Samaritan Infectious Disease - Multi-drug Resistant Organisms

Multi-Drug Resistant Organisms

  • Methicillin Resistant Staph aureus
  • Vancomycin Resistant Enterococcus
  • Isolation - FAQ

Staphylococcus aureus (staph) is a well known, common bacterial human pathogen causing a variety of infections. These include skin and soft tissue infections, bloodstream infections, and infections at a variety of other sites. It is a very aggressive (virulent) pathogen which can cause severe illness and death. It commonly causes infection both in the community and in healthcare settings.

Soon after the advent of antibiotic use staphylococci demonstrated their ability to acquire resistance to antibiotics. In the 1950's resistance to penicillin became a problem.  Semi-synthetic penicillins of which methicillin is the prototype then were developed and became the mainstays of treatment of staphylococcal infections.

Unfortunately, in recent decades staphylococci have also developed resistance to methicillin (MRSA) significantly lessening therapeutic options. To try to contain the spread of this organism within healthcare settings many facilities place patients infected or colonized with MRSA in isolation using barrier methods (gowns and gloves). This is to prevent the spread of these organisms from patient to patient on the hands and clothing of healthcare workers.

Enterococcus species (faecium and faecalis) are bacteria that normally inhabit the human gastrointestinal tract. Though these bacteria are generally of less virulence than Staphylococcus aureus, they are capable of causing significant infections. Typically these infections involve the urinary tract, bloodstream, or are within the abdomen.

Unfortunately, like staphylococci, some strains of enterococci have acquired resistance to antibiotics like vancomycin and penicillin previously effective in treating infections caused by these bacteria. Because of the desire to contain the spread of these resistant strains, patients infected, or more commonly colonized, with these organisms are often placed in contact (barrier) isolation in healthcare facilities. This is to lessen the likelihood that healthcare workers caring for these patients will acquire the organisms on their hands and then inadvertently transfer the organisms to other patients.

Why are some patients put into isolation in healthcare settings?

Some patients are infected with or colonized with micro-organisms easily transmitted to others. Other patients are infected with or colonized with micro-organisms that are highly resistant to standard anti-microbial therapies. In both cases it is desirable to limit the spread of these organisms from person to person. Isolation helps accomplish this.

What are some of the micro-organisms for which isolation is recommended?

  • Tuberculosis
  • Methicillin resistant Staphylococcus aureus (MRSA)
  • Vancomycin resistant Enterococcus (VRE)
  • Meningococcal meningitis/bacteremia
  • Clostridium difficile antibiotic associated diarrhea
  • Chicken pox
  • Influenza

Why are there different types of isolation?

Different organisms requiring isolation can be transmitted by different routes:

  • Contact isolation (gowns, gloves, etc) is used to prevent the transmission of micro-organisms transmissible by direct contact. Examples of such infectious agents include MRSA, VRE, and Clostridium difficile.
  • Droplet isolation (masks) is used to prevent transmission of micro-organisms through the air through relatively large droplets. An example of such an infectious agent is the meningococcus, a cause of meningitis and bloodstream infection.
  • Airborne isolation (fine particle masks) is used to prevent the transmission of very small particle aerosols. Examples of agents transmissible by small particle aerosols include the agents of tuberculosis and chicken pox.

If a patient is in isolation in the hospital, is it necessary to do the same isolation when he/she goes home?

The primary purpose of isolating patients in the hospital is to prevent transmission of infection with certain pathogens to other patients often seriously ill with open wounds, etc. Healthy care givers at home are unlikely to be at the same risk of acquiring infection with these organisms and it is also impractical to pursue the same isolation procedures (gowns, gloves, etc.) in the home. Instead, strict attention to handwashing is important.