Risk Factors for Colistin Resistance; A 10 Year Experience at a Tertiary Medical Center

Abstract

Colistin is an antibiotic of last resort for treatment of Carbapenem-resistant Enterobacteraceae (CRE) infections. Resistance to colistin is associated with increased mortality and has been observed with increasing frequency in Klebsiella spp.(K) Risk factors for colistin-resistant infection have been incompletely studied. All patients admitted to academic tertiary medical center and community hospital from 2006-2016, where routine microbiology susceptibility testing includes gold standard broth micro-dilution. From 2006 to 2011, colistin testing was done by request. Starting in 2012, all Gram-negative organisms underwent colistin testing, except urine isolates where only CRE undergo colistin testing. We searched the clinical data warehouse for patients in whom K was isolated from any source. Logistic regression models were used to create univariate and multivariable predictive models for colistin resistance. Data were analyzed for complete cases only and were analyzed once per hospital admission. From 2006-2016, there were 3,837 admissions with K isolated and 1360 with complete data. There were 93 admissions with colistin-resistant K and 80/93 demonstrated meropenem resistance. Univariate predictors are shown. Table 1 On unadjusted analysis, days in hospital, male gender, skilled nursing residence, black race, increased age, Elixhauser score, and end-stage renal disease were each significantly associated with increased risk of colistin-resistance. On multivariable analysis, the best model included days hospitalized, gender, skilled nursing residence, and Elixhauser score, with an AUROC of 0.81. Table 2 Colistin resistance among patients with Klebsiella is significantly associated with skilled nursing facility residence, male gender, prolonged hospitalization, and increased comorbidity. Further studies will look at events within a hospitalization, including patient location, antibiotic exposure to determine modifiable factors associated. L. G. Miller, Sage Products: Study coordination, Conducting studies in healthcare facilities that are receiving contributed product. Xttrium: Study coordination, Conducting studies in healthcare facilities that are receiving contributed product. Clorox: Study coordination, Conducting studies in healthcare facilities that are receiving contributed product. 3M: Study coordination, Conducting studies in healthcare facilities that are receiving contributed product.