New Information on Risk Factors for MRSA
The news media has brought it to our attention that the overuse of antibiotics has led to a new problem called MRSA (pronounced Mersa). MRSA stands for methicillin-resistant staphylococcus aureus. Staphylococcus aureus is known more commonly as a staph infection.

MRSA is a potentially serious problem (it can be fatal) because the staph bacteria have mutated (changed) enough that antibiotics can no longer kill it. Staph can usually be treated with antibiotics. But over many years, some strains of staph -- like MRSA -- have become resistant to antibiotics that once destroyed it. Staph is now resistant to methicillin as well as amoxicillin, penicillin, oxacillin, and many other antibiotics.

MRSA doesn't affect everyone. There are certain people who seem to be more susceptible (more likely to get MRSA). These at-risk groups include people involved in contact sports, athletes sharing equipment, and individuals who are immunosuppressed (poor immune system function). The very young and the very old are two age-related groups at increased risk for developing MRSA. But there's also been a disturbing trend of MRSA infections in patients who have no obvious risk factors.

This study focuses on MRSA in one particular part of the body: the hand. Hand surgeons reviewed the medical charts for 159 patients treated at their trauma center for a hand infection to find out two things: 1) How often do MRSA infections of the hand occur? and 2) Are there any specific risk factors related to the hand?

The MRSA infections included in this study were called community acquired, which is to say the person was exposed to the bacteria somewhere out in their work, home, or recreational environment. In other words, they didn't pick up the bacteria while being hospitalized. They were, however hospitalized because of this community-acquired hand infection that required surgical intervention (infection drainage).

These cases occurred over a period of 11 years so the authors were able to see a trend of ever increasing numbers of community-acquired MRSA (CA-MRSA). At the same time, the number of patients with non-MRSA hand infections remained steady. During the chart review, the researchers collected data on what types of infections were treated, how many surgical procedures were needed to get control of the infection, and the antibiotics used to treat each patient.

What puts people at risk of CA-MRSA hand infections? Intravenous drug use was the number one risk factor. This refers to shooting up illegal drugs, not the administration of intravenous medications. A second possible risk factor was the use of antibiotics for a similar hand infection prior to this one. Age and gender (male versus female) were not risk factors. And neither was being homeless or incarcerated (in jail).

Looking at the results of treatment from this and other studies may shed some light on how to prevent community-acquired MRSA. Surgical treatment to drain the wound without using antibiotics afterwards produced positive results for most of the patients studied. That suggests that drainage may be all that's needed to treat these kinds of soft-tissue infections.

The authors suggest that some groups of patients with hand infections may still benefit from the post-operative use of antibiotics but this must be studied further. For example, it is widely believed that living in close quarters (e.g., jails, dormitories, barracks) is a risk factor for CA-MRSA. Patients in any of these population groups may need a post-operative course of antibiotics to prevent further infection.
Scott D. Imahara, MD, and Jeffrey B. Friedrich, MD. Community-Acquired Methicillin-Resistanti Staphylococcus aureus in Surgically Treated Hand Infections. In The Journal of Hand Surgery. January 2010. Vol. 35A. No. 1. Pp. 97-103.