Analysis of Susceptibilities of Carbapenem Resistant Enterobacterales to Colistin in Intra-Abdominal, Respiratory and Urinary Tract Infections from 2015 to 2017.

PURPOSE

To evaluate the susceptibility rates of carbapenem-resistant (CR)-Enterobacterales strains from Chinese intra-abdominal infections (IAI), respiratory tract infections (RTI) and urinary tract infections (UTI) between 2015 and 2017 to colistin.

METHODS

In total, 7138 Enterobacterales including 1074 CR-Enterobacterales strains were isolated from IAI+UTI+RTI samples and collected in 21 hospitals across 7 regions of China. Antimicrobial susceptibilities were determined at a central laboratory using CLSI broth microdilution and interpretive standards.

RESULTS

From 2015 to 2017, (51.4%) and (30.0%) accounted for the majority of Enterobacterales isolated from IAIs, UTIs and RTIs. The percentage of CR strains within the species was highest for (27.9%), followed by (24.8%), (22.6), (19.5%), (17.7%), (12.5%), (11.0%) and lowest for (6.9%). Colistin susceptibilities were generally higher in CS than in CR isolates and were 83.5% for CR-, 88.6% for CR-, 79.2% for CR- and 87.5% for CR-. . For IAI and UTI isolates in particular, CR- and CR- showed a trend of decreasing susceptibility, which was especially noted for CR- in UTI isolates, and for both organisms in IAI isolates susceptibility dropped markedly in 2017.

CONCLUSION

Colistin was a last resort antibiotics for empirical CR-Enterobacterales treatments, since especially the percentage of CR- was 30.0% of all IAI, UTI and RTI isolates, with an incidence of 24.8% CR strains, of which 88.6% were susceptible to colistin. Also other analyzed CR-Enterobacterales showed colistin susceptibilities of ≥80.0%. However, resistance rates of IAI derived CR- and CR-, and CR- UTI isolates to colistin increased between 2015 and 2017, which should further be closely monitored.