Tuesday, April 15, 2014

            Welcome to the blog! My name is Joseph Lucas, and I am a graduate student at the Biology Department of Western Illinois University. My research at WIU involves the development of a model of artificial gene transfer in the bacterial organism Leuconostoc citreum, in order to study the genes it used to manufacture a set of unique complex carbohydrates. Over the course of our Medical Mycology class with Dr. Andrea Porras-Alfaro, we were given the opportunity to research and write a blog about a medically significant fungal disease of our choice, and I decided upon Chromoblastomycosis, a fungal disease of the skin. I hope you find it interesting!

Chromoblastomycosis

What is Chromoblastomycosis?
            Chromoblastomycosis is a fungal disease normally confined to the skin, primarily occurring in tropical and subtropical climates, though cases in locations such as the United Kingdom have been reported.[1] Diagnosis is often difficult, as the symptoms often resemble a variety of different skin diseases, such as squamous cell carcinoma.[2] The disease is caused by a variety of fungal pathogens, but the primary two causative species are Cladophialophora carrionii and Fonsecaea pedrosoi.

Causative Agents: Cladophialophora carrionii and Fonsecaea pedrosoi
            The most common cause of Chromoblastomycosis is the Ascomycota fungus Fonsecaea pedrosoi, a darkly pigmented, saprophytic fungus.[3] It primarily appears as a filamentous mold in its usual habitat, usually decaying plant matter, but exhibits in vivo dimorphism when it infects humans; as opposed to its usual filamentous appearance, the fungus produces rounded structures called sclerotia that are visible in biopsies of infected tissue.[3,4] Macroscopically, colonies of Fonsecaea are filamentous and grow slowly, generally over the course of two weeks, and appear olive green near the edges, darkening to near black at the center.[4] When examined microscopically, the hyphae are septate, with erect, pale-brown conidiophores.[4] The conidia themselves are elongated, usually 1.5 – 2.5 microns wide and 3 – 6 microns long, and are produced by a variety of distinct processes involving the production of secondary conidia from primary conidia.

Fig. 1: Conidiophore of F. pederosoi. Note the primary conidia attached to the main hyphal stalk, and producing secondary conidia.

            Cladophialophora carrionii is the next most common cause of chromoblastomycosis. It is ubiquitous in arid areas of South America, and, like Fonsecaea pedrosoi, is a darkly pigmented, saprophytic fungus.[5] Colonies of this fungus are generally wooly and darkly colored, more so at the center than the edges, and grow fairly rapidly in comparison to F. pedrosoi.[6] The microscopic feature of the fungus are similar to F. pedrosoi, such as darkly pigmented septate hyphae, but differs from it in regards to the conidia; whereas F. pedrosoi produces primary conidia that then produce secondary conidia, C. carrionii simply produce unicellular primary conidia, and there is no distinction between vegetative hyphal strands and conidiophores.[6] The conidia themselves are lemon-shaped and very elongated, usually 4.5 - 6 microns long by  2 – 3 microns wide, and exhibit extensive branching.[6]

Fig. 2: Conidiophore of C. carrionii. Note the long chains of lemon-shaped conidia.


Symptoms and Epidemiology
            Symptoms of chromoblastomycosis are usually not life-threatening, but can be disfiguring if the disease is allowed to progress from an extended period of time without treatment, as it primarily affects the skin and subcutaneous tissues.[7] The primary symptom is a chronic infection of the skin, which produces a crusted or ulcerated lesion that slowly grows as the fungus expands its habitat, and be appear in a range of colors, from a flaking white to a black that looks similar to necrosis.[8] Biopsies taken from this lesion, when examined microscopically, will yield sclerotic bodies characteristic of the disease.[8]

Fig. 3: Chromblastomycosis lesion on the arm of a 9 year-old Indian child (Pradeepkumar & Joseph, 2011).

Fig. 4: Histopathology sample displaying a fungal sclerotia characteristic of the disease, often referred to as a, "copperpenny body." (Roy, Das,& Deka, 2013).


C. carrionii and F. pedrosoi Taxonomy[9]
Phylum: Ascomycota
Class: Eurotiomycetes
Order: Chaetothyriales
Family: Herpotrichiellaceae

Geographic Distribution and Habitat
            Both C. carrionii and F. pedrosoi are primarily distributed in the arid regions of Central and South America, typically residing in soil and dead vegetative material[10]. For this reason, commonly infected demographics include children, as well as adults whose work involved working with these materials, especially agricultural workers.[10]

Similar Species
            Both C. carrionii and F. pedrosoi resemble a variety of darkly pigmented fungi macroscopically, including fungi of the genus Cladosporium, another pathogenic fungus that causes skin lesions.[11] For this reason, it is necessary to microscopically examine samples taken and cultured from potential chromoblastomycosis patients, searching for specific conidia and sclerotia.

Diagnosis and Treatment
            Making a diagnosis of chromoblastomycosis requires the assembly of several different characters, as the lesions symptomatic of the disease are highly diverse in nature, and can be easily confused with those of other infections.[12] To begin a diagnosis, a skin scraping is taken, treated with 10% KOH solution and stained, usually with methanamine silver. This is followed by microscopic examination; in cases of chromoblastomycosis, this usually reveals the presence of round, brown-pigmented sclerotia in the tissue.[13] This should be supplemented with culturing of tissue biopsies on solid media, such as Sabouraud’s Dextrose Agar (SDA).
            Treating cases of chromoblastomycosis depends on the severity of the infection. Minor cases can be treated by excision of infected tissue or by application of topical antifungals, while more severe infections require treatment with systemic antifungal drugs, such as itraconazole or terbinafine [14]. 

Case Studies
1   This case involved a 9 year old boy from the town of Andhra Pradesh in India, who came to the hospital with a large, dark lesion on his left arm, which was reported to have been present for 18 months, starting as a small nodule and increasing in size over time. Due to these symptoms he was initially diagnosed with cutaneous tuberculosis and treated with the appropriate drugs, but showed no improvement over the next year and a half. The patient’s history was surprisingly tame: no prior lesions had been observed, and a physical revealed no additional abnormalities or malnutrition. Tests performed on biopsies taken from the lesion were negative for most bacteria, however, deeper samples revealed small, round, golden-brown structures present in the tissue, an indicator of chromoblastomycosis. Additional tests were performed, all providing negative results, except for culturing the tissue on Sabouraud’s dextrose agar supplemented with antibiotics. This media revealed a slow growing fungus on the ninth day of incubation, maturing over the next two weeks. The fungus was fuzzy and grey-green, gradually changing to olive green as it grew. Microscopic examination, as well as growth and metabolic tests, led doctors to identify the fungus as Cladophialophora carrionii. The patient was treated with the antifungal drugs itraconazole and terbinafine for two months, and was negative for the fungus after treatment[8]. 

2     This case involves a 55 year old agricultural worker, who was admitted to the hospital with a large plaque extending from the ankle to mid-thigh of his left leg. The plaque was scaly, with defined edges, and covered in small black ‘dots.’ His medical history was largely unremarkable, save for a diabetes mellitus diagnosis when he was 40. The plaque had been previously treated topically with ointments containing itraconazole, fluconazole, and terbinafine, but none of these led to any real improvements. Biopsies of the plaque were taken, and while no cultures were able to grow any fungus, staining and microscopic examinations of the tissue revealed darkly pigmented fungal cells. The combination of microscopic observations and clinical manifestations led to a diagnosis with severe Chromoblastomycosis. The patient was treated with oral itraconazole (400 mg daily), and after two months of treatment, there had been significant improvement of the lesion. By 12 months, the lesion was completely healed.[15]

Works Cited
1.      Bhagwat, P., Tophakhane, R., Kudligi, C., & Noronha, T. (2010). Multiple asymptomatic verrucous plaques over the legs. Indian Journal of Dermatology, Venereology and Leprology, 76(1), 86. doi:10.4103/0378-6323.58707

2.      Roy, A. D., Das, D., & Deka, M. (2013). Chromoblastomycosis - A clinical mimic of squamous carcinoma. The Australasian Medical Journal, 6(9), 458–460. doi:10.4066/AMJ.2013.1806

3.      Nimrichter, L., Cerqueira, M. D., Leitão, E. A., Miranda, K., Nakayasu, E. S., Almeida, S. R., … Rodrigues, M. L. (2005). Structure, Cellular Distribution, Antigenicity, and Biological Functions of Fonsecaea pedrosoi Ceramide Monohexosides. Infection and Immunity, 73(12), 7860–7868. doi:10.1128/IAI.73.12.7860-7868.2005

4.      “Fonsecaea spp.” Doctorfungus.org. Last updated January 27th 2007. Accessed April 1st 2014. <http://www.doctorfungus.org/thefungi/Fonsecaea.php>.

5.      Mouchalouat, M. de F., Galhardo, M. C. G., Fialho, P. C. M., Coelho, J. M. C. de O., Zancopé-Oliveira, R. M., & Valle, A. C. F. do. (2008). Cladophialophora carrionii: a rare agent of chromoblastomycosis in Rio de Janeiro State, Brazil. Revista Do Instituto de Medicina Tropical de São Paulo, 50(6), 351–353. doi:10.1590/S0036-46652008000600008

6.      “Cladialophora spp.” Doctorfungus.org. Last updated January 27th 2007. Accessed April 1st 2014. <http://www.doctorfungus.org/Thefungi/cladophialophora.php>.

7.      N Namratha, S. N. (2010). Chromoblastomycosis due to Cladosporium carrionii. Journal of Laboratory Physicians, 2(1), 47–8. doi:10.4103/0974-2727.66704

8.      Pradeepkumar, N. S., & Joseph, N. M. (2011). Chromoblastomycosis caused by Cladophialophora carrionii in a child from India. The Journal of Infection in Developing Countries, 5(07), 556–560. doi:10.3855/jidc.1392

9.    http://www.indexfungorum.org/

10.  De Hoog, G. S., Nishikaku, A. S., Fernandez-Zeppenfeldt, G., Padin-Gonzalez, C., Burger, E., Badali, H., … van den Ende, A. H. G. G. (2007). Molecular analysis and pathogenicity of the Cladophialophora  carrionii complex, with the description of a novel species. Studies in Mycology, 58, 219–234. doi:10.3114/sim.2007.58.08

11.  “Cladosporium spp.” Doctorfungus.org. Last updated January 27th 2007. Accessed April 1st 2014. < http://www.doctorfungus.org/thefungi/Cladosporium.php>.

12.  Queiroz-Telles, F., Esterre, P., Perez-Blanco, M., Vitale, R. G., Salgado, C. G., & Bonifaz, A. (2009). Chromoblastomycosis: an overview of clinical manifestations, diagnosis and treatment. Medical Mycology, 47(1), 3–15. doi:10.1080/13693780802538001

13.  “Chromoblastomycosis” mycology.adelaide.edu.au. University of Adelaide. Last updated 2014. Accessed April 2nd 2014. <http://www.mycology.adelaide.edu.au/Mycoses/Subcutaneous/Chromoblastomycosis/http://www.doctorfungus.org/thefungi/Cladosporium.php>.

14.  “Chromoblastomycosis.” Doctorfungus.org. Last updated January 27th 2007. Accessed April 2nd 2014. <http://www.doctorfungus.org/mycoses/human/other/chromoblastomycosis.php>.

15.  Antonello, V. S., Silva, M. C. A. da, Cambruzzi, E., Kliemann, D. A., Santos, B. R., & Queiroz-Telles, F. (2010). Treatment of severe chromoblastomycosis with itraconazole and 5-flucytosine association. Revista Do Instituto de Medicina Tropical de São Paulo, 52(6), 329–331. doi:10.1590/S0036-46652010000600008