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You are here: The Fungi > Descriptions >

Paecilomyces spp.
(described by Bainier in 1907)

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Taxonomic classification

Kingdom: Fungi
Phylum: Ascomycota
Class: Euascomycetes
Order: Eurotiales
Family: Trichocomaceae
Genus: Paecilomyces

Description and Natural Habitats

Paecilomyces is a cosmopolitan filamentous fungus which inhabits the soil, decaying plants, and food products. Some species of Paecilomyces are isolated from insects. The telemorphs of Paecilomyces are classified in the genera Byssochlamys, Chromocleista, Talaromyces, and Thermoascus [531]. Paecilomyces is usually considered as a contaminant but may also cause infections in humans and animals.


The genus Paecilomyces contains several species. The most common are Paecilomyces lilacinus and Paecilomyces variotii. The color of the colony and certain microscopic features help in differentiation of the Paecilomyces species from each other [531]. Another feature that helps in species identification is thermophilicity. Paecilomyces crustaceus and Paecilomyces variotii are thermophilic and can grow well at temperatures as high as 50° and possibly 60°C [531, 2202].

See the list of obsolete names, synonyms, and telemorphs for Paecilomyces spp.

Pathogenicity and Clinical Significance

Paecilomyces species can cause various infections in humans. These infections are occasionally referred to as paecilomycosis. Corneal ulcer, keratitis, and endophthalmitis [1772] due to Paecilomyces may develop following extended wear contact lens use or ocular surgery. Paecilomyces is among the emerging causative agents of opportunistic mycoses in immunocompromised hosts [908]. Direct cutaneous inoculation may lead to these infections [1695]. These infections may involve almost any organ or system of human body. Soft tissue [2437], pulmonary [355], and cutaneous infections [1695, 1998], cellulitis [1110], onychomycosis [746], sinusitis [923, 1938], otitis media [585], endocarditis [969, 1476, 2109, 2274], osteomyelitis [456], peritonitis [482, 1238, 1928], and catheter-related fungemia [412, 2221] have all been reported. Paecilomyces species can also cause allergic disorders, such as allergic alveolitis [33].

Paecilomyces can cause infections in animals as well. It has been reported as a cause of hyalohyphomycosis in various animals, such as cats [663], laboratory rats [1265], turtles [1833], and goats [1754].

Macroscopic Features

Colonies of Paecilomyces grow rapidly and mature within 3 days. Paecilomyces crustaceus and Paecilomyces variotii are thermophilic and can grow well at temperatures as high as 50° and possibly 60°C. The colonies are flat, powdery or velvety in texture. The color is initially white, and becomes yellow, yellow-green, yellow-brown, olive-brown, pink, or violet, depending on the species. The reverse is dirty white, buff or brown. A sweet aromatic odor may be associated with older cultures [531, 1295, 2144].

Microscopic Features

Septate hyaline hyphae, conidiophores, phialides, conidia, and chlamydospores are observed. Conidiophores (3-4 µm wide and 400-600 µm long) are often branched and carry the phialides at their tips. The phialides are swollen at their bases and taper towards their apices. They are usually grouped in pairs or brush-like clusters. Conidia are unicellular, hyaline to darkly colored, smooth or rough, oval to fusoid, and form long chains. Chlamydospores are occasionally present [1295, 2202].

Ascomata, asci, and ascospores are produced by the telemorphic species, such as Thermoascus crustaceus [531].

Histopathologic Features

Septate hyphae may be observed. See also our histopathology page.

Compare to


Phialides of Paecilomyces are basally swollen, taper towards their apices and are organized slighly apart from eachother. Phialides of Penicillium, on the other hand, have thicker apices and are organized in tight clusters. Colonies of Penicillium are commonly blue-green in color while those of Paecilomyces are not.

Laboratory Precautions

No special precautions other than general laboratory precautions are required.


Very limited data are available and these data include Paecilomyces fumosoroseus, Paecilomyces javanicus, Paecilomyces lilanicus, Paecilomyces marquandii, and Paecilomyces variotii. The MICs of amphotericin B tend to be low, except for strains of Paecilomyces lilanicus. On the other hand, the MICs of flucytosine tend to be very high, except for strains of Paecilomyces variotii. Fluconazole yields considerably high MICs for all species tested. Itraconazole and ketoconazole MICs are lowest for Paecilomyces variotii compared to other species [23]. Voriconazole has been tested against Paecilomyces lilanicus and Paecilomyces variotii and has promisingly low MICs for both of these species [687, 2432]. Posaconazole [1434], the novel triazole UR-9825 [374], and terbinafine [2308] appear active in vitro against Paecilomyces. Caspofungin, on the other hand, is active in vitro against Paecilomyces variotii but lacks meaningful activity against Paecilomyces lilanicus [558, 1780].

