Which genus is a gram-positive rod that is sometimes associated with pharyngitis?

• A. Arcanobacterium haemolyticum
• B. Bacillus cereus
• C. Corynebacterium urealyticum
• D. Erysipelothrix rhusiopathiae

Answer: (A)

Arcanobacterium haemolyticum is a gram-positive rod that is classically associated with pharyngitis, especially in adolescents and young adults. It can cause an exudative sore throat that resembles strep throat, which is why this organism is frequently tested for in questions about pharyngitis presentations. In the lab, recognizing it helps distinguish it from the more common Streptococcus pyogenes, since management may differ and accurate identification guides appropriate antibiotic choices. The other organisms listed tend to cause infections in different contexts—Bacillus cereus with food poisoning, Corynebacterium urealyticum with urinary tract issues and stone formation, and Erysipelothrix rhusiopathiae with skin infections after fish or meat exposure—so they are not characteristically linked to pharyngitis.

So, Arcanobacterium haemolyticum is the best match for a gram-positive rod occasionally associated with pharyngitis.