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Fungal contamination of bedding

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It is currently believed that most fungal exposure occurs external to the home. To enumerate the fungal flora of used synthetic and feather pillows and the dust vacuumed from them, in the UK. 10 pillows aged between 1.5 and >20 years in regular use were collected and quantitatively cultured for fungi. Swatches were taken from nine sections of the pillow and dust was also collected by vacuum from five pillows. Pillow vacuuming was carried out prior to pillow culture. All were cultured at room temperature, 30 and 37 degrees C for 7 days in broth before plating, and a subset were also cultured for 24 h in broth and then plated. Fungi were identified by standard morphological methods. The commonest three species isolated were Aspergillus fumigatus (n = 10), Aureobasidium pullulans (n = 6) and Rhodotorula mucilaginosa (n = 6). Another 47 species were isolated from pillows and vacuum dust. The number of species isolated per pillow varied from 4 to 16, with a higher number from synthetic pillows. Compared with the nonallergenic A. pullulans, more A. fumigatus was found in synthetic than feather pillows. We have examined pillows for fungal contamination, and show that the typical used pillow contains a substantial load of many species of fungi, particularly A. fumigatus. Given the time spent sleeping, and the proximity of the pillow to the airway, synthetic and feather pillows could be the primary source of fungi and fungal products. This has important implications for patients with respiratory disease, and especially asthma and sinusitis.
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Short communication
Fungal contamination of bedding
Asthma prevalence has increased progressively over the
past three decades in the UK. Numerous theories have
been promulgated including the hygiene hypothesis,
additional exposure to house dust mite etc., none of
which have been substantiated on detailed study. An
association with fungal exposure is less well studied. It is
often assumed that such exposures generally occur
outside, apart from mouldy buildings.
One substantial life-style change over the last 30 years
has been altered bedding – from feather/flock pillows and
sheets/blankets, to mainly polyester pillows and quilts.
With no need for feather containment, the covers on
pillows are more porous with pore size increasing from 2
to >10 lm. Synthetic pillows are a risk for both
prevalence and for severity of asthma. Butland et al.
estimated that the increase in synthetic bedding could
explain 50% of the increase in prevalence in wheezing (1).
We have considered the hypothesis that fungi growing
on bedding could be an environmental health risk. Adults
may produce up to 100 l of sweat in bed every year, which
for approximately 8 h/24 is at approximately 30C and
high humidity – an ideal fungal culture medium. Fungal
contamination of kapok pillows was noted in 1936, and
associated with wheezing (2).
Methods
Both synthetic and feather pillows that had been used for years in
family homes, were collected and stored in sterile bags prior to
culture. All pillows were cut into nine equal sections and then
smaller samples (swatches) were prepared from each section of
pillow; approximately 2 ·2·2 cm for synthetic pillows and 0.25 g
for feather pillows. For five pillows, additional dust samples for
culture were obtained by vacuuming the pillow through the cover
for 2 min, prior to culture processing.
Pillow swatches and vacuum dust samples were transferred into
20 and 10 ml of Sabouraud glucose liquid medium containing
antibiotics (ciprofloxacin 2 mg/l, gentamicin 16 mg/l and vancomy-
cin 8 mg/l) respectively, vortexed for 20 s and then allowed to stand
for 24 h or 7 days. The pillow swatch broths were vortexed and
haemocytometer counts were performed to give an estimation of
fungal load. Vacuum dust broths were vortexed, centrifuged
(3000 rpm/10 min) and the supernatant was counted on a haemo-
cytometer. Based on these counts, two selected 10-fold dilutions of
each broth in phosphate-buffered saline were inoculated onto
Sabouraud glucose agar in duplicate, and then the plates were
incubated at room temperature, 30Cor37C for up to 1 week.
Colony counts were performed and isolates identified using stand-
ard laboratory methods. Any isolate that could not be identified in
our laboratory was sent to Centraalbureau voor Schimmelcultures
(CBS), the Netherlands. Isolates were quantitated by colony-
forming units (CFU) per gram pillow.
Background: It is currently believed that most fungal exposure occurs external to
the home.
