Lesson 2 of 1
In Progress

The Ugly Face of MRSA Lesson #1

September 25, 2014

 

Here is an MRSA Power Point Presentation PPT for this course. Please download and watch all the slides.

Terminology/ Key Terms to Aid Your Understanding

Airborne droplets: Small particles suspended in air that can carry bacteria.
Antibiotic resistance: Antibiotics are not effective in killing the bacteria.
Carrier: A person who is colonized with bacteria.
Colonization: Presence of bacteria without active infection.
Contact precautions: Preventing the spread of germs by direct touch.
Mortality rates: A measure of the number of deaths.

Introduction

Picture1 mrsaStaphylococcus aureus is a common bacteria found on the skin or in the nose. It is often referred to as “Staph” for short. About one person out of every three has these bacteria on them. MRSA is a resistant strain of S. aureus. Staph bacteria is commonly carried on the skin or in the nose of healthy people and is one of the most common causes of skin infections in the U.S. The name Staphylococcus comes from the Greek staphyle, meaning a bunch of grapes, and kokkos, meaning berry, and that is what Staph bacteria look like under the microscope, like a bunch of grapes or little round berries. 

Enterococci is a bacteria that is usually located in the gut and can cause infections anywhere. Vancomycin is the drug of choice for treatment of an infection by enterococci. VRE are resistant to this drug. Many people are colonized with MRSA/VRE. Colonization is where the bacteria lives on or in one or more body sites but does not cause any problems or infections. Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that causes infections in different parts of the body. MRSA is tougher to treat than most strains of staphylococcus aureus — or staph — because it’s resistant to some commonly used antibiotics.

Understanding MRSA

Facts

A basic understanding of how infection is spread is important to know in order to really understand how to stop it.

BACTERIA: Bacteria are one-celled, microscopic organisms. They are classified by three factors. First is the cell shape and arrangement. Shapes include sphere, rods, and spirals.

Arrangements can be in pairs, clusters, or chains. The second factor is gram stain. This is a process where bacteria are stained with a dye, which reveals chemical differences in the cell wall of the bacteria. The third factor is aerobe versus anaerobe. Aerobes live and grow in the presence of oxygen, whereas anaerobes live and grow without oxygen. Bacteria cause disease by two main mechanisms. The first mechanism is the bacteria’s ability to invade the host. The second mechanism is how much toxin the bacteria produce. The proteins in the bacteria’s wall help them adhere to certain tissues depending on the bacteria. The toxins released by the bacteria cause reactions in the host body such as fever, inflammation, diarrhea, vomiting, tissue damage, and neurological and central nervous system damage. How bad the infection is depends on the combination of the bacteria’s ability to invade the host and the amount of toxins released.

How do antibiotics work against bacteria?

There are certain microorganisms that produce antibiotics. Sometimes these substances can be modified in the lab to produce further antibiotics. Other antibiotics are completely made in the lab setting. Goals for all antibiotics are to inhibit or kill the bacteria while causing little damage to the person. Antibiotics are divided into classes based on how they affect bacteria, the types of bacteria sensitive to the antibiotic, and where the antibiotics attack the bacteria. They affect the bacteria by either stopping their growth so the body can attack the bacteria or they kill the bacteria outright. Sensitivity can range from narrow spectrum antibiotics, which kills limited types of bacteria, to broad spectrum antibiotics, which kills many types of bacteria. Antibiotics can attack the bacteria’s cell wall, stop bacteria from making proteins, stop bacteria from growing, or stop the bacteria’s DNA from working.

How do bacteria get resistant to antibiotics? 

Bacterial resistance is the result of overuse of antibiotics. The longer bacteria are exposed to antibiotics, the more they change to protect themselves from the antibiotics. Examples include production of new enzymes that make antibiotics less effective, changes in the bacteria’s cell wall that prevent the antibiotic from entering the bacteria, and changes in the bacteria where the antibiotics are simply no longer effective.

What is MRSA? „„ Methicillin –resistant  Staphylococcus aureus

  • A type of staph  that is resistant to certain antibiotics
  • First recognized in 1961 –one year after antibiotic Methicillin was introduced for treating S. Aureus infections
  • Occurs most frequently among persons in hospitals and healthcare facilities
  • Divided into Hospital Acquired MRSA and Community Acquired MRSA

Two basic types of MRSA exist. One is healthcare associated (HA-MRSA); the other, community acquired (CA-MRSA). Though the two differ distinctly, some experts worry the distinction will blur as more CA-MRSA makes its way into healthcare settings and more HA-MRSA follows healthcare workers home—possibly leading to infections that are much harder to manage and eradicate.

What is CA–MRSA? 

