Antimicrobial Activity of Colistin Against Contemporary (2015-2017)P. aeruginosaandA. baumanniiIsolates From a Chinese Surveillance Program

Objective To investigate the incidence and susceptibilities of non-fermenting bacteria isolates from Chinese respiratory (RTI), intra-abdominal (IAI) and urinary tract (UTI) infections to antimicrobial agents between 2015 and 2017. Methods In total, 3,246 non-fermentative bacteria were collected from 21 hospitals and 9 hospital departments across 7 regions of China. A central testing laboratory was employed to determine antimicrobial susceptibilities using appropriate standards of interpretation. Results The majority of the isolates wereAcinetobacter baumannii(n= 1,360, 41.9%) andPseudomonas aeruginosa(n= 1,341, 41.3%). Overall multidrug resistance (MDR) and carbapenem resistance (CR) rates ofAcinetobacter baumanniiwere 80.1 and 78.7% with MDR and CR rates in RTIs, IAIs, and UTIs of 82.0 and 81.0%, 82.6 and 81.0% as well as 53.1 and 46.9%. Overall MDR and CR rates ofPseudomonas aeruginosaisolates were 36.2 and 38.9% with 41.8 and 44.3%, 29.3 and 36.1% as well as 24.2 and 20.2% MDR and CR rates in RTIs, IAIs, and UTIs. Overall susceptibility rates to imipenem, meropenem, amikacin, ciprofloxacin, cefepime and piperacillin-tazobactam were 21.1, 21.3, 33.0, 18.4, 19.2, and 19.6% forAcinetobacter baumanniiand 56.5, 58.5, 88.4, 63.1, 63.1, and 55.63% forPseudomonas aeruginosaisolates, whereas for colistin they were 95.7 and 94.6%, respectively. In all departments and regions of China, susceptibility rates ofPseudomonas aeruginosaandAcinetobacter baumanniiisolates to colistin were constantly above 80%. Conclusion Due to the high MDR and CR rates forPseudomonas aeruginosaandAcinetobacter baumannii, isolates obtained from RTIs, IAIs, and UTIs only maintained high susceptibility rates to colistin between 2015 and 2017.