Phoma betae

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Code: m13
Latin name: Phoma betae; synonym: Pleospora betae
Source material: Spores and mycelium
Family: Pleosporaceae


A mould, which may result in allergy symptoms in sensitised individuals.

Allergen Exposure

Members of the genus Phoma have a worldwide distribution and are ubiquitous in nature, with over 2 000 species having been described; they are found in soil, as saprophytes on various plants, and as pathogens to plants and humans. (1) Phoma is a very common soil fungus attacking weak or damaged plants. It is frequently isolated from different soils, dead plant tissues and potato. Phoma is frequently found indoors as a contaminator of humid surfaces, in connection with bio-deterioration of painted walls; producing coloured spots, often pink or purple, several centimetres in diameter.

In plants, Phoma species are common pathogens. The fungi can cause a condition known as Phoma blight, characterised by a withering and fading of the leaves of the plant. The blight eventually kills the plant, and may spread to other plants and trees in the vicinity. Phoma blight can be a very serious problem for nurseries, as the fungus may spread across a wide area before people realize what the problem is. Phoma can lie dormant in the soil until plants are returned to the area, causing a recurrence of the initial blight.

Phoma species are not always easily identified. Various species have been shown to have affected particular plants, e.g. P. sclerotioides causes brown root rot in alfalfa and other perennial forage legumes in regions with harsh winters. (2) P. fimeti has been found in bathrooms and washing machines. (3) Strains of the genus Phoma have often been isolated from various environmental samples – including cereals and maize, in which P. pomorum is found particularly often. (4) Phoma has been known to infect the seed samples of both sorghum and pearl millet. (5) P. glomerata has caused crown rot disease of fennel in southern Italy. (6) Phoma has been reported to be especially common in alfalfa sprouts. (7)

After harvest, vegetables are often spoiled by a wide variety of microorganisms including many bacterial and fungal species. Fungi commonly causing spoilage of fresh vegetables include Botrytis cinerea, various species of the genera Alternaria, Aspergillus, Cladosporium, Colletotrichum, Phomopsis, Fusarium, Penicillium, and Phoma. (8)

Mould growth may occur on fermented meat products, e.g. fermented sausage and liver pâté. In the processing areas of two fermented sausage processing plants and two liver pâté processing plants, 336 samples were examined and at least 17 different genera were identified. The main genera isolated were identified as Aspergillus, Botrytis, Cladosporium, Epicoccum, Eurotium, Penicillium, Phaeoacremonium and Phoma. (9)

Thread mould is a defect which occurs sporadically in maturing vacuum-packaged Cheddar cheese, and is caused by the growth of fungi in folds and wrinkles of the plastic film in which the cheese is packaged. In a study of 110 Cheddar cheese blocks exhibiting typical thread mould defects, the major causative species were found to be Cladosporium cladosporioides, Penicillium commune, C. herbarum, Penicillium glabrum and a Phoma species. Fungal species which can cause thread mould defects were also found in the cheese factory environment, on cheese-making equipment, in air, and in curd and whey, providing a wide range of potential sources of contamination. (10)

Mycotoxins may be present in feeds without any visible signs of mould contamination. Samples from commercial chicken feed (maize kernels), cattle feed (lucerne, grass and hay) and milk were analysed for the presence of certain mycotoxins and cultured for fungi. Results of fungal profiles showed that most samples were contaminated by moulds belonging to the genera Alternaria, Aspergillus, Fusarium, Penicillium, Mucor, Phoma and Rhizopus. (11)

Some species of Phoma secrete phytotoxin and anthraquinone pigments as secondary metabolites, which have great potential for the biological control of weeds. Other species produce pharmaceutically active metabolites, viz. Sirodesmins, Phomenoic acid, Phomenolactone, Phomadecalins, Phomactin A, Phomasetin, Squalestatin-1 (S1), and Squalestatin-2 (S2), which may be utilised as antibiotics and as biocontrol agents. (12)

Phoma colonies are spreading, greyish-brown, powdery or suede-like, producing large, globose, membranous to leathery, darkly pigmented, ostiolate pycnidia. (1)

Allergen Description

No allergens have been characterised.

