Rationale:
Complement deficiency are known to be predisposed to disseminated gonococcal infection (DGI). We herein present a case of DGI involving a Japanese man who latently had a complement 7 deficiency with compound heterozygous variants.
Patient concerns:
A previously healthy 51-year-old Japanese man complained of sudden-onset high fever. Physical examination revealed various skin lesions including red papules on his trunk and extremities, an impetigo-like pustule on left forearm, and tendinitis of his right forefinger.
Diagnosis:
Blood culture testing detected gram-negative cocci, which was confirmed to be
Neisseria gonorrhoeae
based on mass spectrometry and a pathogen-specific PCR test.
Interventions:
Screening tests for underlying immunocompromised factors uncovered that complement activities (CH50) was undetectable. With a suspicion of a congenital complement deficiency, genetic analysis revealed rare single nucleotide variants in complement 7 (C7), including c.281-1G>T and a novel variant c.1454C>T (p.A485V). CH50 was normally recovered by adding purified human C7 to the patient's serum, supporting that the patient has C7 deficiency with compound heterozygous variants.
Outcomes:
Under a diagnosis of DGI, the patient underwent an antibiotic treatment with cefotaxime for a week and was discharged without any sequela.
Lessons:
DGI is a rare sexually-transmitted infection that potentially induces systemic complications. Complement immunity usually defeats
N. gonorrhoeae
and prevents the organism from causing DGI. This case highlighted the importance of suspecting a complement deficiency when a person develops DGI.
