Study design, participants and sampling method.
This was a hospital based descriptive cross-sectional study conducted between September 2015 and February 2016 and included 1200 patients who attended Otorhinolaryngology (ORL) Department at Muhimbili National Hospital. Convenient sampling technique was utilized.
Inclusion and exclusion criteria
All adult patients who consented to participate in the study and those under the age of 18 years whose parents/caretakers consented on their behalf. Patients on regular follow up were excluded.
Specimen Collection Procedures
Pus swab was collected from the external auditory canal and introduced into Amies transport medium bottle and sent for laboratory analysis.
Laboratory Procedures
From each specimen, a portion was subjected to primary gram stain for pus cells and possible organism while the remaining portions were inoculated into Blood agar (Oxoid, UK), and MacConkey agar (Oxoid, UK) and incubated aerobically at 370C for 24-48 Hours.
Identification of Bacterial Pathogens
Identification of pathogens was based on Microscopy (Gram stain, shape, cells arrangement) and colony characteristics (colony morphology, hemolysis on blood agar, changes in the physical appearance of the differential media). Organisms from discrete colonies were cultured into Nutrient Agar (Oxoid, UK) for subsequent. Biochemical tests. Gram positive isolates were tested for catalase and Coagulase tests while biochemical tests for gram negative isolated bacteria were tested for oxidase, Triple sugar Iron (TSI), Sulphur indole and motility (SIM), urease production and citrate utilization [15].
Antimicrobial Susceptibility Testing
Antibiotic susceptibility pattern of isolated bacteria pathogens was performed using modified Kirby Bauer disc diffusion method according to the guidelines of the clinical and Laboratory Standard Institute(CLSI) [16].
A colony suspension with concentration equivalent to 0.5 McFarland solution was prepared for each identified isolate and inoculated into Mueller Hinton-Agar (Oxoid, UK). Appropriate Selected Antibiotic discs were placed onto the media and incubated at 37°Celsius for 24 hours.
Gram positive isolates were tested against Ampicillin (10µg), Amoxicillin/clavunate (20/10µg), Ceftriaxone(30µg), Gentamycin (10µg), Ciprofloxacin (5µg), Trimethoprim/sulfamethoxazole (1.25/23.75µg), Chloramphenicol (30µg), Amikacin (17 µg) and Cephalexin (18 µg).
Gram negative organisms were tested against Ampicillin (10µg), Amoxicillin/clavulanate (20/10µg),Ceftriaxone(30µg),Gentamicin(10µg),Ciprofloxacin,(5µg),Triomethoprim/sulfamethoxazole (1.25/23.75µg) and Chloramphenicol (30µg). Reference stains used for quality control were Staphylococcus aureus (American Type Culture Collection; ATCC 25922 and ATCC 29213), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC2785) [15,16].
Data analysis
Data analysis was done using the Statistical Package for Social Sciences version 21. p-value of <0.05 was considered statistically significant.