Exploring Antibiotic Susceptibility in Otomycosis: Uncovering Mixed Infections of Fungal and Bacterial Origin in Indonesia

Otomycosis is a common fungal ear infection affecting people worldwide. Cases may be exacerbated by mixed fungal-bacterial infections, especially those involving antibiotic-resistant bacteria. Understanding the microbiological features and antibiotic susceptibility patterns of the pathogens involved is critical for treatment. This study aimed to investigate the prevalence of mixed fungal-bacterial infections in otomycosis cases in Indonesia, to identify the bacterial species involved, and to determine their antibiotic susceptibility patterns.

In this study, 47 ear swab specimens were collected from 41 clinically-diagnosed otomycosis cases from April to August 2022. The collected samples were processed by culture and microscopy to identify fungal and bacterial isolates. Antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method.

Fungal isolates alone were detected in 80.9% of the specimens, while 19.1% showed mixed fungal-bacterial growth. The most common fungi were Aspergillus (57.1%) and Candida (42.9%) species. Among bacterial isolates, Staphylococcus aureus was the most frequent (observed in 66.7% of mixed cases), followed by Pseudomonas aeruginosa (22.2%). Also, two of the six S. aureus isolates were methicillin-resistant (MRSA). Both P. aeruginosa isolates were extended-spectrum beta-lactamase (ESBL) producers.

Many otomycosis cases in this study demonstrated polymicrobial etiology. The emergence of antibiotic-resistant bacteria poses diagnostic and therapeutic challenges to healthcare systems.