The genus Paecilomyces may be distinguished from the closely related genus Penicillium by having long slender divergent phialides and colonies that are never typically green. Colonies are fast growing, powdery or suede-like, gold, green-gold, yellow-brown, lilac or tan, but never green or blue-green as in Penicillium. Phialides are swollen at their bases, gradually tapering into a rather long and slender neck, and occur solitarily, in pairs, as verticils, and in penicillate heads. Long, dry chains of single-celled, hyaline to dark, smooth or rough, ovoid to fusoid conidia are produced in basipetal succession from the phialides.
Cultures of P. variotii (a) and P. lilacinus (b) showing colony pigmentation.
Paecilomyces are common environmental moulds and are seldom associated with human infection. However, some species such as P. variotii, P. marquandii and P. lilacinus are emerging as causative agents of mycotic keratitis and of hyalohyphomycosis in the immunocompromised patient. Clinical manifestations include peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD), endophthalmitis following lens implantation, endocarditis, pyelonephritis, sinusitis and cutaneous lesions.
Domsch, K.H., W. Gams, and T.H. Anderson. 1980. Compendium of soil fungi. Volume 1. Academic Press, London, UK.