Potential Cross-Reactivity

No studies have evaluated the cross-reactive potential of Phoma betae.

In a study of sensitisation to fungi in extrinsic asthmatic children living in an urban environment in Hungary, the authors suggested that the frequency of cross-reactions observed both with skin tests and specific-IgE determinations suggested the presence of a common allergen, or epitope, between Alternaria alternata and Phoma betae. (13)

Clinical Experience

IgE-mediated reactions

Anecdotal evidence suggests that Phoma betae may induce symptoms of asthma and hypersensitivity pneumonitis in sensitised individuals. However, few studies have been reported to date; it is possible that the allergy occurs more frequently than has been reported. Dermatomycoses and phaeohyphomycosis have been reported.

In patients with seasonal or summer asthma, 10% proved to be allergic to fungal spores, especially Alternaria and Phoma. (14) In a study of serum IgE antibodies in samples from American patients, hypersensitivity to Phoma was the second most common found. (15)

In a study in Sao Paulo, Brazil evaluating sensitisation in 201 patients with asthma and/or allergic rhinitis to 42 airborne fungi using skin-prick tests, 15 were shown to be sensitised to Alternaria, 15 to Aspergillus, 23 to Aureobasidium, 37 to Candida, 15 to Chaetomium, 19 to Epicoccum, 17 to Mucor, and 20 to Phoma. (16)

In a study of sensitisation to fungi in extrinsic asthmatic children living in an urban environment in Hungary, 10.6% of those examined by skin-prick test were sensitive to the fungi in 1977, 30.4% in 1985 and 38.5% in 1987/88. The authors attributed the increase to the increasing frequency of sensitivity to Alternaria alternata and Phoma betae. Of those sensitive to P. betae, 83% were also sensitive to A. alternata, and 87.5% of those sensitive to A. alternata were also sensitive to P. betae. The authors suggested that the frequency of cross-reactions observed both with skin tests and specific-IgE determinations suggested the presence of a common allergen, or epitope. Importantly, P. betae allergy was not related to detectable mould, humidity or number of pot-plants in the home. (12)

A 48-year-old patient who had no contact with pets, birds, drugs, or moulds at home developed hypersensitivity pneumonitis. He played the saxophone as a hobby. Two moulds, Ulocladium botrytis and Phoma spp., were detected in the saxophone. Precipitating antibodies to these moulds were present in his serum. An additional study confirmed the frequent colonisation of saxophones with potentially pathogenic moulds, such as Fusarium spp., Penicillium spp., and Cladosporium spp. (17)

Other reactions

The genus Phoma contains several species. Most of the strains isolated from human infections have not been identified to species level. These infections may be cutaneous, subcutaneous, corneal, or (rarely) systemic.

Three cases of foot dermatomycoses in immune-competent subjects due to Phoma have been described. (18)

Fatal Phoma exigua lung infection in a patient with acute myeloid leukaemia and diabetes has been described. (19)

Phaeohyphomycosis is a mycotic disease caused by dematiaceous fungi that produce brown yeast-like cells, pseudohyphae and irregular true hyphae in tissues. Causative organisms may include Phoma spp. Presentation may include abscesses and/or verrucous plaque present as skin lesions, and may involve all exposed areas of the body. (20)

Phoma spp was found to be the cause of an aggressive, deep-compartment hand infection in a renal transplant recipient. (21)

Compiled by Dr Harris Steinman.


