Oropharyngeal and nasal Staphylococcus aureus carriage by healthy children.

BACKGROUND: As healthy children are the main reservoir of respiratory pathogens and the main cause of bacterial diffusion in the community, it could be interesting to investigate the type of screening that should be used during the early years of life in order to obtain a more precise estimate of Staphylococcus aureus circulation. The aim of this study was to evaluate oropharyngeal and nasal S. aureus carriage in otherwise healthy children and adolescents aged 6-17 years. METHODS: The oropharyngeal and nasal samples were collected in December 2013 from 497 healthy students attending five randomly selected schools in Milan, Italy, using an ESwab kit, and S. aureus was identified using the RIDA®GENE methicillin-resistant S. aureus (MRSA) system. RESULTS: Two hundred and sixty-four subjects (53.1%) were identified as S. aureus carriers: 129 (25.9%) oropharyngeal carriers and 195 (39.2%) nasal carriers, of whom 60 (12.1%) were both oropharyngeal and nasal carriers. Oropharyngeal carriage increased with age (p < 0.001), whereas nasal carriage decreased. There was little or no agreement between oropharyngeal and nasal carriage in any of the age groups. MRSA was identified in only three cases (0.6%), always in nasal samples. There were no differences between the carriers and non-carriers in terms of the distribution of age, gender, ethnicity, the number of siblings in the household, exposure to passive smoking, previous clinical history, allergic sensitisation, or previous influenza, pneumococcal and meningococcal vaccinations. The frequency of male children was higher among the subjects with positive nasal and oropharyngeal swabs (66.7%) than among those with positive oropharyngeal swabs alone (46.4%; p = 0.02). CONCLUSIONS: The oropharyngeal carriage of mainly methicillin-sensitive S. aureus is frequent in otherwise healthy children, including a relatively high proportion of those without nasal colonisation. These findings highlight the importance of adding throat to nasal screening when monitoring the circulation of S. aureus in the community.

Genetic polymorphisms and risk of recurrent wheezing in pediatric age.

BACKGROUND: Wheezing during early life is a very common disorder, but the reasons underlying the different wheezing phenotypes are still unclear. The aims of this study were to analyse the potential correlations between the risk of developing recurrent wheezing and the presence of specific polymorphisms of some genes regulating immune system function, and to study the relative importance of the associations of different viruses and genetic polymorphisms in causing recurrent episodes. METHODS: The study involved 119 otherwise healthy infants admitted to hospital for a first episode of wheezing (74 of whom subsequently experienced recurrent episodes) and 119 age- and sex-matched subjects without any history of respiratory problem randomly selected from those attending our outpatient clinic during the study period. All of the study subjects were followed up for two years, and 47 single nucleotide polymorphisms (SNPs) in 33 candidate genes were genotyped on whole blood using an ABI PRISM 7900 HT Fast Real-time instrument. RESULTS: IL8-rs4073AT, VEGFA-rs833058CT, MBL2-rs1800450CT and IKBKB-rs3747811AT were associated with a significantly increased risk of developing wheezing (p = 0.02, p = 0.03, p = 0.05 and p = 0.0018), whereas CTLA4-rs3087243AG and NFKBIB-rs3136641TT were associated with a significantly reduced risk (p = 0.05 and p = 0.04). IL8-rs4073AT, VEGFA-rs2146323AA and NFKBIA-rs2233419AG were associated with a significantly increased risk of developing recurrent wheezing (p = 0.04, p = 0.04 and p = 0.03), whereas TLR3-rs3775291TC was associated with a significantly reduced risk (p = 0.03). Interestingly, the study of gene-environment interactions showed that rhinovirus was significantly associated with recurrent wheezing in the presence of IL4Ra-rs1801275GG and G (odds ratio [OR] 6.03, 95% confidence interval [CI]: 1.21-30.10, p = 0.03) and MAP3K1-rs702689AA (OR 4.09, 95% CI: 1.14-14.61, p = 0.03). CONCLUSIONS: This study shows a clear relationship between the risk of wheezing and polymorphisms of some genes involved in the immune response. Although further studies are needed to confirm the results, these findings may be useful for the early identification of children at the highest risk of developing recurrent episodes and possibly subsequent asthma.

Knowledge of malaria among women of Burundi and its impact on the incidence of the disease.

