Antimicrobial Susceptibilities of Aerobic and Facultative Gram-Negative Bacilli from Intra-abdominal Infections in Patients from Seven Regions in China in 2012 and 2013

Abstract

To evaluate the antimicrobial susceptibility of Gram-negative bacilli that caused hospital-acquired and community-acquired intra-abdominal infections (IAIs) in China between 2012 and 2013, we determined the susceptibilities to 12 antimicrobials and the extended-spectrum β-lactamase (ESBL) statuses of 3,540 IAI isolates from seven geographic areas in China in a central laboratory using CLSI broth microdilution and interpretive standards. Most infections were caused by Escherichia coli (46.3%) and Klebsiella pneumoniae (19.7%). Rates of ESBL-producing E. coli (P = 0.031), K. pneumoniae (P = 0.017), and Proteus mirabilis (P = 0.004) were higher in hospital-acquired IAIs than in community-acquired IAIs. Susceptibilities of enterobacteriaceae to ertapenem, amikacin, piperacillin-tazobactam, and imipenem were 71.3% to 100%, 81.3% to 100%, 64.7% to 100%, and 83.1% to 100%, respectively, but imipenem was ineffective against P. mirabilis (<20%). Although most ESBL-positive hospital-acquired isolates were resistant to third- and fourth-generation cephalosporins, the majority were susceptible to cefoxitin (47.9% to 83.9%). Susceptibilities of ESBL-positive isolates to ampicillin-sulbactam (<10%) were low, whereas susceptibilities to ciprofloxacin (0% to 54.6%) and levofloxacin (0% to 63.6%) varied substantially. The prevalences of cephalosporin-susceptible E. coli and K. pneumoniae were higher in the northeastern and southern regions than in the central and eastern regions, reflecting the ESBL-positive rates in these areas, and were lowest in the Jiangsu-Zhejiang (Jiang-Zhe) area where the rates of carbapenem resistance were also highest. Ertapenem, amikacin, piperacillin-tazobactam, and imipenem are the most efficacious antibiotics for treating IAIs in China, especially those caused by E. coli or K. pneumoniae. Resistance to cephalosporins and carbapenems is more common in the Jiang-Zhe area than in other regions in China.

FIG 1

Map of Chinese regions in which IAI strains were collected during 2012 and 2013.

FIG 2

Comparison of the percentages of ESBL-producing E. coli and K. pneumoniae in hospital-acquired (HA) IAI isolates from the various regions of China with those in community-acquired (CA) isolates from the same regions. The numbers above the bars indicate the total numbers of isolates from the regions. No data were available for community-acquired isolates from the southwestern region.

FIG 3

Susceptibilities of E. coli and K. pneumoniae IAI isolates from the northeastern, northern, central, eastern, southern, and southwestern regions of China to the indicated antimicrobials.

FIG 4

Comparison of antimicrobial susceptibilities of E. coli and K. pneumoniae IAI isolates from the Jiang-Zhe area with those of isolates from other regions of China.

FIG 5

Comparison of the overall antimicrobial susceptibilities of E. coli, K. pneumoniae, P. mirabilis, and K. oxytoca in hospital-acquired IAI isolates with those of the community-acquired isolates.