Multidrug resistance to antimicrobials as a predominant factor influencing patient survival.

The impact of multidrug resistance to antimicrobials was assessed in a cohort of 243 patients with microbiologically documented infections by a variety of susceptible and multidrug-resistant (MDR) species. Multidrug resistance was defined as resistance to more than two antimicrobial agents of different chemical structure. Cox regression analysis was performed to define differences and the significance of any predisposing factors. Overall survival of patients infected by susceptible isolates was prolonged compared with patients infected by MDR isolates (P=0.013). Mortality rates of infections caused by susceptible and MDR isolates were 4.87% and 16.15%, respectively (P=0.013); the higher mortality rate for MDR isolates was more pronounced for infections by Klebsiella pneumoniae and Pseudomonas aeruginosa. Mean (+/-standard error (S.E.)) survival of patients infected by susceptible and MDR isolates in patients without signs of severe sepsis was 28 days and 27.29+/-0.35 days, respectively (P=not significant). Mean (+/-S.E.) survival of patients with severe sepsis caused by susceptible and MDR isolates was 7.70+/-4.62 days and 10.45+/-2.18 days, respectively (P=0.048). Diabetes mellitus type 2, the presence of severe sepsis and any underlying malignancy were the most important risk factors affecting survival. It is concluded that infections by MDR isolates were accompanied by higher mortality rates and decreased survival compared with infections by susceptible isolates. Diabetes mellitus type 2 and underlying malignancies were significant co-morbid conditions, whereas survival after infection by susceptible isolates was particularly decreased in the event of severe sepsis.