For MICs of various antifungal drugs for Paecilomyces, see our susceptibility database.

Despite high MICs in vitro, amphotericin B and flucytosine combination has been succesfully used in treatment of some cases with paecilomycosis due to Paecilomyces lilanicus [412, 1110]. Caspofungin combined with itraconazole has also been found to be successful in a case infected with Paecilomyces lilanicus [1998].





Paecilomyces lilacinus
Paecilomyces lilacinus
Image courtesy of Julio Garcia


23. Aguilar, C., I. Pujol, J. Sala, and J. Guarro. 1998. Antifungal susceptibilities of Paecilomyces species. Antimicrob. Agents Chemother. 42:1601-1604.

33. Akhunova, A. M., and V. I. Shustova. 1989. Paecilomycosis. Probl Tuberk:38-42.

355. Byrd, R. P., T. M. Roy, C. L. Fields, and J. A. Lynch. 1992. Paecilomyces variotii penumonia in a patient with diabetes mellitus. J Diabetes Complic. 6:150-153.

374. Capilla, J., M. Ortoneda, F. J. Pastor, and J. Guarro. 2001. In vitro antifungal activities of the new triazole UR-9825 against clinically important filamentous fungi. Antimicrob. Agents Chemother. 45:2635-2637.

412. Chan-Tack, K. M., C. L. Thio, N. S. Miller, C. L. Karp, C. Ho, and W. G. Merz. 1999. Paecilomyces lilacinus fungemia in an adult bone marrow transplant recipient. Med Mycol. 37:57-60.

456. Cohen-Abbo, A., and K. M. Edwards. 1995. Multifocal osteomyelitis caused by Paecilomyces varioti in a patient with chronic granulomatous disease. Infection. 23:55-7.

482. Crompton, C. H., J. W. Balfe, R. C. Summerbell, and M. M. Silver. 1991. Peritonitis with Paecilomyces complicating peritoneal dialysis. Pediatr Infect Dis J. 10:869-71.

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.

585. Dhindsa, M. K., J. Naidu, S. M. Singh, and S. K. Jain. 1995. Chronic supparative otitis media caused by Paecilomyces variotii. J Med Vet Mycol. 33:59-61.

663. Elliot, G. S., M. S. Whitney, W. Reed, and S. F. Tuite. 1984. Antemorte diagnosis of paecilomycosis in a cat. J Am Vet Med Ass. 1:93-94.

687. Espinel-Ingroff, A. 2001. In vitro fungicidal activities of voriconazole, itraconazole, and amphotericin B against opportunistic moniliaceous and dematiaceous fungi. J Clin Microbiol. 39:954-958.

746. Fletcher, C. L., R. J. Hay, G. Midgley, and M. Moore. 1998. Onychomycosis caused by infection with Paecilomyces lilanicus. Br J Dermatol. 139:1133-1135.

908. Groll, A. H., and T. J. Walsh. 2001. Uncommon opportunistic fungi: new nosocomial threats. Clin Microbiol Infect. 7:8-24.

923. Gucalp, R., P. Carlisle, P. Gialanella, S. Mitsudo, J. McKitrick, and J. Dutcher. 1996. Paecilomyces sinusitis in an immunocompromised adult patient: Case report and review. Clin. Infect. Dis. 23:391-393.

969. Haldane, E. V., J. L. MacDonald, W. O. Gittens, K. Yuce, and C. E. van Rooyen. 1974. Prosthetic valvular endocarditis due to the fungus Paecilomyces. Can Med Assoc J. 111:963-5, 968.

1110. Jade, K. B., M. F. Lyons, and J. W. Gnann. 1986. Paecilomyces lilacinus cellulitis in an immunocompromised patient. Arch Dermatol. 122:1169-70.

1238. Korzets, A., M. Weinberger, A. Chagnac, A. Goldschmied-Reouven, M. G. Rinaldi, and D. A. Sutton. 2001. Peritonitis due to Thermoascus taitungiacus (anamorph Paecilomyces taitungiacus). J Clin Microbiol. 39:720-724.

