Clinical and microbiologic characteristics of Ochrobactrum anthropi bacteremia

Ochrobactrum anthropi is an oxidase-positive, nonfermenting, gram-negative bacillus that is an emerging pathogen in immunocompromised patients, particularly in those with indwelling central venous catheters. Reports of clinical manifestation of O. anthropi bacteremia are rare. Herein, we report the clinical and microbiologic characteristics of O. anthropi bacteremia in 15 patients. There were eight males and seven females, whose ages ranged from 1 month to 84 years (mean, 34 years). Ten infections were community acquired. All patients had severe underlying disease and manifested primary O. anthropi bacteremia with no obvious focus. Only three patients had central venous catheters in place at the onset of bacteremia, but none of these showed evidence of catheter-related infection. The mean duration of fever was 4 days (range 0-11) and the mean white blood cell count was 13 x 10(9)/L (range 5.5-28 x 10(9)). All O. anthropi isolates tested were resistant to ampicillin, cephalothin, cefonicid, amoxicillin/clavulanic acid, piperacillin, aztreonam, and ceftazidime, and all were susceptible to gentamicin, amikacin, imipenem, ceftriaxone, and cefoperazone. Most were also susceptible to cefotaxime and moxalactam. Monotherapy with an aminoglycoside or an appropriate beta-lactam (such as cefotaxime or ceftriaxone) yielded good clinical response. None of the 15 patients died directly from O. anthropi bacteremia. Our findings indicate that O. anthropi is often community acquired and can be pathogenic in critically ill or immunocompromised patients with or without indwelling catheters. Although O. anthropi can produce clinically significant infections, the organism seems to be of relatively low virulence.