Aims: To enumerate the fungal flora of used synthetic and feather pillows and
the dust vacuumed from them, in the UK.
Methods: 10 pillows aged between 1.5 and >20 years in regular use were col-
lected and quantitatively cultured for fungi. Swatches were taken from nine
sections of the pillow and dust was also collected by vacuum from five pillows.
Pillow vacuuming was carried out prior to pillow culture. All were cultured at
room temperature, 30 and 37C for 7 days in broth before plating, and a subset
were also cultured for 24 h in broth and then plated. Fungi were identified by
standard morphological methods.
Results: The commonest three species isolated were Aspergillus fumigatus
(n¼10), Aureobasidium pullulans (n¼6) and Rhodotorula mucilaginosa (n¼6).
Another 47 species were isolated from pillows and vacuum dust. The number of
species isolated per pillow varied from 4 to 16, with a higher number from
synthetic pillows. Compared with the nonallergenic A. pullulans,more
A. fumigatus was found in synthetic than feather pillows.
Conclusions: We have examined pillows for fungal contamination, and show that
the typical used pillow contains a substantial load of many species of fungi,
particularly A. fumigatus. Given the time spent sleeping, and the proximity of the
pillow to the airway, synthetic and feather pillows could be the primary source of
fungi and fungal products. This has important implications for patients with
respiratory disease, and especially asthma and sinusitis.
A. A. Woodcock
1
, N. Steel
2
,
C. B. Moore
2
, S. J. Howard
2
,
A. Custovic
1
, D. W. Denning
1,2
1
North West Lung Centre, Wythenshawe Hospital
and University of Manchester, Manchester;
2
Antifungal Laboratory, Microbiology Department,
Hope Hospital, Stott Lane, Salford, UK
Key words: brevicaulis;Cladosporium;flavus;
Penicillium; vacuum.
Ashley A. Woodcock
North West Lung Centre
Wythenshawe Hospital and University of
Manchester
Southmoor Road
Manchester M23 9LT
UK
Accepted for publication 11 June 2005
Allergy 2005 DOI: 10.1111/j.1398-9995.2005.00941.x Copyright Blackwell Munksgaard 2005
ALLERGY
DOI: 10.1111/j.1398-9995.2005.00941.x
Results
Pillows ranged in age from 18 months to >20 years.
Substantial quantities of numerous fungi were cultured
from all pillows. The commonest three species in pillow
swatches were Aspergillus fumigatus (n¼10), Aureoba-
sidium pullulans (n¼6) and the yeast Rhodotorula
mucilaginosa (n¼6) (Table 1). Other species cultured
from pillows included Aspergillus flavus (n¼5), A. niger
(n¼1), A. sydowii (n¼1), A. glaucus (n¼1) and
another unidentified Aspergillus species, Penicillium spp.
(n¼6), Cladosporium herbarum (n¼6, all only at room
temperature), C. cladosporioides (n¼2) and C. tenuiss-
imum (n¼1), Epicoccum nigrum (n¼1), Botrytis cinerea
(grey mould of grape; n¼1), Pithomyces chartarum (n¼
1), probable Trametes spp. (bracket fungus; n¼1), three
different species of Agaricales (typical gilled mushrooms),
Stereum cf. sanguinolentum (encrustation or bracket
fungus on stumps; n¼1), Arthrinium phaeospermum
(n¼1), Pholiota spp. (colourful inedible gilled mush-
rooms; n¼1) and 2 yeasts comprising Candida parapsi-
losis (n¼1) and C. guilliermondii (n¼1). Vacuum dust
usually grew A. pullulans, but also Pithomyces chartarum
(n¼2), A. vitus (n¼2), Scopulariopsis brevicaulis (n¼
1), R. mucilaginosa (n¼1) and Ar. phaeospermum (n¼
1). Some isolates (all filamentous fungi; n¼16) were not
identifiable by us or at CBS.
