Changing Trends in the Fungal Aetiology of Chronic Suppurative Otitis Media and Antifungal Susceptibility Patterns of Isolated Fungi: A Pilot Study From a Tertiary Care Centre in Central India

Introduction Middle-ear and mastoid mucosal inflammation that persists for at least six weeks with discharge is known as chronic suppurative otitis media (CSOM). It is prevalent in India, and fungal infections contribute to a notable proportion of cases. Irrational use of steroids and antibiotics is associated with increased fungal isolates. This study aims to evaluate the presence, profile, and antifungal susceptibility (AFST) of fungi in CSOM patients, using Sensititre™ YeastOne® (Thermo Fisher Scientific, Waltham, MA, USA) colorimetric broth microdilution for yeasts and disk diffusion for moulds, although bacterial causes are well established. Materials and methods This study was a one-year cross-sectional study conducted in the Department of Microbiology in collaboration with the Departments of Microbiology and ENT-Head & Neck Surgery. This one-year cross-sectional study included patients aged 12 years or older with purulent ear discharge lasting at least six weeks. Samples of middle ear exudate were gathered and prepared for mounting and culture in 10%-20% potassium hydroxide (KOH). Isolates of yeast or mould were identified at the species level using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS; Bruker Daltonics, Bremen, Germany). For the isolated yeasts, AFST was performed using the Sensititre™ YeastOne® colourimetric broth microdilution method in accordance with the CLSI M27-A3 standard, and results were interpreted according to the M60 guideline. The data were collected in an Excel sheet (Microsoft® Corp., Redmond, WA, USA), and the statistical analysis involved both descriptive and inferential techniques. Results A total of 136 clinical samples were analyzed in the study. Of these, 27 (19.9%) were KOH positive, including 12 (44.4%) that were culture negative. Overall, 30 samples (22.1%) were culture positive, of which 15 (50%) were KOH negative. The overall fungal prevalence in the study was 42 (30.9%). Among the 30 culture-positive cases, six (20%) were moulds, and 24 (80%) were yeasts. Candida albicans (n = 9) was less common than non-albicans Candida (NAC) isolates (n = 15); however, it was the most prevalent single yeast species among culture isolates (30%). Trichomonascus ciferrii and Candida auris each had four (13.3%) isolates. Candida orthopsilosis (3, 10.0%), Candida metapsilosis (2, 6.7%), and Candida tropicalis (2, 6.7%) were among the other yeasts found. Aspergillus fumigatus was the most prevalent species among mould isolates (3, 10.0%), followed by Aspergillus flavus (1, 3.3%), Aspergillus niger (1, 3.3%), and Fusarium solani (1, 3.3%). After performing AFST on yeast isolates, most isolates showed resistance to one or more antifungal drugs tested, particularly C. auris and T. ciferrii isolates. Conclusion There is currently a change in the fungal etiological pattern in CSOM patients, with increased isolation of new species, including T. ciferrii, C. auris, C. orthopsilosis, and C. metapsilosis. Identification of fungi to the species level is crucial for treatment, as many yeast species have demonstrated resistance to one or more antifungal drugs. Echinocandins and amphotericin B continue to work, but yeasts - particularly NAC species, like C. auris and T. ciferrii - often exhibit significant azole resistance.