Background: Hospital-acquired infections (HAIs) can be considered the most frequent adverse event threatening the life of patients. HAIs, added to the underlying disease, increase morbidity and mortality and have a considerable economic impact. This study aims at evaluating the prevalence of HAIs in a metropolitan hospital, to identify the risk factors and to assess the potential clinical implication.

Patients and Methods: This is a retrospective observational study conducted in Catania, Italy. Demographic, epidemiological and clinical data were recorded for each patient with at least one available bacterial culture, hospitalized in the period from March 2005 to April 2010. HAIs were identified and classified according to the CDC/NHSN criteria. Mortality and duration of hospital stay were considered an outcome. The Chi-squared test and odds ratio were used for nominal variables, the Chi-squared test for trend was used to evaluate the trend of percentages over time.

Results: 599 positive cultures were identified from 372 patients. In 216 (58%) patients we observed at least a HAI: 149 (40%) developed a single HAI, 67 (18%) developed more than one HAI. 300 HAIs were identified: 170 lung infections, 102 blood stream infections. The risk of infection was greater for patients with invasive devices. The probability of death in the presence of HAI was 52.9%. The mortality rate increased with age, comorbidity and number of HAIs. The development of an HAI by A. baumannii was an important risk factor for death during hospitalization. HAIs were associated with prolonged length of stay.

Conclusions: In this study we found that HAIs play a critical role in patients’ management, length of stay, mortality, and augmented hospitalization cost.