61 Stachybotrys
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61 Stachybotrys Dongyou Liu and R.R.M. Paterson contents 61.1 Introduction ..................................................................................................................................................................... 503 61.1.1 Classification, Morphology, and Biology ............................................................................................................ 503 61.1.2 Clinical Features and Pathogenesis ..................................................................................................................... 504 61.1.2.1 Clinical Features ................................................................................................................................... 504 61.1.2.2 Pathogenesis .......................................................................................................................................... 504 61.1.3 Diagnosis ............................................................................................................................................................. 505 61.2 Methods ........................................................................................................................................................................... 505 61.2.1 Sample Preparation .............................................................................................................................................. 505 61.2.1.1 Trichothecene Collection and Analysis ................................................................................................ 505 61.2.2 Detection Procedures ........................................................................................................................................... 505 61.3 Conclusion ....................................................................................................................................................................... 506 References ................................................................................................................................................................................. 506 61.1 IntroductIon or pigmented and cylindrical in shape, with swollen upper portions, forming clusters of 3–61. Conidia (4.5 × 9 μm) are 61.1.1 ClassifiCation, Morphology, and Biology oval, hyaline or pigmented, one-celled, and in clusters. The genus Stachybotrys is an asexually reproducing, dema- First identified from a mold growing on domestic wallpa- tiaceous fungus belonging to the mitosporic Hypocreales per in Prague in 1837, Stachybotrys is a member of the Fungi group, order Hypocreales, class Sordariomycetes, subphy- Imperfecti known as “black mold” or “toxic black mold.” lum Pezizomycotina, phylum Ascomycota, and kingdom The fungus is an inhabitant of soil and strata rich in cellu- Fungi. The mitosporic Hypocreales group encompasses the lose (e.g., hay, straw, grain, hemp, plant debris, dead roots, genera of Acremonium, Acrostalagmus, Cephalosporium, wood pulp, cotton, fabrics, paper, book bindery glue, plant Chaetopsina, Cylindrocladiella, Escovopsis, Fusarium, fiber-processing plants, etc.). It has been isolated from con- Gliocladiopsis, Gliocladium, Hobsonia, Illosporium, taminated grains, tobacco, insulator foams, indoor air, and Myrothecium, Parasarcopodium, Polycephalomyces, water-damaged buildings. The fungus tolerates temperature Rotiferophthora, Sesquicillium, Solheimia, Stachybotrys, up to >60°C and survives over winter. Stachybotrys spores Stilbella, Trichothecium, Tubercularia, Ustilaginoideae, stay viable for years to decades, and conidia retain viability Verticillium, and Xenocylindrocladium [1]. after passage through the gastrointestinal tract. However, the In turn, the genus Stachybotrys is divided into 15 recog- organism is killed by composting degradation of manure and nized species: Stachybotrys bisbyi, Stachybotrys chartarum, by disinfectants [4]. Stachybotrys chlorohalonata, Stachybotrys cylindrospora, Stachybotrys chartarum is a known producer of tricho- Stachybotrys dichroa, Stachybotrys echinata, Stachybotrys thecene mycotoxins and stachylysin (a hemolysin). The elegans, Stachybotrys kampalensis, Stachybotrys longis- best characterized trichothecenes include satratoxins F, G, pora, Stachybotrys microspora, Stachybotrys nephrospora, and H, roriden E, verrucarin J, and trichoverrols A and B, Stachybotrys oenanthes, Stachybotrys parvispora, which share chemical formula of C25H34O6 or C26H38O6 and Stachybotrys subsimplex, and Stachybotrys theobromae, in are tricyclic sesquiterpenes with a 12,13-epoxy-trichothec- addition to 13 unassigned species. Two species, S. chartarum 9-ene ring. Stachybotrys species also produce spirolactams (obsolete synonyms: