Stool Screening for Campylobacter Species in Hypogammaglobulinemic Patients Receiving Immunoglobulin Therapy

Hypogammaglobulinemia (HG) predisposes patients to gastrointestinal Campylobacter infections. This prospective study determined the prevalence of Campylobacter in stool samples from patients with immunoglobulin (Ig)-substituted HG at Bordeaux University Hospital. 73 patients (42 women, median age: 61) receiving Ig substitution therapy were enrolled from July 2022 to July 2024. Stool samples were analysed with culture, PCR, faecal calprotectin levels, and immune profiles were also assessed. A second stool sample was collected from 38 patients after 6-12 months, totalling 111 samples. 53 patients had primary HG (32 common variable immunodeficiency, 7 IgG subclass deficiencies, 4 Bruton's agammaglobulinemias) and 20 had secondary HG (7 drug-induced, 8 lymphoid hemopathy-related, 5 mixed). Campylobacter were detected in 11 patients (15.1%), with species identified as Campylobacter jejuni, Campylobacter coli, and Aliarcobacter butzleri. Diarrhea was reported in 42% of Campylobacter-positive patients versus 15% of negative patients. Campylobacter-positive patients exhibited higher median faecal calprotectin levels (255 µg/g vs. 52 µg/g). Among positive patients, 44% (versus 34% in negative patients) had non-infectious complications such as immune complications. Mean residual IgG levels were similar between groups, although IgA and IgM were lower in Campylobacter-positive patients (0 vs. 0.36 g/L and 0.17 vs. 0.40 g/L, respectively). The mean CD4/CD8 ratio was also lower in the positive group (1.71 ± 0.85 vs. 2.06 ± 1.18). This study reveals a high prevalence of Campylobacter in HG patients despite receiving Ig therapy. Elevated faecal levels of calprotectin in symptomatic patients suggests active infection. Screening for Campylobacter should be considered in HG patients presenting with digestive symptoms.