MICROBIOLOGY

• Aerobic, gram-negative, lactose fermenter [Fig] and oxidase positive.
  
  • Part of the family Alcaligenaceae in the Burkholderiales order.
  • May grow anaerobically.
  • Motile, has peritrichous (meaning evenly distributed) flagella.
  • Has been cultured using MacConkey, Mueller-Hinton, NAC and Salmonella-Shigella agars.
• Found widely in the environment, including soil and waters fresh and brackish.
  • It may be a component of normal GI flora.
  • Known to be associated with biofilm formation and is found in humidifiers and well water.
• Intrinsic and acquired multi-drug resistance are common. Two main mechanisms:
  • Multidrug efflux pumps
  • Metallo-β-lactamases, most commonly OXA-114-like (chromosomal)
• A. xylosoxidans: most commonly implicated in active infections.
  • Intrinsically resistant to aminoglycosides, aztreonam, tetracyclines, and many penicillins/cephalosporins.
  • Formerly called Alcaligenes xylosoxidans.
  • Many other species that MALDI-TOF MS may be most helpful to identify. Some of the most common isolates seen in human infection are:
    • A. denitrificans
    • A. dolens
    • A. insuavis
    • A. piechaudii
    • A. ruhlandii