Respiratory microbiology of patients with cystic fibrosis in the United States, 1995 to 2005.

BACKGROUND: Numerous improvements in diagnostic and therapeutic strategies for patients with cystic fibrosis (CF) have occurred during the past 2 decades. We hypothesized that these changes could impact trends in respiratory microbiology. METHODS: Data from the Cystic Fibrosis Foundation Patient Registry were used to examine trends in the incidence and prevalence of bacterial pathogens isolated from patients with CF in the United States from 1995 to 2005. RESULTS: The number of patients with CF in the patient registry increased from 19,735 in 1995 to 23,347 in 2005. During the study period, the reported annual prevalence of Pseudomonas aeruginosa significantly declined from 60.4% in 1995 to 56.1% in 2005 (p < 0.001). The decline was most marked in children 6 to 10 years old (48.2 to 36.1%) and adolescents 11 to 17 years old (68.9 to 55.5%). Both the incidence (21.7% in 1995 and 33.2% in 2005) and prevalence (37.0% in 1995 and 52.4% in 2005) of methicillin-susceptible Staphylococcus aureus significantly increased and the age-specific prevalence was highest in patients 6 to 17 years old. The prevalence of methicillin-resistant S aureus increased from 0.1% in 1995 to 17.2% in 2005 and from 2002 to 2005 was highest in adolescents 11 to 17 years old. Both the prevalence and incidence of Burkholderia cepacia complex declined, while the prevalence of Haemophilus influenzae, Stenotrophomonas maltophilia, and Alcaligenes xylosoxidans increased. CONCLUSIONS: Data from the patient registry suggest that the epidemiology of bacterial pathogens in patients with CF changed during the study period. Future studies should continue to monitor changing trends and define the association between these trends and care practices in CF.

IgA deficiency: clinical correlates and responses to pneumococcal vaccine.

We surveyed historical and laboratory data for 127 IgA-deficient patients (ages 2-67), referred to an immunology clinic; the commonest medical history was recurrent respiratory infections (50%), followed by autoimmunity (28%) asthma and allergy (13%). Fifty-two subjects have been given a pneumococcal vaccination; vaccine responses to 12 serotypes were significantly related to serum IgG2 levels (P = 0.004). Six immunized IgA/IgG2-deficient subjects produced insignificant amounts of antibodies to these pneumococcal serotypes; 10 others with normal IgG2 levels also had subnormal vaccine responses. IgA-deficient patients who had at least one B8 allele (n = 19) had a significantly greater response to this vaccine than the HLA-B8-negative subjects (n = 24) (P = 0.024). There was no relationship between a history of recurring infections and pneumococcal vaccine responses; HLA status was not related to a history of autoimmunity.

Efficacy of intravenous immunoglobulin in the prevention of pneumonia in patients with common variable immunodeficiency.

BACKGROUND: Common variable immunodeficiency (CVID) is a primary immune disorder characterized by antibody deficiency and a decrease in serum IgG and IgA, IgM, or both levels at least 2 SDs below the mean for age and not attributed to other known immunologic disorders. These patients often present with frequent and severe episodes of pneumonia before diagnosis. The standard treatment, intravenous immunoglobulin (IVIG), has been available for the past 20 years. No large-scale study has compared the incidence of pneumonia in these patients before and after IVIG treatment. OBJECTIVE: The aim of this study was to document the effectiveness of intravenous immunoglobulin treatment on the incidence of pneumonia in patients with CVID. METHODS: We performed chart reviews and interviews of patients with laboratory-confirmed CVID seen at our clinical center. The number of episodes of pneumonia was documented before and after treatment with immunoglobulin replacement therapy. RESULTS: The histories of 50 patients were reviewed (mean current age, 42 +/- 16.3 years; age range, 10-78 years; 20 male and 30 female patients). Forty-two (84%) of the 50 patients with CVID had pneumonia at least once before receiving immunoglobulin treatment, and 11 of 42 of these patients had multiple episodes. After treatment with gamma globulin over a mean period of 6.6 +/- 5.2 years (range, <1-20 years), the number of patients experiencing pneumonia significantly decreased to 11 (22%) of 50. In most cases these patients had pneumonia in the first year of immunoglobulin treatment. CONCLUSION: The treatment of CVID with IVIG significantly reduces the incidence of pneumonia.