Impact of IgG replacement therapy and antibiotic treatment on the colonization of non-encapsulated Haemophilus influenzae in the nasopharynx in patients with hypogammaglobulinaemia.

Non-typable Haemophilus influenzae (NTHI) and Streptococcus pneumoniae are regarded as the main pathogens in patients with humoral immunodeficiency. These patients have been given IgG replacement therapy since the 1950s. However, a number of individuals still suffer from recurrent episodes of respiratory tract infections. Nasopharyngeal cultures were obtained on a regular basis over a 3-6-month period from 11 patients with common variable immunodeficiency disease in 1989 and 1998. The proportion of cultures positive for NTHI decreased from 56% in 1989-90 to 16% in 1998-99 (p < 0.003). After 9 y of IgG therapy, 7 of the 11 patients were free from NTHI in the nasopharynx. Specific NTHI strains were analysed by pulsed-field gel electrophoresis and compared, with regard to genetic relatedness, on an intra-individual basis. In 1 patient the same NTHI strain was found in both 1989 and 1999. The apparent absence of NTHI from the nasopharynx in most of the patients was assumed to be due to subcutaneous IgG treatment, as well as adequate antibiotic treatment.