A young man is seen in a shelter in San Antonio after being evacuated from New Orleans after the devastating floods of Hurricane Katrina (Figure 127-1). He has facial pain and swelling and noticeable pus near the eye. His vision is normal. The area is anesthetized with lidocaine and epinephrine. The abscess is drained with a #11 blade. The patient is started on oral trimethoprim/sulfamethoxazole double-strength, two tablets twice daily, because of the proximity to the eye and the local erythema and swelling that could represent early cellulitis. A culture to look for methicillin-resistant Staphylococcus aureus (MRSA) was not available in the shelter, but close follow-up was set for the next day, and the patient was doing much better.
Abscess seen on the face of a man after evacuation from the floodwaters of New Orleans following Hurricane Katrina. (Reproduced with permission from Richard P. Usatine, MD.)
An abscess is a collection of pus in infected tissues. The abscess represents a walled-off infection in which there is a pocket of purulence. In abscesses of the skin, the offending organism is almost always S. aureus.1
ETIOLOGY AND PATHOPHYSIOLOGY
Most cutaneous abscesses are caused by S. aureus.1,3
MRSA is the most common type of S. aureus found in abscesses (Figures 127-2 and 127-3).
One study that evaluated management of skin abscesses drained in the emergency department showed that there was no significant association between amount of surrounding cellulitis or abscess size and the likelihood of MRSA-positive cultures.4
A dental abscess can spread into tissue outside the mouth, as in the person experiencing homelessness in Figure 127-4.
MRSA abscess on the back of the neck that patient thought was a spider bite. Note that a ring block was drawn around the abscess with a surgical marker to demonstrate how to perform this block. (Reproduced with permission from Richard P. Usatine, MD.)
Large MRSA abscess on the leg in a 62-year-old man beginning to drain spontaneously. The abscess cavity was large, and patient was placed on trimethoprim-sulfamethoxazole (TMP-SMX) to cover the surrounding cellulitis. (Reproduced with permission from Richard P. Usatine, MD.)
Neck abscess secondary to dental abscess in a homeless man. ...