Polymyxin B for Gram Negative Multidrug Resistant Bacteria in a Hispanic Population.

OBJECTIVE: This study intends to determine the prevalence of multidrug resistant (MDR) infections by A. baumannii, K. pneumoniae and P. aeruginosa in a tertiary care teaching hospital intensive care unit (ICU) in San Juan, PR, estimate the mortality rate and compare the morbidity and mortality differences among those treated with and without polymyxin B. METHODS: We selected adults patients admitted to the ICU who had positive cultures from January 2012 to June 2013. Sample consisted of 25 patients with age ranges from 27-78 years, 13 women and 12 men. RESULTS: The median age at death was 60 years. Polymyxin B nephrotoxicity was identified on 15% of the patients. Variables related to higher survival were younger age, female sex, use of polymyxin B, and the use of daptomycin. The use of vancomycin and vasopressors were associated with worse outcome. Mortality associated to single MDR bacteria was 88% for A. baumannii, 84% for K. pneumoniae and 67% for P. aeruginosa. All patients with more than one MDR infection died in the ICU. CONCLUSION: The use of polymyxin B was associated with an ICU mortality reduction. Unexpectedly we found a significantly improved survival in patients who received polymyxin B in combination with daptomycin, which awaits prospective confirmation.