Frequency, Types and Antimicrobial Susceptibility Pattern of Bacteria in Culture Positive Ear Swabs of Patients Attending Referral Hospital in Southern Zone of Tanzania

Abstract

Background: Ear infections affect adults and children, and when left untreated, they may cause hearing loss and lifethreatening
complications. In our setting, ear infections are a common health problem. However, there is paucity of
information on the etiology and antimicrobial susceptibility pattern.
Objective: This study aimed to determine the spectrum of bacteria causing ear infection and their antimicrobial
susceptibility patterns at Secondary-level health facilities.
Methods: This cross sectional retrospective hospital-based study reviewed 288 data of patients diagnosed with ear
infections from January 2021 to March 2023. Demographic, isolates and antimicrobial susceptibility information’s were
abstracted. Multidrug resistance (MDR) was regarded as resistance to at least one antibiotic in three or more categories/
groups of antibiotics. Analysis was done using STATA software version 15. Descriptive analysis was summarized as
frequency and proportion for categorical variables, and results presented using tables.
Results: We included 288 (50.4%) positive bacteria culture out of ear swab samples collected for culture in the analysis.
Of the total bacterial isolates, majority were gram-negative, 178 (58.2%). The predominant isolate was Staphylococcus
aureus 124 (40.5%), followed by Pseudomonas aeruginosa 80 (26.1%). Mixed bacterial infection was observed in
18 (6.2%) patients. Most enterobacterales were resistant to ampicillin, amoxicillin/clavulanic acid, tetracycline and
trimethoprim-sulfamethoxazole. Pseudomonas aeruginosa was highly resistant to piperacillin. Multidrug resistance (MDR)
was observed in 245 (80%) of the isolates. Gram positive isolates showed high resistance to erythromycin. Methicillinresistant
Staphylococcus aureus (MRSA) was observed in 67(59.3%) isolated Staphylococcus aureus.
Conclusion: Staphylococcus aureus and Pseudomonas aeruginosa were the predominant isolates in ear infections. Most
of the bacteria were resistant to commonly used antibiotics. Multidrug resistance and MRSA were highly observed.
Therefore, an antibiotic susceptibility test is important to guide antibiotic prescription practice.