In immunocompromised hospitalized patients, which organism is an aerobic gram-positive rod known to cause bacteremia?

• A. Bacillus anthracis
• B. Corynebacterium jeikeium
• C. Corynebacterium ulcerans
• D. Corynebacterium urealyticum

Answer: (B)

In immunocompromised hospitalized patients, bloodstream infections often arise from organisms that normally colonize the skin and can seed intravascular devices. Corynebacterium jeikeium fits this scenario perfectly: it is a gram-positive rod that is aerobic, part of the skin flora, and a well-known cause of catheter-associated bacteremia in patients with weakened immune defenses. Its significance also lies in its resistance profile, which makes infections challenging to treat and often steers clinicians toward vancomycin or similar agents.

The other organisms listed don’t fit as cleanly for this specific setting. Bacillus anthracis is a dangerous pathogen that causes anthrax with a distinct clinical picture, not typical nosocomial bacteremia in these patients. Corynebacterium ulcerans and Corynebacterium urealyticum can cause disease, but they are less characteristically associated with bacteremia in immunocompromised inpatients; urealyticum is more linked to urinary infections due to its urease activity, while ulcerans is linked to diphtheria-like illness.