Infection Prevention: Unique Aspects of Burn Units

Endogenous and Exogenous Sources of Infection in the Burn Unit

Infection in a burn unit originates via two potential sources: endogenous (from the patient) and exogenous (from the environment) [2]. Burn unit design must therefore consider both of these infection portals. Endogenous causes of infection, i.e. from the burn patients themselves, are the primary source of organisms for infectious outbreaks in burn units. Potential patient-endogenous micro-organism–generating elements include body fluids, such as respiratory secretions; orifices, including mouth, nose, and anus; and the patient's own skin flora in addition to the burn wound itself. The secondary source may be the patient caregiver, shared equipment, ventilation systems, or even cleaning teams (if cleaning materials are transported from room to room). Patients with large wounds (>30% total body surface area [TBSA]), predominance of full-thickness burns, with delays in initial treatment and prolonged open wounds are at highest risk of developing an infection [2]. In the first week post-injury, burn patient wounds are colonized with predominantly gram-positive organisms, which are then replaced by antibiotic-susceptible gram-negative organisms. If the wounds heal, the colonization abates. However, if wound healing is delayed, the development of antibiotic-resistant bacteria, yeast, and fungi may occur. Many of these organisms survive on surfaces and require dedicated cleaning solutions for removal.

Early excision and grafting have been shown to decrease wound bacterial load, infection incidence (including multi-drug–resistant organisms), and incidence of sepsis and wound infection [8,9]. Additional interventions to stem endogenous infection at the patient level include meticulous dressing changes with removal of devitalized tissue, oral hygiene, aggressive pulmonary toilet, appropriate nutrition, topical antimicrobial agents, restricted use of intravenous antibiotics, and early mobility. Organisms can spread via airborne, contact, or droplet methods. As such, each burn patient should be isolated to prevent infection spread.

The exogenous environment may also contribute to the spread of infection via multiple routes, including contact with objects colonized with infectious organisms (such as bed rails, equipment); healthcare personnel contact, ventilation systems, visitors, and water sources. Burn unit design and management cannot eliminate endogenous sources of infection, however, it can minimize the propagation of the endogenous source in the exogenous environment.

Burn Unit Design Considerations in Preventing Endogenous Sources of Infection

Burn unit design must consider that patients are susceptible to infection and the source of infection. As such, burn units require dedicated facilities and equipment; physical separation of patients; proximity to the operating room; separation from other populations, both other infectious populations and immunosuppressed populations; dressing change capability; and consideration of patient and visitor flow [10].

The room environment plays a key role in burn wound care and must be planned carefully. Patients often require advanced monitoring, making electrocardiogram, pulse oximetry, and advanced hemodynamic monitoring capability a priority. To minimize risk of infection, disposable electrocardiogram leads and pulse oximetry probes and cables are ideal. An alternative is meticulous cleaning and monitoring of cleaning efficacy for these devices if not disposable. Because of fluid and heat losses associated with burn injury, both high humidity and high temperatures are required during dressing changes, which promotes droplet production as well as fungal and bacterial growth. Heating elements should be fixed and temperature regulation should be room specific. Rooms must allow for sufficient space for both stationary and transportable equipment as well as patient care and surveillance. Special care must be taken for mobile equipment. Mobile equipment should be cleaned both prior to and upon leaving the room. When possible, mobile equipment used in burn patient rooms (such as portable radiographs, intra-pulmonary percussive ventilation [IPV], dialysis, ultrasound) should be covered with plastic and then cleaned upon leaving. Sufficient space minimizes equipment contact with the patient. Fixed room equipment, particularly water-containing equipment such as sinks and toilets should be cleaned meticulously and monitored for infection. Several infectious outbreaks have been associated with sink contamination [11]. Appropriate connections for ventilator tubing and suction are essential to decrease the risk of droplet contamination. Finally, room design must make hand washing and sinks readily available upon both room entry and departure.

Cleaning and disinfection are important elements in any burn unit. The environment should be decontaminated between patients. Rooms should be designed to minimize difficult-to-clean areas. For example, if curtains are used, they should be changed between patients and at regular intervals during patient hospital stay. Ideally, tinted windows would avoid this issue. Sink design can minimize splash of contaminated water from sink traps between patients. Some organisms, such as Acinetobacter, are difficult to eradicate from surfaces and may require potent bleach solutions and surface monitoring.

Hydrotherapy for wound care is also a source of infection. Although used to reduce wound microbial burden, facilitate eschar separation, remove exudate and creams, loosen adherent dressings, and facilitate physiotherapy, hydrotherapy poses infection control issues. Tubs are difficult to clean, have long filling times, are a breeding ground for bacteria, pose a droplet contamination risk, and have a potential drowning risk [12]. Newer hydrotherapy designs place the patient on a removable stretcher, use shower nozzle to deliver water, use the tub only to catch water, and have a removable lining that is changed between patients. All equipment is easy to clean. However, the system is far from perfect. The tub still needs to be cleaned, the patient is moved through the unit to the tub, and there is a potential for cross-contamination. Hence, use of hydrotherapy should be reserved for stable patients with smaller wounds.

Surface contamination can be a substantial source of infectious organism transmission in the burn unit. Common sites include the bed rail, sink handles, door handles, bedside table, side rails, intravenous fluid administration pump, television remote, and mattresses. All equipment used in the burn unit must be either cleanable or disposed between patients or when soiled. Closed cabinets and drawers should not be used in burn units to store supplies, because they can be difficult to clean and be the source of micro-organisms. If possible, supplies should be kept outside the room; once inside, they need to stay inside the room, even if unopened. Ample space and size of garbage containers is important to prevent the spread of organisms from removed dressings.

Ventilation in burn rooms should be considered carefully because airborne contamination, particularly of fungus, can be problematic. Doors and rooms should be air locked with air ventilation filters and laminar air flow throughout. Negative pressure rooms, although ideal, are not feasible for many settings. In addition, ventilation system filters should be changed and regularly tested for appropriate seals.

Personnel in burn rooms must maintain universal precautions, including hat, gown, mask, gloves, and shoe covers during dressing changes. Protective equipment should be strategically placed to facilitate both donning and doffing of this equipment. Isolation carts outside each patient room for burns greater than 20% TBSA may be advisable to both encourage staff and visitor use of protective coverings and decrease the incidence of nosocomial transmission of microorganisms. Sufficient space must be available for changing into protective wear.

Perhaps one of the greatest challenges in infection prevention in burn units is the frequent movement of burn patients. Unlike many other ill patient populations, burn patients leave their rooms frequently. Care of the major burn requires multiple operations, thus the patient must be transported to and from the operating room. Ideally, the burn unit is located strategically near the operating room to minimize environment contamination or patient contamination of the environment. Post-operative recovery is perhaps best facilitated by immediate transfer of the patient from the operating theater to the burn unit to avoid contamination of the recovery room. In addition to the operating room, burn patients also require transport throughout the hospital for radiologic examinations as well as physical and occupational therapy. Early mobility initiatives in the critically ill burn patient must plan how to engage the patient in activities without contaminating the intensive care unit environment. Careful design of therapy equipment as well as all surfaces in contact with the patient's wounds to facilitate cleaning is in order. Of particular concern are those patients with resistant gram-negative bacteria, which tend to collect on environmental structures.

An estimated 20%–40% of health-care–associated infections are from unclean surfaces or healthcare workers, yet only 34%–40% of hospital surfaces are cleaned to policy standards [13,14]. One method for ensuring environment cleanliness that is coming to the fore is the use of adenosine triphosphatase (ATPase) detectors. Adenosine triphosphate monitoring measures residual organic matter that may remain after a surface is cleaned. Surfaces are swabbed, usually after cleaning, and placed in a luminometer, which detects organic matter remaining on the surface. Although this method does not measure bacterial burden directly, which traditionally is done by quantifying aerobic colony counts, a process that takes several days, it provides an indication of cleaning efficacy within minutes, which can direct cleaning efforts. Burn units should be regularly monitored for surface contamination and cleaning protocols assessed for efficacy.

One of the most important (and often least considered) aspect of burn unit design is the flooring. The type of floor dictates cleaning protocols, equipment movement, and potentially impacts infection transmission. The flooring in a burn unit must be cleanable, resilient, and protected from permanent staining because of topical antimicrobial agents, body fluids, and blood. Units that regularly use topicals such as silver nitrate, which permanently stains objects because of oxidation, usually use mats or floors with multiple layers of wax, which is stripped after patient discharge.

Conclusions

Burn patients are among the most susceptible to infection because of the loss of skin protection, burn immunosuppression, wounds, and mobility. Burn unit design needs to consider endogenous and exogenous sources of contamination carefully, with particular attention paid to dedicated facilities and equipment, physical separation of patients, proximity to the operating room, separation from other populations, dressing change capability, and consideration of patient, staff, and visitor flow. Routine monitoring of the environment as well as strict adherence to infection control guidelines is necessary to minimize morbidity and mortality caused by infection in the burn patient.