As early as 1971, it was noted that with the introduction of topical mafenide acetate,
wound infections caused byPhycomycetesandAspergillusincreased 10-fold (26), and further
measures such as patient isolation, wound excision, and other topical chemotherapy decreased
bacterial infections dramatically while having no effect on the fungi (27). In recent years, as a
perverse consequence of the effectiveness of current wound care, fungi have become the most
common causative agents (72%) of invasive burn wound infection. Fungal burn wound
infections typically occur relatively late in the hospital course (fifth to seventh postburn week)
of patients with extensive burns who have undergone successive excision and grafting
procedures, but have persistent open wounds. The perioperative antibiotics, which those
patients receive for each grafting procedure, suppress the bacterial members of the burn
wound flora thereby creating an ecological niche for the fungi. The most common nonbacterial
colonizers areCandidaspecies, which fortunately seldom invade underlying unburned tissues
and rarely cross tissue planes. Isolation of this organism in two sites has been associated with
longer wound healing and length of hospital stay, use of artificial dermis, and use of imipenem
for bacterial infection (28).
AspergillusandFusariumspecies, in that order, are the most common filamentous fungi
that cause invasive burn wound infection, and these organisms may cross tissue planes and
invade unburned tissues (Fig. 4). The most aggressive fungi are thePhycomycetes, which
readily traverse fascia and produce ischemic necrosis as a consequence of the propensity of
their broad nonseptate hyphae to invade and thrombose dermal and subdermal vessels.
Rapidly progressing ischemic changes in an unexcised or even excised burn wound should
alert the practitioner to the possibility of invasive phycomycotic infection as should proptosis
of the globe of an eye. One should be particularly alert to the possibility of invasive
phycomycotic infection in patients with persistent or recurrent acidosis. The comorbid effect of
a positive fungal culture or fungal infection has been recently reported to be equal to an
additional 33% body surface area burn (29). Further work from this group reported that fungal
elements were found in 44% of all those who died and underwent an autopsy and death was
attributed to fungal wound infection in one-third of these (30).
The appearance of any of those changes mandates immediate assessment of the microbial
status of the burn wound. Because of the nature of the wound, bacteria and fungi will be
found, some commensals and others opportunists. The mere presence of an organism,
Figure 3 Gross appearance of invasivePseudomonasinfection in the burn wound. Note the focal areas of dark
green discoloration distributed unevenly in the burn eschar and exposed subcutaneous tissue in the base of the
escharotomy incision.
Infections in Burns in Critical Care 365