Kyle J Gontjes, Brendan J Kelly, Leigh Cressman, Anne Jaskowiak-Barr, Laurel Glaser, Laura L Cowden, Alexa Patel, Jennifer Han, Ellie J C Goldstein, Warren B Bilker, Evan S Snitkin, Ebbing Lautenbach
The comparison of clinical CRKP isolates collected from the same healthcare network and separated by nearly a decade revealed increasing ST diversity, mainly due to the introduction of numerous epidemic lineages, which coincided with differing patterns of circulating resistance-associated genotypes and antibiotic resistance.
BACKGROUND: The epidemiology of carbapenem-resistant Klebsiella pneumoniae (CRKP) must be monitored over time to understand resistance dynamics to existing and novel antibiotics.
METHODS: Antibiotic susceptibility testing and whole-genome sequencing were performed on clinical CRKP isolates collected from the same California long-term acute care hospital network across two time periods: 2014-15 (period 1) and 2021-23 (period 2). Differences in sequence type (ST) diversity, carbapenem resistance-associated genotypes, and resistance to clinically important antibiotics were evaluated.
RESULTS: Eight hundred eighty-one isolates were collected (period 1, 374; period 2, 507). Study period 1's population was dominated by ST258 (94.1%). ST diversity markedly increased in period 2, with a reduced prevalence of ST258 (41.6%) and an increased abundance of other epidemic lineages: ST14 (27.4%), ST307 (6.9%), and ST17 (6.5%). Changes to circulating resistance genotypes and plasmids reflected the increased ST diversity. Increases in blaKPC-3-harboring isolates (66.0% vs. 76.1%) and non-carbapenemase-containing isolates (2.7% vs 12.6%) aligned with decreases in blaKPC-2-harboring isolates (30.5% vs. 6.3%). Statistically significant differences in resistance patterns were also observed between study periods, including colistin (35.0% vs. 20.2%), fosfomycin (27.0% vs. 13.4%), meropenem-vaborbactam (9.4% vs. 2.0%), and ceftazidime-avibactam (1.1% vs. 9.1%). Differential patterns of resistance emergence and spread across circulating STs largely drove resistance patterns in study period 2.
CONCLUSIONS: The comparison of clinical CRKP isolates collected from the same healthcare network and separated by nearly a decade revealed increasing ST diversity, mainly due to the introduction of numerous epidemic lineages, which coincided with differing patterns of circulating resistance-associated genotypes and antibiotic resistance.