Acinetobacter baumannii bloodstream infection: clinical features and antimicrobial susceptibilities of isolates

The number of nosocomial infections caused by Acinetobacter baumannii has increased in recent years. The purposes of this study are to discover the risk factors of transmission to prevent the nosocomial infection of A. baumannii. We retrospectively studied 36 patients with A. baumannii bacteremia at China Medical College Hospital from January 1996 to December 1997. There were 23 males and 13 females. All bacteremia were acquired nosocomially. Malignancy (n = 8) and intracranial hemorrhage (n = 6) were the most common underlying diseases. Only one patient on arterial line disclosed intraarterial catheter-related A. baumannii bacteremia and 3 patients had evidence of A. baumannii pneumonia. Twenty-one patients (58%) had central venous catheters in place at the onset of bacteremia, but none was proven to be catheter-related infection. There were 32 patients (89%) with unknown portal of entry. Multivariate logistic regression analysis revealed that potential risk factors related to A. baumannii bacteremia were prior antimicrobial therapy (P < 0.05). The most common clinical features of A. baumannii bacteremia were, in descending order, fever, leukocytosis, thrombocytopenia and hypotension. Eleven patients (30.6%) died directly from A. baumannii bacteremia. All isolates were resistant to ampicillin, cephalothin, cefonicid and moxalactam. The most alarming evidence was that 19% of isolates showed resistance to imipenem. Our findings emphasized that A. baumannii bacteremia had the following characteristics: usually acquired nosocomially, unknown portal of entry, and high multiresistance, especially the increasing resistance rate to imipenem. Imipenem must be reserved as a last-line agent to treat A. baumannii infections, so we want to suggest that the treatment of choice for A. baumannii is gentamicin, amikacin or ceftazidime.