METHYLOBACTERIUM SPECIES - AN INCREASINGLY IMPORTANT OPPORTUNISTIC PATHOGEN

Methylobacterium species rarely cause human disease. Those isolated fr om humans are usually found as opportunistic pathogens in patients wea kened by an underlying disease process. This report describes a case o f Methylobacterium bacteremia in a 35-year-old woman with AIDS, compar es the clinical presentation of this case with that of other previousl y reported cases of Methylobacterium infection, and provides a history of the Methylobacterium genus and its relevant taxonomy. Recommendati ons for presumptive identification include pink to orange colony growt h on blood or Sabouraud agar but not on MacConkey agar; gram-negative, vacuolated bacillus or coccobacillus; growth at 25 degrees to 30 degr ees C and not at 42 degrees C; and positive results on tests for oxida se and urease. Antibiotics with demonstrated efficacy against Methylob acterium species include amikacin, gentamicin, ciprofloxacin, trimetho prim-sulfamethoxazole, ceftizoxime, and ceftriaxone.