February 1, 2008

Infection Control and Healthcare

Keith F. Woeltje, M.D., Ph.D.
Dr. Woeltje is Associate Professor of Medicine, Infectious Diseases, Washington University School of Medicine, St. Louis, MO.

Healthcare-associated infections (HAI) — that is, infections that are contracted during medical treatment — are not a widely or easily discussed subject. Neither patients nor doctors like to think about them because hospitals and other health care facilities are places we go to get well, not to get sicker.

Somewhere between 5 and 15% of patients who spend a significant amount of time in the hospital acquire some type of infection there. Medicine has traditionally used mysterious, unevocative terms for this phenomenon such as iatrogenic ("due to medical treatment") or nosocomial ("hospital-acquired") infection. Only if you are a medical professional or fluent in ancient Greek would the meaning of these words be clear.

According to studies in the U.S., an infection develops in about 1 in 20 hospitalized patients, an estimated 1.7 million patients per year. Infections acquired during home care or from outpatient treatment get less attention but certainly occur. Why do HAI happen? There are many reasons, not all of which are preventable. After all, hospitals are full of severely ill patients with weakened immune systems; these people are at increased risk for any infection. On the bright side, knowledge of how to prevent HAI is steadily improving and medical attitudes toward HAI are changing.

Medicine has traditionally used mysterious, unevocative terms for this phenomenon such as iatrogenic ("due to medical treatment") or nosocomial ("hospital-acquired") infection.

In the past, HAI were assumed to be an inevitable cost of doing business. But as many hospitals have succeeded in driving their rates of HAI lower than was ever thought possible, it has been recognized that the vast majority of HAI can be prevented. HAI rates will never reach zero. But already, in many medical centers, rates of some HAI, such as catheter-associated bloodstream infections (CABSI) and ventilator-associated pneumonia (VAP), are approaching zero.

For patients and their families, knowledge of HAI and the types of precautions used in hospitals can make you a more educated healthcare consumer who is better able to notice and report infections or risky practices and better manage infection control at home.

What Are HAI?
A healthcare-associated infection is any infection that develops during or as a result of medical treatment.

Programs designed to prevent or control HAI tend to focus on a short list of the most common and most dangerous infections, with higher priority given to HAI which are more preventable. In some states, keeping track of particular HAI may be mandated by law and may be required to be reported to state authorities and eventually the CDC (Centers for Disease Control).

Device-Associated Infections
One of the main sources of infection are medical devices such as catheters, ventilators, feeding tubes and IV lines, mainstays of modern medical care. While they certainly save lives, they also significantly increase the risk of infection. These devices are used a great deal in ICUs,. In addition to their increased exposure to these devices, ICU patients tend to be at higher risk for infection simply because they are very ill. Catheters can cause bloodstream infections and urinary tract infections. Ventilators can cause pneumonias.

Surgical Site Infections
Infections can also occur at surgical sites. Coronary-artery bypass graft surgeries (CABGs) and hip and knee joint replacements are examples of surgeries that are commonly tracked for infection rates by hospitals.

In addition to tracking infections, hospitals have begun to institute a variety of procedures to lower the rates of HAIs.

Hand Hygiene
It may sound simple, but good hand hygiene is the single most important way to fight HAI. Unfortunately, despite the widespread lip service paid to the need for good hand washing, the reality is that healthcare providers, like the rest of us, are not very conscientious about washing hands.

Except in certain areas — in operating rooms 100% compliance is the norm — surveys report that healthcare workers wash their hands less than 40% as often as they should. With the introduction of alcohol-based hand-rub products, the broader term "hand hygiene" has been introduced to cover both traditional hand-washing with soap and water and hand disinfection with an alcohol-based product. Because alcohol-based hand-rub dispensers can be placed in many more locations than sinks, they make it much more likely that healthcare workers will actually perform hand hygiene. Alcohol-based hand-rubs take far less time than traditional soap-and-water washing.

Table 1 shows the CDC-recommended indications for hand hygiene. Hand washing with soap and water should be done whenever the hands are visibly soiled. Otherwise, use of an alcohol-based product for hand hygiene is acceptable. Both the CDC and the World Health Organization have made improved hand hygiene a major goal.

Table 1.
Times When Medical Staff Should Use Hand Hygiene.
  • Patient contact
  • Donning gloves when inserting a CVC
  • Inserting urinary catheters, peripheral vascular catheters, or other invasive devices that don't require surgery
  • Contact with a patient's skin
  • Contact with body fluids or excretions, non-intact skin, wound dressings
  • Contact with inanimate objects (including medical equipment) in the immediate vicinity of the patient
  • Removing gloves

Standard Precautions
There are a number of precautions that can prevent the spread of infection in healthcare settings. These precautions should be followed at all times for all patients. In addition to good hand hygiene, gloves should be worn whenever there may be contact with any damaged skin or bodily fluid. Protective equipment should be removed and disposed of before leaving the patient's room so that common areas are not inadvertently contaminated.

