Ear infections are a common cause of deafness in low/middle-income countries, with many patients delaying seeking medical attention, resulting in complications. Bacteria, such as Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, and Klebsiella species, are the primary pathogens causing ear infections globally. At the same time, Candida spp and Aspergillus spp are the dominant fungal isolates responsible for ear infections.
However, due to limited diagnostic opportunities, fungal ear infections are often undiagnosed, especially in resource-limited countries like Tanzania. Empirical treatment and adherence to standard treatment guidelines without laboratory investigation and antimicrobial susceptibility testing have created a gap in managing most ear infections, which raises the risk of acquiring multidrug-resistant bacteria.
In a new study published in BMJ Journals, researchers have found that understanding the aetiology of ear infections and resistance patterns is crucial in managing and planning interventions for ear infections. The study found that a substantial proportion of ear infections are caused by bacteria, with S. aureus and P. s aeruginosa being the leading bacterial aetiological agents. The study also found that fungi, including Candida spp and Aspergillus spp, can cause ear infections, with risk behaviors such as excessive use of ear drops containing antibiotics, regular cleaning of ears, and swimming increasing the risk of fungal ear infections.
The study revealed many multidrug-resistant bacteria, including MRSA and ESBL-PE, with Klebsiella spp being the dominant ESBL-PE. Overusing antibiotics, self-prescribing, and empirically prescribing antibiotics without considering laboratory culture and sensitivity and the increased tendency to visit hospital facilities due to chronic ear infections contributed to the high incidence of ESBL and MRSA. In addition, using inanimate objects to remove earwax also contributed to the high proportion of ESBL and MRSA.
The study found that most isolated bacteria were resistant to amoxicillin/clavulanic acid, with nearly three-quarters of Gram-negative bacteria being resistant to ceftazidime and about half being resistant to trimethoprim-sulfamethoxazole. ESBL-PE and MRSA isolates were found to be resistant to the most common antimicrobial agents compared with non-MRSA and non-ESBL-PE.
The study also revealed that most isolated bacteria were sensitive to meropenem and ciprofloxacin, with ciprofloxacin being a drug of choice for ear infections as per STGs. Quinolones are still beneficial as first-line topical antibiotics for ear infections.
However, the study has some limitations, including the inability to identify the fungi isolates to the species level due to insufficient funding and lack of equipment to isolate anaerobic bacteria from the collected pus specimen. The results of this study indicate that bacteria are the most common cause of ear infections in the studied context. The study highlights the need for antimicrobial susceptibility testing to guide clinicians in appropriately managing ear infections in the studied setting.