Are you and your patients in safe hands?

Have you read or heard about the crisis associated with methicillin-resistant Staphylococcus aureus (MRSA) that is sweeping across the United States? Hospitals, nursing homes, schools, sports facilities, correctional facilities and child day-care centers are reporting outbreaks of human nosocomial infections with methicillin-resistant staphylococci.

Figure 1: Blood agar plate illustrating growth of transient bacteria on the fingers of the right hand of a hospital employee after administering a routine inoculation. These bacteria were incubated at 37-degrees centigrade for 24 hours.

MRSA is a type of bacteria that is resistant to certain antibiotics. These antibiotics include methicillin and other more-common antibiotics such as oxacillin, penicillin and amoxicillin. Staph infections, including MRSA, occur most frequently among persons in hospitals and health-care facilities (such as nursing homes and dialysis centers) who have weakened immune systems. MRSA infections that occur in otherwise healthy people who have not been recently (within the past year) hospitalized or had a medical procedure (such as dialysis, surgery, catheters) are known as community-associated MRSA infections. These infections usually are skin infections, such as abscesses, boils and other pus-filled lesions.

Three-inch headlines on the front page of the Sunday issue of the Dec. 2, 2007 Star Tribune, the leading newspaper in Minneapolis/St. Paul, screamed, "Stalking a superbug." The headline was followed by the following statement in bold print: "As the MRSA outwits science's best weapons, a UM microbiologist is at the forefront of finding ways to conquer the deadly bacteria." This message was followed by a photograph of Paul Schlievert, a University of Minnesota microbiologist, transferring MRSA from one Petri dish to another. He did not appear to be wearing any type of protective barriers except a white lab coat. He was further described in this way: "In the war between killer bugs and humanity, Schlievert is one of the generals. As an expert on staph and toxic shock with 30 years' experience, he is comfortable handling the bacteria without gloves, because (the gloves) are not always foolproof. But, he uses exacting safety precautions and washes his hands often."

Have you considered the risks associated with MRSA and the chance that you may be exposed to this potentially lethal microbe? Sometimes MRSA leads to a toxic-shock syndrome; on occasion virulent strains of MRSA act as flesh-eating bacteria. The Centers for Disease Control and Prevention estimates that nearly 2 million patients in the United States each year get an infection in hospitals, and about 90,000 of these patients die as a result of their infections. Virulent strains of MRSA contributed to the deaths of at least 19,000 people in 2005.

What about your hospital or clinic? Is it a safe environment for you, your employees and/or colleagues and your patients? Is MRSA lurking there? Although MRSA was once primarily a problem for humans, overuse and misuse of antimicrobial medications appear to be associated with a rise in MRSA infections in horses, dogs, cats, pigs, dairy cattle and chickens. Results of some studies suggest that MRSA can be directly spread from humans to animals, and vice-versa.

How can you protect yourself and your associates from being infected with virulent microbes like MRSA? There is undeniable evidence that one of the most effective methods of minimizing the spread of MRSA is a low-tech procedure. It is known as hand hygiene and primarily consists of properly and frequently washing and moisturizing your hands.

In human and veterinary hospitals, it has been convincingly established that proper hand hygiene is the single most cost-effective procedure to minimize nosocomial infections. Yet several recent studies indicate that hand washing is the most violated of all infection-control procedures. Is this statement applicable to your hospital? How often have you forgotten or neglected to wash your hands? In terms of proper hand-hygiene technique, are you a role model for your staff? If your situation is like mine, there is room for improvement. Would you like to minimize everyone's chances of becoming a victim of MRSA? Please consider the following points:

Resident, transient microflora

Normal human skin is protected by secretions from sebaceous and sweat glands. However, human skin is capable of harboring a large quantity and variety of noninfectious and infectious microbes. It has been estimated that one square inch of hand-surface area on average has a bioburden of about 10,000 microbes, including gram-positive and gram-negative bacteria, fungi, yeasts and viruses. To a casual observer, 10,000 microorganisms per square-inch of hand surface probably would not appear to be soiled.

