SUSCEPTIBILITY PROFILES OF MULTIPLE ANTIBIOTIC-RESISTANT BACTERIAL ISOLATES FROM HEALTHY EARS OF STUDENTS TO SELECTED BRANDS OF GENTAMICIN AND CHLORAMPHENICOL EAR DROPS MARKETED IN NIGERIA
HABIB ADEMOLA BAKENNE1*, MICHEAL OLUWOLE OSUNGUNNA1, FLORENCE OLUBUNMI AKINWUMI1, DEBORAH IFEOLUWA ONIFADE1
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria.
Afr. J Pharm Res Dev; Volume 18(1): 599-607 ; 2026
ABSTRACT
The human ear has a diverse microbial community, some of which may turn into opportunistic pathogens under favourable conditions. Antimicrobial resistance among ear flora is a rising public health concern in healthy individuals. In our study, we investigated the susceptibility profiles of bacteria isolated from healthy ears of students to systemic antibiotics and selected commercial eardrop formulations. Ear swab samples from healthy students were cultured, and isolates were identified through morphological, Gram stain, and biochemical tests. The susceptibility of the identified organism to commonly used antibiotics was evaluated using the disc diffusion method and interpreted in accordance to CLSI guidelines. The organisms recognized to be multidrug resistant were further tested against five brands of gentamicin ear drops and one brand of chloramphenicol ear drops using the agar well diffusion method, with constant volumes, controls, and formulation details recorded. A total of 100 isolates were recovered, comprising Staphylococcus, Micrococcus, and Bacillus species. There was high susceptibility to levofloxacin, ciprofloxacin, chloramphenicol, and gentamicin, with resistance mainly to azithromycin and Meropenem among the isolates. Majority of the isolates were resistant to multiple antibiotics. However, all identified multiple antibiotic-resistant isolates were susceptible to the tested eardrop formulations. The findings highlight the persistence of multidrug resistant bacteria in the normal ear flora. It also affirms the retained efficacy of quality topical preparations, thus providing a basis for their value in localized infections.
Keywords: Healthy ear, antimicrobial resistance, gentamicin, chloramphenicol, ear drops, multi-drug resistance
Email of correspondence: bakenneademola@gmail.com;
https://doi.org/10.59493/ajopred/2026.1.20 ISSN: 0794-800X (print); 1596-2431 (online)