Transmission-based Precautions
Standard precautions cannot prevent the spread of all pathogens. For certain diseases, additional precautions are necessary. Your individual hospital's Infection Prevention and Control Department should be contacted for specific details. Transmission-based precautions include:

Droplet Precautions
These precautions should be implemented when patients are known or suspected to have an illness spread by large respiratory droplets, such as N. meningitides, the cause of meningococcal meningitis (the most common form of bacterial meningitis), or influenza. Because the infectious particles are not suspended in the air for long periods, special air handling (see below) is not necessary. A surgical mask or isolation mask is considered to be sufficient respiratory protection from these illnesses.

Airborne Precautions
Because the infectious particles in airborne-spread diseases can remain suspended in air for long periods of time and can travel long distances, so-called special air handling is required for patients with these infections. Patients must be isolated in airborne infection isolation rooms (AIIR, or negative-pressure ventilation rooms). Air pressure in these rooms is kept lower than the air pressure in the adjacent hallway. Thus, air comes in from the hallway, moves through the room and then is removed.

For diseases where there is natural or vaccine-acquired immunity (e.g., chicken pox or measles), healthcare workers who are immune do not usually need any additional respiratory precautions to enter the AIIR. Non-immune workers should not enter the room; in an emergency, they could use the procedure for diseases where there is no immunity (see below).

For tuberculosis or other diseases where there is no question of immunity, some form of personal respiratory protection is required. At a minimum, a respirator is recommended for anyone entering the room.

For diseases where there is natural or vaccine-acquired immunity (e.g., chicken pox or measles), healthcare workers who are immune do not usually need any additional respiratory precautions to enter the AIIR.

It is imperative that patients who are even suspected of having TB, chicken pox or measles be placed on airborne precautions promptly. Although this will lead to a certain degree of isolation, that is far preferable to having other patients and healthcare workers infected because isolation seemed like too much trouble.

Contact Precautions
Contact precautions are used with patients infected or colonized with organisms that are spread primarily via the hands of healthcare workers, or via contact with contaminated surfaces (such as,hospital bedrails, blood-pressure cuffs). While many organisms can spread this way, contact precautions are reserved for organisms that are either:
  • Drug resistant: The current rise in methicillin-resistant Staphylococcus aureus (MRSA) is one example
  • Very dangerous in the healthcare setting: An example is chicken pox, which can be dangerous to adults, particularly those with suppressed immune systems.
  • Both: This is the case of Clostridium difficile, an intestinal bacteria that is normally held in check by the healthy bacteria in our digestive tract. It becomes a problem in people taking antibiotics that destroy the body's natural defenses against the bacteria, resulting in severe diarrhea. Because it is brought on by antibiotic use, it is particularly antibiotic resistant. People may pick up the bacteria in the hospital, making them susceptible to diarrhea if they are later put on antibiotics.
Healthcare workers and family members should always wear gowns and gloves before entering the room of a patient on contact precautions. The gown and gloves should be removed immediately prior to the healthcare worker leaving the room, and hand hygiene should be performed upon exiting the room. At least one study has shown that both gown and gloves are superior to gloves alone in preventing the spread of resistant organisms.

Controlling the Spread of Drug-Resistant Organisms
Multi-drug resistant organisms (MDROs) have become an increasing problem in American hospitals. MDROs include MRSA, VRE, C. diff and multi-drug resistant gram-negative rods (MDR-GNR). Reports from the CDC indicate that in ICUs MRSA now makes up 60% of S. aureus cases. Likewise, resistance in other categories of disease-causing bacteria showed a steady increase. Unfortunately, few new antibiotics are in the production pipeline. Thus, as MDROs become increasingly resistant, there may be no effective means to treat patients infected with them. Already hospitals are seeing increasing numbers of infections with Acinetobacter that are resistant to all available antibiotics. This makes it all the more important that infections with these organisms be prevented in the first place.

Unfortunately, few new antibiotics are in the production pipeline. Thus, as MDROs become increasingly resistant, there may be no effective means to treat patients infected with them.

The mainstay of preventing the spread of MDROs is the effective use of contact precautions.

Unfortunately, MDROs are becoming more and more common. This may be caused in part by poor adherence to contact precautions, standard precautions and hand hygiene on the part of healthcare workers. Nevertheless, traditional efforts have not proven to be entirely effective, especially with so-called "colonized" patients who have no symptoms but who can act as "reservoirs" that spread infection unpredicably to other patients.8,9 Modern, molecular-based testing allows for rapid identification of colonized patients. Some states, such as Illinois, have mandated active surveillance for MRSA in hospitals.

Device-Associated Infections
While any medical device that enters the body can carry an increased risk of infection, the device-associated infections that are most common — and that receive the most attention — are catheter-associated bloodstream infections (CABSI), ventilator-associated pneumonia (VAP) and catheter-associated urinary tract infections (CAUTI). The surest way to prevent a device-associated infection is not to use the device. The need for these devices should be evaluated daily and they should be discontinued as soon as they are no longer necessary.