The actual yield and quantitative culture results varied
substantially by temperature of incubation and time (24 h
or 7 days). Species yield was always higher at 7 days, and
A. fumigatus CFU climbed by about 5 logs between 24 h
and 7 days. There was a thick layer of matted hyphae and
conidia on the surface of the culture broth after 7 days
incubation, and so the increase in A. fumigatus CFU was
probably artefactual. Incubation at 37C inhibited the
growth of A. pullulans, and slightly reduced the growth of
R. mucilaginosa.
There was a poor relationship between the species
cultured directly from pillows and the dust collected prior
to pillow culture. In particular A. fumigatus was never
cultured from vacuum samples, although it was the most
prevalent fungus found in the pillow. The same was true
of A. flavus, but not of A. vitus, which was isolated from
the vacuum samples of two pillows. In contrast much
higher CFU of A. pullulans were obtained from vacuum
samples than in the pillow itself (Table 1).
Comparison of synthetic pillows with feather pillows
showed a larger number of species cultured from synthetic
pillows (Table 2), although there was substantial differ-
ences between individual pillows. In addition, the pre-
dominant species in synthetic pillows was A. fumigatus,
whereas it was A. pullulans in feather pillows.
Discussion
We have shown high levels of fungi in pillows with
substantial interpillow variation in flora and some differ-
ences between feather and synthetic pillows.
Of the three most abundant fungi found, A. fumigatus
is a well recognized allergenic fungus. Indeed more
allergens have been identified in A. fumigatus than any
other fungus to date. In addition to the approved 18
allergens (3), another 60+ immunoglobulin E (IgE)-
binding proteins have been identified (4). In contrast,
A. pullulans is also common in the environment but
without any allergens described, although it has been
associated with an outbreak of extrinsic allergic alveolitis,
when found in profusion in an air conditioning system
(5). Rhodotorula mucilaginosa has been found to be
allergenic in skin prick testing (6), and a single enolase
antigen identified (7). Some of the other fungi found in
the pillows are allergenic including C. herbarum,A. flavus,
A. niger and Penicillium spp. Of note, we did not grow
Alternaria from any pillow, a common allergenic fungus
in outdoor air closely associated with so-called Ôthunder-
storm asthmaÕ(8).
Synthetic pillows are made of inert hollow fibrils of
polyester, with a variety of coatings, e.g. oleic acid, for
ease of spinning. It might be expected that the closer
weave of feather pillow covers might prevent larger
spores from entering or exiting feather pillows, but we
grew E. nigrum which has spores of 15–30 lm from a
Table 1. Quantitative results from 24 h cultures of pillows (n¼6) and vacuum
samples (n¼4)
Sample Species N(%)
Pillow (CFU/g),
mean (range)
Pillow swatch Aspergillus fumigatus 6 (100) 2130 (110–4500)
Aspergillus pullulans 5 (83) 3571 (436–8530)
Rhodotorula mucilaginosa* 2 (33) 6500 (2500–10 500)
Aspergillus flavus 2 (33) 236 (226–245)
Cladosporium spp. 4 (67) 73 (28–133)
Vacuum from
pillow surface
Aureobasidium pullulans 4 (100) 90 520
(34 800–2 910 000)
Penicillium spp. 1 (25) 15 100
Aspergillus vitus
1 (25) 27 800
Rhodotorula mucilaginosa
1 (25) 69 400
Aspergillus glaucus
1 (25) 41 700
Scopulariopsis brevicaulis
1 (25) 13 900
*Previously known as Rhodotorula rubrum.
Isolated from one feather pillow.
Table 2. Comparison of feather and synthetic pillows
Pillow type N
Predominant
species
Mean
(CFU/g, 24 h)
Morphologically
identifiable species
cultured*, mean (range)
Synthetic 5 Aspergillus fumigatus 2745 10 (6–16)
Aureobasidium pullulans 1926
Feather 5 Aspergillus fumigatus 1863 7.8 (4–12)
Aureobasidium pullulans 5110
*Includes vacuum samples.
Woodcock et al.
feather pillow. Both colonisation and exit of larger fungal
spores (Cladosporium etc.) will be greater although the
coarser weave cover on synthetic pillows, consistent with
Butland et al.Õs (1) data, although some escape of the
small 2–3 lm spores of A. fumigatus is likely through the
finer weave covers.
