Molecular epidemiology of the nasal colonization by methicillin-susceptible Staphylococcus aureus in Swiss children.

Nasal carriage of Staphylococcus aureus contributes to an increased risk of developing an infection with the same bacterial strain. Genetic regulatory elements and toxin-expressing genes are virulence factors associated with the pathogenic potential of S. aureus. We undertook an extensive molecular characterization of methicillin-susceptible S. aureus (MSSA) carried by children. MSSA were recovered from the nostrils of children. The presence of Panton-Valentine leukocidin (PVL), exfoliatins A and B (exfoA and exfoB), and the toxic-shock staphylococcal toxin (TSST-1) and agr group typing were determined by quantitative PCR. A multiple-locus variable-number of tandem repeat analysis (MLVA) assay was also performed for genotyping. Five hundred and seventy-two strains of MSSA were analysed. Overall, 30% were positive for toxin-expressing genes: 29% contained one toxin and 1.6% two toxins. The most commonly detected toxin gene was tst, which was present in 145 (25%) strains. The TSST-1 gene was significantly associated with the agr group 3 (OR 56.8, 95% CI 32.0-100.8). MLVA analysis revealed a large diversity of genetic content and no clonal relationship was demonstrated among the analysed MSSA strains. Multilocus sequence typing confirmed this observation of diversity and identified ST45 as a frequent colonizer. This broad diversity in MSSA carriage strains suggests a limited selection pressure in our geographical area.

Twelve-year follow-up after discontinuation of preseasonal grass pollen immunotherapy in childhood.

BACKGROUND: In a previous controlled study, we demonstrated that preseasonal grass pollen immunotherapy for 3 years was effective in children. Moreover, a significant clinical benefit could still be observed 6 years after discontinuation of specific immunotherapy (SIT). In the current study, we examined the same group of patients again to investigate whether there is a prolonged benefit 12 years after SIT is stopped. METHODS: Twenty-two patients with previous SIT (from 1989 through 1991) or standardized seasonal pharmacotherapy only were prospectively followed during the grass pollen season of 2003. Primary end points were symptom score, medication use, and combined symptom and medication score. In addition, skin prick test reactivity, development of new sensitizations, and prevalence of seasonal asthma were evaluated. RESULTS: Total hay fever symptom score (P < 0.03), use of medication (P < 0.05), and combined symptom and medication score (P < 0.03) remained lower in patients with previous SIT when compared with the control group. Decreased immediate skin response to grass pollen returned 12 years after cessation of SIT. The percentage of new sensitization, however, continued to be significantly smaller in patients with previous SIT (58%) compared with the controls (100%, P < 0.05). There was a tendency for lower prevalence of seasonal asthma in the post-SIT group (P = 0.08). CONCLUSION: This prospective controlled prolonged follow-up study demonstrates the ongoing clinical benefit 12 years after discontinuation of SIT. Furthermore, the reduction in onset of new sensitization, which was found 6 years after discontinuation of SIT, is sustained 6 years later.

Long-term efficacy of preseasonal grass pollen immunotherapy in children.

BACKGROUND: In a previous controlled study we demonstrated that preseasonal grass pollen immunotherapy for three years was effective in children. In the current study we examined the same group of patients to see if there is still a benefit six years after discontinuation of treatment. METHODS: Thirteen of 14 patients with previous specific immunotherapy (SIT) and 10 out of 14 patients of the control group were prospectively followed during the grass pollen season. Outcome measures were seasonal symptom scores for eyes, nose and chest, the use of symptomatic medication and visual analog scale. Objective measures included skin prick test reactivity to seasonal and perennial allergens and conjunctival provocation testing. RESULTS: During the 13 week observation time scores for overall hayfever symptoms (P < 0.004) and individual symptoms for eyes (P < 0.02), nose (P < 0.04) and chest (P < 0.01) as well as combined symptom and medication scores (P < 0.002) remained lower in the group with previous SIT. Only 23% of patients with previous pollen-asthma who had received SIT experienced pollen-associated lower respiratory tract symptoms compared to 70% in the control group (P < 0.05). There was no significant difference in the use of pharmacological treatment during the pollen season except for asthma medication. The average visual analog scale was lower in the post-SIT group (P < 0.05). Six years after cessation of SIT the immediate skin response to grass pollen remained decreased compared to the reaction of the controls (P < 0.01). There was also a tendency for higher allergen concentration to provoke a conjunctival response in the post-SIT group but without reaching statistical significance. Eight years after commencement of SIT, 61% of the initially pollen-monosensitized children had developed new sensitization to perennial allergens compared to 100% in the control group (P < 0.05). CONCLUSIONS: There is still a significant clinical benefit six years after discontinuation of preseasonal grass pollen immunotherapy in childhood. SIT in children with pollen-allergy reduces onset of new sensitization and therefore has the potential to modify the natural course of allergic disease.

Reactogenicity of DTPa-HBV/Hib vaccine administered as a single injection vs DTPa-HBV and Hib vaccines administered simultaneously at separate sites, to infants at 2, 4 and 6 months of age.

