Alcaligenes xylosoxidans bacteremia: clinical features and microbiological characteristics of isolates.

Bacteremia caused by Alcaligenes xylosoxidans is rare. Between 1999 and 2002, 12 cases of bacteremia caused by A. xylosoxidans were diagnosed at a tertiary referral center in central Taiwan. The clinical features of these patients and the antimicrobial susceptibilities and pulsed-field gel electrophoresis (PFGE) pattern of their blood isolates were studied. All infections were acquired nosocomially. All of the adult patients had underlying diseases, and 10 (83%) had undergone an invasive procedure. The clinical syndrome included primary bacteremia in 7 patients (58%), and catheter-associated bacteremia, surgical wound infection, pneumonia, urinary tract infection, and empyema in 1 each. Polymicrobial bacteremia was found in 1 patient. The case-fatality rate was 17% (2/12). All isolates were susceptible to piperacillin and ceftazidime and resistant to aminoglycoside, ciprofloxacin and cefepime. Susceptibility to imipenem (67%), ampicillin-sulbactam (75%) and trimethoprim-sulfamethoxazole (92%) was variable. Genetic fingerprints obtained by PFGE showed identical pattern in the isolates from 2 neonates, indicating the epidemiologic relatedness of these infections. We conclude that A. xylosoxidans isolates are multi-resistant and A. xylosoxidans bacteremia should be considered as a possible etiology of infection after invasive procedures in patients with underlying diseases. Strict infection control is needed to prevent this infection.