Bacterial burden control and infection

Recommendations

Identify and Treat the Cause
1 Take a careful history Level of Evidence
Not Assessed


Address patient-centered Concerns
2 Control pain and ensure comfort Level of Evidence
Not Assessed


Provide Local Wound Care
3 Perform infection surveillance of burn wounds, every 24–48 hours during the first few days or weeks after injury, and less frequently after excision, if clinical signs of infection are not present. Level of Evidence
Not Assessed
4 Use superficial swabs for excised wounds and areas that are too thin to biopsy. Level of Evidence
Not Assessed
5 Perform quantitative culture and histologic analysis of wound tissue biopsies for unexcised wounds and wounds in patients with sepsis. Level of Evidence
Not Assessed
6 Perform simultaneous culture of tissue biopsies and blood and urine samples in patients with sepsis and to identify uncommon types of infection. Level of Evidence
Not Assessed
7 Use topical antimicrobial therapy twice daily on burns until epithelialization is complete. Level of Evidence
Not Assessed
8 Select a topical antimicrobial agent based on the organisms cultured, the spectrum of the agent, results of nosocomial infection monitoring, and institutional resistance patterns. Level of Evidence
Not Assessed
9 Use individual culture and susceptibility data to guide selection of effective antibiotic therapy for prophylaxis and for management of infection. Level of Evidence
Not Assessed
10 Use systemic antibiotic therapy selectively in burn patients and for a limited duration. Level of Evidence
Not Assessed
11 Give prophylactic antibiotics to provide antibiotic coverage for burn excision, especially in patients with extensive injury. Level of Evidence
Not Assessed


Provide Organizational Support
12 Empower the burn team to provide excellent care and infection control. Level of Evidence
Not Assessed


Background

Topical and prophylactic systemic antibiotics, advances in infection control in burn units, and early excision and grafting have all contributed to reducing infection-related morbidity and mortality among patients with serious burns. Serious burns destroy the skin barrier and depress the local and systemic immune response. The wound also provides a protein-rich avascular and necrotic environment favouring microbial colonization and proliferation and impairing migration of immune cells and delivery of systemic antibiotics. Burn wound infection delays epidermal maturation and increases scarring. Microbial invasion below the dermis may also cause bacteremia, sepsis, and multiple-organ dysfunction syndrome.

Within 48 hours of the injury, gram-positive organisms, such as staphylococci, heavily colonize the wound unless topical antimicrobials are used. After 5–7 days, other gram-positive organisms and gram-negative bacteria are also present. These organisms may be derived from the host’s gastrointestinal or upper respiratory flora or from the hospital environment. Yeasts and fungi may predominate later, due to use of broad-spectrum antibiotic therapy. Gram-negative organisms are now the most common bacteria implicated in invasive wound infections, due to their virulence and antimicrobial resistance. Organisms originating from the hospital environment tend to be more resistant than the patient’s normal flora. Emergence of bacterial resistance among a wide variety of pathogens limits treatment options for bacterial wound infections.

Wound colonization must be differentiated from infection. Colonization is present when bacteria can be cultured from the wound in the absence of clinical or microbiological signs of infection or histologic evidence of invasion into deeper tissues. Risk of invasive infection is influenced by the extent and depth of the burn, host factors and quantity and virulence of organisms colonizing the wound. Staphylococcus aureus is frequently responsible for early burn infections. In some centres, Pseudomonas aeruginosa is the most common cause of burn infections. Infection due to other bacteria, fungi and viruses has also increased. Anaerobic bacteria may occur with electrical burns or when open dressings rather than occlusive dressings are used. Burn infection has been categorized into several different types:
• Burn wound impetigo: This type of infection may or may not be associated with systemic infection. Impetigo is associated with loss of epithelium from a previously epithelialized site, including grafts, partial-thickness burns healing by secondary intention, and donor sites. Impetigo is unrelated to hematoma formation, inadequate wound excision or mechanical graft disruption.

• Burn-related surgical wound infection: Surgical infection includes unepithelialized excision and donor sites. Culture-positive purulent exudate, loss of wound covering, changes in wound appearance, and erythema in the normal skin around the wound characterize surgical infections.

• Burn wound cellulitis: Cellulitis develops from extension of infection into healthy soft tissue around the wound or donor site. Burn wound cellulitis may be associated with localized pain, tenderness, swelling or heat; progression of erythema and swelling; and signs of lymphangitis and/or lymphadenitis extending from the affected area.

• Invasive infection in unexcised burns: Unexcised deep burn wounds have an increased risk of invasive infection. Invasive infection may be associated with a rapid change in burn wound appearance or character, inflammation of surrounding normal tissue, histologic evidence of microbial invasion into tissue adjacent to the burn, positive blood cultures and systemic signs of sepsis.

Burn wound infection surveillance

The best approach to infection surveillance depends on the specific clinical situation. Samples should be collected every 24–48 hours during the first few days or weeks after injury. A single surface swab or biopsy sample does not adequately represent the microbial population of the wound. Multiple samples should be collected from various areas of the burn. After wound excision, sampling frequency can be decreased to weekly, as long as clinical signs of infection are not present.
• Superficial swabs are the most convenient, least invasive approach for sampling excised burns. Swabs provide an adequate sampling of the flora on the wound surface and are also appropriate for areas where the skin is too thin for biopsy.
• Quantitative culture and histologic analysis of wound tissue biopsies is the preferred technique for unexcised wounds and wounds in patients with sepsis. Quantitative bacteriology, however, is not predictive of sepsis or graft loss.
• Simultaneous culture of tissue biopsies and blood and urine samples is the best approach to identify causative organisms in patients with sepsis and to diagnose uncommon types of infection. Positive blood cultures are a late sign of invasive infection.

