MRSA In The Healthcare Field And The Drug Of Choice
Methicillin-resistant Staphylococcus Aureus (MRSA) is a problem that is growing in the healthcare field today. In 1973 MRSA infections only accounted for 2% of all Staphylococcus infections, in 2004 that figure was up to 63%. At last count that figure was still rising. It is thought that, as much as 1% of the entire human population has MRSA whether they know they have it or not.
There are two classifications of MRSA infections, HA-MRSA and CA-MRSA. HA-MRSA is hospital-acquired MRSA. CA-MRSA is community acquired MRSA.
All classifications of MRSA have a mec-A gene that is responsible for its drug resistance. This drug resistant gene is located on an element called staphylococcal cassette chromosome (SCCmec). The CA-MRSA classification is associated with more febrile days and higher complications of osteomyelitis.
The HA-MRSA classifications tend to be less virulent but are more prevalent. The prevalence shows in the statistics with at least 60% of intensive care patients contracting MRSA and 30% in hospitals and long-term care facilities.
MRSA is antibiotic resistant except for Vancomycin, which is the antibiotic of choice. the Center for Disease Control (CDC) does have 6 confirmed cases of MRSA being vancomycin-resistant to Staphylococcus aureus (VRSA) and 21 confirmed cases of vancomycin-intermediate Staphylococcus aureus (VISA) in the United States.
New studies show that there is a huge barrier to limb preservation for both classifications of MRSA. Patients with MRSA infections have an increased mortality rates compared to patients without MRSA, as much as 2.7% higher. Patients contracting MRSA also have triple the length of stay in hospitals compared to patients who do not contract MRSA during their hospital stays. Patients who have diabetes are 40 times more likely to need amputations once they contract MRSA. The diabetic is at risk if they develop ulcers of the foot.
Alternative treatment for MRSA that have shown to have some effectiveness include trimethoprim-sulfamethoxazole, tetracycline (doxycycline) or clindamycin. When MRSA is erythromycin-resistant Vancomycin, linezolid or daptomycin, quinupristin-dalfopristin and tigecyline are recommended.
Vancomycin has been the pharmacological treatment of choice for MRSA soft tissue and bone infections. Vancomycin has also been effective in cancerous bone infections. There is however an increased risk for nephrotoxicity with vancomycin treatment.
When complicated skin and skin structure infections exist linezolid is just as effective as vancomycin.
Another promising drug is daptomycin which has shown to have a 75% cure rate as compared to 69% with vancomycin.
In determining the best drug of choice physicians should ask the following questions:
Where is the source of infection?
What is the underlying etiology of the skin breakdown?
What is the patient's recent medical and surgical history?
What final sensitivities have shown up in wound cultures?