Human respiratory tract exposure could be to the spores
themselves, to hyphae, to volatile fungal secondary
metabolites or to fungal degradation products. Only a
few recognized antigens are found on the spore surface (9),
most being expressed once spore swelling and germination
have taken place, although often very early after germina-
tion (10). Thus, direct mucosal exposure to spores may not
induce a typical allergic response, if the respiratory tract is
normal and spore germination does not take place. Sinus
or airways blockage from respiratory infection, with excess
mucous and local epithelial damage, may however provide
a germination medium, allowing antigenic exposure. This
might explain why adults are so much more frequently
sensitized to fungi than children. Asthma severity in adults
is related to fungal sensitization in long-standing asthma-
tics (11, 12) in which varying degrees of bronchiectasis
is common. In these patients, fungal colonisation and
germination may be a semipermanent fixture of the
airways, and so providing continuous antigenic exposure.
Exposure during sleep because of fungal contamination of
bedding could initiate and drive the process.
The majority of asthma commences in childhood.
Evidence of abnormal lung function is present in a
substantial proportion of 3-year-old children with a family
history of allergy (13). This implies that lung damage
sustained in early life may lead to the later development of
asthma, when permanent airway remodelling is present.
Fungal products in pillows/bedding could damage the
airways at a sensitive time in their development. For
example, b-(1,3)-glucan, an important constituent of
many fungal cell walls, is proinflammatory (14).
Further work is required on the ecology of fungi in
bedding, including the environmental factors which are
important and the relative contribution of duvets and
pillows. Measures of individual fungal exposure need
development. There is little correlation between reser-
voir and airborne fungal levels (15), and it may be that
direct exposure from bedding is more important. The
use of a tight woven or other protective cover such as
Goretex
TM
(W. L. Gore, Livingston, UK) cover might
be protective, and needs investigating. It is extraordin-
ary that such a major unidentified source of fungal
exposure has literally been staring us in the face.
Author contributions
AA Woodcock conceived the idea, and wrote the primary draft of
the paper. N Steel, SJ Howard and CB Moore undertook the
cultures, quantitation and identification of the fungi. A Custovic
and DW Denning contributed to the research plan and writing the
paper.
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Today, buildings still account for almost half of the global energy consumption and carbon emission. This highlights the necessity to increase energy efficiency requirements worldwide in a common effort to reduce the construction sector's impacts on the environment. The current energy policies are driving toward a design that relies on airtight and highly insulated envelopes. As a consequence, energy efficient houses are found to have insufficient indoor air change rates, impacting on the indoor air quality and resulting in higher latent loads. The increased indoor humidity, coupled with the rising trend to use bio-based construction materials, can easily support mould growth and facilitate indoor organic proliferation. It has been estimated that the proportion of buildings damaged by mould is 45% in Europe, 40% in the USA, 30% in Canada and 50% in Australia, highlighting the extent of this issue. Beyond the economic loss due to the remediation works needed to rectify a buildings degradation due to fungi, mould also has significant adverse health effects on the building occupants. Data show that the occurrence of asthmatic symptoms is higher in new energy efficient buildings with low ventilation rate. This paper investigates the effects of building sustainably on the indoor environment in relation to the risk of mould growth. Favourable conditions for growth, causes of growth, effects on health as well as possible solutions are addressed. The conclusions are a step forward toward a more precise and detailed comprehension of mould growth to support policymakers and promote sustainable housing standards.
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To test the hypothesis that airborne microbial cell wall components could induce an inflammatory response in the lungs, measurements were made of the amounts of bacterial endotoxin and (1-->3)-beta-D-glucan in laboratory animal bedding materials. Groups of rats were exposed by inhalation to airborne endotoxin, (1-->3)-beta-D-glucan or a combination of the two for 5 weeks. The results demonstrated that measurable amounts of endotoxin and (1-->3)-beta-D-glucan could be detected in the different bedding materials. In contrast to animals at delivery, those kept on bedding for 5 weeks showed moderate inflammatory reactions in the lung. These were most pronounced among animals exposed to endotoxin and (1-->3)-beta-D-glucan. The results suggest that further studies need to be undertaken to elucidate the role of microbial cell wall products in the development of inflammatory lung responses among research animals.