Antibiotic selection and use

Topical antimicrobial agents are typically used twice daily until epithelialization is complete. Selection of a topical antimicrobial agent is based on the organisms cultured, the spectrum of the agent, results of nosocomial infection monitoring, and institutional resistance patterns. Commonly used agents include silver nitrate, silver sulfadiazine, mafenide acetate, nanocrystalline silver dressings, mupirocin and nystatin.

Prophylactic systemic antibiotic therapy has not been demonstrated to improve outcomes compared with topical therapy plus surgical excision. Furthermore, prophylactic antibiotics may be associated with an increased rate of wound infection; development of secondary infections, including antibiotic-associated diarrhea due to Clostridium difficile overgrowth; and increased resistance of endogenous and pathogenic bacteria.

Systemic antibiotic therapy should therefore be used selectively in burn patients and for a limited duration. Prophylactic antibiotics may be given to provide antibiotic coverage for burn excision, especially in patients with extensive injury. Individual culture and susceptibility data should be used to guide selection of effective antibiotic therapy for prophylaxis and for management of infection.

References

Essential Publications
1 Hyperbaric oxygen therapy Quality Indicator
 Type: Systematic review
Villanueva E, Bennett MH, Wasiak J, Lehm JP. Hyperbaric oxygen therapy for thermal burns. Cochrane Database of Systematic Reviews 2004, Issue 2.
This is a well-conducted systematic review that highlights the need for more evidence related to the topic of HBOT effectiveness, with important implications for both practice and research. In one RCT, the mean healing time was 19.7 days in those patients treated with HBOT versus the control group (mean: 43.8 days). Adverse events (pulmonary barotrauma, drug reactions, injury or death related to chamber fire) however were also reported from the treatment group.
2 Early enteral nutrition Quality Indicator
 Type: Systematic review
Marik PE, GP Zaloga. Early Enteral Nutrition in Acutely Ill Patients: A Systematic Review. Critical care medicine 2001: 29(12): 2264-70.
The results indicate that early feeding decreases infectious complications (p = 0.00006) and length of stay (p = 0.002). There results however should be interpreted with caution because of the significant heterogeneity between studies.
3 Early enteral nutrition Quality Indicator
 Type: Systematic review
Wasiak J, Cleland H, Jeffery R. Early Versus Late Enteral Nutritional Support in Adults with Burn Injury: A Systematic Review. Journal of Human Nutrition & Dietetics 2007; 20(2): 75-83.
In this systematic review of RCTs and CCTs, the quality of the individual studies was poor and the findings inconclusive. As a result, more well-designed studies are required to explore the benefits of early enternal nutritional support.
4 Immunonutrition Quality Indicator
 Type: Systematic review
Montejo JC, Zarazaga A, Lopez-Martinez J, Urrutia G, Roque M, Blesa AL, Celaya S, Conejero R, Galban C, Garcia de Lorenzo A, Grau T, Mesejo A, Ortiz-Leyba C, Planas M, Ordon~ez J Jimenez FJ. Immunonutrition in the Intensive Care Unit. A Systematic Review and Consensus Statement. Clinical Nutrition 2003; 22(3): 221
This well-conducted systematic review contains important, detailed recommendations for future studies and systematic reviews illustrating the improvement in infection rate and length of hospital stay with pharmaconutrients. The use of diets enriched with pharmaconutrients could be recommended in ICU patients requiring enteral feeding. More investigation are however required in order to target the appropriate population of patients that can benefit from this nutritional therapy.
5 Honey Quality Indicator
 Type: Systematic review
Moore OA, Smith LA, Campbell F, Seers K, McQuay HJ, Moore RA. Systematic Review of the use of Honey as a Wound Dressing. BMC Complementary & Alternative Medicine 2001.
This review highlights the lack of high-quality studies. Nonetheless, the potential benefits of honey treatment for wound healing and infection rates have been elucidated, but these findings are inconclusive.
6 Honey Quality Indicator
 Type: RCT
Mashhood AA, Khan TA, Sami AN. Honey compared with 1% silver sulfadiazine cream in the treatment of superficial and partial thickness burns. Journal of Pakistan Association of Dermatologists 2007; 16(1): 14-19.
This is a RCT that explores the benefits in terms of healing rate, pain relief and bacterial clearance from honey treatment in comparison to 1% silver sulfadiazine. Patients treated with honey had their burns healed completely by 4 weeks versus 6 weeks in the 1% silver sulfadiazine group. As well, all patients in the treatment group were pain free by 3 weeks, while in the 1% silver sulfadiazine group this took 4 weeks. It took 3 weeks and 5 weeks for a positive swab culture from the wound to show no pathogens with honey and 1% silver sulfadiazine respectively
7 High-release nanocyrstalline dressing (Acticoat) Quality Indicator
 Type: RCT
Huang Y, Li X, Liao Z, Zhang G, Liu Q, Tang J, Pang Y, Liu X, Lou Q. A randomized comparative trial between Acticoat and SD-Ag in the treatment of residual burn wounds, including safety analysis. Burns 2007; 33(2):161-166.
In this well designed multi-centre RCT comparing high-release nanocyrstalline dressing (Acticoat) with SD-Ag, a non-significant trend toward Acticoat having shorter healing time was detected. As well, this study suggests significant evidence supporting the efficacy of Acticoat in bacterial clearance.


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