Survival analysis of carbapenemase-producing enterobacteriaceae infections in hospital patients

The Centers for Disease Control and Prevention (CDC) estimate that more than two million people are sickened every year with antibiotic-resistant bacterial infections, and at least 23,000 die as a result of these infections in the U.S. alone. Carbapenem-resistant Enterobacteriaceae (CRE) are a particularly important subgroup with the ability to share genetic material, including the gene responsible for the production of carbapenemase enzyme. As a major threat to public health, CRE primarily affects sick patients in acute long-term health care facilities, such as Intensive Care Units. This study uses clinical data from a major U.S. hospital, as well as survival analysis methods to estimate time-to-colonization, patient risk of CRE colonization, and risk factors. A survival model was developed using Cox proportional-hazards regression to estimate time of infection. Additionally, we also used Kaplan-Meier estimation to approximate survival time. Our results support CDC's understanding of CRE infection. Sick patients with a history trauma and of staying in an ICU, which undergo certain procedures such as dialysis, fluoroscopy, respiratory intubation and mechanical ventilation, are more likely to get colonized by CRE. The fit was evaluated using the likelihood ratio test and we have found all our models to be significant.