This case study examines infectious conjunctivitis, focusing on a patient named John. It identifies Staphylococcus aureus as the likely cause of his eye infection, differentiating it from other microorganisms like Legionella pneumophila, Plasmodium ovale, and Adenovirus. The study delves into the mechanism of action of gentamicin, an antibiotic used to treat the infection, and its adverse reactions. It also explores the physiological basis of the signs and symptoms, including painful, red, and swollen eyes, as well as purulent discharge. Furthermore, the case study addresses infection control issues related to personal hygiene and physical impairments in elderly patients. It explains the transmission of the infection and outlines procedures for breaking the chain of infection, such as maintaining personal hygiene and handwashing. The assignment adheres to APA 6th edition referencing style and is supported by relevant literature.