Surveillance of Carbapenem-Resistant Klebsiella pneumoniae: Tracking Molecular Epidemiology and Outcomes through a Regional Network

Abstract

ABSTRACTCarbapenem resistance in Gram-negative bacteria is on the rise in the United States. A regional network was established to study microbiological and genetic determinants of clinical outcomes in hospitalized patients with carbapenem-resistant (CR)Klebsiella pneumoniaein a prospective, multicenter, observational study. To this end, predefined clinical characteristics and outcomes were recorded andK. pneumoniaeisolates were analyzed for strain typing and resistance mechanism determination. In a 14-month period, 251 patients were included. While most of the patients were admitted from long-term care settings, 28% of them were admitted from home. Hospitalizations were prolonged and complicated. Nonsusceptibility to colistin and tigecycline occurred in isolates from 7 and 45% of the patients, respectively. Most of the CRK. pneumoniaeisolates belonged to repetitive extragenic palindromic PCR (rep-PCR) types A and B (both sequence type 258) and carried eitherblaKPC-2(48%) orblaKPC-3(51%). One isolate tested positive forblaNDM-1, a sentinel discovery in this region. Important differences between strain types were noted; rep-PCR type B strains were associated withblaKPC-3(odds ratio [OR], 294; 95% confidence interval [CI], 58 to 2,552;P< 0.001), gentamicin nonsusceptibility (OR, 24; 95% CI, 8.39 to 79.38;P< 0.001), amikacin susceptibility (OR, 11.0; 95% CI, 3.21 to 42.42;P< 0.001), tigecycline nonsusceptibility (OR, 5.34; 95% CI, 1.30 to 36.41;P= 0.018), a shorter length of stay (OR, 0.98; 95% CI, 0.95 to 1.00;P= 0.043), and admission from a skilled-nursing facility (OR, 3.09; 95% CI, 1.26 to 8.08;P= 0.013). Our analysis shows that (i) CRK. pneumoniaeis seen primarily in the elderly long-term care population and that (ii) regional monitoring of CRK. pneumoniaereveals insights into molecular characteristics. This work highlights the crucial role of ongoing surveillance of carbapenem resistance determinants.