Bacterial carriage in infancy: Risk factors and consequences - The Generation R Study

In this thesis various studies on the prevalence, risk factors and consequences of carriage of Streptococcus pneumoniae (pneumococcus), Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus in young children are presented. These bacteria are considered important (airway) pathogens in this age group. The definition of pathogen needs further explanation, since the boundary between commensal organisms and pathogenic organisms is not always obvious. According to Casadevall and Pirofski, defining a pathogen as an organism that causes disease in a host is inadequate because some pathogens do not cause disease in all human hosts. The adjective opportunistic is used for pathogens that cause disease only in hosts that are immunocompromised or whose pathogenesis is facilitated by traumatic breaching of an epithelial barrier. For example, about 50% of children two years of age are colonized by S. pneumoniae. This does not lead to disease in most cases, and thus, the pneumococcus can be considered a commensal organism. Weiser et al. have shown that colonization is the natural state of the pneumococcus, and invasive disease, also from the perspective of the pneumococcus, is not favourable. However, S. pneumoniae is the main cause of bacterial otitis media and bacterial pneumonia in young children worldwide. It is also an important cause of life threatening sepsis and meningitis. Moreover, pneumonia is “the leading killer in children”, and since S. pneumoniae is considered to cause more than half the cases of bacterial pneumonia worldwide, it is without any doubt a fearful pathogen

Fetal growth influences lymphocyte subset counts at birth: The generation R study

Background: Preterm born and low-birth-weight infants are at risk for severe infections in infancy. It has been suggested that these infants have an immature immune system. Objective:To assess the associations of gestational age, birth weight and fetal growth with absolute lymphocyte subset counts at birth. Methods: This study was conducted in 571 infants participating in the Generation R Study, a population-based prospective cohort study from fetal life onwards. Gestational age and birth weight were obtained from midwives and hospital registries. Fetal growth was defined as increase in weight between late pregnancy and birth. Lymphocytes and T lymphocyte subset counts in cord blood were determined by 6-color flow cytometry. Multivariate linear regression models with adjustment for gender, maternal education, smoking, alcohol use, fever and mode of delivery were applied. Results: Per week increase of gestational age, T, B and NK lymphocyte counts increased with 3, 5 and 6%, respectively (p < 0.05). Helper, cytotoxic and naive T lymphocyte counts increased with 3, 4 and 5%, respectively (p < 0.05), but memory T lymphocyte counts did not. Increased birth weight and fetal growth were significantly associated with higher B lymphocyte counts, independent of gestational age, but not with the other lymphocyte subset counts. Conclusions: Lymphocyte subset counts increase with prolonged gestation, suggesting an ongoing development of the immune system. Birth weight and fetal growth seem to influence only B lymphocyte counts. Copyrigh

Fulminant cerebral edema as a lethal manifestation of COVID-19

The contribution of neurological symptomatology to morbidity and mortality after infection with Severe Acute Respiratory Syndrome-associated Coronavirus (SARS CoV II) is ill-defined. We hereby present a case of a 57-year old male patient, in excellent physical condition, who was admitted to the Intensive Care Unit (ICU), with respiratory distress duo to SARS Co

Risk factors for otitis media in children with special emphasis on the role of colonization with bacterial airway pathogens: the Generation R study

Acute otitis media is the most frequent diagnosis in children visiting physicians’ offices. Risk factors for otitis media have been widely studied. Yet, the correlation between bacterial carriage and the development of otitis media is not entirely clear. Our aim was to study in a population-based prospective cohort the risk factors for otitis media in the second year of life with special emphasis on the role of colonization with Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. The study was embedded in the Generation R Study. Data on risk factors and doctor-diagnosed otitis media were obtained by midwives, hospital registries and postal questionnaires in the whole cohort (n = 7,295). Nasopharyngeal swabs were obtained at the age of 1.5, 6 and 14 months in the focus cohort (n = 1,079). Of these children, 2,515 (47.2%) suffered at least one period of otitis media in their second year of life. The occurrence of otitis media during the follow-up period in the first 6 months of life and between 6 and 12 months of age was associated with the risk of otitis media in the second year of life (aOR, 1.83 95% CI 1.24–2.71 and aOR 2.72, 95% CI 2.18–3.38, respectively). Having siblings was associated with an increased risk for otitis media in the second year of life (aOR 1.42, 95% CI 1.13–1.79). No associations were found between bacterial carriage in the first year of life and otitis media in the second year of life. In our study, otitis media in the first year of life is an independent risk factor for otitis media in the second year of life. Surprisingly, bacterial carriage in the first year of life did not add to this risk. Moreover, no association was observed between bacterial carriage in the first year of life and otitis in the second year of life

Comparative study of different methods to genotype hepatitis C virus type 6 variants

Hepatitis C virus (HCV) genotype 6a is found frequently in Southeast Asia. In Thailand, however, genotype 6 variants may exist which posses a genotype 1 like sequence in the 5′ non-coding region. In order to genotype correctly these viruses, four different methods; INNO-LiPA assay, two RFLP assays on the core region (using different restriction enzymes) and phylogenetic analysis of the core sequences were compared. Samples from 17 chronic HCV patients from the Netherlands and Thailand and 18 anti-HCV positive blood donors recruited from Thailand were tested. The INNO-LiPA could not distinguish genotype 6 variants. The RFLP methods used could not, or only in combination with 5′NCR genotyping methods, identify type 6 variants. In conclusion, for identification of type 6 variants at least two different regions of the HCV genome have to be analyzed (both 5′NCR and core).</p