  1. Phoma species. Accessed 15 January 2011.
  2. Wunsch MJ, Bergstrom GC. Genetic and morphological evidence that Phoma sclerotioides, causal agent of brown root rot of Alfalfa, is composed of a species complex. Phytopathology. 18 Oct 2010 (Epub ahead of print).
  3. Hamada N, Abe N. Growth characteristics of four fungal species in bathrooms. Biocontrol Sci. 2010;15(3):111-5.
  4. Sørensen JL, Aveskamp MM, Thrane U, Andersen B. Chemical characterization of Phoma pomorum isolated from Danish maize. Int J Food Microbiol. 2010;136(3):310-7.
  5. Zida PE, Sérémé P, Leth V, Sankara P, Somda I, Néya A. Importance of seed-borne fungi of sorghum and pearl millet in Burkina Faso and their control using plant extracts. Pak J Biol Sci. 2008;11(3):321-31.
  6. Lahoz E, Caiazzo R, Fanigliulo A, Comes S, Crescenzi A. Phoma glomerata as causal agent of crown rot disease of fennel in southern Italy. Commun Agric Appl Biol Sci. 2007;72(4):875-8.
  7. Tournas VH. Moulds and yeasts in fresh and minimally processed vegetables, and sprouts. Int J Food Microbiol. 2005;99(1):71-7.
  8. Tournas VH. Spoilage of vegetable crops by bacteria and fungi and related health hazards. Crit Rev Microbiol. 2005;31(1):33-44.
  9. Sørensen LM, Jacobsen T, Nielsen PV, Frisvad JC, Koch AG. Mycobiota in the processing areas of two different meat products. Int J Food Microbiol. 2008;124(1):58-64.
  10. Hocking AD, Faedo M. Fungi causing thread mould spoilage of vacuum packaged Cheddar cheese during maturation. Int J Food Microbiol 1992;16(2):123-30.
  11. Naicker D, Marais GJ, Van den Berg H, Masango MG. Some fungi, zearalenone and other mycotoxins in chicken rations, stock feedstuffs, lucerne and pasture grasses in the communal farming area of Rhenosterkop in South Africa. J S Afr Vet Assoc. 2007;78(2):69-74.
  12. Rai M, Deshmukh P, Gade A, Ingle A, Kövics GJ, Irinyi L. Phoma Saccardo: distribution, secondary metabolite production and biotechnological applications. Crit Rev Microbiol. 2009;35(3):182-96.
  13. Szantho A, Osvath P, Horvath Z, Novak EK, and Kujalek E. Study of mold allergy in asthmatic children in Hungary. J Invest Allergol Clin Immunol 1992;2:84-90.
  14. Buisseret PD. Seasonal allergic symptoms due to fungal spores. BMJ 1976;ii:507-8.
  15. Karlsson-Borgå Å, Jonsson P, Rolfsen W. Specific IgE antibodies to 16 widespread mold genera in patients with suspected mold allergy. Ann Allergy 1989;63(12):521-6.
  16. Mohovic J, Gambale W, Croce J. Cutaneous positivity in patients with respiratory allergies to 42 allergenic extracts of airborne fungi isolated in Sao Paulo, Brazil. Allergol Immunopathol (Madr) 1988;16(6):397-402.
  17. Metzger F, Haccuria A, Reboux G, Nolard N, Dalphin JC, De Vuyst P. Hypersensitivity pneumonitis due to molds in a saxophone player. Chest 2010;138(3):724-6.
  18. Tullio V, Banche G, Allizond V, Roana J, Mandras N, Scalas D, Panzone M, Cervetti O, Valle S, Carlone N, Cuffini AM. Non-dermatophyte moulds as skin and nail foot mycosis agents: Phoma herbarum, Chaetomium globosum and Microascus cinereus. Fungal Biol. 2010;114(4):345-9.
  19. Balis E, Velegraki A, Fragou A, Pefanis A, Kalabokas T, Mountokalakis T. Lung mass caused by Phoma exigua. Scand J Infect Dis 2006;38(6-7):552-5.
  20. Suh MK. Phaeohyphomycosis in Korea. Nippon Ishinkin Gakkai Zasshi 2005;46(2):67-70.
  21. Everett JE, Busick NP, Sielaff T, Wahoff DC, Dunn DL. A deeply invasive Phoma species infection in a renal transplant recipient. Transplant Proc 2003;35(4):1387-9.



As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.