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Background: Exposure to fungi is often assessed by culturing floor dust or air samples. Our objective was to evaluate the relationships between dustborne and airborne fungi and to identify factors that modify these relationships. Methods: From November 1994 to September 1996 sequential duplicate 45-l air samples were collected in bedrooms of 496 homes in the Boston area, using a Burkard culture plate sampler. After air sampling, bedroom floors were sampled with a vacuum cleaner that was modified to collect dust in a cellulose extraction thimble. Dust was sieved, and the fine dust was dilution-plated onto DG-18 media. Results: Concentrations of total culturable fungi per gram of bedroom-floor dust were correlated weakly, but significantly, with those of indoor air (r = 0.13, P < 0.05). Concentrations of some individual taxa in the dust and indoor air were also weakly associated. Adjusting for the concentrations of fungi in outdoor air, dustborne fungal concentrations were positively associated with those in indoor air for the taxa Cladosporium and Penicillium, but not for total fungi. The indoor air fungal levels were often predicted by different covariates to those predicting fungal levels in dust. The type of housing (house or apartment) and the presence of carpeting were often predictive factors for dust fungi. In contrast, outdoor fungal levels were often predictive of the indoor air fungal levels. Conclusions: Because our data do not indicate a strong overall relationship between culturable fungi in dust and indoor air, the results from these two methods (dust and air sampling) likely represent different types of potential fungal exposures to residents. It may be essential to collect both air and dust samples, as well as information on housing characteristics, as indicators for fungal exposure.
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Exposure to airborne spores of the common mold Alternaria alternata has been implicated in asthma attacks. Such exposure is particularly frequent in the Midwest during the summer and fall months. To determine the role of A. alternata in triggering severe asthma attacks, we investigated the cases of 11 patients with asthma who had sudden respiratory arrest and determined the frequency of sensitivity to this allergen in these patients. The 11 patients (age range, 11 to 25 years) with initial episodes of respiratory arrest, which was fatal in 2 patients, were identified in the course of their care in our pediatric and adult clinical allergy practice and by a retrospective review of all Mayo Clinic records of patients with severe asthma cared for between 1980 and 1989. Skin-test reactivity to A. alternata and levels of IgE antibody against this mold in the 11 patients were compared with those in 99 matched controls with asthma who had no history of respiratory arrest. All the patients came from the upper Midwest, and the episodes of respiratory arrest occurred in the summer or early fall. Ten of the 11 patients with asthma who had respiratory arrest (91 percent) had positive skin-puncture tests for sensitivity to alternaria, as compared with 31 percent of the controls (P less than 0.001), and the serum levels of IgE antibodies to alternaria were elevated in all 9 patients tested. Among the covariates we examined (age, sex, and distance from the Mayo Clinic), only age was a significant confounder. After adjustment for age, alternaria skin-test reactivity was found to be associated with an increase of approximately 200-fold in the risk of respiratory arrest (adjusted odds ratio, 189.5; 95 percent confidence interval, 6.5 to 5535.8). Exposure to the aeroallergen A. alternata is a risk factor for respiratory arrest in children and young adults with asthma.
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Symptoms consistent with hypersensitivity pneumonitis developed in several workers in two multistory buildings in an industrial complex. A health questionnaire survey was conducted to determine the extent of the problem. Eighty-seven percent of the population of 1050 employees completed the health questionnaire. Serological testing identified 152 positive precipitin reactors to the fungus Aureobasidium pullulans; 115 reactors were symptomatic. The clinical and laboratory features at the time of the acute illness and during four years of follow-up are described. The agent, A pullulans, was identified as a contaminant of the heating-cooling ventilation units containing open waterspray chambers. Control was accomplished by replacement of the ventilation systems. A secondary source of antigen was found to be corrugated cardboard. Some sensitized employees required removal from work exposure to corrugated cardboard to prevent recurrent symptoms.
