Fusarium species are ubiquitous and may be found in the soil, air and on pl
ants. Fusarium species can cause mycotoxicosis in humans following ingestio
n of food that has been colonized by the fungal organism. In humans, Fusari
um species can also cause disease that is localized, focally invasive or di
sseminated. The pathogen generally affects immunocompromised individuals wi
th infection of immunocompetent persons being rarely reported. Localized in
fection includes septic arthritis, endophthalmitis, osteomyelitis, cystitis
and brain abscess. In these situations relatively good response may be exp
ected following appropriate surgery and oral antifungal therapy. Disseminat
ed infection occurs when two or more noncontiguous sites are involved. Over
eighty cases have been reported, many of which had a hematologic malignanc
y including neutropenia. The species most commonly involved include Fusariu
m solani, Fusarium oxysporum, and Fusarium moniliforme (also termed F. vert
icillioides). The diagnosis of Fusarium infection may be made on histopatho
logy, gram stain, mycology, blood culture, or serology. Portals of entry of
disseminated infection include the respiratory tract, the gastrointestinal
tract, and cutaneous sites.
The skin can be an important and an early clue to diagnosis since cutaneous
lesions may be observed at an early stage of the disease and in about seve
nty-five cases of disseminated Fusarium infection. Typical skin lesions may
be painful red or violaceous nodules, the center of which often becomes ul
cerated and covered by a black eschar. The multiple necrotizing lesions are
often observed on the trunk and the extremities. Onychomycosis most common
ly due to F. oxysporum or F. solani has been reported. The onychomycosis ma
y be of several types: distal and lateral subungual (DLSO), white superfici
al (WSO), and proximal subungual (PSO). In proximal subungual onychomycosis
there may be associated leukonychia and/or periungual inflammation. Patien
ts with Fusarium onychomycosis have been cured following therapy with itrac
onazole, terbinafine, ciclopirox olamine lacquer, or topical antifungal age
nt. In other instances nail avulsion plus antifungal therapy has been succe
ssful. In patients with hematologic malignancy or bone marrow transplant, w
ho may experience prolonged or severe neutropenia during the course of ther
apy, the skin and nails should be carefully examined and consideration give
n to treating potential infection sites that may serve as portals for syste
mic dissemination. When disseminated Fusarium infection is present therapy
with antifungal agents has generally been disappointing with the chances of
a successful resolution being enhanced if the neutropenia can be corrected
in a timely manner. Curr Opin Infect Dis 13:121-128. (C) 2000 Lippincott W
illiams & Wilkins.