Staphylococcus aureus, also called S. aureus or “staph,” is a bacterium that frequently colonises the human skin and is present in the nose of about 25-30% of U.K. adults. S. aureus can exist in this form without harming its host or causing symptoms. However, if there is a break in the patient’s skin from a wound surgery or indwelling device (including intravenous catheters), or if there is a depression in the person’s immune system, then colonising S. aureus can cause an infection. S.aureus frequently causes localised skin infections, such as folliculitis, furuncles, and impetigo. It can also cause abscesses and spread into the bones (osteomyelitis), lungs (staphylococcal pneumonia), blood (bacteraemia or sepsis), heart (endocarditis – which can damage the heart valves), and other organs. S.aureus may also be transmitted to close contact from both infected and colonised people to other people through inadequate hand hygiene or throughsharing contaminated objects, such as towels or razors.
Hospital-acquired infections (Healthcare-associated infections, HAI)
S.aureus infections acquired while a patient is in a hospital, long-term care facility, or other health care setting have been a challenge for many years. Hospital conditions, including the widespread use of antibiotics, have selected for antibiotic-resistant strains of S. aureus. These strains are called Meticillin Resistant Staphylococcus Aureus (MRSA), named after the antibiotic treatment that was developed in 1960 to treat penicillin-resistant strains. MRSA is inherently resistant to flucloxacillin and most other antibiotics belonging to a class of antibiotics known as the 'beta-lactams', which includes penicillin. MRSA is also frequently resistant to a wide variety of other antibiotics. Infections are associated with significantly higher rates of morbidity and mortality, higher health care costs, and longer hospital stays than infections caused by methicillin susceptible S. aureus (MSSA).
Risk factors for MRSA infection in the hospital include surgery, prior antibiotic therapy, admission to intensive care, close contact with MRSA-colonised patients and health care workers, being in the hospital more than 48 hours, and having an indwelling catheter or other medical device that goes through the skin. The risk of spread of MRSA is reduced through adequate hand hygiene amongst all close contacts, particularly healthcare professionals.
One strategy that may be used in an effort to control the spread of MRSA includes active surveillance for the detection of MRSA infection or colonisation amongst patients admitted to intensive care units (ICUs) and other high risk areas. Another approach is to screen all patients admitted to a health care facility. UK Health Security Agency (UKHSA; formerly known as Public Health England or the Health Protection Agency) actively manages mandatory surveillance of MRSA on behalf of the Department of Health. The period of April 2021 to 2022, 5.2% of S. aureas bacteramia reported were caused by MRSA, this is a decrease from when records were started in April 2011 to March 2012, where 11.3% were caused by MRSA.
MRSA infections have been associated with outbreaks and deaths in non-medical settings where individuals are in close contact, including prisons, day care facilities, military units, and contact sports. These infections are occurring in people who do not have classic MRSA risk factors as described above. A significant number of those affected have had to be hospitalised for what appears to be a simple but persistent skin infection or for pneumonia that develops after a bout of influenza.
There is increased awareness of community-acquired MRSA (CA-MRSA) amongst the medical community and the community at large. With CA-MRSA, conventional therapy options have frequently failed. Investigations of outbreaks have revealed that the CA-MRSA was spread from infected or colonised patients to those around them through skin contact (such as sports-related cuts and abrasions), through droplets from the respiratory tract, or through exposure to contaminated objects, such as shared sports equipment, towels, toys, or playground equipment. Investigations have also revealed that the S. aureus strains involved in CA-MRSA are genetically different from those that have been causing hospital-acquired MRSA. Effective treatment is usually readily available.