What is the preferred first antibiotic choice for malignant otitis externa?

Malignant otitis externa is a severe infection that typically occurs in individuals with diabetes or immunocompromised states and is often caused by Pseudomonas aeruginosa. The preferred first-line treatment for this condition involves an antibiotic that has excellent coverage against Pseudomonas.

Ciprofloxacin is a fluoroquinolone that is particularly effective against Pseudomonas aeruginosa, making it the ideal choice for treating malignant otitis externa. Its mechanism of action involves inhibiting bacterial DNA gyrase and topoisomerase IV, which are essential for bacterial DNA replication and cell division. This targeted approach helps to significantly reduce the bacterial load and manage the infection effectively.

Other antibiotics listed, such as amoxicillin, while effective against many common bacterial infections, do not provide adequate coverage for Pseudomonas aeruginosa. Vancomycin is primarily used for treating infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and does not cover Pseudomonas. Ceftriaxone has a broader spectrum but is not as effective against Pseudomonas compared to ciprofloxacin.

Therefore, the choice of ciprofloxacin is based on its efficacy in treating the specific pathogens associated with malignant otitis externa,