Immunocompromised Patients Present a Special Challenge to Infection Control
By Kathy Dix
The focus of the movie "John Q." was a much-needed heart transplant for the protagonist's son. But Hollywood ignored a storyline of much greater interest to infection control personnel. For an organ transplant patient -- or any other immunocompromised subject -- the real story begins when the recovery process starts.
Post-surgery, an organ transplant patient is at his most vulnerable state. The immunosuppressive medications coursing through his veins enable him to keep the new organ, but at the price of a defenseless immune system. Burn patients, minus the protective barrier of their skin, have much the same problem. ICU patients, neonates, HIV-positive patients and the elderly -- each group is at a higher risk of infection than the average hospital occupant. It is the infection control staff's duty to assess the risk factors, minimize as many as possible and annihilate infectious organisms that take advantage of the situation.
Bacteria, fungi and viruses are all potential invaders. Bacteria generally receives the most press coverage, simply because a "flesh-eating" bacteria appears to be more newsworthy than fungi, the red-headed stepchild of pathogens. But fungi are increasingly an issue for at-risk populations. "The changing patterns of newer immunosuppressive agents, complex surgical techniques and artificial devices, and donor considerations all have contributed to the intrinsic risk for fungal infection in organ recipients," writes Bernard Kubak, MD, associate clinical professor of internal medicine and infectious diseases at the UCLA School of Medicine.1
In transplant patients, fungal infection is still a significant cause of morbidity and mortality. The lifelong immunosuppression they will undergo makes them vulnerable to nosocomial, endemic and newly recognized fungal pathogens. And new fungal organisms -- either unrecognized or unappreciated as a risk -- have now been acknowledged as "legitimate pathogens." Because they have only recently been recognized as dangerous (and thus, have not been treated as such before now), the newer fungi can result in higher morbidity than the average fungal infection. Even when they are treated, they may not respond to conventional antifungal therapies "due to a reduced susceptibility or frank resistance in the context of an impaired immune system."
But bacterial infections are still a noteworthy basis of morbidity and mortality in solid-organ transplant recipients, due to epidemiologic exposure or the overall state of immunosuppression.2
In organ transplant patients, it is often difficult to determine whether symptoms are from infection or from other causes of graft dysfunction. This, Kubak writes, "may delay the diagnosis of bacterial infections in solid-organ recipients." There can be many possible causes of fever and other signs and symptoms that generally indicate infection. These other possibilities include: graft rejection, medication adverse effect or systemic inflammatory response.
If transplant patients are febrile, empiric antimicrobial therapy may be the first choice, but some transplant centers prefer to wait for culture results before initiating such treatment. But delaying diagnosis and treatment can significantly influence survival rates. Kubak cites a statistic that survival is as high as 85 percent if there is early intervention, but is only 35 percent if the diagnosis is delayed.
The medical world has long been aware that infections are the primary cause of death in burn patients. Thus, keeping infectious agents at bay and eliminating the ones that do invade is the highest priority for infection control workers in this field. A guide offered by the Eurasia Health Knowledge Network outlines the main considerations for the care of burn patients. The basic objectives for infection control in this subgroup of immunocompromised patients include:
- Keeping exogenous microorganisms away from patients and personnel
- Controlling endogenous flora
- Maintaining current defense mechanisms in burn patients 3
"On the whole, the environment plays a far more important role in (nosocomial infection) development for burn patients than for other categories of patients," write the authors. Transmission routes of microorganisms can include the hands of medical personnel, medical instruments or equipment, or other contaminated environmental objects, such as stethoscopes, EKG sensors, mattresses and bedding or equipment for hydrotherapy.
Patients' intestinal excreta can also be a source of microorganisms; these microorganisms are most often found in burn sites in the inguinal region, on the buttocks and perineum and on the inside of the upper thighs.
Of note, at least airborne transmission to burn site surfaces is not as much a concern as the aforementioned routes. But healthcare workers (HCWs) should keep in mind the following risk factors to burn patients:
- "Deep damage to the skin, which is one of the main defensive barriers across the infection route; such damage is accompanied by profound immunologic disturbances that reduce the infection resistance of the patient's body
- Extent and depth of the burn site; the more extensive the wound, the greater is the risk of colonization and infection
- Burns in the respiratory tract; there is an increased risk of pneumonia
- Invasive procedures
To reduce the risk of burn site infection, wounds should be closed quickly and finally by the use of dissection and skin grafting. Ensure that HCWs follow handwashing protocol as well as standard precautions. Personal protective equipment should be worn (gowns, masks and gloves), and even if HCWs are working with the same patient, contaminated gloves should be changed after each area is cleaned. Medical items and equipment should be cleaned and disinfected if being used for several patients.
Patients with extensive burns and patients with multiple-resistant microorganisms should be housed in separate wards. Those with extensive burns should be in wards with ventilation systems with laminar airflow. Visitors of such patients should follow handwashing protocol, wear personal protective equipment and be checked for standard infections.
Other points to remember in the prevention of infection in burn patients:
- Antibacterial agents should be used on burn surfaces, as they retard bacterial multiplication in the burn crust. Suggested agents are silver nitrate, silver sulfadiazine and 0.2 percent silver digluconate in 1 percent silver sulfadiazine.
- Eliminate potentially contaminated foods from the patients' diets. Potentially risky foods include fresh fruit and vegetables.
- To prevent blood infections, avoid introducing intravascular catheters through the burn surface. When inserting any intravenous catheter, follow the rules of asepsis.
- To prevent urinary tract infections, limit the time that urinary catheters remain in place and prevent urethral meatus contamination associated with water used in hydrotherapy.
- To prevent pneumonia, treat cleaner areas first (such as the nasopharynx or tracheostoma) before moving on to more severely contaminated areas (such as burn sites or urinary catheters).
The possibility of colonization after transmission increases with the size of the burn wound; colonization is also affected by topical application of antimicrobial and antiseptic agents. However, it is possible for microorganisms to develop resistance to these substances.4
The best means of preventing infection in burn patients is "prompt, permanent closure of the wound by excision and grafting," according to the Association for Professionals in Infection Control and Epidemiology (APIC). Handwashing, standard precautions and protective equipment are also crucial.
If hydrotherapy is incorporated -- the controversial treatment is sometimes replaced by local wound care with sterile saline solution -- APIC recommends that hydrotherapy tanks use plastic liners with air channels for agitation instead of mechanical agitators. Also, the addition of antiseptic agents to the hydrotherapy water should be considered.
If infection does occur in these patients, a broad-spectrum antibiotic combination is recommended; this should be modified accordingly if a microbiologic diagnosis can be made. However, constant observation is necessary to prevent a "superinfection" with a resistant organism.
Defects in the Body's Defense Mechanisms
Immunocompromised patients consist of those with one or more defects in the body's normal defense mechanisms, according to the APIC Text of Infection Control and Epidemiology. This group is continually in a state of growth due to the aging U.S. population and medical developments that prolong the lives of those who formerly would not have survived an underlying disease.
Host defects that are associated with impaired resistance include: