Specific antibody deficiency was previously known as selective antibody deficiency with normal immunoglobulins (SADNI). The diagnosis of SAD depends on normal immunoglobulin and IgG subclass levels, as well as a normal reaction to protein-based and conjugate vaccinations. The only immunologic deficiency in patients with SAD is an abnormal response to polysaccharide antigens, as found in the PPV23, known as the twenty-three valent pneumococcal vaccine.

The patient is a 32-year-old male with a past medical history of intravenous (IV) drug use and a recently diagnosed methicillin-resistant Staphylococcus aureus right calf abscess who presented with a two-week history of left eye pain.