Proton pump inhibitor therapy predisposes to community-acquired Streptococcus pneumoniae pneumonia.

BACKGROUND: The pathophysiological mechanisms which contribute to an increased risk of community-acquired pneumonia (CAP) in patients using proton pump inhibitors are not well established. AIM: To examine differences in microbial etiology in patients with CAP between patients with and without proton pump inhibitor (PPI) therapy and its possible impact on disease severity. METHODS: All individuals consulting the emergency care unit were prospectively registered and underwent chest radiography. Sputum, urine, nose-throat swabs and blood samples were obtained for microbial evaluation. We evaluated the association between use of proton pump inhibitors, etiology of CAP and severity of illness with multivariate regression analysis. RESULTS: The final cohort comprised 463 patients, 29% using proton pump inhibitors (PPIs). Pathogens regarded as oropharyngeal flora were more common in CAP patients using PPI therapy compared to those who did not (adjusted OR: 2.0; 95% CI: 1.22-3.72). Patients using proton pump inhibitors more frequently had an infection with Streptococcus pneumoniae (28% vs. 14%) and less frequently with Coxiella burnetii (8% vs. 19%) compared to nonuser of PPI. Adjusted for baseline differences, the risk of PPI users being infected with S. pneumonia was 2.23 times (95% CI: 1.28-3.75) higher compared to patients without PPI's. No risk between PPI use and any other microbial pathogen was found. There was no difference in severity of CAP between patients with and without using PPI therapy. CONCLUSIONS: Proton pump inhibitor therapy was associated with an approximately 2-fold increased risk to develop community-acquired pneumonia possibly as a result of S. pneumoniae infection.

Paediatric reference values for the peripheral T cell compartment.

Immunophenotyping of blood lymphocyte subpopulations is an important tool in the diagnosis of immunological and haematological diseases. Paediatric age-matched reference values have been determined for the major lymphocyte populations, but reliable reference values for the more recently described T lymphocyte subpopulations, like different types of memory T lymphocytes, recent thymic emigrants, regulatory T cells and CXCR5(+) helper T lymphocytes, are not sufficiently available yet. We determined reference values for the absolute and relative sizes of T lymphocyte subpopulations in healthy children using the lysed whole blood method, which is most often used in diagnostic procedures. When the absolute numbers of some or all T lymphocyte subpopulations fall outside these reference ranges, this may indicate disease. The reference values show the course of T lymphocyte development in healthy children. Absolute T lymphocyte numbers increase 1.4-fold during the first months of life, and after 9-15 months, they decrease threefold to adult values; this is mainly caused by the expansion of recent thymic emigrants and naive cells. Helper and cytotoxic T lymphocytes show the same pattern. Regulatory T cells increase in the first 5 months of life and then gradually decrease to adult values, although the absolute numbers remain small. The relative number of CXCR5(+) cells within the CD4(+) CD45RO(+) T lymphocytes increases during the first 6 months of life and then remains more or less stable around 20%.

Age-matched reference values for B-lymphocyte subpopulations and CVID classifications in children.

Age-matched reference values are generally presented with 5th and 95th percentiles as 'normal' reference range. However, they are mostly determined in relatively small groups, which renders this presentation inaccurate. We determined reference values for B-lymphocyte subpopulations in healthy children with the statistical method of tolerance intervals that deals far better with the relatively small numbers tested, and compared these to the cut-off values used in the currently used EUROclass classification for common variable immunodeficiency disorders (CVID) in children. CVID is a heterogeneous group of primary immunodeficiency diseases characterized by low serum immunoglobulin levels and inadequate response to vaccination. Disease-modifying heterozygous amino acid substitutions in TACI are found in around ±10% of CVID patients. Interestingly, we found that age is the primary determinant of TACI-expression on B-lymphocytes, independent of switched memory B-lymphocyte numbers. Immunophenotyping of B-lymphocyte subpopulations is increasingly used to classify patients with CVID into subgroups with different clinical prognosis according to the composition of their B-lymphocyte compartment. These classifications were mainly developed with data obtained in adults. Because of the maturing paediatric immune system, they may not be equally applicable in children: our and other age-matched reference values show great changes in the composition of the B-lymphocyte compartment during development. Although the greatest changes in B-lymphocyte subpopulations occur below the age of 2 years, when the diagnosis of CVID cannot yet be made, it is likely that a classification developed in adults cannot be used to classify the prognosis of children.

Development of lymphocyte subpopulations in preterm infants.

In preterm neonates the immune system is thought to be less developed at birth, but very little is known about the actual size of lymphocyte subpopulations, and even less about the maturation of these subpopulations during the first months after a premature birth. To evaluate the development of lymphocyte subpopulations in preterm infants during the first 3 months after birth, we performed a prospective longitudinal study in two hospitals in the Netherlands. Preterm neonates (n = 38) of all post-menstrual ages were included and blood samples were taken from cord blood, and at 1 week, 6 weeks, and 3 months. Lymphocyte subpopulations were measured by four-colour flow cytometry. The data were compared with follow-up data obtained in healthy term neonates (n = 8), and with single samples from school age children (n = 5) and adults (n = 5). Overall, we found a similar pattern of post-natal development of lymphocyte subpopulations in the term and preterm infants. Both B lymphocytes and helper and cytotoxic T lymphocytes mainly consist of naive cells at birth and during the 3 months of follow-up in all neonatal age groups. So, the preterm immune system seems to be able to generate an outburst of naive T and B lymphocytes from the thymus and bone marrow within the same time span after the start of post-natal antigenic stimulation from the environment as the term immune system, but, with lower post-menstrual age, the absolute counts of naive helper T lymphocytes are lower.

The value of an artificial neural network in the decision-making for prostate biopsies.

PURPOSE: In majority of patients who are subjected to prostate biopsies, no prostate cancer (PCa) is found. It is important to prevent unnecessary biopsies since serious complications may occur. An artificial neural network (ANN) may be able to predict the risk of the presence of PCa. METHODS: Included were all patients, who underwent transrectal ultrasound-guided prostate biopsies between June 2006 and June 2007 with a total PSA (tPSA) level between 2 and 20 microg/l. The patients were divided into two groups according to their tPSA level (2-10 microg/l and 10-20 microg/l). The ANN Prostataclass of the Universitätsklinikum Charité in Berlin was used. The predictions of the ANN were compared to the pathology results of the biopsies. RESULTS: Overall 165 patients were included. PCa was diagnosed in 53 patients, whereas the ANN predicted "no risk" in 19 of these patients (36%). The ANN output receiver operator characteristic (ROC) plots for the range of tPSA 2-10 microg/l and tPSA 10-20 microg/l showed an area under the curve (AUC) of 63 and 88% for the initial biopsy group, versus 69 and 57%, respectively, for the repeat biopsy group. CONCLUSIONS: The ANN resulted in a false negative rate of 36%, missing PCa in 19 patients. For use in an outpatient-clinical setting, this ANN is insufficient to predict the risk of presence of PCa reliably.

Intrinsic defect of the immune system in children with Down syndrome: a review.

Down syndrome (DS) is the most frequent cause of mental retardation in man. Immunological changes in DS have been observed since the 1970s. The neurological system appears to be ageing precociously, with early occurrence of Alzheimer disease; until now, the observed immunological differences have been interpreted in the same context. Looking back at past and present results of immunological studies in DS children in relation to the clinical consequences they suffer, we conclude that it is more likely that the DS immune system is intrinsically deficient from the very beginning.