CHICAGOFifteen to 20 years ago, treatment of patients infected with Pseudomonas aeruginosa infection after stem cell transplantation was limited to certain beta-lactam and aminoglycoside antibiotics that were active against the organism.
Because newer antibiotics, such as the fluoroquinolones and the cephalosporins cefotaxime(Drug information on cefotaxime) (Claforan) and cefepime(Drug information on cefepime) (Maxipime), have greater activity against P aeruginosa and less toxicity than previously prescribed antibiotics, there has been every reason to believe that treatment has improved and mortality has declined.
According to a study from Fred Hutchinson Cancer Research Center, Seattle, P aeruginosa infections occur only rarely after stem cell transplantation, but overall mortality exceeds 30%. More than 35% of patients relapse after antibiotic treatment, and for these individuals, mortality is 90%.
"Even though the incidence of these infections is only about 1%, when these people get infected, they have a very poor prognosis for the initial infection. Once the initial infection appears to be treated successfully, there is still a fairly high risk of relapse, and when patients do relapse, the prognosis is terrible," said Morgan Hakki, MD, a senior fellow in the Program in Infectious Diseases at Fred Hutchinson.
46 Cases of Invasive P aeruginosa
The study, presented in a poster session at the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC abstract 780), was a retrospective review of 46 cases of invasive P aeruginosa infection in individuals who underwent hematopoietic stem cell transplantation between 1990 and 2000.
Although patients were treated with combination antibiotics for an average of 16.8 days, the mortality rate attributable to P aeruginosa was 31.4%. Ten of 28 survivors (35.7%) relapsed with P aeruginosa infection a median of 9 days after the cessation of antibiotic therapy, and 90% of these individuals died within 36 days.