Acinetobacter bacteraemia in a teaching hospital, 1989-1998

Background: The mortality rate from bacteraemia is one of the highest among infections in hospitals, especially in the intensive care unit (ICU). Recently, an increase in nosocomial bacteraemia caused by gram-negative resistant pathogens has been observed. In this work we review the clinical and laboratory findings of adult patients with Acinetobacter bacteraemia in order to identify risk factors associated with mortality. Methods: A retrospective review of the medical records of patients with Acinetobacter bacteraemia identified by blood cultures from the Diagnostic Microbiology Laboratory was conducted between January 1989 and March 1998. Results: We identified 59 cases of Acinetobacter bacteraemia. Most of the infections (71%) were nosocomial; the majority occurred in the Department of Internal Medicine (28.8%), followed by Haematology (27%) and the ICU (23%). A. lwoffii was isolated in 52.5% of cases and A. baumannii in 47.5%. The related mortality was 17%. Staying in the ICU was associated with A. baumannii bacteraemia (P<0.004). An intravascular catheter was the leading source of infection (37%). Main risk factors were mechanical ventilation (28%), parenteral nutrition (23%) and the presence of a urinary catheter (22%). In the multivariate analysis the independent prognostic factors for mortality were the presence of shock (P<0.05) and the severity of the underlying disease, according to the classification of McCabe (P<0.05). Conclusions: The incidence of Acinetobacter bacteraemia has increased in the last decade, mainly since 1995. The development of septic shock and the severity of the underlying disease appear to be associated with an increase in mortality.