Complement C7 deficiency presenting as recurrent aseptic meningitis

Background: Complement deficiency states are rare inherited disorders that may predispose affected individuals to angioedema, collagen vascular disease, or infection due to encapsulated organisms, especially Neisseria meningitidis. Objectives: To report the case of a 36-year-old man of Irish descent with recurrent culture-negative neutrophilic meningitis, to offer potential reasons for the inability to recover a causative pathogen, and to review the genetics and prevalence of complement deficiency states, the methods of screening for such deficiencies, the features of meningococcal infection as they relate to such deficiencies, and management strategies for clinicians caring for patients with such deficiencies. Methods: The patient presented in 1988 and again in 2002 with culture-negative neutrophilic meningitis. His second episode was characterized by a rash suggestive of meningococcal infection, prompting immunologic evaluation. Results: Immunologic evaluation revealed ail undetectable CH50 level. Levels of C1, C2, and C5 through C9 were normal except for C7, which was undetectable. Further testing revealed that the patient's sister was also C7 deficient. Conclusions: Complement component deficiencies are relatively rare; individuals with collagen vascular disease and systemic neisserial infection should be screened using either the CH50 or the APH-50 assay. Key to the management of a late-complement component-deficient host is counseling, education about meningococcal infection, and discussions about the potential benefits of chemoprophylaxis and immunoprophylaxis. The ability to detect the bacterial cause of meningitis in such patients is organism dependent and may be influenced by factors such as cerebrospinal fluid bacterial concentration and previous antibiotic drug exposure.