Resident microflora

The microbial flora of skin can be subdivided into two general groups: resident microbes and transient microbes. Healthy skin has a relatively stable normal flora of resident microbes. Resident microbes are termed "colonizing" because they grow easily in the skin and its adnexal structures. Most resident microbes are found in superficial layers of the skin, but about 10 percent to 20 percent are located deep within the keratinized layers of stratum corneum and inside adnexal structures such as hair follicles, sebaceous glands and sweat ducts. Compared to transient microbes found on the surface of the skin, resident microbes are not easily removed by ordinary soaps and mechanical friction. Therefore they serve as a microbial reservoir for rapid repopulation of the skin following hand washing. The normal resident skin flora consists primarily of bacteria (including the genera Staphylococcus, Enterobacter, Proprionobacterium, and Corynebacterium), certain viruses and yeasts.

With some notable exceptions, resident microbes that survive and multiply on the skin are not highly virulent and are not usually implicated in nosocomial infections. Unless introduced into body tissues by trauma or medical devices such as intravenous catheters, the pathogenic potential of the resident flora is low. However, infections with some resident microbes can occur in immunocompromised patients, and following surgery or other invasive procedures that allow these microbes to enter deep tissues.

Transient microflora

In contrast to resident microbes, the transient microflora of the skin contains microbes deposited from contact with contaminated surfaces. Because most of the transient microbes can survive for only a limited time, they are also termed "noncolonizing microflora". They are abundant on exposed skin, under nails, etc., but are relatively scarce on clean, unexposed skin. Transient microbes acquired by contact vary greatly in number and kind (Photo 1, p. 46). Examples of transient organisms include Escherichia coli, Enterococcus spp., and Pseudomonas spp. Transient microorganisms found on the hands of hospital personnel often include pathogens acquired from contact with infected patients. These microbes are common causes of nosocomial infections.

Hand washing with plain soaps and detergents is effective in removing many transient micro flora. In contrast, resident microorganisms located in the deep layers may not be removed by hand washing with plain soaps and detergents. However, their numbers usually can be reduced with hand washing products that contain antimicrobial ingredients.

When should hands be washed?

The indications for hand washing in a hospital environment depend on the type, intensity, duration and sequence of activity of hospital staff. In general, hand disinfection procedures in hospital settings can be separated into two general categories: hygienic and surgical.

The primary purpose of hygienic hand washing is to block transmission of microbial pathogens from health-care personnel to patients by quickly and effectively removing dirt, organic debris and transient microbes. Whereas surgical hand washing is designed to kill or remove as many bacteria as possible (including resident bacteria), the principal focus of hygienic procedures is directed against the transient skin flora.

A sustained antimicrobial action directed against the resident flora as required for surgical disinfection is of little significance in context of the goals of hygienic hand-washing procedures.

Let us return to the question of when to wash your hands. Here are some generalities. (See checklist, p. 48.)

In context of these guidelines, how frequently during the day do you wash your hands? Would you let a health-care worker care for you if he or she followed the same pattern of hand hygiene that you follow?

Reinforce theimportance

Hand washing should be encouraged when personnel are in doubt about the need to do so. However, to minimize nosocomial infections, more is required than knowing when to wash your hands. Knowing how you wash your hands and what preparations to use is as important as knowing when to wash.

We will consider the answers to these and related questions in next month's Diagnote column.

In the meantime, you may find additional information on MRSA and proper hand hygiene at the Web sites listed in the Suggested Reading box.

Hand-washing checklist for veterinarians and staff

Using hygienic procedures, staff should wash their hands:

• When arriving to the hospital, and before leaving.

• Between direct contacts with individual patients.

• After touching objects likely to be contaminated with pathogenic organisms, such as urinary catheters, soiled surgical drapes and cages in hospital wards.

• Before taking care of particularly susceptible patients, especially those in critical-care units.

• After taking care of infected patients or those likely to be colonized with microbes of special clinical significance (e.g., bacteria that are resistant to multiple antibiotics).

• Before preparing medications for patients.

• Before and after touching wounds.

• Before performing invasive procedures such as biopsies, placing intravenous catheters or urinary catheters.

• After removing gloves. Gloves could have manufacturing defects and might become damaged in use. Bacteria on hands multiply rapidly inside the warm, moist environment of gloves (also called glove juice), even without external contamination.

• After hands have been contaminated with urine, feces, blood or other body excretions and secretions.

• When hands are visibly soiled, and after personal bodily functions including urination, defecation, sneezing, coughing or blowing your nose.

Dr. Osborne, a diplomate of the American College of Veterinary Internal Medicine, is professor of medicine in the Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota.