Microbial content of household dust associated with exhaled NO in asthmatic children

Fractional exhaled nitric oxide (FeNO) among school children in Java and Sumatra, Indonesia: associations with respiratory symptoms, house dust mite sensitization and the home environment

OBJECTIVE

To study associations between fractional exhaled nitric oxide (FeNO) and asthma, airway symptoms, sensitization to common allergens, outdoor pollution and home environment among 380 students in eight junior high schools in two areas in Indonesia.

METHODS

Data on health and home were collected by a face-to face interview before measuring FeNO and performing skin prick test against common allergens. Exploratory linear mixed and logistic regression models were employed.

RESULTS

Geometric mean of FeNO was 17.8 ppb (GSD 2.09) and 139 students (36.6%) had elevated FeNO (>20 ppb). In total, 107 students (28.2%) were sensitized to house dust mite (HDM) (Der p1 or Der f1), 4 (1.1%) to cat and 3 (0.8%) to mold (Cladosporium or Alternaria). Moreover, 20 students (5.3%) had diagnosed asthma, 38 (10.0%) had current wheeze, and 107 (28.2%) had current rhinitis. HDM sensitization, diagnosed asthma, current wheeze, and current rhinitis were associated with FeNO. In total, 281 students (73.9%) had mold or dampness, 232 (61.1%) had environmental tobacco smoke (ETS) and 43 (11.3%) had other odor at home. Indoor mold or dampness and other odor at home were associated with FeNO. ETS was negatively associated with FeNO.

CONCLUSION

HDM sensitization and elevated FeNO can be common among children in this part of Indonesia. The high prevalence of elevated FeNO indicate that undiagnosed childhood asthma is common. Dampness, mold and odor at home can be associated with increased FeNO while ETS can be associated with decreased FeNO.

Identification of environmental Actinobacteria in buildings by means of chemotaxonomy, 16S rRNA sequencing, and MALDI-TOF MS

Actinobacteria are abundant in soil and other environmental ecosystems and are also an important part of the human microbiota. Hence, they can also be detected in indoor environments and on building materials, where actinobacterial proliferation on damp materials can indicate moisture damage. The aim of this study was to evaluate the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of 28 environmental strains of Actinobacteria isolated from building materials and indoor and outdoor air samples, mainly collected in the context of moisture damage investigations in buildings in Finland. The 16S rRNA gene sequencing and chemotaxonomic analyses were performed, and results were compared with the MALDI-TOF MS Biotyper identification. Using 16S rRNA gene sequencing, all isolates were identified on the species or genus level and were representatives of Streptomyces, Nocardia, and Pseudonocardia genera. Based on MALDI-TOF MS analysis, initially, 11 isolates were identified as Streptomyces spp. and 1 as Nocardia carnea with a high identification score. After an upgrade in the MALDI-TOF MS in-house database and re-evaluation of mass spectra, 13 additional isolates were identified as Nocardia, Pseudonocardia, and Streptomyces. MALDI-TOF MS has the potential in environmental strain identification; however, the standard database needs to be considerably enriched by environmental Actinobacteria representatives.

IMPORTANCE

The manuscript addresses the challenges in identifying environmental bacteria using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) Biotyper-based protein profiling. The matter of the studies-actinobacterial strains-has been isolated mostly from building materials that originated from a confirmed moisture-damaged situation. Polyphasic taxonomy, 16S RNA gene sequencing, and MALDI-TOF mass spectrometry were applied for identification purposes. In this experimental paper, a few important facts are highlighted. First, Actinobacteria are abundant in the natural as well as built environment, and their identification on the species and genus levels is difficult and time-consuming. Second, MALDI-TOF MS is an effective tool for identifying bacterial environmental strains, and in parallel, continuous enrichment of the proteomics mass spectral databases is necessary for proper identification. Third, the chemical approach aids in the taxonomical inquiry of Actinobacteria environmental strains.

Fractional exhaled nitric oxide (FeNO) and respiratory symptoms in junior high school students in Penang, Malaysia: the role of household exposure

We studied associations between fractional exhaled nitric oxide (FeNO), health and household exposure among school children (N = 348) in Penang, Malaysia. Multiple logistic regression and linear mixed models were applied. Overall, 46.0% had elevated FeNO (>20 ppb) and 10.6% diagnosed asthma. Male gender (p = 0.002), parental asthma or allergy (p = 0.047), cat allergy (p = 0.009) and seafood allergy (p < 0.001), diagnosed asthma (p = 0.001), wheeze (p = 0.001), ocular symptoms (p = 0.001), rhinitis (p = 0.002) and respiratory infections (p = 0.004) were all associated with FeNO. Students exposed to ETS had lower FeNO (p = 0.05). Dampness and mould was associated with wheeze (p = 0.038), especially in wooden homes (interaction p = 0.042) and among students with elevated FeNO (interaction p = 0.024). Cat keeping increased rhinitis (p = 0.041) and respiratory infections (p = 0.008) and modified the dampness associations. In conclusion, FeNO can be associated with ocular and respiratory symptoms. Elevated FeNO, cat keeping and a wooden house can enhance the risk of wheeze when exposed to dampness and mould.

Fractional exhaled nitric oxide (FeNO) in students in Northern Thailand: associations with respiratory symptoms, diagnosed allergy and the home environment

OBJECTIVE

There are few studies on fractional exhaled nitric oxide (FeNO) among children in subtropical areas. We studied associations between FeNO and respiratory symptoms, reported diagnosed allergies and indoor and outdoor environmental factors in first grade junior high school students (N = 270) in upper northern Thailand.

METHODS

Data on demographics, health and home environment were collected by a questionnaire distributed in dry season (February-March 2018). FeNO was measured when the research team visited the school. Daily outdoor pollution data (PM₁₀ and ozone) were collected from the nearest monitoring station 3 days (lag 3) and 7 days (lag 7) before the FeNO measurements. Two-level (student, school) linear mixed models were used to analyze associations, adjusting for gender and family education level.

RESULTS

In total, 29.6% had elevated FeNO level (>20 ppb) and 7.8% reported any allergy diagnosed by a doctor. Male gender (p = 0.02), diagnosed allergy (p = 0.001), especially to cat (p = 0.001) and house dust mite (HDM) allergies (p = 0.001) were associated with FeNO. Eye symptoms (p = 0.01), rhinitis symptoms (p = 0.03) and dyspnea (p = 0.05) in the last 3 days were associated with FeNO. Household indoor mold (p = 0.03), gas cooking (p = 0.03) and PM₁₀ (lag 3 and lag 7) were negatively (protective) associated with FeNO.

CONCLUSIONS

Diagnosed allergy, especially to cat and HDM, can be associated with increased FeNO. Indoor mold and gas cooking can be associated with lower FeNO. Ocular, nasal and dyspnea symptoms reported by students in dry season in northern Thailand can be associated with FeNO, a biomarker of Th2 driven airway inflammation.

Microbial Agents in the Indoor Environment: Associations with Health

There is international consensus that damp buildings and indoor mould can increase the risk of asthma, rhinitis, bronchitis and respiratory tract infections but we do not know which types of microbial agents that are causing the observed adverse health effects. Microbial indoor exposure is a broader concept than microbial growth in buildings. Other sources of indoor microbial exposure include the outdoor environment, humans (crowdedness) and furry pet keeping. Microbial exposure can have different health effects depending on the dose, different exposure route, genetic disposition and the timing of exposure. Microbial stimulation linked to large microbial diversity in early life can protect against disease development, especially for allergic asthma and atopy. Protective effects are more often reported for bacterial exposure and adverse health effects are more often linked to mould exposure. There are many studies on health associations for indoor exposure to endotoxin, mainly from homes. The risk of getting atopic asthma may be less if you are exposed to endotoxin in childhood but the risk of non-atopic asthma may increase if exposed to endotoxin especially in adulthood. Moreover, genetic disposition modifies health effects of endotoxin. Epidemiological studies on muramic acid (from gram-positive bacteria) or ergosterol (from mould) are few. Studies on health effects of indoor exposure to beta-1-3-glucan (from mould) have conflicting results (positive as well as negative associations). Epidemiological studies on health effects of indoor exposure to mycotoxins are very few. Some studies have reported health associations for MVOC, but it is unclear to what extent MVOC has microbial sources in indoor environments. Many studies have reported health associations for fungal DNA, especially as a risk factor for childhood asthma at home. Since most studies on health effects of indoor exposure to mould, bacteria and microbial agents are cross-sectional, it is difficult to draw conclusions on causality. More prospective studies on indoor microbial exposure are needed and studies should include other indoor environments than homes, such as day care centers, schools, hospitals and offices.

Microbial growth in building material samples and occupants' health in severely moisture-damaged homes

There is no commonly approved approach to detect and quantify the health-relevant microbial exposure in moisture-damaged buildings. In 39 single-family homes with severe moisture damage, we studied whether concentrations of viable microbes in building material samples are associated with health among 71 adults and 68 children, and assessed with symptoms questionnaires, exhaled NO, and peak expiratory flow (PEF) variability. Symptoms were grouped into three scores: upper respiratory symptoms, lower respiratory symptoms, and general symptoms. The homes were divided into three groups based on viable counts of fungi, actinomycetes, and total bacteria cultivated from building material samples. Highest group of actinomycete counts was associated with more general symptoms, worse perceived health, and higher daily PEF variability (aOR 12.51; 1.10-141.90 as compared to the lowest group) among adults, and with an increase in lower respiratory symptoms in children, but the confidence intervals were wide. We observed significant associations of fungal counts and total microbial score with worse perceived health in adults. No associations with exhaled NO were observed.

Cough and environmental air pollution in China

With fast-paced urbanization and increased energy consumption in rapidly industrialized modern China, the level of outdoor and indoor air pollution resulting from industrial and motor vehicle emissions has been increasing at an accelerated rate. Thus, there is a significant increase in the prevalence of respiratory symptoms such as coughing, wheezing, and decreased pulmonary function. Experimental exposure research and epidemiological studies have indicated that exposure to particulate matter, ozone, nitrogen dioxide, and environmental tobacco smoke have a harmful influence on development of respiratory diseases and are significantly associated with cough and wheeze. This review mainly discusses the effect of air pollutants on respiratory health, particularly with respect to cough, the links between air pollutants and microorganisms, and air pollutant sources. Particular attention is paid to studies in urban areas of China where the levels of ambient and indoor air pollution are significantly higher than World Health Organization recommendations.

Application of nitric oxide measurements in clinical conditions beyond asthma

Fractional exhaled nitric oxide (FeNO) is a convenient, non-invasive method for the assessment of active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid diagnosis and monitoring in several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory, infectious, and/or immunological conditions. In this short review, we provide an overview of several clinical studies and discuss the status of potential applications of NO measurements in clinical conditions beyond asthma.

Applicability of the environmental relative moldiness index for quantification of residential mold contamination in an air pollution health effects study

The Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS) investigated the impact of exposure to traffic-related air pollution on the respiratory health of asthmatic children in Detroit, Michigan. Since indoor mold exposure may also contribute to asthma, floor dust samples were collected in participants homes (n = 112) to assess mold contamination using the Environmental Relative Moldiness Index (ERMI). The repeatability of the ERMI over time, as well as ERMI differences between rooms and dust collection methods, was evaluated for insights into the application of the ERMI metric. ERMI values for the standard settled floor dust samples had a mean ± standard deviation of 14.5 ± 7.9, indicating high levels of mold contamination. ERMI values for samples collected from the same home 1 to 7 months apart (n = 52) were consistent and without systematic bias. ERMI values for separate bedroom and living room samples were highly correlated (r = 0.69, n = 66). Vacuum bag dust ERMI values were lower than for floor dust but correlated (r = 0.58, n = 28). These results support the use of the ERMI to evaluate residential mold exposure as a confounder in air pollution health effects studies.