Antimicrobial Susceptibility Pattern and Biofilm Forming Potential of Bacteria Isolated from Suspected External Ocular Infected Patients Attending Jimma University Medical Center Eye Clinic, Southwest Ethiopia

Abstract

Background: Ocular disease and its complications are a significant health problem worldwide with particular significance to developing countries that impacts greatly on quality of life. Ocular infections due to bacteria can cause damage to structure of the eye, which can leads to reduced vision and blindness. The emergence of antimicrobial resistance and development of bacterial biofilm in ocular infection is currently increasing the risk of treatment failure with potentially serious consequences. Objective: The study was aimed to assess the antimicrobial susceptibility pattern and biofilm forming potential of bacteria isolated from suspected external ocular infected patients at Jimma University Medical Center, Jimma, Ethiopia. Method: A cross sectional study was conducted on 319 suspect patients with external ocular infections from March 2017 to June 2017 at Jimma University Medical Center, department of ophthalmology. External ocular specimens were collected using sterile swabs after patients were examined by ophthalmologists. The specimens were shipped in Amiens transport media to Microbiology Laboratory for isolation and identification. Samples were inoculated onto Blood agar, Chocolate agar, MacConkey agar and Mannitol salt agar. Presumptive isolates of gram positive and gram negative bacteria were further identified by a series of biochemical tests. The antimicrobial susceptibility pattern of the isolates was determined by disk diffusion method according to CLSI 2015. Microtiter (96 wells) plate method was used to screen the biofilm formation by measuring optical density at 570nm using ELISA reader. Result: Out of 319 study participants with external ocular infection, prevalence of bacterial pathogens was 46.1%. The predominant bacterial isolate were Coagulase negative staphylococcus (CoNS) (27.7%) followed by Staphylococcus aureus (19.7%). Among gram negative, Pseudomonas aeroginosa (6.8%) was the leading isolate. Increased antimicrobial resistance was observed in tetracycline (64%), erthromycin (66.7%) and penicillin (77.1%). Amoxicillin-clavulanic acid, ciprofloxacin and gentamicin were the most effective drugs for both gram negative and gram positive ranging from 69-100%. About 13.8% of S. aureus was methicillin resistant (MRSA). Multidrug resistance accounted for 68.7%. The overall biofilm formation rate of isolates was 66.1% with P. aeroginosa (40%), CoNS (34.1%) and S. aureus (31%) formed strong biofilm. Conclusion: The prevalence of bacterial isolates among external ocular infection was high. Almost all bacterial isolate were resistant to atleast one or more drugs. Multidrug resistance pathogens were observed increasingly biofilm formers. Therefore, antimicrobial susceptibility testing should be practiced to guide treatment of patients and to control the emergence of drug resistant bacteria.