Patient with thin painless otorrhoea, multiple perforations of the tympanic membrane and failure to respond to antimicrobial treatment. What is the most probable causative organism ?
**Core Concept**
Chronic suppurative otitis media (CSOM) is a persistent infection of the middle ear that can lead to perforation of the tympanic membrane and failure of antimicrobial treatment. This condition is often caused by bacteria that are resistant to common antibiotics.
**Why the Correct Answer is Right**
The most probable causative organism in this scenario is Pseudomonas aeruginosa. This bacterium is known to cause chronic otitis media, particularly in patients with a history of recurrent infections or perforated eardrums. Pseudomonas aeruginosa is a Gram-negative rod that is highly resistant to many antibiotics, which makes it challenging to treat. It produces biofilms that adhere to the surface of the tympanic membrane, leading to persistent infection and resistance to antimicrobial therapy.
**Why Each Wrong Option is Incorrect**
* **Option A:** Staphylococcus aureus is a common cause of acute otitis media, but it is less likely to cause chronic suppurative otitis media with multiple perforations.
* **Option B:** Haemophilus influenzae can cause otitis media, but it is not the most probable causative organism in this scenario, especially given the presence of multiple perforations.
* **Option D:** Streptococcus pneumoniae is a common cause of acute otitis media, but it is less likely to cause chronic suppurative otitis media with multiple perforations and failure to respond to antimicrobial treatment.
**Clinical Pearl / High-Yield Fact**
Pseudomonas aeruginosa is a common cause of chronic suppurative otitis media, particularly in patients with a history of recurrent infections or perforated eardrums. It is essential to consider this bacterium in the differential diagnosis of chronic otitis media, especially in patients who have failed to respond to antimicrobial treatment.
**Correct Answer:** C. Pseudomonas aeruginosa