Type A immunoglobulin deficiency presenting as a mixed polymicrobial brainabscess: Case report

OBJECTIVE AND IMPORTANCE: We present a case report of a patient with a left frontal brain abscess. Cultures obtained from the abscess at the time of s urgery were identified as dental flora known to establish a synergistic rel ationship in polymicrobial infections. This type of synergistic relationshi p makes the clearance of an infection more difficult for an intact immune s ystem. A serum immunoglobulin (Ig) Type A deficiency was identified postope ratively. This immunodeficiency may have contributed to the development of the abscess. CLINICAL PRESENTATION: The patient presented with headaches and photophobia . Computed tomography of the head performed with intravenously administered contrast demonstrated a left frontal brain abscess. INTERVENTION: The patient was operated on through a left frontal approach, carefully avoiding the frontal sinus. The abscess was aspirated, and the pa tient was treated with intravenous antibiotics for several weeks. Postopera tively, the patient did well. There were no signs of enhancement on follow- up computed tomographic scans at 7 and 12 months postoperatively. CONCLUSION: Through a comprehensive immunological workup, an IgA deficiency was identified postoperatively. Although the deficiency of a single type o f Ig may be asymptomatic, complications from recurrent or chronic bacterial infections may occur. The deficiency of IgA, combined with a synergistic p olymicrobial infection, contributed to the development of an intracranial a bscess. A patient presenting with a brain abscess without any predisposing medical history should be evaluated for an underlying immune deficiency.