Bacteremia with Acinetobacter species: risk factors and prognosis in different clinical settings

Acinetobacter species are widespread environmental gram-negative coccobacilli that are associated with nosocomial infections; these bacteria are considered to be of relatively low virulence and rarely cause invasive disease. Fifty-two cases of bacteremic episodes due to Acinetobacter species were reviewed, and risk factors and outcomes of these cases were examined. It was noted that these cases belonged to a few clinical groups with markedly different outcomes. Eighteen patients had malignancies (predominantly hematologic), and bacteremia often developed after respiratory infection. Nine patients suffered traumatic injuries and developed bacteremia with Acinetobacter species after endotracheal intubation in the intensive care unit and respiratory colonization. Four burn patients, three of whom had burns covering > or = 50% of their body surface areas, had burn infections prior to bacteremia. While many patients had central venous catheters, in only four cases were the catheters clearly infected prior to the positive blood culture. Prior use of antibiotics was widespread in all groups of patients, and isolates showed high levels of antimicrobial resistance, particularly to beta-lactam agents. The outcome of infection correlated more closely with the type of underlying illness than with other factors such as biovar, polymicrobial bacteremia, or appropriate therapy. Patients with malignancies and burn patients fared poorly (10 of 18 and 2 of 4 patients, respectively, died), while trauma patients and patients with other illnesses did well.