When Drugs Don’t Kill ‘Bugs’

BY ROBERT J. SHARBAUGH, PHD, CIC

The good news for long-term care facilities is that some of the most highly drug-resistant bacteria are generally confined to other settings-for example, multiple-drug-resistant tuberculosis is found in prisons and in HIV-positive or homeless populations.

The bad news for long-term care is that other antibiotic-resistant bacteria exist throughout the general population and are being seen more and more often in LTC facilities. These include methicillin-resistant S aureus (MRSA) and vancomycin-resistant enterococci (VRE), as well as strains of Streptococcus pneumoniae, pseudomonas species, Neisseria gonorrhea, salmonella species, and others.

What can be done to protect LTC residents from being infected with these drug-resistant bacteria? When residents are admitted to a nursing home or assisted living residence directly from a hospital, could they already be infected with drug-resistant bacteria? Or might these new residents be carriers, bringing the microorganisms into the facility even though they themselves haven’t developed an infection? This article will address these questions with infection-control strategies aimed specifically at the problem of antibiotic resistance, with particular attention being given to MRSA.

In general, the staphylococci, including S aureus, are common members of the human microflora and can routinely be found on the skin, in the oropharynx, and in the lower colon. S aureus causes many infectious complications, including wound infections, carbuncles, cystitis, food poisoning, pneumonia, bacteremia, endocarditis, and osteomyelitis. The vast majority of strains of S aureus are susceptible to many antibiotics, including methicillin. However, certain of the staphylococci, called coagulase-negative strains, are notoriously resistant to many antibiotics, including methicillin, a semisynthetic penicillin developed to treat penicillin-resistant bacteria. Fortunately, these strains are much less frequently involved as infectious agents, although they can sometimes cause surgical-site infections, infected prostheses, and bacteremias associated with in-dwelling vascular catheters, especially central lines. It is important to remember that resistance to methicillin also implies resistance to two other semisynthetic penicillins: oxacillin and nafcillin.

MRSA is not new to the United States, having first been reported in the early 1970s. While its initial presence was noted primarily in VA hospitals and large teaching hospitals, it has, over the years, become widespread in nursing homes and in communities-at-large throughout the country and the world. Its presence, then, is certainly not restricted to the hospital, or nosocomial, setting.

In spite of its ubiquity, MRSA has not been found to be any more virulent than methicillin-sensitive strains of this organism. There are, however, some high-risk factors that tend to predispose one to infection with MRSA and other AROs. Such factors would include respiratory complications (e.g., chronic obstructive pulmonary disease, pulmonary edema, and emphysema), open wounds, and invasive devices (e.g., central lines or tracheostomies). MRSA also tends to have a predilection for intravenous drug abusers and for patients who receive prolonged antibiotic therapy, especially with cephalosporins.

The staphylococci, including MRSA, are transmitted primarily through direct contact with the hands of healthcare providers. As a result, hand washing and the use of appropriate barrier precautions (e.g., gloves) are paramount in preventing the spread of this and other microorganisms. Hand washing is especially important after having contact with a resident’s intact skin (e.g., when taking a pulse, or blood pressure or lifting a resident), before inserting in-dwelling urinary catheters or other invasive devices, and after contact with body fluids or excretions, mucous membranes, non-intact skin, and wound dressings.

Although many LTC residents and healthcare personnel have been shown to be colonized, but not infected, with MRSA in the nasopharynx, there is little supporting evidence that nasal carriage is a major threat. In addition, neither airborne transmission nor environmental contamination is viewed as a major mode of the spread of staphylococci. Thus, the use of masks and gowns is neither necessary nor recommended when one is involved in the delivery of routine nursing care unless soiling is felt to be likely.

The current drug of choice for MRSA infection is vancomycin. There are, however, several disadvantages associated with its use, including (1) cost, (2) the need for parenteral administration (i.e., administered intravenously), and (3) nephrotoxicity (toxicity to the kidneys). Alternatively, ciprofloxacin was used with some early success, but unfortunately, many strains of MRSA have become resistant to ciprofloxacin, and empirical use of this antibiotic without laboratory confirmation of its effectiveness can be dangerous.

Upon the transfer of a patient colonized and/or infected with MRSA from a hospital, private facility or another facility to a nursing home or other long-term care facility, nursing and ancillary personnel need to understand that AROs are primarily opportunistic pathogens, in that they tend to cause infections in individuals who are debilitated and prone to the development of infectious complications, such as LTC residents. AROs, including MRSA and VRE, do not pose any significant threat to healthcare providers who enjoy a good state of health. However, it also needs to be emphasized that healthcare personnel must understand the concept of Standard Precautions (SPs) and follow those patient-care practices known to be effective in the prevention of cross-contamination.

Management of MRSA and other antibiotic-resistant microorganisms has been achieved by a variety of means. Probably more than anything else, however, the consistent practice of SPs will prevent or minimize the transmission of MRSA, as well as other microorganisms. SPs are designed to reduce the risk of transmission of microorganisms from both recognized and unrecognized sources of infection. They apply to (1) blood; (2) all body fluids, secretions, and excretions except sweat, regardless of whether they contain visible blood; (3) nonintact skin; and (4) mucous membranes. The primary components of SPs include:

• Hand washing
• Appropriate barrier precautions (e.g., gloves, gowns when soiling is likely, and masks when there is the potential for splashing, spraying, or aerosolization of body fluids)
• Sharps precautions
• Resuscitation precautions
• Patient (resident) placement-residents with active infection involving AROs preferably should be housed in a private room. Alternatively, resident cohorting (those with the same infecting microorganism) may be employed. If this is also not possible, care should be taken to avoid placing residents who are at high risk for infection in the same room with a patient infected with an ARO. This would include residents with in-dwelling lines, open wounds, significant immunosuppression, and those with cardiopulmonary complications.

A facility policy addressing AROs should include ongoing education, proper resident placement, surveillance, the proper use of barrier precautions, and good hand washing. These are the basic necessities in preventing the transmission of all microorganisms, including MRSA. NH

Suggested Reading
Boyce JM, Jackson MM, Pugliese G, et al. Methicillin-resistant Staphylococcus aureus (MRSA): A briefing for acute care hospitals and nursing facilities. The AHA Panel on Infections Within Hospitals. Infec Control Hosp Epidemiol 1994;15:105-15.

Garner JS. Guideline for isolation precautions in hospitals. Part I, Evolution of isolation practices, and Part II, Recommendations for isolation precautions in hospitals. Am J Infect Control 1996; 24:24-52.

Joyce JM, Pittet D. Guideline for hand hygiene in health-care settings. Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. MMWR, Morbidity and Mortality Weekly Report 2002;51(RR-16): 1-44.

Mulligan ME, Murray-Leisure KA, Ribner BS, et al. Methicillin-resistant Staphylococcus aureus: A consensus review of the microbiology, pathogenesis, and epidemiology with implications for prevention and management. Am J Med 1993;94: 313-28.