Bacterial microflora of allergenic pollens

Radoslaw Spiewak, Zofia Prazmo, Jolanta Sitkowska, Jacek Dutkiewicz

Department of Aerobiology, Institute of Agricultural Medicine, Lublin, Poland

Published in: R. Spiewak (Editor): "Pollens and Pollinosis: Current Problems". Institute of Agricultural Medicine, Lublin (Poland) 1995, pages 34-35. (The book's table of contents.)

Objective

To determine the bacterial microflora typical for allergenic pollens of wind-pollinated plants.

Material

Samples of rye pollen (Secale cereale, harvested 1994), mugwort (Artemisia vulgaris, harvested 1994), birch (Betula verrucosa, 1994), and alder (Alnus glutinosa, 1995).

Methods

The pollens were suspended in sterile and pyrogen-free 0.9% NaCl solution in proportion 100 mg/10 ml. Next, the serial dilutions 10^-2, 10^-3, 10^-4 were cultured on blood agar for mesophilic bacteria and on half-strength tryptic soya agar for thermophilic actinomycetes. Colonies were counted and differentiated and the results were expressed in colony forming units (CFU) per one gram.

Results

Table 1 presents results of the pollens' cultures on blood agar. It may be seen that both Gram-negative and Gram-positive mesophilic bacteria were cultured in the numbers of 10³-10⁴ CFU per gram.

Table 1.

Sample	Bacteria	Concentration (CFU/g)
Rye (Secale cereale) 1994	Gram-negative bacteria	1000
	Gram-positive bacteria	2000
Mugwort (Artemisia vulgaris) 1994	Gram-negative bacteria	7000
	Gram-positive bacteria	21000
Birch (Betula verrucosa) 1994	Gram-negative bacteria	30000
Alder (Alnus glutinosa) 1995	Gram-positive bacteria	11000

The results of allergenic pollens' culture on tryptic soya agar are shown in Table 2. Thermophilic actinomycetes were less numerous than mesophilic bacteria. The most common species was Thermoactinomyces thalpophilus. Only one cultured microorganism was not a Thermoactinomyces species.

Table 2.

Sample	Bacteria	Amount (CFU/g)
Rye (Secale cereale) 1994	-	0
Mugwort (Artemisia vulgaris) 1994	Thermoactinomyces vulgaris	2500
	Thermoactinomyces thalpophilus	1000
	Streptomyces spp.	5000
Birch (Betula verrucosa) 1994	Thermoactinomyces thalpophilus	10000
Alder (Alnus glutinosa) 1995	Thermoactinomyces thalpophilus	10000

Discussion

Our observation that different microorganisms can be cultured from the pollens of anemophilous plants is in accordance with the previous report [2]. It is known that bacterial products may cause various adverse effects which can be attributed to specific hypersensitivity or to immunotoxic reactions [1]. It is possible that a part of allergic symptoms caused by exposure to pollens may be due to the presence of bacteria and their products on pollen grains. For example, endotoxin produced by Gram-negative bacteria activates macrophages to produce IL-1, TNF and other cytokines [1, 3, 4] initiating inflammatory processes in the airway. Thermoactinomyces produces strong allergens and is one of major agents causing allergic alveolitis [3].

Conclusion

A mixed bacterial flora, consisting of mesophilic Gram-negative bacteria, mesophilic Gram-positive bacteria and thermophilic actinomycetes, is present on the allergenic pollen.

References

1. Burrell R. Human immune toxicity. Molec Aspects Med 1993, 14, 1-81.
2. Colldahl H., Carlsson G. Allergens in pollen. Acta Allergol 1968, 23, 387-395.
3. Lacey J., Crook B. Review: Fungal and actinomycete spores as pollutants of the workplace and occupational allergens. Ann Occup Hyg 1988, 32, 515-533.
4. Michel O., Duchateau J., Sergysels R. Effect of inhaled endotoxin on bronchial reactivity in asthmatic and normal subjects. J Appl Physiol 1989, 66, 1059-1064.
5. Michel O., Ginanni R., Le Bon B., Duchateau J. Effect of endotoxin contamination on the antigenic skin test response. Ann Allergy 1991, 66, 39-42.

The final results of this study were published in:

1. Spiewak R., Skorska C., Prazmo Z., Dutkiewicz J. Bacterial endotoxin associated with pollen as a potential factor aggravating pollinosis. Ann Agric Environ Med 1996, 3, 57-59.
2. Spiewak R., Krysinska-Traczyk E., Sitkowska J., Dutkiewicz J. Microflora of allergenic pollens - a preliminary study. Ann Agric Environ Med 1996, 3, 127-130.

For personal use only. © Radoslaw Spiewak.
Page created: 29 April 2004, last updated: 13 February 2006.