More people die of an MRSA infection than HIV/Aids

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for several difficult-to-treat infections in humans.

MRSA is, by definition, any strain of Staphylococcus aureus bacteria that has developed resistance to beta-lactam antibiotics, which include the penicillins (methicillin, dicloxacillin, nafcillin, oxacillin, etc.) and the cephalosporins.

MRSA is especially problematic in hospitals, where patients with open wounds, invasive devices and weakened immune systems are at greater risk of infection than the general public.

S. aureus most commonly colonises the anterior nares (the nostrils), although the respiratory tract, opened wounds, intravenous catheters, and urinary tract are also potential sites for infection. Healthy individuals may carry MRSA asymptomatically for periods ranging from a few weeks to many years. Patients with compromised immune systems are at a significantly greater risk of symptomatic secondary infection. MRSA can be detected by swabbing the nostrils of patients and isolating the bacteria found inside.

MRSA progresses substantially within 24–48 hours of initial topical symptoms. After 72 hours, MRSA can take hold in human tissues and become resistant to treatment. The initial presentation of MRSA is small red bumps that resemble pimples, spider bites, or boils that may be accompanied by fever and occasionally rashes. Within a few days the bumps become larger, more painful, and eventually open into deep, pus-filled boils.

About 75% of CA-MRSA infections are localised to skin and soft tissue and usually can be treated effectively. However CA-MRSA strains display enhanced virulence, spreading more rapidly and causing illness much more severe than traditional HA-MRSA infections, and they can affect vital organs and lead to widespread infection (sepsis), toxic shock syndrome and necrotizing (“flesh-eating”) pneumonia.

These infections present a huge social as well as financial burden on the health system. In the US 2 million people acquire bacterial infections in hospitals each year and 90,000 die as a result. Over 18,000 die from MRSA infection alone.