Article
Prevalence surveys of asthma and/or wheezing among all children aged between 7 1/2 and 8 1/2 attending state and private schools in the London Borough of Croydon were conducted in February 1978 and February 1991. Two population based case-control studies drawn from the survey responders were used to investigate the association between childhood wheeze and characteristics of the home environment and to assess whether changes in these characteristics between 1978 and 1991 may have contributed to an increase in the population prevalence of wheeze among school children. Information on exposure to potential indoor environmental risk factors was obtained from parents by home interview and compared between cases-that is, children with frequent (> or = 5) or in-frequent (1-4) attacks of asthma or wheezing in the past 12 months- and controls, with adjustment for study. Changes in exposure over time were assessed by comparing control groups. Between 1978 and 1991 the population prevalence odds of wheeze increased by 20% (OR 1.20; 95% CI 1.04 to 1.39). Change in parental smoking, gas cooking, pet ownership, and central heating did not appear to explain the rise. Use of non-feather pillows was positively associated with childhood wheeze even after adjusting for other risk factors and after re-coding from non-feather to feather cases thought to have changed pillow in response to symptoms (OR 1.54; 95% CI 1.13 to 2.10). The proportion of control children reportedly using non-feather pillows was 44% in 1978 and 67% in 1991. Increased use of non-feather pillows was the only domestic indoor exposure studied which appeared to explain a modest rise in prevalence of wheeze from 1978 to 1991. Our analysis attempts to address behavioural change in response to the child's symptoms but an artifact arising from lifelong avoidance of feather bedding in atopic families cannot be entirely discounted.
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The aim of this study was to determine the aeroallergen sensitivity of allergic rhinitis patients. A total of 100 cases (female: 59, male: 41, aged between 10-59 years, mean age 27.9 years) who were diagnosed with allergic rhinitis by history and clinical presentation, underwent a prick skin test with 30 aeroallergens, and the important sensitizing allergens were assessed. Skin test reactivity showing > or = 3 mm wheal with erythema as the positive skin test, was recorded. The results of patients with positive skin tests follow. TREES: acacia 19%, mango 16%, coconut 12%. GRASSES: bermuda 17%, johnson 21%, timothy 16%, bahia 16% orchard 18%. WEEDS: pigweed 16%, kochia 14%. MOLDS: alternaria 11%, cladosporium 11%, aspergillus 12%, penicillium 16%, helminthosporium 16%, botrytis 15%, rhodotorula 20%, fusarium 26%, curvularia 26%, smut mix 11%, rust 9%. EPIDERMALS: cat 29%, dog 28%, feathers 37%. INDOOR ALLERGENS: house dust 72%, D. pteronyssinus 76%, D. farinae 79%, American cockroach 60%, German cockroach 41%, kapok 30%. Eighty-five percent of patients sensitive to house dust mites were positive to both D. pteronyssinus and D. farinae, indicating substantial cross-reactivity. The study shows that the house dust mite and the cockroach are important aeroallergen sensitizers among the Thai population, since more than half the patients were skin-test positive to the house dust mite and the cockroach.
Article
The development of a method to assess lung function in young children may provide new insight into asthma development. Plethysmographic measurement of specific airway resistance (sR(aw)) is feasible in this age group. We aimed to identify risk factors associated with low lung function in early childhood in a prospective birth cohort. Children were prenatally assigned to risk group according to parental atopic status (high risk, both parents atopic; medium risk, one parent atopic; low risk, neither parent atopic) and followed prospectively until age 3 years. We measured sR(aw) in 503 symptom-free children using whole-body plethysmography during tidal breathing. 803 of 868 children attended the clinic, of whom 503 obtained satisfactory sR(aw) readings. 200 who wheezed at least once during first 3 years of life had significantly higher sR(aw) than the 303 who had never wheezed (mean difference 5.8%, 95% CI 2.2-9.3, p=0.002). For children who had never wheezed there were significant differences in sR(aw) between risk groups (p<0.001). Children at high risk (n=87) had a higher sR(aw) (geometric mean 1.17 kPa/s, 1.12-1.22) than children at medium risk (n=162; 1.02 kPa/s, 1.00-1.05) and at low risk (54; 1.04 kPa/s, 0.99-1.11). Atopic children (n=62) had significantly higher sR(aw) (1.15 kPa/s, 1.09-1.21) than those who were not atopic (232; 1.05 kPa/s, 1.02-1.07, p=0.002). For non-atopic children, those at high risk (58) had higher sR(aw) (1.13kPa/s, 1.07-1.18) than those at medium risk (125, 1.01kPa/s, 0.98-1.05) or at low risk (49, 1.04 kPa/s, 0.97-1.10, p=0.003). We showed a significant interaction between history of maternal asthma and child's atopic status (p=0.006). Even in the absence of respiratory symptoms, children of atopic parents and those with personal atopy have impaired lung function in early life.