Catheter-Associated Bloodstream Infections
Over 250,000 CABSIs are estimated to occur each year in U.S. hospitals, prolonged hospitalization before catheterization, prolonged duration of catheterization, internal jugular catheterization, femoral catheterization (in adults) and substandard catheter care (e.g., many line breaks; low nurse-to-patient ratio) are factors that increase a patient's risk of CABSI.

A number of measures have been proven to reduce the risk of CABSI — these are listed in Table 1. The use of maximal sterile barrier precautions during catheter placement means that the inserter should have a sterile gown and gloves on, as well as a surgical mask and hair-cover. Any assistant working nearby should be similarly attired. The patient should be covered with a broad sterile drape that covers most, if not all, of the body. Comprehensive programs to prevent CABSI, including extensive education of healthcare workers, have led to CABSI rates as low as 0 in many ICUs.

Table 2.
Ways to Reduce the Risk of CABSI.
  • Educate healthcare workers on proper catheter placement and maintenance
  • Perform hand hygiene prior to catheter insertion or manipulation
  • Use a chlorhexidine-based skin antiseptic (for patients over 2 months old) prior to catheter insertion and during dressing changes
  • Use maximal sterile barrier precautions during catheter insertion
  • Avoid using the femor as a site for adult patients
  • Use either sterile gauze or sterile, transparent, semi- permeable dressing to cov
  • Replace dressing if it becomes damp, loosened or visibly soiled
  • Change dressings at least weekly for adult and adolescent patients
  • Do not use topical antibiotic ointment or creams on insertion sites
  • Do not routinely replace central venous or arterial catheters
  • Promptly remove any intravascular catheter that is no longer essential
Ventilator-Associated Pneumonia
Ventilator-associated pneumonia (VAP) is primarily a problem of intensive care units. Rates in the U.S. range from 2.5-12.3 episodes of VAP per 1000 ventilator days. The death rate is about 10%. Table 3 lists recommendations for reducing the risk of VAP. The top 10% of all U.S. ICUs reporting to NHSN have a VAP rate of 0 and for some ICU types the top 25% have a rate of 0. These results demonstrate what can be achieved with heightened efforts.

Table 3.
Ways to Reduce the Risk of VAP.
  • Minimize sedation
  • Raise head of bed 30-45 degrees
  • Consider sucralfate for ulcer prevention
  • Change ventilator circuits only when they are visibly soiled or malfunctioning
  • Remove condensation from ventilator tubing
  • Use aseptic techniques for manipulating ventilator tubing
  • Provide good oral care for intubated patients
  • Consider using endotracheal tubes with subglottic suctioning
  • Remove the device as soon as possible
Urinary Tract Infections
Catheter associated urinary tract infections (CAUTI) are the most common device-associated infection. Although UTIs are often not seen as "serious" infections, they do cause increases in hospital length of stay and cost. Table 4 lists measures that can reduce the risk of a CAUTI. While proper catheter insertion and care techniques can reduce the risk, the likelihood of eventually developing a CAUTI is a near certainty if the urinary catheter is left in long enough. The primary focus in CAUTI reduction is to ensure that urinary catheters are discontinued as soon as they are no longer medically necessary.

Surgical Site Infections
Surgical site infection rates vary tremendously, depending on the surgical procedure involved. A number of measures, however, have been clearly demonstrated to lower surgical site infection rates.17
  1. Use clippers or depilatories, rather than shaving, to remove hair before an operation. This is because razors cause microscopic skin nicks that provide a reservoir for bacteria.
  2. Keep traffic in operating rooms to a minimum during surgery
  3. Reduce the use of "flash sterilization"
  4. Reduce the length of the surgical procedure as much as possible. Use antibiotics preventatively. Most surgical site infections are caused by bacteria living on or in the patient at the time of surgery. Giving pre-operative antibiotics aimed at the most common causes of infection has led to significant reductions in surgical site infections. Antibiotics given after operations have not been shown to reduce the risk of SSI.
  5. Discontinue antibiotics within 24 hours after surgery (48 hours after cardiothoracic surgery
There is increasing evidence that healthcare-associated infections are largely preventable. Increased public awareness and legislative efforts have helped spur healthcare institutions to implement better infection-control procedures. It is very likely that soon, all healthcare workers will have at least some knowledge of the basics regarding the detection and prevention of healthcare associated infections, and, more importantly, take steps to implement sound infection prevention measures.

Additional Resources
Lautenbach E, Woeltje K, editors. SHEA Practical Handbook for Healthcare Epidemiologists, 2nd Edition. Thorofare, NJ: SLACK, Inc.; 2004.

Society for Healthcare Epidemiology of America (SHEA)

Association of Professionals in Infection Control and Epidemiology

CDC Division of Healthcare Quality Promotion (DHQP)
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