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(described by Boedijn in 1933)
Curvularia is a dematiaceous filamentous fungus. Most species of Curvularia are facultative pathogens of soil, plants, and cereals in tropical or subtropical areas, while the remaining few are found in temperate zones. As well as being a contaminant, Curvularia may cause infections in both humans and animals [1219, 1295, 1806, 2144].
The genus Curvularia contains several species, including Curvularia brachyspora, Curvularia clavata, Curvularia geniculata, Curvularia lunata, Curvularia pallescens, Curvularia senegalensis, and Curvularia verruculosa. Curvularia lunata is the most prevalent cause of disease in humans and animals.
See the summary of synonyms and teleomorph-anamorph relations for Curvularia spp.
Curvularia spp. are among the causative agents of phaeohyphomycosis. Wound infections, mycetoma, onychomycosis, keratitis, allergic sinusitis, cerebral abscess, cerebritis, pneumonia, allergic bronchopulmonary disease, endocarditis, dialysis-associated peritonitis, and disseminated infections may develop due to Curvularia spp. Curvularia lunata is the most commonly encountered species. Importantly, the infections may develop in patients with intact immune system. However, similar to several other fungal genera, Curvularia has recently emerged also as an opportunistic pathogen that infects immunocompromised hosts [62, 66, 580, 642, 726, 913, 1262, 1285, 1429, 1475, 1927, 2042, 2252, 2270, 2297, 2468].
Curvularia produces rapidly growing, woolly colonies on potato dextrose agar at 25°C. From the front, the color of the colony is white to pinkish gray initially and turns to olive brown or black as the colony matures. From the reverse, it is dark brown to black [531, 1295, 2144, 2202].
Septate, brown hyphae, brown conidiophores, and conidia are visualized. Conidiophores are simple or branched and are bent at the points where the conidia originate. This bending pattern is called sympodial geniculate growth. The conidia (8-14 x 21-35 µm), which are also called the poroconidia, are straight or pyriform, brown, multiseptate, and have dark basal protuberant hila. The septa are transverse and divide each conidium into multiple cells. The central cell is typically darker and enlarged compared to the end cells in the conidium. The central septum may also appear darker than the others. The swelling of the central cell usually gives the conidium a curved appearance [531, 1295, 2144, 2202].
The number of the septa in the conidia, the shape of the conidia (straight or curved), the color of the conidia (dark vs pale brown), existence of dark median septum, and the prominence of geniculate growth pattern are the major microscopic features that help in differentiation of Curvularia spp. among each other. For instance, the conidia of Curvularia lunata have 3 septa and 4 cells, while those of Curvularia geniculata mostly have 4 septa and 5 cells.
See our histopathology page.
Curvularia is distinguished from Bipolaris and Drechslera by its conidial septa lying from one side wall to the other (not distoseptate). Also, unlike that of Bipolaris, conidium of Curvularia is usually curved, has an enlarged, darker central cell, thinner cell wall, and narrower septations between the cells [1295, 2144].
No special precautions other than general laboratory precautions are required.
Very few data are available and there is as yet no standard method for in vitro susceptibility testing of Curvularia spp. Notably, flucytosine yielded very high MICs for Curvularia isolates tested. The MICs of fluconazole were also quite high. In contrast, amphotericin B, ketoconazole, miconazole, itraconazole, and voriconazole showed favorable activity and generated acceptably low MICs for most of the Curvularia isolates tested [786, 913, 1491]. Caspofungin also appeared active in vitro against Curvularia lunata .
For MICs of various antifungal drugs for Curvularia, see our susceptibility database.
Treatment modalities for Curvularia infections have not been standardized yet. Amphotericin B, itraconazole, and terbinafine have so far been used to treat Curvularia infections. However, the prognosis is usually poor, particularly for immunocompromised patients. For treatment of allergic sinusitis, surgical treatment and administration of steroids are usually required as well as antifungal therapy. Surgery may be required in other infections as well, such as keratitis and localized cutaneous infections [462, 1262, 2270, 2297].
62. Anaissie, E., G. P. Bodey, H. Kantarjian, J. Ro, S. E. Vartivarian, R. Hopfer, J. Hoy, and K. Rolston. 1989. New spectrum of fungal infections in patients with cancer. Rev Infect Dis. 11:369-378.
66. Anaissie, E. J., G. P. Bodey, and M. G. Rinaldi. 1989. Emerging fungal pathogens. Eur. J. Clin. Microbiol. Infect. Dis. 8:323-330.
462. Collier, L., A. Balows, and M. Sussman. 1998. Topley & Wilson's Microbiology and Microbial Infections, 9th ed, vol. 4. Arnold, London, Sydney, Auckland, New York.
531. de Hoog, G. S., J. Guarro, J. Gene, and M. J. Figueras. 2000. Atlas of Clinical Fungi, 2nd ed, vol. 1. Centraalbureau voor Schimmelcultures, Utrecht, The Netherlands.
558. Del Poeta, M., W. A. Schell, and J. R. Perfect. 1997. In vitro antifungal activity of pneumocandin L-743,872 against a variety of clinically important molds. Antimicrob. Agents Chemother. 41:1835-1836.
