A 17-year-old boy has pus-filled cysts on his face and upper back.Microscopic examination reveals gram-positive rods.This infection is caused by

Question

Quizplus · Accepted Answer

Propionibacterium acnes is a gram-positive rod-shaped bacterium that is commonly found on the skin of humans. It is a normal resident of the skin microbiota, but can cause infections such as acne when there is overgrowth due to factors such as hormonal changes or poor hygiene. The presence of pus-filled cysts on the face and upper back in this patient suggests an acne infection, and microscopic examination showing gram-positive rods is consistent with the morphology of P. acnes.

Other options are not relevant to the given symptoms and microscopic findings. Acanthamoeba is a protozoan that causes severe eye infections, herpes simplex virus causes cold sores or genital herpes, Staphylococcus aureus causes a wide range of infections but usually presents with characteristic clusters of gram-positive cocci, and Streptococcus pyogenes also causes a wide range of infections but usually presents with chains of gram-positive cocci.

A 17-Year-Old Boy Has Pus-Filled Cysts on His Face and Upper