Multi-Drug Resistant Organisms (MDRO)

Reviewed by LeeAnn Bryant, MHS, RN, CIC Wendi Drummond,

What are multi-drug resistant organisms?

Multi-drug resistant organisms (MDRO) are common bacteria (germs) that have developed resistance to multiple types of antibiotics. These bacteria are present on the bodies of many people, including on the skin, in the nose or other moist areas of the body, and in secretions. Antibiotic resistance often occurs following frequent antibiotic use or frequent exposure to a health care setting. For most healthy people, these bacteria don’t cause a problem.
MDRO can enter the body and cause infection. MDRO are most likely to enter the body if:
  • There is an open wound in the skin
  • There is an IV, catheter or other invasive device in place
  • The person has a suppressed immune system.


What does MDRO mean?

MDRO stands for Multi-Drug Resistant Organisms. Most types of bacteria can be treated with antibiotics. Over time, some types of bacteria have become resistant to certain antibiotics. This means the antibiotic does not work to treat the bacteria. Another antibiotic will need to be used to treat the bacteria. MDRO can be more difficult to treat, because they are resistant to certain antibiotics.

Examples of MDRO include:

  • Methicillin resistant staphylococcus aureus (MRSA)

  • Vancomycin resistant enterococcus (VRE)

  • Pseudomonas aeruginosa resistant to multiple antibiotics.


What is the difference between colonization and infection?

Colonization means MDRO are present in or on the body but are not causing illness. Healthy people may carry MDRO without becoming ill. Infection means MDRO are present in or on the body and are causing illness. Symptoms of infection with MDRO vary depending on the part of the body that is infected.
Infection can occur in any part of the body, including the skin, lungs, urinary tract or bloodstream.


How are MDRO diagnosed?

A culture of the suspected infected areas may be sent to the lab to identify the bacteria and to test for what antibiotics will be effective against the bacteria. 


How are MDRO spread?

MDRO are commonly spread by direct contact between people or with contaminated surfaces in the environment. This means MDRO are often spread by the hands when patients, visitors or health care workers do not clean their hands. MDRO can be contracted in the hospital or community setting. A patient can also develop an MDRO through antibiotic use, especially if the antibiotics are inappropriately prescribed or inappropriately taken.


How are MDRO treated?

MDRO can be difficult to treat, depending on the antibiotics to which the bacteria are resistant. Even when the infection is treated, MDRO are often still present on the skin or in the nose (colonization). 

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