Results from the Survey of Antibiotic Resistance (SOAR) 2009-11 and 2013-14 in China

Objectives: To compare antibiotic susceptibility of community-acquired respiratory bacteria in China during 2009-11 and 2013-14. Methods: Susceptibility was determined by Etest (R) (bioMerieux) or disc diffusion according to CLSI, EUCAST and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints, except for azithromycin where Etest (R) breakpoints (in CO2 incubation) were used in place of standard CLSI breakpoints. Statistical significance of differences in susceptibility across time periods was evaluated using Fisher's exact test. Results: During 2009-11, 434 Streptococcus pneumoniae, 307 Haemophilus influenzae and 140 Moraxella catarrhalis were collected from eight centres and during 2013-14, 208 S. pneumoniae, 185 H. influenzae and 80 M. catarrhalis were collected from five centres. Penicillin-non-susceptible isolates remained stable at similar to 66% over both time periods but susceptibility decreased significantly for amoxicillin/clavulanic acid (or amoxicillin) and cefaclor. For H. influenzae, the proportion of beta-lactamase-positive isolates and beta-lactamase-negative ampicillin- resistant strains (CLSI definition) was higher in 2013-14 (25.4% and 7.0%, respectively) than in 2009-11 (16.3% and 3.6%, respectively), with decreased ampicillin and cephalosporin susceptibility. By 2009-11 and 2013-14, only amoxicillin/clavulanic acid (amoxicillin), levofloxacin, penicillin (intravenously) and chloramphenicol inhibited >70% of S. pneumoniae. During 2013-14, M. catarrhalis showed increasing resistance, with cefaclor and levofloxacin susceptibility decreasing significantly. However, amoxicillin/clavulanic acid, cefuroxime and levofloxacin continued to inhibit >90% of isolates. Conclusions: On the whole, antimicrobial susceptibility decreased in China between 2009-11 and 2013-14. In 2013-14, amoxicillin/clavulanic acid, levofloxacin and chloramphenicol were the most active antibacterial agents tested against community-acquired respiratory pathogens when assessed by CLSI, EUCAST or PK/PD breakpoints. Resistance to other antibacterials in China was generally high. Our data demonstrate the need to harmonize breakpoints for these pathogens.