Clinical relevance of spore and pollen counts

Many people with allergies monitor daily pollen and spore counts with the belief that they can act on that information to improve their health. Because many factors can affect personal exposure, the value of community-wide counts for an individual is questionable. These factors include the presence of local pollen and spore sources, diurnal variations, weather effects, air pollution, and a particle-free bioaerosol. To take advantage of bioparticulate counts, the public needs to be informed about their meaning and factors that can influence personal exposure.

Are our impressions of allergy test performances correct?

BACKGROUND

The clinical diagnosis is often subjective and susceptible to bias, yet it is the primary standard by which diagnostic tests are judged. Consequently, our opinions regarding various diagnostic tests may not be entirely accurate.

OBJECTIVE

To investigate the accuracy of the clinical history compared with concordant skin and quantitative specific IgE (s-IgE) measurements.

METHODS

Consecutive, consenting patients (N = 152) at 2 different allergy centers were examined by history and physical examination (HPE) alone to determine their sensitivity to 7 common allergens. Results were classified as positive, negative, or indeterminate. The HPE results were then compared to concordant skin prick testing (SPT) and s-IgE measurements and to quantitative IgE antibody measurements with and without knowledge of the SPT results.

RESULTS

Diagnosis by HPE deviated considerably from concordant SPT and s-IgE results. This deviation differed between allergists and allergens, reflecting a positive HPE bias that averaged 22%. Seventy-six percent of the HPE results judged indeterminate were resolved as negative. Using additional information from the quantification of s-IgE antibodies, considerable differences between the sites in the level of s-IgE associated with a positive HPE result with and without SPT results were observed.

CONCLUSIONS

Relative to the SPT and quantification of s-IgE antibodies, the diagnosis by HPE alone to common allergens is not consistent. Discrepancies were dependent on both allergen and allergist. The quantitative s-IgE data revealed that allergists use available information from the HPE and SPT differently. Since the HPE is the primary standard used in judging test efficacy (sensitivity and specificity), our current impressions of test performances are not likely to be accurate.

IgE-reactive proteins from Stachybotrys chartarum

BACKGROUND

Stachybotrys chartarum has been associated with idiopathic pulmonary hemorrhage in infants. This is thought to be mycotoxin-related. There are increasing numbers of reports linking this fungus to the indoor environment of patients with other pulmonary problems, including allergies and asthma.

OBJECTIVE

Given the potential significance of this fungus as a pulmonary pathogen, this work evaluates the antigenic proteins of S. chartarum as to their molecular size and the prevalence of immunoglobulin (Ig)E and IgG directed against them in the general population.

METHODS

S. chartarum was isolated from a local home. S. chartarum for extract production was grown on minimum salts and glucose. Plasma from 132 healthy individuals was evaluated for IgE and IgG directed against S. chartarum using direct and inhibition enzyme immunoassay. The number and molecular size of those proteins that were bound by IgE from pooled sera known to contain IgE to S. chartarum were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis immunoblotting.

RESULTS

Enzyme immunoassay indicated 65 of 132 (49.2%) sera tested contained IgG against S. chartarum and 13 of 139 (9.4%) sera tested contained IgE against S. chartarum. Pooled sera identified two IgE-binding proteins from extracts of S. chartarum spores and mycelia. These proteins are 34 and 52 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis immunoblot.

CONCLUSIONS

We conclude sensitivity to S. chartarum is potentially much more widespread than previously appreciated. This fungus may impact the asthmatic and allergic population through both immunologic and toxic mechanisms. Its significance in the milieu of allergenic fungi may need to be re-evaluated.

Allergen immunotherapy

Allergen immunotherapy plays an important role in the treatment of allergic diseases and asthma. This article is a brief review of the current approaches, including patient and allergen selection, routes of administration, and use of standardized allergen vaccines. New approaches offering potentially useful strategies based on recent studies of T-cell epitopes, cytokines, and anti-IgE and DNA vaccines also are considered.

Safety of fexofenadine in children treated for seasonal allergic rhinitis

BACKGROUND

The incidence of allergic rhinitis in children is increasing.

OBJECTIVE

To evaluate the safety of fexofenadine HCI in children ages 6 through 11 years for treatment of seasonal allergic rhinitis.

METHODS

Two large, double-blind, randomized, placebo-controlled, parallel studies with identical protocols included patients with a positive skin test to fall allergen(s) and allergic rhinitis symptoms. Patients were randomized to receive fexofenadine 15, 30, or 60 mg or placebo twice daily for 2 weeks after a 1-week placebo lead-in. Safety was evaluated through adverse event reporting, electrocardiograms, and pre- and posttreatment laboratory panels and physical examinations.