  • Community-acquired Methicillin Staphylococcus aureus-„„ MRSA infections that are acquired by persons who  have not been recently hospitalized or had a medical procedure
  • About 85% of infections from CA–MRSA are NOT invasive and will NOT require hospitalization
  • HA–MRSA refers to MRSA acquired in the hospital or health care setting, is a different strain and more serious than MRSA acquired in the community

 

CDC statistics

National population-based estimates of invasive MRSA infections

– 94,360 invasive MRSA infections annually in the US

– Associated 18,650 deaths each year

– 86% of all invasive MRSA infections are healthcare-associated

 

Background: Impact

  • MRSA has emerged as one of the predominant pathogens in healthcare-associated infections
  • Treatment options for MRSA are limited and less effective than options available for susceptible S. aureus infections and result in higher morbidity and mortality
  • High prevalence influences unfavorable antibiotic prescribing, which contributes to further spread of resistance – prevalent MRSA equals more vancomycin use, more vancomycin resistance (VRE and VRSA)  equals more linezolid/daptomycin use, which equals more resistance….., do you see the vicious cycle?
  • MRSA adds to overall S. aureus infection burden
  • Preventing MRSA infections reduces overall burden of S. aureus infections
  • MRSA is a marker for ability to contain transmission of important pathogens in the healthcare setting
  • Once acquired, MRSA colonization can be long-lasting — months or years in some subpopulations
  • A patient acquiring MRSA colonization during a hospital stay has increased risk for MRSA infections following discharge, or during subsequent acute and long-term care admissions
  • MRSA carriers also serve as reservoirs for further transmission as they move through and across healthcare facilities

 

MRSA and VRE

Staphylococcus aureus is a common bacteria found on the skin or in the nose. It is often referred to as “Staph” for short. About one person out of every three has these bacteria on them. MRSA is a resistant strain of S. aureus. Enterococci is a bacteria that is usually located in the gut and can cause infections anywhere. Vancomycin is the drug of choice for treatment of an infection by enterococci. VRE are resistant to this drug. Many people are colonized with MRSA/VRE. Colonization is where the bacteria lives on or in one or more body sites but does not cause any problems or infections. A carrier of MRSA/VRE is a person who is colonized with MRSA/VRE but does not have an infection. A MRSA/VRE infection is where the bacteria caused illness or disease. An infection with MRSA/VRE can be very serious and life threatening. There is a higher death rate with infections caused by MRSA/VRE.

Treatment options for MRSA/VRE infections are limited. As quickly as new antibiotics are introduced, resistance starts developing to these new antibiotics. Hospitalizations, increased costs, and increased mortality rates all result from MRSA/VRE infections. Members of the healthcare team must do all that they can to minimize the spread of MRSA/VRE from patient to patient using MRSA/VRE precautions. Because the precautions are the same for MRSA and VRE, all information that follows will refer to MRSA, but know that the same applies to VRE.

Who gets MRSA infections?

There are certain types of patients who are at a higher risk for MRSA infections. Any patient with a weakened immune system is at an increased risk. Patients with weakened immune systems include those being treated for cancer, post-transplant patients, patients on long-term steroid treatment, or patients with an immune deficiency disease. Elderly patients also present with an increased risk. As we age, our immune system weakens. Plus, elderly homecare patients are often in frail health with multiple medical problems. Patients who have an invasive device, such as a Foley catheter, IV line, tracheotomy, or wound drain, are also at an increased risk. Any type of open wound also puts a patient at an increased risk for MRSA infection. This may be a surgical wound, trauma wound, pressure ulcer, venous stasis ulcers, arterial ulcer, diabetic ulcer, skin tear, or cellulitis. Patients who have prolonged and frequent hospitalizations are also at an increased risk. Patients who received long-term antibiotics or who have been improperly treated with antibiotics are at an increased risk. The most serious MRSA infections are blood stream infections, surgical site infections, and pneumonia. MRSA infections at these areas have a higher death rate.

How is MRSA spread?

MRSA is, quite simply, spread through contact, most commonly through person-to-person contact. This can be physical contact with someone who is infected or who is a carrier. It can also be passed by physical contact with objects like bed linens, medical equipment, and bathroom fixtures that have been touched by a MRSA-infected person. Patients with pneumonia due to MRSA can transmit by airborne droplets. In the healthcare field, spread of MRSA mainly occurs through hands of healthcare workers from one patient to another when hand hygiene has not been done properly or when medical equipment has not been properly disinfected.

According to the CDC, anyone can get MRSA through direct contact with an infected wound or by sharing personal items, such as towels or razors, that have touched infected skin. MRSA infection risk can be increased when a person is in certain activities or places that involve crowding, skin-to-skin contact, and shared equipment or supplies.