Bacteriological Profile, Drug Resistance Pattern and its Molecular Characterisation Among Patients with Chronic Suppurative Otitis Media at a Tertiary Care Hospital in South India

Millions of people worldwide suffer from chronic suppurative otitis media (CSOM), a recurrent infection of the ear that is particularly common in low-resource environments. Although there are several etiological factors, bacterial infection is a significant one. The two most frequently isolated bacteria are Staphylococcus aureus and Pseudomonas aeruginosa. Due to the emergence and spread of bacterial resistance to several antimicrobial agents and also their ability to form biofilms, treatment and recovery are made more challenging. Our aim was to identify the clinico-bacteriological profile, their antimicrobial susceptibility pattern and a molecular method to identify the antibiotic resistance genes of the most common isolates in this study. Following approval from the Institutional Human Ethics Committee (IHEC) and patient informed consent, we obtained ear discharge samples from 100 CSOM patients over a two-year period. The isolates were recognized by conventional microbiological methods. Polymerase chain reaction (PCR) was used for molecular characterisation in order to identify genes linked to antibiotic resistance (e.g., efflux pump-related genes associated with P. aeruginosa and mecA for S. aureus). Of the 100 patient samples, 84 samples showed positive results for culture; 58% of the Gram-positive cocci were S. aureus and 42% of Gram-negative bacilli were P. aeruginosa. Methicillin resistance in S. aureus is indicated by the presence of the mecA gene (43%) and carbapenem resistance in P. aeruginosa is indicated by the presence of the blaVIM gene (22%), according to genotypic study. Our work provides insight with regard to the genetic makeup of P. aeruginosa and S. aureus in CSOM patients, which demonstrates that these bacteria have several resistance genes that enable them to withstand antimicrobial therapy.