Antibiotic sensitivity testing determines how effective antibiotic therapy is against bacterial infections. It involves identifying pathogens from patient samples, testing their sensitivity to antibiotics, and determining the appropriate dosage. Kirby-Bauer disk diffusion is a common method that uses antibiotic-impregnated disks placed on inoculated agar plates, and the zone of growth inhibition is measured to determine sensitivity. Regular testing is needed since bacteria can develop resistance over time.