Diagnosing MRSA

Today we will discuss how infection with MRSA is diagnosed.

Initially, you may notice some symptoms of staph infection. You may see a little bump on the skin that looks infected - it might be red and swollen with pus. MRSA infections are commonly initially mistaken for a spider bite. You may have a fever as well - this is when it's time to call your health care provider right away.

A MRSA infection could also become quite severe, especially if it spreads to the bloodstream, or other areas like the heart and lungs (this is more common in those who are already hospitalized). Symptoms of this infection include chest pain, cough or shortness of breath, fatigue, fever and chills, general ill feeling, headache, rash, and wounds that don't heal.

Once infection is suspected, the actual diagnosis is made in the lab. If you have a wound, a health care professional will swab it and take the sample to the lab. The lab will take the sample, place it into a solution, and look for Gram-positive cocci clusters (this describes the color and shape of the stained bacteria).

The sample is tested for Staphylococcus aureus as well. This is done by placing it in a tube with plasma from rabbit's blood and free coagulase. If they find that a clump has formed, this indicates that staph is present.

The next test is to see if this type of bacteria is resistant to medicine. If it continues to grow despite antibiotics, then this is how it is confirmed to be MRSA.

There are also several other ways of obtaining samples to test for MRSA. These include sputum cultures - this is when you simply cough up sputum that can be tested. Urine cultures are also used quite frequently. This could be collected from a foley catheter, or with a cup. If a blood culture is tested and returns positive for MRSA, this would diagnose a bloodstream infection.


Sources:
http://www.cdc.gov/mrsa/pdf/MRSA_Broch_Parent.pdf
http://www.nytimes.com/health/guides/disease/mrsa-infection/overview.html
http://www.wikihow.com/Test-for-MRSA
http://www.healthline.com/health/mrsa#Diagnosis6

MRSA Pathophysiology

Today we will be looking into the pathophysiology and etiology of MRSA - essentially, looking at how this bacteria causes infection, and why it is resistant to antibiotics.

As mentioned, MRSA is a bacteria that causes infections. According to ScienceDirect, this bacteria is found in the nose, throat, mucous membranes, and skin. It is often harmless. However, as we've talked about it can sometimes infect humans. This can often happen in crowded areas with shared equipment such as a gym, or a hospital. If a nurse or other healthcare provider touches a MRSA carrier, but then does not wash hands before touching another patient, the second patient could become infected. This bacteria could enter the patient's body through a hair follicle, some kind of break in the skin (such as a wound), or through the respiratory tract (Epidemiology and Pathogenesis of C. difficile and MRSA in the Light of Current NHS Control Policies: A Policy review, ScienceDirect).

According to this article, the antibiotic Methicillin was first introduced in 1959-60. Within a year, methicillin-resistant isolates were being reported.

In order to explain how a bacteria can become resistant to an antibiotic, I highly recommend the following video:

Essentially, mutations  in the bacterial DNA can cause the bacteria to gain the ability to change in a way that allows them to become resistant to the powers of the antibiotic. MRSA specifically is resistant to beta-latctin antibiotics like penicillin and methicillin. This can make it more difficult to treat, although the story does not end there!

Sources:
http://www.sciencedirect.com/science/article/pii/S2049080112700122
https://www.youtube.com/watch?v=znnp-Ivj2ek

Epidemiology of MRSA

In the previous post, we learned a little about what MRSA is. In this post we will explore the incidence and prevalence of this bacterial infection in the US.

The Center for Disease Control breaks down MRSA infections as occurring in the community, and in healthcare settings.

When MRSA occurs in the community, it is usually a skin infection. While 1 in every 3 people carry staph in their nose (especially healthcare workers), about two in every 100 person carries MRSA.

Skin infections in the community are most likely to happen to athletes, in daycare/school settings, lockers rooms, etc. According to the CDC, "MRSA infection risk can be increased when a person is in certain actuates or places that involve crowding, skin-to-skin contact, and shared equipment or supplies. This might include athletes, daycare and school students, military personnel in barracks, and people who recently received inpatient medical care."

MRSA can also be acquired in healthcare settings. In the hospital, it can be spread from an infected wound or on the hands of a healthcare provider. It can become a very serious infection, especially if it spreads to the bloodstream. 

There is good news though - the CDC has studied MRSA in the healthcare setting closely, and are finding from a variety of sources that the number of MRSA infections are declining. According to the CDC, "Invasive MRSA infections that began in hospitals declined 54% between 2005 and 2011, with 30,800 fewer severe MRSA infections. In addition, the study showed 9,000 fewer deaths in hospital patient in 2011 versus 2005." If you're interested in learning more about this data, you can find links to several studies at this webpage: http://www.cdc.gov/mrsa/healthcare/index.html#q1.

References:
http://www.cdc.gov/mrsa/community/index.html#q1
http://www.cdc.gov/mrsa/healthcare/index.html
http://www.naccho.org/topics/WBS/hai.cfm
http://en.wikipedia.org/wiki/Staphylococcus_aureus#/media/File:Staphylococcus_aureus_VISA_2.jpg

MRSA Today - What is it?

MRSA. It is an alarming word. MRSA is a bacteria we will be exploring in detail over the course of this blog, with the hope of taking away some of the unknowns and subsequent alarm that can result. We will also be looking into some very new developments in the ways we can fight MRSA.

My definition, MRSA stands for Methicillin-resistant Staphylococcus aureus. Essentially, it is a bacteria that causes infection. It is a pesky one because it has developed resistance to many of the antibiotics commonly used to treat infections. 

MRSA is often acquired in the hospital. Hospital workers may unknowingly carry the infection to vulnerable patients. Patients most at risk are those who are immunosuppressed (for example cancer patients receiving chemotherapy), experiencing invasive devices such as indwelling catheters, or those who have breaks in their skin such as wounds, that create an area where bacteria can enter the body.

The following video is an excellent primer on MRSA. It introduces us to MRSA through a patient's story, and helps us understand the essentials. 

References:
https://www.youtube.com/watch?v=iGgobi91LOA

Lewis, S., Dirksen, S., Heitkemper, M., Bucher, L., Camera, I. (2011). Medical-Surgical Nursing (8th ed., p. 238). St Louis, Mo.: Mosby/Elsevier.