1265. Kunstyr, I., F. Jelinek, U. Bitzenhofer, and W. Pittermann. 1997. Fungus Paecilomyces: a new agent in laboratory animals. Lab Anim. 31:45-51.

1295. Larone, D. H. 1995. Medically Important Fungi - A Guide to Identification, 3rd ed. ASM Press, Washington, D.C.

1434. Marco, F., M. A. Pfaller, S. A. Messer, and R. N. Jones. 1998. In vitro activity of a new triazole antifungal agent, Sch 56592, against clinical isolates of filamentous fungi. Mycopathologia. 141:73-77.

1476. McClellan, J. R., J. D. Hamilton, J. A. Alexander, W. G. Wolfe, and J. B. Reed. 1976. Paecilomyces varioti endocarditis on a prosthetic aortic valve. Journal of Thoracic & Cardiovascular Surgery. 71:472-475.

1695. Orth, B., R. Frei, P. H. Itin, M. G. Rinaldi, B. Speck, A. Gratwohl, and A. F. Widmer. 1996. Outbreak of invasive mycoses caused by Paecilomyces lilacinus from a contaminated skin lotion. Ann. Intern. Med. 125:799-806.

1754. Pepin, G. A., and G. C. Pritchard. 1984. Fungal mastitis in a goat due to infection with Paecilomyces variotii. Vet Med J. 5:12.

1772. Pettit, T. H., R. J. Olson, R. Y. Foos, and W. J. Martin. 1980. Fungal endophthalmitis following intraocular lens implantation. A surgical epidemic. Arch. Ophthalmol. 98:1025-1039.

1780. Pfaller, M. A., F. Marco, S. A. Messer, and R. N. Jones. 1998. In vitro activity of two echinocandin derivatives, LY303366 and MK-0991 (L-743,792), against clinical isolates of Aspergillus, Fusarium, Rhizopus, and other filamentous fungi. Diagn. Microbiol. Infect. Dis. 30:251-255.

1833. Posthaus, H., M. Krampe, O. Pagan, E. Gueho, C. Suter, and L. Bacciarini. 1997. Systemic paecilomycosis in a hawksbill turtle (Eretmochelys imbricata). J Mycol Med. 7:223-226.

1928. Rinaldi, S., E. Fiscarelli, and G. Rizzoni. 2000. Paecilomyces variotii peritonitis in an infant on automated peritoneal dialysis. Pediat Nephrol. 14:365-366.

1938. Rockhill, R. C., and M. D. Klein. 1980. Paecilomyces lilacinus as the cause of chronic maxillary sinusitis. J. Clin. Microbiol. 11:737-739.

1998. Safdar, A. 2002. Progressive cutaneous hyalohyphomycosis due to Paecilomyces lilacinus: Rapid response to treatment with caspofungin and Itraconazole. Clin Infect Dis. 34:1415-1417.

2109. Silver, M. D., P. G. Tuffnell, and W. G. Bigelow. 1971. Endocarditis caused by Paecilomyces varioti affecting an aortic valve allograft. J Thorac Cardiovasc Surg. 61:278-81.

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.

2221. Tan, T. Q., A. K. Ogden, J. Tillman, G. J. Demmler, and M. G. Rinaldi. 1992. Paecilomyces lilacinus catheter-related fungemia in an immunocompromised pediatric patient. J. Clin. Microbiol. 30:2479-2483.

2274. Uys, C. J., P. A. Don, V. Schrire, and C. N. Barnard. 1963. Endocarditis following cardiac surgery due to the fungus Paecilomyces. South African Medical Journal. 21 Dec:1276-1280.

2308. Venugopal, P. V., and T. V. Venugopal. 1994. Antifungal activity of allylamine derivatives. Indian J Med Res. 99:71-3.

2432. Wildfeuer, A., H. P. Seidl, I. Paule, and A. Haberreiter. 1998. In vitro evaluation of voriconazole against clinical isolates of yeasts, moulds and dermatophytes in comparison with itraconazole, ketoconazole, amphotericin B and griseofulvin. Mycoses. 41:309-319.

2437. Williamson, P. R., K. J. Kwon-Chung, and J. I. Gallin. 1992. Successful treatment of Paecilomyces varioti infection in a patient with chronic granulomatous disease and a review of Paecilomyces species infections. Clin. Infect. Dis. 14:1023-1026.

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