A 75-year-old gentleman undergoes a cholecystectomy for recurrent bouts of gallstones. Ten days after the surgery he develops pain and swelling of the right parotid gland. Which of the following is most likely to be the cause of the parotid swelling?

b. This patient has acute infection of the parotid gland or acute parotitis. Patients with poor dental hygiene and those who have been intubated are most at risk. Staphylococcus aureus is the organism most commonly responsible for this. Most often the treatment for this condition would require surgical drainage and antibiotics. Mumps is a common cause of parotitis although now only seen in outbreaks usually among children and young adults that have failed to be immunised. Haemorrhage into the gland is incredibly rare and trauma during this surgery is unlikely due to its position. Sialolithiasis or stones in the salivary glands could be the cause of this presentation, although there is no relationship between stone development and surgery.