In order to investigate whether the persistently high incidence of malaria in Burundi is due to a lack of knowledge of the disease, mothers of children admitted to the hospital of Kiremba in Burundi were anonymously administered a semi-structured questionnaire about malaria. A total of 539 questionnaires were evaluated. About 75% of the women knew that malaria is transmitted by mosquitoes, and respectively 58.3 and 23.9% knew that it could lead to the death of a fetus or a low birth weight. Fewer than half of the women (44.7%) knew that malaria can be definitely diagnosed by means of a blood examination and only 39.7% indicates that artesunate-amodiaquine was the first-line therapy recommended by the Burundian health authorities. Long-lasting insecticidal or insecticide-treated nets were used by only 33.0%. Burundian women generally know little about malaria. Public awareness programmes should be conducted before any malaria control initiatives are planned.

Streptococcus pneumoniae and Staphylococcus aureus carriage in healthy school-age children and adolescents.

Streptococcus pneumoniae and Staphylococcus aureus are common commensals of the upper respiratory tract in children and adolescents. Understanding the relationship between these two pathogens, including their potential for mutual interference, is needed to evaluate the epidemiology of the diseases they cause, the factors that condition acquisition and carriage, and the impact of related preventative measures. We obtained oropharyngeal and nasal swabs from 497 healthy subjects aged 6-17 years. S. pneumoniae detection and serotyping were performed using a real-time PCR and S. aureus detection was performed using the RIDAGENE MRSA system. We found that 136 (27.3%) of the children were carriers of both species, 121 (24.3%) of the children carried S. pneumoniae alone and 128 (25.7%) of the children carried S. aureus alone. S. aureus carriage was similar between children who carried S. pneumoniae (136/257, 52.9 %, 95% confidence interval [CI]: 46.8-58.9%) vs those who did not (128/240, 53.3%, 95% CI: 47.0 -59.5%) and was independent of age and vaccination with 7-valent pneumococcal conjugate vaccine (PCV7). Vaccination with PCV7 did not affect S. aureus carriage [S. pneumoniae: 84/143 (58.7%, 95% CI: 50.5 -66.5%) vaccinated children vs 171/351 (48.7%, 95% CI: 43.5 -53.9%) unvaccinated children; S. aureus: 67/143 (46.9%, 95% CI: 38.9-55.0 %) vaccinated children vs 195/351 (55.6%, 95% CI: 50.3 -60.7%) unvaccinated children]. Pneumococcal serotype also did not appear to affect S. aureus carriage. These findings suggested that the carriage of S. pneumoniae did not affect that of S. aureus in older children and adolescents, regardless of age, PCV7 vaccination and pneumococcal serotype.

Oropharyngeal and nasopharyngeal sampling for the detection of adolescent Streptococcus pneumoniae carriers.

Monitoring the dynamics of pneumococcal carriage makes it possible to evaluate the epidemiological characteristics of Streptococcus pneumoniae disease and the theoretical coverage offered by pneumococcal vaccines. It has been demonstrated that the nasopharyngeal (NP) sampling of respiratory secretions is superior to oropharyngeal (OP) sampling for identifying pneumococci carried by younger children, but adult data are conflicting and there are no published studies of adolescents. In order to compare the efficiency of OP and NP sampling in identifying and quantifying S. pneumoniae carriage in healthy adolescents, 2 swab samples were obtained from 530 adolescents aged 15-19 years, the first taken from the posterior pharyngeal wall through the mouth (OP) and the second through the nose (NP). Bacterial genomic DNA was tested for the autolysin-A-encoding gene (lytA) and wzg (cpsA) gene of S. pneumoniae in order to evaluate pneumococcal carrier status. All of the positive cases were serotyped. S. pneumoniae was identified in 35.8% of the OP swabs and 3.5% of the NP swabs (P<0.0001). The serotypes included in the 13-valent pneumococcal conjugate vaccine (PCV13) were found in all but two OP samples (98.9%) and only 64.7% of the NP samples (P<0.0001). The most frequently identified PCV13 serotype in both groups was 19F, followed by serotypes 5 and 9V. In conclusion, OP sampling appeared significantly more effective than NP sampling in identifying and characterizing pneumococcal carrier status in adolescents. This suggests that OP sampling should be used when evaluating the dynamics of pneumococcal carriage among adolescents and the theoretical coverage offered by PCV13.