Relapsing Campylobacter jejuni Systemic Infections in a Child with X-Linked Agammaglobulinemia

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency of the humoral compartment, due to a mutation in the Bruton tyrosine kinase (BTK) gene, characterized by a severe defect of circulating B cells and serum immunoglobulins. Recurrent infections are the main clinical manifestations; although they are especially due to encapsulated bacteria, a specific association with Campylobacter species has been reported. Here, we report the case of a boy with XLA who presented with relapsing Campylobacter jejuni systemic infections. His clinical history supports the hypothesis of the persistence of C. jejuni in his intestinal tract. Indeed, as previously reported, XLA patients may become chronic intestinal carriers of Campylobacter, even in absence of symptoms, with an increased risk of relapsing bacteraemia. The humoral defect is considered to be crucial for this phenomenon, as well as the difficulties to eradicate the pathogen with an appropriate antibiotic therapy; drug resistance is raising in Campylobacter species, and the appropriate duration of treatment has not been established. C. jejuni should always be suspected in XLA patients with signs and symptoms of systemic infection, and treatment should be based on antibiogram to assure the eradication of the pathogen. 1. Introduction X-linked agammaglobulinemia (XLA) is a primary immunodeficiency characterized by an abnormal development of B lymphocytes and severe hypogammaglobulinemia, due to a mutation in the Bruton Tyrosine Kinase (BTK) gene. Campylobacter is responsible for persistent infections in XLA patients [1]. We report the case of a boy with XLA who presented with relapsing Campylobacter jejuni systemic infections. 2. Case Report A one-year-old boy admitted for severe Staphylococcus aureus impetigo and sepsis was diagnosed with XLA (missense mutation of BTK gene 1706 G>C, R525P; absent expression of BTK protein from western blot analysis). Treatment with intravenous immunoglobulins (IVIGs) every 28 days was started. Followup had been uneventful until the age of 8 when he was admitted for painful swelling and hyperemia of the left knee, suggestive for a cellulitis. Anamnesis was negative for recent infections or trauma. A knee ultrasound revealed a small intra-articular fluid collection. Blood exams showed neutrophilic leukocytosis with normal. C-reactive protein and IgG level was 807？mg/dL. Microbiological investigations could not be performed. Empiric treatment with piperacillin/tazobactam was promptly started, with a rapid resolution of symptoms. During admission, the child presented