identified and controlled. In fact, investigators have shown that 17% of burned patients who
develop sepsis associated with multiple organ failure will not have a preceding diagnosis of
infection (42). In this condition, a thorough search should be made for an infectious source,
including careful and repeated examination of the wound. Other potential sources include the
urinary tract, endocarditis, catheter related sepsis, and meningitis. A perirectal abscess must
also be considered. If a source is still not found, it is conceivable that an overwhelming signal
of inflammation from the wound could be the cause. It must be emphasized that this is a
diagnosis of exclusion, and even after the diagnosis is made, the search for a source of infection
must continue. Such patients are often treated with presumptive wide-spectrum antibiotics. In
this case, anti-fungal medications might also be considered.
Of late, investigators have been in search of genetic markers that herald the development
of sepsis, which could be related to the condition described earlier. Barber et al. recently
described two single nucleotide polymorphisms (SNPs) in the DNA of patients who were more
susceptible to the development of severe sepsis defined as signs of sepsis such as fever and
high white blood cell count, and organ dysfunction or septic shock. The first, TLR4 +896
G-allele, imparted a 1.8-fold increased risk of developing severe sepsis following burn relative
to AA homozygotes. The second, tumor necrosis factor-alpha308 A-allele, imparted a
1.7-fold increase in risk compared to GG homozygotes. However, these alleles were not
associated with mortality (43). This early work signifies that slight genetic differences are likely
to result in different responses to injury such as a burn. Identification of these alleles may
eventually assist practitioners in the care of these patients who are at risk and even mandate
treatment modifications.
VIRUSES
On occasion, fevers will develop in the burned patient in association with the development of
herpetic lesions. These initially present as papules with or without an erythematous rash that
progress to vesicles and pustules. These lesions commonly rupture and develop crusts on the
denuded base. Crusted, shallow, serrated lesions at the margin of a healing or recently healed
partial thickness burn, particularly in the nasolabial area, are typical of herpes simplex virus-1
infections. Cytomegalovirus infections have also been reported in burned patients. Titers for
antibodies to cytomegalovirus and herpes simplex virus-1 may be found to increase, and
intranuclear inclusion bodies in a biopsy specimen from the lesion may also be found.
Excision is not required for the treatment of herpetic burn wound infections unless
secondary invasive bacterial infection occurs in the herpetic ulcers, in fact, no changes in
mortality or length of stay was found in those with viral infections and those without (44). The
cutaneous ulcerations of herpetic infections should be treated with twice-a-day application of a
5% acyclovir ointment to decrease symptoms. Identified viral infection is usually self-limited,
but in severe cases, consideration can be given to systemic or topical treatment with acyclovir
or ganciclovir. Systemic herpes simplex virus-1 infections involving the liver, lung, adrenal
gland, and bone marrow, though rare, are typically fatal and justify systemic acyclovir
treatment.
PNEUMONIA
Pneumonia is now the most common infection in burn patients. The burn injury makes the
patient fivefold more susceptible to the development of pneumonia because of mucociliary
dysfunction associated with inhalation injury, atelectasis associated with mechanical ventila-
tion, and impairment of innate immune responses (45) (Fig. 5). However, with better microbial
control of the burn wound, the route of pulmonary infection has changed from hematogenous
to airborne, and the predominant radiographic pattern has changed from nodular to that of
bronchopneumonia (46). Nonetheless, some investigators still report a pneumonia rate of 48%
in severely burned patients treated in a burn center (47,48). Others have observed much lower
rates (49–51).
The diagnosis of pneumonia in the burned patient is difficult, as the traditional
harbingers of pneumonia such as fever, high white blood cell count, and purulent sputum are
common in the absence of infection in the severely burned, who have inflammation associated
with burn induced SIRS. They are also often intubated for airway control because of inhalation
Infections in Burns in Critical Care 369