A 65 year old diabetic presents with necrosis of the external auditory meatus with foul smelling discharge. The probable organism associated with the condition is?
**Core Concept**
The condition described is likely a result of a polymicrobial infection involving both aerobic and anaerobic bacteria, leading to necrosis of the external auditory meatus. This condition is often associated with diabetes mellitus, which impairs the host's ability to fight off infections.
**Why the Correct Answer is Right**
The probable organism associated with this condition is Pseudomonas aeruginosa, a gram-negative rod that thrives in moist environments. In diabetic patients, Pseudomonas aeruginosa can cause aggressive infections, including otitis externa (swimmer's ear), which is characterized by necrosis of the external auditory meatus and foul-smelling discharge. The bacteria's ability to form biofilms and its resistance to antibiotics contribute to its virulence.
**Why Each Wrong Option is Incorrect**
**Option A:** While Staphylococcus aureus can cause skin and soft tissue infections, it is not the primary organism associated with necrosis of the external auditory meatus in diabetic patients.
**Option B:** Escherichia coli is a common cause of urinary tract infections and some types of diarrhea, but it is not typically associated with otitis externa in diabetic patients.
**Option C:** Klebsiella pneumoniae can cause a range of infections, including pneumonia and urinary tract infections, but it is not the primary organism associated with necrosis of the external auditory meatus in diabetic patients.
**Clinical Pearl / High-Yield Fact**
Diabetes mellitus increases the risk of developing otitis externa due to impaired neutrophil function and altered sweat composition, which creates a moist environment conducive to bacterial growth.
**Correct Answer:** C. Pseudomonas aeruginosa.