Article
To assess whether the severity of asthma is associated with sensitisation to airborne moulds rather than to other seasonal or perennial allergens. Multicentre epidemiological survey in 30 centres. European Community respiratory health survey. 1132 adults aged 20-44 years with current asthma and with skin prick test results. Severity of asthma according to score based on forced expiratory volume in one second, number of asthma attacks, hospital admissions for breathing problems, and use of corticosteroids in past 12 months. The frequency of sensitisation to moulds (Alternaria alternata or Cladosporium herbarum, or both) increased significantly with increasing asthma severity (odds ratio 2.34 (95% confidence interval 1.56 to 3.52) for either for severe v mild asthma). This association existed in all of the study areas (gathered into regions), although there were differences in the frequency of sensitisation. There was no association between asthma severity and sensitisation to pollens or cats. Sensitisation to Dermatophagoides pteronyssinus was also positively associated with severity. In multivariable logistic regressions including sensitisation to moulds, pollens, D pteronyssinus, and cats simultaneously, the odds ratios for sensitisation to moulds were 1.48 (0.97 to 2.26) for moderate v mild asthma and 2.16 (1.37 to 3.35) for severe v mild asthma (P<0.001 for trend). Sensitisation to moulds is a powerful risk factor for severe asthma in adults. This should be taken into account in primary prevention, management, and patients' education.
Article
Rhodotorula mucilaginosa (also known as R. rubra) is among the most commonly found yeast strains in our environment. However, allergens from R. mucilaginosa have not yet been characterized at the molecular level. The purpose of this study was to characterize the enolase allergen from R. mucilaginosa and examine the allergenic/antigenic cross-reactivity among fungal enolases. The full-length cDNA encoding the R. mucilaginosa enolase was isolated through the reverse transcriptase-polymerase chain reaction in conjunction with the 5'-end and 3'-end rapid amplification cDNA end reactions. The corresponding natural enolase from R. mucilaginosa was identified using two-dimensional gel electrophoresis and N-terminal amino acid sequence analysis. The results showed that the enolase from R. mucilaginosa is a protein of 439 residues and is encoded by a cDNA of 1497 bp. It shares high sequence identity with enolase allergens from Candida albicans (85%), Saccharomyces cerevisiae (76%), Penicillium citrinum (76%), Aspergillus fumigatus (76%), Cladosporium herbarum (76.5%), and Alternaria alternata (74%). A 47-kD component in the R. mucilaginosa extracts was found to react with IgE or rabbit anti-enolase antiserum and has an N-terminal amino acid sequence identical to that deduced from the isolated enolase cDNA. Sera from three (21%) of 14 allergic patients sensitized to R. mucilaginosa showed IgE binding to this 47-kD R. mucilaginosa component and the His-tagged recombinant enolase. A rabbit antiserum against the P. citrinum enolase and a monoclonal antibody (MoAb; Afueno 8) against the A. fumigatus enolase reacted with all 5 fungal enolases tested. However, an MoAb (E2a) generated by using the Saccharomyces enolase as antigen could only recognize the immunizing enolase. In addition, heterogeneity in immunoblot profiles of IgE antibodies in serum samples from 9 allergic patients against 5 different fungal enolases tested was also observed. The presence of IgE cross-reactivity among enolase allergens from R. mucilaginosa, C. albicans and P. citrinum was detected by immunoblot inhibition. In conclusion, a new and cross-reactive enolase allergen from R. mucilaginosa (Rho m 1) was identified. Although enolases are highly conserved allergens among different fungal species, most of the allergic patients examined in this study differed in their IgE reactivity to the 5 different fungal enolases tested. The results obtained will be of value in understanding the role of enolase allergen in clinical mould allergy.