Relationship between age and intensive care unit-acquired bloodstream infections in infectious disease patients in Croatia

Introduction: Intensive care unit-acquired bloodstream infections (ICU-BSI) belong to the most important nosocomial infections. Since there is scarce data available on their relationship with older age, we performed this study to estimate the age-related incidence of ICU-BSI and the odds of acquiring ICU-BSI in elderly critically ill infectious disease patients. Methodology: A retrospective observational analysis of prospectively collected demographic and clinical data of adult mechanically ventilated infectious disease patients, treated in a teaching hospital in Croatia between 1994 and 2008, using univariate, bivariate, and multivariate logistic regression analyses. Results: Of the 1,093 included patients, 509 (46.6%) were ≥ 65 years old, among 256 (23.4%) of whom a total of 353 ICU-BSI episodes were recorded. No significant difference among ICU-BSI causative microorganisms between the observed age groups was found (P = 0.4940). The rate of patients with ICU-BSI was higher among elderly ones (26.1 vs. 21.1%, P = 0.048), and elderly patients used the ICU facilities (ICU stay, duration of mechanical ventilation and central venous catheter [CVC] use) significantly longer (P < 0.05). However, older age was not positively related with the development of ICU-BSI (OR 0.99, 95% CI: 0.71-1.38); as opposed to the duration of CVC use (OR 1.09, 95% CI: 1.07-1.10). Conclusion: It seems that among adult mechanically ventilated infectious disease patients, borderline significantly higher rate of ICU-BSI among those aged ≥ 65 years was related to longer use of ICU facilities, rather than to their older age itself. The duration of CVC use was identified as the only factor positively related to the development of ICU-BSI.