The most common sources of sepsis are the wound and/or the tracheobronchial tree; efforts
to identify causative agents should be concentrated there. Another potential source, however, is
the gastrointestinal tract, which is a natural reservoir for bacteria. Starvation and hypovolemia
shunt blood from the splanchnic bed and promote mucosal atrophy and failure of the gut barrier.
Early enteral feeding has been shown to reduce morbidity and potentially prevent failure of the
gut barrier (13). At our institution, patients are fed immediately during resuscitation through a
nasogastric tube. Early enteral feedings are tolerated in burn patients, preserve the mucosal
integrity, and may reduce the magnitude of the hypermetabolic response to injury. Support of
the gut goes along with carefully monitored hemodynamic resuscitation. Enteral feedings can
and should be continued throughout the perioperative and operative periods.
Selective decontamination of the gut has been reported to be of use in preventing sepsis
in the severely burned. de La Cal et al. showed a significant reduction in mortality in severe
burns treated with selective gut decontamination that was associated with a decreased
incidence of pneumonia. This study analyzed 107 patients randomized to placebo or treatment
(14). This is refuted by another smaller study that showed no benefit to selective gut
decontamination, but only an increase in the incidence of diarrhea (15).
BURN WOUND INFECTION
Before the development of effective topical antibacterial chemotherapy, burn wound infections
were the most common infections in burn patients, and invasive burn wound sepsis was the
most common cause of death in patients who died in burn centers (16). Destruction of the blood
vessels in the burned tissue renders it ischemic. The denatured protein comprising the eschar
presents a rich pabulum for microorganisms. Both of these conditions conspire to make the burn
wound alocus minoris resistentiaein the setting of burn-induced immunosuppression. Effective
antimicrobial chemotherapy, achieved by the use of topical agents such as mafenide acetate and
silver sulfadiazine burn creams and silver nitrate soaks or silver-impregnated materials,
impedes colonization and reduces proliferation of bacteria and fungus on the burn wound.
The combined effect of topical therapy and early burn wound excision decreased the
incidence of invasive burn wound sepsis as the cause of death in patients at burn centers from
60% in the 1960s to only 6% in the 1980s. An historical study of the use of mafenide acetate in
burned combatants during the Vietnam War demonstrated a 10% reduction in mortality in
those with severe burns treated with mafenide versus those without topical treatment (17).
In the past 14 years, invasive burn wound infection, both bacterial and fungal, has occurred in
only 2.3% of 3,876 patients admitted to the U.S. Army Burn Center in San Antonio (18) who
were treated with early excision and topical/systemic antibiotics as described above.
The organisms causing burn wound infections change over time and have anticipated,
by approximately a one decade lead time, the predominant organisms causing infections in
other surgical ICUs. Prior to the availability of penicillin, beta-hemolytic streptococcal
infections were the most common infections in burn patients. Soon after penicillin became
available,Staphylococcibecame the principal offenders. The subsequent development of anti-
staphylococcal agents resulted in the emergence of gram-negative organisms, principally
Pseudomonas aeruginosa, as the predominant bacteria causing invasive burn wound infections.
Topical burn wound antimicrobial therapy, early excision, and the availability of antibiotics
effective against gram-negative organisms was associated with a recrudescence of staph-
ylococcal infections in the late 1970s and 1980s, which has been followed by the reemergence of
infections caused by gram-negative organisms in the past 15 years. During this time period, it
was also noted that hospital costs and mortality are increased in those patients from whom
Pseudomonasorganisms were isolated (19).
Assessment of the microbial ecology in burn centers is common. Recent data in the
literature indicate that coagulase-negativeStaphylococcusandS. aureusare the most common
organisms recovered from the burn wound on admission. In the following weeks, these
organisms were superseded byPseudomonas, indicating that these organisms are the most
common found on burn wounds later in the course, and are therefore the most likely
organisms to cause infection (20). In another burn center, it was again found that late isolates
are dominated byPseudomonas, which was shown to be resistant to most antibiotics save
amikacin and tetracycline (21).Of late, common isolates in the burn wound are those of the
Acinetobacterspecies, which are often resistant to most known antibiotics. Currently at the U.S.
Infections in Burns in Critical Care 363