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Interleukin-1 receptor-associated kinase (IRAK)-4 deficiency is a rare primary immunodeficiency disorder characterized by severe, invasive infections with Streptococcus pneumoniae. Using the PFGE technique a genetic linkage was found between two S. pneumoniae serotype 14 isolates causing arthritis and meningitis at 3 and 5½ years of age, respectively, in a boy with IRAK-4 deficiency. This finding suggested that patients with IRAK-4 deficiency may harbour persistent strains of pneumococci. Alternatively, reinfection with strains from close contacts of the patient might cause recurrent invasive disease. It is proposed that eradication of pneumococci from the nasopharynx, and immunization of household contacts may prevent recurrent infection in IRAK-4-deficient patients.

Summary The opsonic requirement for phagocytosis and killing and cell-surface hydrophobicity of five strains of Staphylococcus saprophyticus isolated from clinical sources were studied. Phagocytosis and killing of bacteria by human granulocytes were measured in suspension. Bacterial aggregating cell-surface hydrophobicity was determined by salt aggregation, and the absorptive hydrophobicity was measured by hydrophobic interaction chromatography. All strains were well opsonised by pooled normal human serum 10%. Ingestion of these bacteria could be detected to a variable extent in the absence of extracellular opsonins; heat-inactivated serum 10% or intravenous IgG concentrate 1 mg/ml improved phagocytosis of all strains. Significantly increased rates of both the ingestion and killing of one of the five strains occurred in the presence of IgG or in the absence of opsonins, compared to those found with each of the other four. This particular strain had significantly stronger adsorptive surface hydrophobicity than the other four strains, and with all strains there was a correlation between hydrophobicity and phagocytosis by granulocytes in the absence of opsonins.