Aetiology of ear infection and antimicrobial susceptibility pattern among patients attending otorhinolaryngology clinic at a tertiary hospital in Dar es Salaam, Tanzania: a hospital-based cross-sectional study

Abstract

Objectives: To determine the aetiological pathogens causing ear infections and their antimicrobial susceptibility patterns among patients with ear complaints at a tertiary hospital in Dar es Salaam.

Design: Hospital-based cross-sectional study.

Settings: Otorhinolaryngology clinic at Muhimbili National Hospital, Dar es Salaam, Tanzania.

Participants: Patients presenting with signs and symptoms of ear infection.

Main outcome measure: Bacteria and fungi isolated from ear swab specimens of patients presenting with signs and symptoms of ear infection; and antimicrobial susceptibility patterns of isolated bacteria.

Results: Two hundred and fifty-five participants were enrolled, with a median age of 31 years and an IQR of 15-49. Otitis externa was the predominant type of ear infection, accounting for 45.1%. We observed positive bacteria culture in 53.3% of study participants, in which 41% of isolates were obtained from patients with chronic suppurative otitis media. Moreover, Staphylococcus aureus (27.3%) and Pseudomonas aeruginosa (24.2%) were the most frequently isolated bacteria, while Candida spp, 12 (63.8%) and Aspergillus spp, 9 (36.2%) were the only isolated fungi. Furthermore, we report that 93% of isolated Enterobacterales were resistant to amoxicillin/clavulanic acid, and 73% were resistant to ceftazidime. In addition, we detected 34.4% extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE) and 44.4% methicillin-resistance S. aureus (MRSA). We also found that 22% of the bacteria isolates were resistant to ciprofloxacin, a primary topical antibiotic used in managing ear infections.

Conclusions: The findings from this study reveal that the leading aetiological agent of ear infection is bacteria. Furthermore, our findings show a significant proportion of ESBL-PE and MRSA-causing ear infections. Hence, detecting multidrug-resistant bacteria is crucial to improving ear infection management.

Keywords: BACTERIOLOGY; MYCOLOGY; Microbiology.

Figure 1

Types of ear infection among study participants at MNH. The figure illustrates the distribution of ear infections among patients presenting with signs and symptoms of ear infection attending the otorhinolaryngology clinic at MNH (N=255). CSOM, chronic suppurative otitis media; MNH, Muhimbili National Hospital; OE, otitis externa; OM, otitis externa.

Figure 2

(A–C) Distribution of bacterial isolates. The figure depicts the distribution of bacteria spp isolated among patients with ear infections attending the otorhinolaryngology clinic at MNH (n=131) (A). According to the type of ear infection (n=131), where OM (otitis media), OE (otitis externa) and CSOM (chronic suppurative otitis media) (B). Distribution of ESBL-producing bacteria among isolated gram-negative bacteria in patients attending the otorhinolaryngology clinic at MNH (n=61) (C). ESBL, extended-spectrum beta-lactamase-producing Enterobacterales; MNH, Muhimbili National Hospital.