Which bacterium is the most common pathogen seen in otitis externa infections?

Pseudomonas aeruginosa is the most common pathogen associated with otitis externa infections, often referred to as "swimmer's ear." This bacterium thrives in moist environments, making the ear canal particularly susceptible to infection following water exposure. The infection can lead to inflammation and irritation of the external ear canal, typically presenting with symptoms such as itching, redness, and discharge.

In the context of bacterial characteristics, Pseudomonas aeruginosa is a gram-negative bacillus known for its resistance to many antibiotics and its ability to survive in various environments, which contributes to its prevalence in otitis externa cases. The presence of this pathogen underscores the importance of keeping the ears dry and clean, particularly in those who frequently swim or expose their ears to water.

Other potential pathogens, such as some of the options listed, may cause infections in different contexts but are not as commonly linked with otitis externa specifically. Understanding the predominant bacteria involved allows for targeted treatment and effective preventative measures.