Burns injury - PACT - ESICM

Invasive infections
Infection is a major cause of morbidity and mortality in burn patients. Due to the
broken skin barrier, central i.v. catheters and invasive ventilator therapy, patients
with burn injury are susceptible to infections as early as 24–72 hrs after the incident.
Wound and pulmonary infections are the most common. Early extubation is important
to avoid ventilator associated pneumonia (VAP). Patients with inhalation injury are
particularly susceptible to lung infections, and some of them develop the Acute
Respiratory Distress Syndrome (X-rays in interactive version). Initially, Gram-positive
bacteria (skin organisms) predominate, and the most common microbes are
Staphylococcus epidermidis and aureus. With increasing length of hospital stay,
Gram-negative organisms such as Pseudomonas sp. [image in interactive version] are
common pathogens. Another major problem is the more resistant Gram-positive
organisms such as MRSA and VRE. Fungal infections also appear later, especially if
broad spectrum antibacterials have been used for a long time.
The common signs of infection such as pyrexia, leukocytosis, and other elevated
markers of inflammation are frequently seen in burn injury patients in the absence of
invasive infections. This makes diagnosis tricky. It is important for the clinician to
monitor the patient over time to tailor antibiotic treatment. In addition to the
classical signs of invasive infection, evaluate the general clinical condition of the
patient [higher fever (> 39 C), tachycardia, hypovolaemia, increasing CRP, PCT,
blood sugar and increased gastric residual volume] as indirect signs that might point
to an invasive infection. Always do a septic work-up incorporating new swabs,
protected (brush) sampling (if indicated and the patient is intubated), urine and
blood cultures before antibiotics are introduced or changed.
Sepsis is the major cause of death in patients who survive the initial burn
injury. Remember that central catheters, arterial lines, gall bladder, sinuses,
endocarditis and decubitus ulcers might be the source of an intercurrent infection.
Antibiotics
Prophylactic antibiotics should not be given. Aim for short courses of narrowspectrum
antibiotics targeted to clinical, invasive infection and modify/refine
therapy based on microbiological results.
Perioperative antibiotic use during wound debridement and grafting remains
controversial, but is commonly administered for 24 hrs perioperatively in patients
with large burns. The antibiotics used should be dependent on the microbes
identified in that particular patient or those usually present in the unit. A common
combination is an aminoglycoside and penicillinase resistant penicillin.
The pharmacokinetics are different in burn patients requiring larger doses and more
frequent dosing of antibiotics. A longer therapeutic course may be indicated if the
burn wounds are purulent; the agent of choice being guided by recent (septic workup
or surveillance) culture results. As the volume of distribution is unpredictable and
generally significantly increased, antibiotic concentrations should be monitored;
subtherapeutic concentrations may contribute to the selection of resistant microorganisms.
For more information see the PACT modules on Severe Infection and Sepsis and
MODS.
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