Immunocompromised Patients Present a Special Challenge to Infection Control

Immunocompromised Patients Present a Special Challenge to Infection Control

By Kathy Dix

The focus of the movie "John Q." was a much-needed heart transplantfor the protagonist's son. But Hollywood ignored a storyline of much greaterinterest to infection control personnel. For an organ transplant patient -- orany other immunocompromised subject -- the real story begins when the recoveryprocess starts.

Post-surgery, an organ transplant patient is at his most vulnerable state.The immunosuppressive medications coursing through his veins enable him to keepthe 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. ICUpatients, neonates, HIV-positive patients and the elderly -- each group is at ahigher risk of infection than the average hospital occupant. It is the infectioncontrol staff's duty to assess the risk factors, minimize as many as possibleand annihilate infectious organisms that take advantage of the situation.

ORGAN TRANSPLANTS

Bacteria, fungi and viruses are all potential invaders. Bacteria generallyreceives the most press coverage, simply because a "flesh-eating"bacteria appears to be more newsworthy than fungi, the red-headed stepchild ofpathogens. But fungi are increasingly an issue for at-risk populations."The changing patterns of newer immunosuppressive agents, complex surgicaltechniques and artificial devices, and donor considerations all have contributedto the intrinsic risk for fungal infection in organ recipients," writesBernard Kubak, MD, associate clinical professor of internal medicine andinfectious diseases at the UCLA School of Medicine.¹

In transplant patients, fungal infection is still a significant cause ofmorbidity and mortality. The lifelong immunosuppression they will undergo makesthem 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 theyhave only recently been recognized as dangerous (and thus, have not been treatedas such before now), the newer fungi can result in higher morbidity than theaverage fungal infection. Even when they are treated, they may not respond toconventional antifungal therapies "due to a reduced susceptibility or frankresistance in the context of an impaired immune system."

But bacterial infections are still a noteworthy basis of morbidity andmortality in solid-organ transplant recipients, due to epidemiologic exposure orthe overall state of immunosuppression.²

In organ transplant patients, it is often difficult to determine whethersymptoms are from infection or from other causes of graft dysfunction. This,Kubak writes, "may delay the diagnosis of bacterial infections insolid-organ recipients." There can be many possible causes of fever andother signs and symptoms that generally indicate infection. These otherpossibilities include: graft rejection, medication adverse effect or systemicinflammatory response.

If transplant patients are febrile, empiric antimicrobial therapy may be thefirst choice, but some transplant centers prefer to wait for culture resultsbefore initiating such treatment. But delaying diagnosis and treatment cansignificantly influence survival rates. Kubak cites a statistic that survival isas high as 85 percent if there is early intervention, but is only 35 percent ifthe diagnosis is delayed.

BURN PATIENTS

The medical world has long been aware that infections are the primary causeof death in burn patients. Thus, keeping infectious agents at bay andeliminating the ones that do invade is the highest priority for infectioncontrol workers in this field. A guide offered by the Eurasia Health KnowledgeNetwork outlines the main considerations for the care of burn patients. Thebasic objectives for infection control in this subgroup of immunocompromisedpatients 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 (nosocomialinfection) development for burn patients than for other categories ofpatients," write the authors. Transmission routes of microorganisms caninclude the hands of medical personnel, medical instruments or equipment, orother 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; thesemicroorganisms are most often found in burn sites in the inguinal region, on thebuttocks and perineum and on the inside of the upper thighs.

Of note, at least airborne transmission to burn site surfaces is not as mucha concern as the aforementioned routes. But healthcare workers (HCWs) shouldkeep 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 quicklyand finally by the use of dissection and skin grafting. Ensure that HCWs followhandwashing protocol as well as standard precautions. Personal protectiveequipment should be worn (gowns, masks and gloves), and even if HCWs are workingwith the same patient, contaminated gloves should be changed after each area iscleaned. Medical items and equipment should be cleaned and disinfected if beingused for several patients.

Patients with extensive burns and patients with multiple-resistantmicroorganisms should be housed in separate wards. Those with extensive burnsshould be in wards with ventilation systems with laminar airflow. Visitors ofsuch patients should follow handwashing protocol, wear personal protectiveequipment 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 ofthe burn wound; colonization is also affected by topical application ofantimicrobial and antiseptic agents. However, it is possible for microorganismsto 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 theAssociation 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 sometimesreplaced by local wound care with sterile saline solution -- APIC recommendsthat hydrotherapy tanks use plastic liners with air channels for agitationinstead of mechanical agitators. Also, the addition of antiseptic agents to thehydrotherapy water should be considered.

If infection does occur in these patients, a broad-spectrum antibioticcombination is recommended; this should be modified accordingly if amicrobiologic diagnosis can be made. However, constant observation is necessaryto 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: