Point-Counterpoint: Should You Cover MRSA?
Yes. By Guy R. Pupp, DPM, FACFAS, and Mark A. Kachan, DPM. Given the increasing incidence of methicillin-resistant Staphylococcus aureus, one should consider empiric coverage against MRSA in high-risk patients with infected ulcerations in the lower extremity.
The most common pathogens in nosocomial skin and skin structure infections in the United States and Canada in 2000 were Staph aureus. Researchers have stated that approximately 30 to 60 percent of all Staph aureus isolates are methicillin-resistant Staph aureus (MRSA)-related.1,2 There has been a seemingly logarithmic growth over the past decade in the incidence of MRSA as a pathogen in the diabetic foot. Individuals with foot infections caused by MRSA organisms have been associated with poorer outcomes related to an increased risk of amputations and infection-related mortality.
In general, MRSA is almost always spread by direct physical contact and not through the air. The most common source of transmission is patients who already have a MRSA infection or patients who carry the bacteria on their bodies but do not have symptoms. The main mode of transmission to other patients is through human hands, especially the hands of healthcare workers. A person’s hands usually become contaminated with MRSA bacteria via contact with infected or colonized patients. Methicillin-resistant Staph aureus may also spread through indirect contact by touching contaminated objects such as towels, sheets, wound dressings, clothes, workout areas, etc.
Healthcare-associated MRSA occurs most frequently among patients who undergo invasive medical procedures or who have weakened immune systems, and are being treated in hospitals and healthcare facilities such as nursing homes and dialysis centers. It also tends to be common among elderly, chronically ill patients who have a significant history of receiving antimicrobial therapy. Methicillin resistant Staph aureus has become a major nosocomial pathogen in healthcare settings. It has commonly caused serious and potentially life-threatening infections, accounting for 12 percent of all bacteremias, 21 percent of skin infections and 28 percent of surgical site infections.3
In addition to healthcare-associated infections, MRSA can also be problematic in the community. When MRSA causes infections in patients with no established risk factors for MRSA infections outside of the hospital or healthcare facility, these patients may have community-acquired MRSA (CA-MRSA). This version of MRSA can be found in day care centers, schools and prisons, and generally occurs as skin infections that can look like pimples or boils. These skin infections often occur in otherwise healthy people. They are usually mild, limited to the surface of the skin and can be treated successfully with proper hygiene and antibiotics.
However, these MRSA-related infections can become swollen, painful and have draining purulence. If these wound infections are left untreated or are not recognized early, they can progress to life-threatening blood or bone infections because there are few effective antibiotics available for treatment. Community-acquired MRSA strains are usually sensitive to most other non beta-lactam agents commonly used as anti-staphylococcal drugs.
At this time, there are available treatment options for MRSA but they are limited because MRSA is resistant to many antibiotics.
What The Literature Reveals About The Increasing Incidence Of MRSA
Antibiotic resistance among Staph aureus pathogens has been a problem for over five decades but the incidence of MRSA has truly accelerated in recent years. The National Nosocomial Infections Surveillance (NNIS) System has reported a dramatic increase in the rate of MRSA isolates (40 percent) from 1989 to 2003 in intensive care unit patients.2 Almost 60 percent of Staph aureus isolates in 2003 were healthcare-associated MRSA.2 The incidence of CA-MRSA is also increasing at an alarming rate.4