Bacteriology of Otitis Externa in a Tertiary Health-care Institution in Nigeria

Background: Otitis externa is the inflammation of the external auditory canal (EAC); it may be acute, subacute, or chronic in nature and the causative agents are usually bacteria, though occasionally fungi. Aim: This study aimed to determine the prevalence of bacterial acute otitis externa (AOE) and the pattern of bacterial isolates in AOE. Material and Methods: This was a cross-sectional, hospital-based study involving 100 patients with otitis externa. Patients were recruited from ear, nose, and throat (ENT) outpatient clinic using consecutive sampling technique until the required sample size was achieved. The discharge from discharging ears was taken with ear swabs and evaluated for microbial agents. Data analysis was done using SPSS-IBM version 25. Results: A total of 100 patients were recruited; the patients aged from 4 to 57 years (mean age is 18.78 ± 10.67) years, with a male-to-female ratio of 1:1.1. One hundred and twenty-four external ear discharge samples were cultured among 100 study groups, of which bacteria was isolated in 77 (62.1) and no bacterial agent was isolated in 47 (37.1). Pseudomonas aeruginosa 32 (41.6) was the most common bacteria isolated, followed by Staphylococcus aureus - 13 (16.9); others include Proteus mirabilis - 7 (9.0), Escherichia coli - 4 (5.2), Streptococcus pneumonia - 4 (5.2), Klebsiella pneumoniae - 3 (3.9), Streptococcus pyogenes - 3 (3.9), and Enterobacter aerogenes - 2 (2.6). Conclusion: Otitis externa affects all age groups and genders; bacteria are a more prevalent causative agent. The common predisposing factors are the use of objects in scratching or cleaning EAC, use of earpiece, and swimming. The prevalence of bacterial otitis externa was 7.1, and Gram-negative aerobes are the most prevalent. Keywords: Acute otitis externa, bacteriology, ear discharge, ear swabs, Sokoto