Volume 31, Issue 9, September 2025, 102782Author links open overlay panel, , , , , , , , , Abstract

Disseminated gonococcal infection (DGI) is a rare complication of Neisseria gonorrhoeae infection. Eculizumab, a complement C5 inhibitor used in conditions such as paroxysmal nocturnal hemoglobinuria, increases the risk of invasive Neisseria spp. infections. Although previous reports have described DGI in eculizumab-treated patients, evidence involving individuals with neuromyelitis optica spectrum disorder (NMOSD) is limited, and all cases occurred weeks to months after treatment initiation. In the present case, the patient received a quadrivalent meningococcal vaccine before receiving eculizumab. Two days after the first dose, the patient presented with fever, chills, and headache. Laboratory findings revealed leukocytosis and mildly elevated C-reactive protein levels, with unremarkable urinalysis and cerebrospinal fluid results. Blood cultures revealed the presence of N. gonorrhoeae, confirming DGI. A blood test on day 5 revealed a CH50 level of 6.0 U/mL. Screening for other sexually transmitted infections was negative. Antimicrobial susceptibility testing revealed elevated minimum inhibitory concentrations (MICs) for penicillin G, ciprofloxacin, azithromycin, and minocycline, whereas the MIC for ceftriaxone remained low. The patient received intravenous ceftriaxone for 14 days. Following the patient's refusal to continue eculizumab therapy, the patient has chosen inebilizumab, resulting in stable management of NMOSD symptoms. The patient has been attending outpatient appointments approximately every two months, and no recurrence of gonococcal infection has been observed for at least 2 years. This is a case of DGI in a patient with NMOSD, and the earliest reported onset of DGI following eculizumab initiation. Clinicians should remain vigilant for invasive gonococcal infections, even shortly after initiating complement-inhibiting therapy.

Introduction

Disseminated gonococcal infection (DGI) is a rare complication of Neisseria gonorrhoeae infection, occurring in <3 % of all gonorrhea cases [1]. DGI typically manifests as one of two clinical syndromes: a bacteremic form characterized by fever, polyarthralgia, tenosynovitis, and rash, or a localized septic arthritis form [2,3]. Although its clinical presentation may vary, DGI can occur even in the absence of genitourinary symptoms or known sexual risk factors, making early diagnosis challenging.

The risk of invasive infections caused by Neisseria species, including Neisseria meningitidis and N. gonorrhoeae, and deficiencies in terminal complement components, whether congenital or acquired, are strongly associated [4,5]. Eculizumab, a humanized monoclonal antibody that inhibits C5 [6]. Given this mechanism, the risk of DGI in patients receiving eculizumab is a recognized concern.

Here, we report a case of early onset gonococcal bacteremia that occurred within days of the initiation of eculizumab therapy in a patient with anti-AQP4 antibody-positive neuromyelitis optica spectrum disorder (NMOSD).

Section snippetsCase report

A Japanese man in his 20s was diagnosed with anti-AQP4 antibody-positive NMOSD based on the diagnostic criteria two years prior, following an episode of optic neuritis [7,8]. The patient received one course of high-dose intravenous corticosteroids (the specific dose administered at the previous hospital was unknown), followed by seven sessions of plasma exchange, which resulted in clinical improvement. Subsequently, the patient was administered oral prednisolone at a dose of 10 mg/day. However,

Discussion

We encountered a case of early onset gonococcal bacteremia that occurred two days after the initiation of eculizumab therapy in a patient with NMOSD. Several points must be addressed in this regard.

Eculizumab, a humanized monoclonal antibody that inhibits C5, increases the risk of serious infections caused by Neisseria species by inhibiting terminal complement activity and compromising host immune defense [10,11]. Although N. meningitidis is the most well-known pathogen associated with

Ethical approval

Written Informed consent was obtained from the patient for the publication of this case report.

Funding

This study did not receive any specific grants from funding agencies in the public, commercial, or non-profit sectors.

Conflicts of interest

None.

Acknowledgments

Editage has provided English editing and Publication Support.

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