580. deShazo, R. D., and R. E. Swain. 1995. Diagnostic criteria for allergic fungal sinusitis. Journal of Allergy & Clinical Immunology. 96:24-35.
642. Ebright, J. R., P. H. Chandrasekar, S. Marks, M. R. Fairfax, A. Aneziokoro, and M. R. McGinnis. 1999. Invasive sinusitis and cerebritis due to Curvularia clavata in an immunocompetent adult. Clin Infect Dis. 28:687-689.
726. Fernandez, M., D. E. Noyola, S. N. Rossmann, and M. S. Edwards. 1999. Cutaneous phaeohyphomycosis caused by Curvularia lunata and a review of Curvularia infections in pediatrics. Pediat Inf Dis J. 18:727-731.
786. Fung-Tomc, J. C., B. Minassian, E. Huczko, B. Kolek, D. P. Bonner, and R. E. Kessler. 1995. In vitro antifungal and fungicidal spectra of a new pradimicin derivative, BMS-181184. Antimicrob. Agents Chemother. 39:295-300.
913. Guarro, J., T. Akiti, R. Almada-Horta, L. A. M. Leite, J. Gene, S. Ferreira-Gomes, C. Aguilar, and M. Ortoneda. 1999. Mycotic keratitis due to Curvularia senegalensis and in vitro antifungal susceptibilities of Curvularia spp. J Clin Microbiol. 37:4170-4173.
1219. Knudtson, W. U., and C. A. Kirkbride. 1992. Fungi associated with bovine abortion in the northern plains states (USA). J Vet Diagn Invest. 4:181-5.
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1285. Lake, F. R., J. H. Froudist, R. McAleer, R. L. Gillon, A. E. Tribe, and P. J. Thompson. 1991. Allergic bronchopulmonary fungal disease caused by Bipolaris and Curvularia. Australian & New Zealand Journal of Medicine. 21:871-4.
1295. Larone, D. H. 1995. Medically Important Fungi - A Guide to Identification, 3rd ed. ASM Press, Washington, D.C.
1429. Manning, S. C., S. D. Schaefer, L. G. Close, and F. Vuitch. 1991. Culture-positive allergic fungal sinusitis. Archives of Otolaryngology -- Head & Neck Surgery. 117:174-8.
1475. McAleer, R., D. B. Kroenert, J. L. Elder, and J. H. Froudist. 1981. Allergic bronchopulmonary disease caused by Curvularia lunata and Drechslera hawaiiensis. Thorax. 36:338-344.
1491. McGinnis, M. R., and L. Pasarell. 1998. In vitro testing of susceptibilities of filamentous ascomycetes to voriconazole, itraconazole, and amphotericin B, with consideration of phylogenetic implication. Antimicrob. Agents Chemother. 36:2353-2355.
1806. Pitt, J. I., A. D. Hocking, K. Bhudhasamai, B. F. Miscamble, K. A. Wheeler, and P. Tanboon-Ek. 1994. The normal mycoflora of commodities from Thailand. 2. Beans, rice, small grains and other commodities. International Journal of Food Microbiology. 23:35-43.
1927. Rinaldi, M. G., P. Phillips, J. G. Schwartz, R. E. Winn, G. R. Holt, F. W. Shagets, J. Elrod, G. Nishioka, and T. B. Aufdemorte. 1987. Human Curvularia infections. Report of five cases and review of the literature. Diagn. Microbiol. Infect. Dis. 6:27-39.
2042. Schell, W. A. 2000. Unusual fungal pathogens in fungal rhinosinusitis. Otolaryngol Clin N Amer. 33:367-373,X.
2144. St-Germain, G., and R. Summerbell. 1996. Identifying Filamentous Fungi - A Clinical Laboratory Handbook, 1st ed. Star Publishing Company, Belmont, California.
2202. Sutton, D. A., A. W. Fothergill, and M. G. Rinaldi (ed.). 1998. Guide to Clinically Significant Fungi, 1st ed. Williams & Wilkins, Baltimore.
2252. Travis, W. D., K. J. Kwon-Chung, D. E. Kleiner, A. Geber, W. Lawson, H. I. Pass, and D. Henderson. 1991. Unusual aspects of allergic bronchopulmonary fungal disease: report of two cases due to Curvularia organisms associated with allergic fungal sinusitis. Hum Pathol. 22:1240-8.
2270. Ujhelyi, M. R., R. H. Raasch, C. M. van der Horst, and W. D. Mattern. 1990. Treatment of peritonitis due to Curvularia and Trichosporon with amphotericin B. Rev. Infect. Dis. 12:621-7.
2297. Vartivarian, S. E., E. J. Anaissie, and G. P. Bodey. 1993. Emerging fungal pathogens in immunocompromised patients: classification, diagnosis, and management. Clin. Infect. Dis. 17:S487-91.
2468. Yau, Y. C. W., J. deNanassy, R. C. Summerbell, M. A. G, and S. E. Richardson. 1994. Fungal sternal wound infection due to Curvularia lunata in a neonate with congential heart disease: Case report and review. Clin. Infect. Dis. 19:735-740.
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