John, a 22 year old construction worker, presented to his primary care doctor with a swollen red spot on his upper back. John is overweight and has high blood pressure, for which he takes a diuretic daily. He works outdoors and since it is summer he gets hot and sweaty and will often change his shirt during the day at work. He states over the last few days he has had a sore spot on his back that has gotten larger and it now hurts when he leans back against a chair. During a physical he was found to have a low grade fever, and a fluctuant abscess that was 2cm x 3 cm ovoid, with another 2 cm in surrounding erythema. The area was very tender to the touch and so his doctor performed an I & D (incision and drainage) of the site in the office and prescribed John an oral antibiotic. The wound was packed with gauze and he was told to return in 2 days to have the gauze removed. Required:
a. What are the most common causative agents for abscess formation?
b. If John did not go to his doctor what are some complications that could occur from not seeking treatment for his abscess?
c. What was the purpose of giving John an oral antibiotic and why was the wound packed with gauze?