An open, randomised, multicentre trial was performed to assess the reactogenicity and safety profile of the administration of a candidate Haemophilus influenzae type b (Hib) conjugate vaccine with a quadrivalent diphtheria-tetanus-acellular pertussis-hepatitis B (DTPa-HBV) vaccine as a single injection (Group 1) versus the simultaneous administration of the latter vaccine (DTPa-HBV) and an available Hib conjugate vaccine (Group 2) in opposite thighs, as a primary vaccination course to healthy infants at 2, 4 and 6 months of age. Eight hundred and eighty five infants (9.3+/-1.4 weeks old) were randomly allocated to Group 1 (n=665) and Group 2 (n=221). Oral polio vaccine was given concomitantly to all subjects. Blood samples (pre-vaccination and 1 month after the third dose) were obtained from a subset of infants (Group 1, 73; Group 2, 22) for serological determinations. Local and general symptoms were recorded by parents on diary cards. 2614 diary cards (Group 1, 1966; Group 2, 648) were collected. There were no statistically significant differences in the incidence of local and general symptoms between groups. Pain such that the infant cried when limb was moved was reported in 0.6 and 0.2% in groups 1 and 2, respectively. Redness and swelling (>20 mm in diameter) were recorded between 2.1 and 3% in both groups. Fussiness preventing normal activities was the most frequently reported general symptom in both groups (1.6 and 1.9% in groups 1 and 2, respectively). Fever (rectal temperature >39.5 degrees C) was reported in 0.4% (Group 1) and 0.3% (Group 2). All subjects included in the immunogenicity analysis had seroprotective or seropositive titres to the diphtheria, tetanus, hepatitis B and pertussis components of the vaccines. About 99 and 100% of infants had anti-PRP titres > or =0.15 mcg/ml in groups 1 and 2, respectively. This study indicates that DTPa-HBV vaccine given in a single injection with a candidate Hib conjugate vaccine has a similar reactogenicity profile to that of two commercially available vaccines (DTPa-HBV, Hib) given in two simultaneous injections to infants 2, 4 and 6 months of age.

Air pollution and respiratory symptoms in preschool children.

A diary study on a random sample of 625 Swiss children aged 0 to 5 yr was conducted in two cities in Switzerland to investigate the association between air pollution and respiratory symptoms. Total suspended particulates (TSP), SO2 and NO2 were measured by city monitor. In addition, passive samplers inside and outside the home measured NO2 concentration during the 6 wk each child was on the diary. Diaries were filled out by parents, and 20% were validated with the attending pediatrician's case notes. Incidence and duration of symptom episodes were examined separately. The study included any episode, episodes of coughing without runny nose, upper respiratory episodes, and episodes of breathing difficulty. In regressions using 6-wk average pollution that controlled for medical history, NO2 measured outdoors but not indoors was associated with the duration of any symptom. Total suspended particulates were a more significant predictor of duration of any symptom than NO2. The 6-wk average TSP was significantly associated with incidence of coughing episodes and marginally significant as a predictor of upper respiratory episodes. Previous day's TSP was a significant predictor of incidence of upper respiratory symptoms. Annual average of NO2 was associated with the duration of any episode and of upper respiratory episodes. We conclude that the incidence and duration of respiratory symptom episodes are likely associated with particulate concentrations and duration may be associated with NO2.

[Correlation between respiratory tract symptoms in young children and NO2 concentration of outside air]. / Zusammenhang zwischen Atemwegssymptomen bei Kleinkindern und NO2-Konzentrationen in der Aussenluft.

The aim of a one year study was to ascertain whether air pollution measured as NO2-concentration has an measurable influence on the health of infants in Switzerland. Measurements of NO2-concentration were carried out by means of passive collectors in ambient air, living room and at the child itself. The results of 1225 children printed to a significant coherence between respiratory symptoms per day and child and the NO2 load of ambient air as an guide pollutant. Even in consideration of other childish, familiar and environmental factors the coherence remains. Although no causal relation thereby proved this factor supports the observation of parents and physicians that children more often fall ill of respiratory diseases in polluted air being in accordance with similar investigations abroad.

[Correlation of respiratory tract symptoms in young children and NO2 concentrations of the outside air]. / Zusammenhang zwischen Atemwegssymptomen bei Kleinkindern und NO2-Konzentrationen in der Aussenluft.

In four regions of Switzerland (2 towns, 1 municipal agglomerate, 1 rural area) the relationship between the degree of air pollution measured in terms of NO2 and the incidence of airway symptomatology was investigated in 1,225 young children. The airway symptoms were recorded by the parents in a diary; the NO2 loading was measured with the aid of personal collecting tubes at the place of residence of the child. A significant relationship was found to exist between the mean incidence of airway symptomatology per child and day, and the individually measured NO2 concentration in the outside air at the child's place of residence. This relationship remained significant even when, in a multiple regression analysis, account was also taken of other major factors, such as smoking, nationality, individual susceptibility to airway diseases, the season of the year, and the subjective assessment of the air pollution at the place of residence, were also taken into account.

Significant association between outdoor NO2 and respiratory symptoms in preschool children.

A study of 1225 preschool children was conducted in four regions of Switzerland with different levels of air pollution to investigate the relationship between air pollution and respiratory symptoms. Daily symptoms were recorded by parents on a diary form and air pollution exposure assessed by personal NO2 samplers. Each family participated for 6 weeks and personal samplers were changed every week. The frequency of respiratory symptoms per child and day was found to increase with increasing levels of NO2 measured outdoors. This relationship remained significant in a multiple regression model in which the factors smoking, origin, indoor air pollution, age and sex, season, and parents appreciation of air pollution at the living site were taken into account.