First report of human infection with Staphylococcus aureus subspecies anaerobius

An otherwise healthy 41 year old Korean woman presented to the Emergency Department with spontaneous purulent drainage from a punctum at the right costal margin, associated with right upper quadrant abdominal pain, right shoulder pain, and a diffuse pruritic rash. She had had recurrent subphrenic abscesses since childhood, without a microbiologic diagnosis. She immigrated to the United States at age 10, and last visited Korea 2 years prior to admission. Physical examination revealed fever, a diffuse erythematous rash, and odorless light green pus draining from a punctum at the right costal margin. Laboratories were remarkable for leukocytosis without a left shift and thrombocytosis. Abdominal CT revealed a large right subphrenic fluid collection. Fluid from the external drainage as well as operative cultures from the lumen and wall of the abscess revealed PMNs and Gram-positive cocci. Cultures grew only one organism, found to be an obligate anaerobe, catalase-negative, coagulase-positive, and biochemically consistent with S. aureus subsp. anaerobius. Exams for parasites, fungi, and AFB were negative. Penicillinase-resistant penicillin therapy following open drainage resulted in prompt resolution of the patient's symptoms. S. aureus subsp. anaerobius is the cause of abscess disease in lambs in Europe and Asia. This patient's abscesses have been recurrent since she was five years old, when she was caring for sheep in South Korea. While the duration of infection cannot be proven in this case, this organism might cause persistent infection similar to smalt-colony variant staphylococci. To our knowledge this is the first report of human infection with this organism, which may be under-recognized due to problems in sample handling or identification.