Which gram-negative, non-spore-forming anaerobic bacillus is frequently implicated in brain and lung abscesses?

Which gram-negative, non-spore-forming anaerobic bacillus is frequently implicated in brain and lung abscesses?

• A. Fusobacterium nucleatum
• B. Bacteroides urealyticus
• C. Eubacterium lentum
• D. Peptostreptococcus anaerobius

Answer: (A)

Brain and lung abscesses often originate from aspiration of oral contents, bringing in anaerobic bacteria that are normal residents of the mouth. Among gram-negative, non-spore-forming anaerobic bacilli, Fusobacterium nucleatum is a classic and frequent offender in these infections. It lives in the oropharynx and is well known to participate in polymicrobial abscesses of the brain and lungs following aspiration, making it the best match for this scenario. The other organisms listed don’t fit as neatly: a Bacteroides species like ureolyticus is still a gram-negative anaerobic bacillus but is less characteristically linked to brain and lung abscesses compared with Fusobacterium nucleatum. Eubacterium lentum is gram-positive, not gram-negative, and Peptostreptococcus anaerobius is gram-positive and a cocci, not a bacillus.

Brain and lung abscesses often originate from aspiration of oral contents, bringing in anaerobic bacteria that are normal residents of the mouth. Among gram-negative, non-spore-forming anaerobic bacilli, Fusobacterium nucleatum is a classic and frequent offender in these infections. It lives in the oropharynx and is well known to participate in polymicrobial abscesses of the brain and lungs following aspiration, making it the best match for this scenario.

The other organisms listed don’t fit as neatly: a Bacteroides species like ureolyticus is still a gram-negative anaerobic bacillus but is less characteristically linked to brain and lung abscesses compared with Fusobacterium nucleatum. Eubacterium lentum is gram-positive, not gram-negative, and Peptostreptococcus anaerobius is gram-positive and a cocci, not a bacillus.