Which disease is associated with rapidly growing and contagious bacteria that can cause an infection, and which in early stages is associated with a yellow-green spot?

• A. Staphylococcus aureus
• B. Pseudomonas aeruginosa
• C. Herpes simplex
• D. Salmonella enterica

Answer: (B)

Pseudomonas aeruginosa is known for growing quickly and thriving in moist environments, which makes it a common culprit in skin and nail infections that can spread in settings like salons through contaminated tools or water. A distinctive clue it provides early on is its pigment, which gives a yellow-green color to colonies and to the discharge or affected area. That yellow-green hue is a hallmark of this organism and helps clinicians recognize it before other signs become obvious. In nail cases, this can appear as a yellow-green spot on the nail plate as the pigment begins to contribute to the color.

Other options don’t fit this color clue or the typical context as well. Herpes simplex is viral and presents with vesicles rather than pigment-related coloration. Salmonella enterica is primarily a gastrointestinal pathogen with different clinical signs. Staphylococcus aureus can cause many infections and sometimes shows golden-yellow pigment, but not the characteristic yellow-green coloration associated with Pseudomonas.

So the combination of rapid growth, ability to spread in moist environments, and a yellow-green pigment-producing infection points to Pseudomonas aeruginosa.