RESULTS

A total of 875 patients from both studies were eligible for safety analyses. Ten patients (5 on placebo, 5 on fexofenadine) discontinued because of an adverse event; no event that resulted in discontinuation was judged to be caused by study medication. Incidence of adverse events was similar in active and placebo groups, and did not increase with increasing fexofenadine dose: 36.2% (83 of 229) in the placebo group versus 35.3% (79 of 224), 36.8% (77 of 209), and 34.7% (74 of 213) in the 15, 30, and 60 mg twice-daily fexofenadine groups, respectively. Headache was the most commonly reported adverse event (6.6%, 8.0%, 7.2%, and 9.4% in the placebo, 15, 30, 60 mg twice-daily fexofenadine groups, respectively). Clinical, vital sign, electrocardiogram, and laboratory measures were similar in active and placebo groups. There was no statistically significant mean change from baseline in any electrocardiogram parameter after fexofenadine treatment.

CONCLUSIONS

Fexofenadine, 15, 30, and 60 mg twice daily, was safe and well tolerated in this large pediatric patient population.

Allergenic materials in the house dust of allergy clinic patients

INTRODUCTION

Environmental agents including animal, fungal, tree, and weed antigens are known to cause allergic rhinitis and asthma. The following study was performed to measure the antigen concentration of several of these in house dust of children seen in an allergy clinic. Comparisons are made between household allergen levels of children seen for asthma and children seen for other reasons.

METHODS

Dust samples were solicited from patients in a pediatric allergy specialty clinic and other individuals associated with the clinic. Persons submitting dust were asked to complete a questionnaire describing their house. Samples were extracted, centrifuged, and filtered for sterility. Samples were stored in 50% glycerol at -20 degrees C. Specific antigens for Alternaria, Cladosporium, Aspergillus, Candida, Dermatophagoides farinae, cat, dog, oak, fescue, ragweed, plantain, and cockroach were measured using inhibition assays developed with whole antigen extract. Allergens Der p1, Der f 1, Alt a 1, and Alt a 70 kD were measured using double monoclonal antibody assays.

RESULTS

Significant concentrations of whole antigen from cat, dog, oak, Alternaria, and Cladosporium were detected. Between 0.1 and 18 microg of Der f1 and Der p1 per gram of dust were also measured. Alt a 1 and Alt a 70 kD levels varied between 3.0 and 1000 U/g of dust. Significant positive correlations were observed in levels of dust mite and Alternaria allergen for patients with an evaluation of asthma.

CONCLUSIONS

We found measurable levels of fungal antigens (Alternaria, Cladosporium), mite antigens, and animal antigens (dog and cat) in the majority of dust samples in this self-selected set of allergy clinic patients. Specific allergens Alt a 1, Alt a 70kD, and Der p 1 were significantly higher in the homes of asthmatic patients when compared with patients seen for reasons other than asthma. These studies support the hypothesis that fungal allergen exposure is an important component in the pathogenesis of the clinical condition known as asthma.

Hourly variation of airborne ragweed pollen in Kansas City

INTRODUCTION

Ragweed pollen is one of the major causes of allergic rhinitis in the midwest United States. Previous studies have demonstrated that ragweed pollen production begins after sunrise and airborne pollen levels peak several hours later. Variations in this pattern that may be of clinical importance within a small region and the effect of weather on these variations have not been investigated.

METHODS

Volumetric pollen collectors were stationed at four sites around the metropolitan area. Ten-minute grab samples were taken at each location every 2 hours for continuous 24-hour periods during the 1997 ragweed season. The downtown location had a weather station that logged meteorological conditions at hourly intervals during this time. Ragweed pollen grains were counted microscopically at 400 x. Uninterrupted data covering at least 20 days during the season were evaluated for each collection site.

RESULTS

The lowest ragweed pollen counts occur at 6:00 AM and the highest occur at noon for both suburban and urban sites. Rainfall was seen to be the most influential weather-related factor. Significant rainfall events effectively removed pollen grains from the air.

CONCLUSIONS

Though ragweed pollen emission begins at 6:00 AM, peak pollen exposure occurs at midday. This observation is in agreement with many other studies. The myth that highest ragweed exposure occurs in the early morning hours is not supported by this or previous studies.

Efficacy of a single diagnostic test for sensitization to common inhalant allergens

BACKGROUND

UniCAP Phadiatop is a single laboratory test designed to determine the presence or absence of specific IgE to a variety of common inhalants. Its purpose is to aid in the differentiation of patients with symptoms attributable to allergic disease from other common causes.

METHODS

Consecutive children and adolescent patients (n = 145) at two centers were examined by having their history and physical examination performed by two board certified allergists. Their conclusions along with skin prick tests and specific IgE measurements regarding seven common inhalants (mite, oak, ragweed, grass, dog, cat, Alternaria) were compared with UniCAP Phadiatop test results. This was done using concordance of all test results. Attempts to resolve test discrepancies, when found, included specific RAST inhibitions, total IgE values, and physicians' judgment after testing.

RESULTS

All patients with resolved diagnoses (143 of 145, 103 positive and 40 negative) were identified correctly by the UniCAP Phadiatop test. Skin test results and specific IgE measurements correlated well, but neither correlated well with the history by itself, suggesting a minimal false-positive component of the history of 23%. UniCAP Phadiatop results demonstrated a quantitative relationship between the patient's score and the amount of IgE specific to these individual allergens.

CONCLUSIONS

The UniCAP Phadiatop test was shown to be highly sensitive and specific in differentiating individuals who are sensitized to common inhalants from those who are not. This test is recommended to all physicians as an aid in diagnostic and referral decisions for patients suspected of having an inhalant allergic diathesis.

Comparison of the Burkard and Allergenco MK-3 volumetric collectors

BACKGROUND

The Burkard sampler is a widely used volumetric pollen and spore collector, in part, because it is wind-oriented, it has consistent flow characteristics, and it permits time-discrimination of collected particles. Its main disadvantages are that it is heavy, expensive, and visual counting is very time-consuming. A less-expensive volumetric collector with time discrimination capabilities could permit more widespread particle counting which would enhance our understanding of aerobiology.

OBJECTIVE

The objective of this study is to compare the collection recoveries of the Burkard sampler with a less-expensive non-wind oriented collector, the Allergenco MK-3, under various wind speeds.

METHODS

Pollen and spore counts were compared on 20 sampling days during the spring pollen season using a Burkard and Allergenco MK-3 located next to each other on the roof of a 5-story hospital building. A weather station was placed nearby and wind velocity was concurrently measured.

RESULTS

The median wind velocity was 6 miles/hour with a maximum of 35 miles/hour. The Burkard and Allergenco MK-3 collectors displayed similar collection characteristics at all wind velocities for both pollen and spores. The Burkard gave lower counts than the Allergenco when absolute particle counts were low and similar values at higher absolute counts.

CONCLUSIONS

Given our data, we conclude that ambient wind speed has no significant effect on collection efficiency at velocities commonly found on the roof of our hospital and that the collection characteristics of the Burkard and Allergenco MK-3 are comparable.

Comparison of outdoor allergenic particles and allergen levels

INTRODUCTION

Spore and pollen counts have been used traditionally to determine aeroallergen exposure. Using a liquid based collector and enzyme immunoassays, we have developed methods for measuring airborne allergen concentrations. In this work we test the hypothesis that airborne allergen concentrations are directly related to spore and pollen counts.

METHODS

Test samplers used included a high-volume cyclonic liquid impinger (SpinCon) and a standard spore trap (Burkard). Samples were collected on a weekly basis from May to October and were analyzed microscopically for spores and pollen grains. The liquid samples were analyzed by enzyme-linked immunoassay for the presence of allergens from Alternaria, Cladosporium, Aspergillus, oak, fescue, ragweed, and plantain. Specific Alternaria allergens Alt al and GP70 also were measured.

RESULTS

Pollen counts for the SpinCon and Burkard collectors were similar, though spore counts were lower with the SpinCon. Detectable amounts of three of the seven allergenic species including fescue, ragweed, and Alternaria were present in air samples. Concentrations of pollens were seen in their respective seasons while fungal allergen levels varied throughout the period. Allergen levels generally agreed with particle counts, however peak allergen levels and peak particle counts for individual species did not correlate well.

CONCLUSIONS

At flow rates of 236 L/min, the SpinCon is comparable to the Burkard for counting airborne pollen and spores. Samples collected by the SpinCon permit quantitative determination of allergen levels in outdoor air. The poor correlation between measured airborne allergen and related particles indicates the potential for significant allergen exposure in the absence of identifiable particles in air.

Infant pulmonary hemorrhage in a suburban home with water damage and mold (Stachybotrys atra)

The American Academy of Pediatrics recently issued guidelines regarding the potential toxic effect of indoor molds. We now report another case of an infant with pulmonary hemorrhage whose residential environmental assessment revealed the presence of the toxigenic mold Stachybotrys atra. We used a questionnaire to identify environmental factors that could predispose the home to fungal contamination. We collected air samples from multiple locations in the home that we felt would reflect areas of relevant exposure. Surface samples were collected with a piece of transparent tape for semiquantitative measurement of spores present. We classified spores into their respective genera based on shape, size, and color. We also measured mycotoxin levels. Air sampling revealed significantly elevated total spore counts in the patient's bedroom and in the attic. Aspergillus/Penicillium species were predominant. Stachybotrys spores were found in the air sampled in the patient's bedroom, as well as from surfaces sampled in the patient's closet and the attic ceiling. Additionally, a small patch of Stachybotrys-contaminated area in the closet ceiling was sent for mycotoxin analysis. This material proved to be highly toxigenic. As the link between the presence of Stachybotrys in the home and pulmonary hemorrhage in infants increases, further efforts should be made to educate physicians, health care providers, and new parents about the potential toxic effects of this mold.

Monoclonal antibody-based assay for Alt a1, a major Alternaria allergen

BACKGROUND

Allergenic materials from Alternaria are significant causes of human disease. One 31-kD glycoprotein, designated Alt a1, has been described previously as being a significant allergen.

OBJECTIVES

The purpose of this study is to characterize purified Alt a1 and to provide a method for measuring it in laboratory and environmental samples.

METHODS

Monoclonal antibodies directed to the purified allergen were produced and used to construct a double monoclonal assay for Alt a1. The purified allergen detected by this assay was tested for IgE binding in vitro and in vivo.

RESULTS

Purified allergen detected by this assay was shown to bind IgE from patients sensitive to Alternaria and gave a positive skin test in 15 of 16 patients skin test reactive to commercial Alternaria extracts. The assay is sensitive to Alt a1 concentrations as low as 0.2 microg/nmL and is very specific for the allergen. The three commercial Alternaria extracts assayed contained measurable quantities of the allergen varying from 12 to 84 microg/mL.

CONCLUSIONS

Alt a1 is a significant Alternaria allergen. The ability to measure this allergen may assist in standardizing Alternaria extracts and lead to an understanding of the significance of exposure to this allergen.

Northern blot identification of mRNA containing sequence for protein allergen, Alt a1, in eight strains of Alternaria alternata

BACKGROUND

Concentrations of Alt a1, a major allergen from Alternaria alternata extracts, exhibit significant batch-to-batch variability. This variability may result from basic strain-related genetic differences or from environmental influences such as growth conditions or extraction methods.

OBJECTIVE

The objective of this work is to determine if strain-to-strain allergen variability in Alternaria alternata, Alt a1 allergen occurs at the nucleic acid level.

METHODS

We compared the content of mRNA for a segment known to contain sequence coding for the reported N-termini of this allergen in eight strains of Alternaria obtained from three individual sources grown under identical conditions. RNA was extracted from rapidly growing mycelia and analyzed by northern blot analysis for the content of a specific segment containing sequence for the Alt a1 allergen. Blots were also analyzed for the content of a specific 5.8S rRNA segment.

RESULTS

The size of the mRNA for this protein was about 700 bases. Sequence for the specific segment was found in all of the eight strains tested. When normalized for extraction variabilities using the content of 5.8S rRNA, the calculated concentrations of Alt a1 mRNA of seven of the eight strains were similar.

CONCLUSIONS

The results of these experiments suggest that this Alt a1 related allergen sequence is found in many strains of Alternaria and that variabilities in allergen protein content noted previously result from posttranslational events.

Development of mupirocin resistance among methicillin-resistant Staphylococcus aureus after widespread use of nasal mupirocin ointment

All methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from colonized or infected patients in a 625-bed public teaching hospital during an epidemic, and for 3 years thereafter, underwent susceptibility testing to mupirocin. Mupirocin resistance among MRSA increased markedly over this period (1990, 2.7%; 1991, 8.0%; 1992, 61.5%; 1993, 65%) in association with increased use of mupirocin ointment as an adjunct to infection control measures.

Evaluation of four bioaerosol samplers in the outdoor environment

INTRODUCTION

A comparative evaluation of four air samplers was performed using bioaerosol collection in the outdoor environment.

METHODS

Test samplers used included a Rotorod, a Kramer-Collins suction trap, an all-glass impinger (AGI-30), and a high-volume cyclonic liquid impinger (SpinCon). All samples were analyzed microscopically for spores and pollen. The two collectors providing a liquid sample (AGI-30 and SpinCon) also were analyzed for specific allergen content by enzyme-linked immunoassay.

RESULTS

The SpinCon collected a larger number of spores than the other devices. The number of spores collected by this unit per volume of air sampled was comparable to the AGI-30. The Rotorod and Kramer-Collins collected a lower number of spores per unit of air but collected a larger number of pollen grains per volume sampled. Alternaria allergens Alt a I and GP70 were collected by both liquid impingers; however, the SpinCon collected more Alt a I and the AGI-30 collected more GP70.

CONCLUSIONS

The SpinCon is a device that is capable of efficiently sampling a high volume of air and concentrating it in a form that can be analyzed for the presence of spores and fungal allergens. It is less useful for collecting intact pollen grains. Pollen allergen quantitation has not yet been performed on the SpinCon effluent.