A. xylosoxidans is a Gram-negative rod that does not form spores. It is motile, with peritrichous flagella that distinguish it from Pseudomonas species, and is oxidase-positive, catalase-positive, and citrate-positive. It is urease and indole-negative. It produces acid oxidatively from xylose, but not from lactose, maltose, mannitol, or sucrose. It grows well on MacConkey agar and other inhibitory growth media such as deoxycholate, Salmonella-Shigella, and nalidixic acid-cetrimide agars.[3][7][8]
It is usually resistant to a variety of antibiotics including penicillins, cephalosporins, quinolones, and aminoglycosides. Ampicillin and carbenicillin, which are penicillins, are an exception. It is variably susceptible to tetracyclines, chloramphenicol, trimethoprim-sulfamethoxazole, and colistin.[7]
Pathogenesis and clinical characteristics
Originally isolated from patients with otitis media,[7]A. xylosoxidans has since been periodically described as a pathogen of humans. In addition to otitis, it can cause a variety of other infections, including pneumonia, pharyngitis, peritonitis in association with catheters used for peritoneal dialysis, and urinary tract infections.[3][9] Infection is sometimes associated with underlying immunodeficiency, including immunoglobulin M deficiency, various cancer chemotherapies, inhaled steroids, surgical procedures, prolonged or broad-spectrum antimicrobial treatment for other infections,[3] and cystic fibrosis.[5] It has also been the cause of hospital-acquired infections.[9]