S. alternans and S. atra) and S. echinata and spirolactones (related to anticomplement components), (obsolete synonym: Memnionella echinata), are implicated phenylspirodrimanes (inhibitor of complement activation), in human diseases [2,3]. cyclosporins, and endothelin receptor antagonists [5–7]. Stachybotrys spp. grow rapidly and mature in approxi- Trichothecenes modulate inflammatory reactions and mately 4 days. Colonies are “cottony,” white initially and alter alveolar surfactant phospholipid concentrations, besides turning black with age. Septate hyphae are hyaline first and being potent inhibitors of protein synthesis (e.g., scirpen- become darkly pigmented later. Conidiophores are simple or triol, 15-acetoxyscirpendiol, diacetoxyscirpenol (DAS or branched, bearing phialides at apices. Phialides are hyaline anguidine), verucarin A, and T-2 toxin) and elongation or 503 K10626_C061.indd 503 1/20/2011 10:03:44 AM 504 Molecular Detection of Human Fungal Pathogens termination (e.g., trichodermin, trichodermol, crotocol, Since then, other clinical manifestations have been associ- trichothecolone, trichothecin, and verrucarol). They are ated with exposure to Stachybotrys chartarum mycotoxins AQ1 susceptible to destruction by alkali although resistant to and spores, ranging from (1) chronic fatigue or headaches, sunlight, UV light, x-rays, heat (up to 120°C), acids, and (2) fever, (3) irritation to the eyes, mucous membranes of the trichothecenes. The mycotoxins have been isolated from dust mouth, nose, and throat, (4) sneezing, (5) rashes, (6) chronic (e.g., satratoxins, trichoverrols, verrucarol, verrucarins, and coughing, (7) nausea, (8) memory loss, (9) vomiting, (10) trichoverrins) and grain (T-2 toxin, nivalenol, and deriva- bleeding in the lungs and nose, (11) hypersensitivity pneu- tives of others). Humans may develop toxin-related disease monitis (HP), (12) allergic rhinitis, and (13) asthma exacer- by ingestion of food products contaminated with the fungus bations. Occupants of mold-contaminated, water-damaged and/toxins, exposure to mycotoxins in building (sick-building buildings often develop symptoms in the central nervous syndrome), and/or inhalation of propogules while undertak- system (CNS) and the immune system as well as pulmonary ing experiments with the fungus [8]. diseases, allergy, and inflammatory reactions. Occupational stachybotrytoxicosis acquired by inhalation showed chest 61.1.2 CliniCal features and pathogenesis and upper airway symptoms, fever, leucopenia, and derma- titis, which started within 2–3 days of exposure and lasted 61.1.2.1 clinical Features for 3 weeks [18]. In a recent investigation of 32 patients with Stachybotrys may induce disease by (1) infection, (2) genera- symptoms attributed to mold exposures at work, 25 (88%) tion of a deleterious immune response, and (3) toxic-irritant patients nominated S. chartarum as well as Aspergillus and effects from mold metabolites. Together with other molds (e.g., Penicillium. 79%, 70%, and 64% of the 32 patients presented Aspergillus, Penicillium, Alternaria, and Cladosporium), with cough, shortness of breath, and chest tightness, respec- Stachybotrys may play a role in the development of sick- tively, which persisted more than 6 weeks in 91%, sugges- building syndrome [9–25]. tive of sick-building syndrome. Thirty one percent of these Stachybotrys was first noted as a pathogen of horses in patients had positive skin test to fungal extracts, suggesting Ukraine in the early 1930s. After the ingestion of hay con- IgE-mediated or other nonimmune mechanisms could be the taminated with Stachybotrys, horses developed lip edema, cause of their symptoms [25,29]. stomatitis, oral necrosis, rhinitis, conjunctivitis, coagulopa- thy, hemorrhage, and neurologic disorders (irritability, gait 61.1.2.2 Pathogenesis disturbance, and blindness). So-called “superinfections” Contemporary construction methods that use cellulose sub- occurred and deaths were observed. The disease syndrome strates (e.g., fiber board) favor the growth of cellulolytic fungi is referred to as stachybotrytoxicosis. In a rare “atypical” such as S. chartarum (Meggs [23]). The fungus is shown or “shocking” form, the disease was primarily neurologi- to produce trichothecene mycotoxins as mentioned above, cal and highly fatal, with areflexia (loss of sensorimotor although several other fungi (e.g., Fusarium, M. verrucaria, reflexes), hyperesthesia (hypersensitivity to pain), hyperir- M. roridum, Trichothecium, Trichoderma, Cephalosporium, ritability, blindness, and stupor. Cattle were also affected to Verticimonosporum, and Cylindrocarpon) also synthesize a lesser extent, and younger animals fared better than older these compounds. S. chartarum macrocyclic trichothecene one. Similar diseases have been reported in other parts