A 54-year-old man with long-standing type 2 diabetes and peripheral neuropathy presents with a plantar ulcer under the first metatarsal head with surrounding erythema and foul-smelling discharge. He is febrile to 38.5 °C and has tachycardia 104 beats/min. Pedal pulses are diminished. X-ray suggests possible osteomyelitis. According to Australian practice, what is the most appropriate next step?