those determined using M100-S20.ConclusionsThese up-to-date epidemiology and antimicrobial resistance surveillance data are crucial to select appropriate treatment of IAIs.