What the scientists actually did was a laboratory-based study to investigate why hospital-acquired MRSA bacteria rarely—and not frequently or easily as the tabloids had reported—caused infection in healthy people.
First recognized in the United States in the late 1960s, MRSA gained public attention in 2007 with the publication of studies that attributed to it more than 19,000 deaths and 94,000 serious infections every year—more deaths than caused by AIDS in the United States in a year.
But what the new study found wasn’t a new strain of bacteria emerging.
Instead, researchers uncovered exactly how healthcare-acquired MRSA’s high level of antibiotic resistance came at the cost of reduced virulence or less ability to cause infection.
Conversely, they discovered exactly why the type of MRSA that is usually caught in a community setting is more virulent or contagious—but weaker against treatment with antibiotics.
In fact, the findings specifically state that, “As a direct result of its high level of antibiotic resistance, healthcare-acquired MRSA is impaired in its ability to cause infection, which can explain its inability to cause infection in community settings, where antibiotic usage and the prevalence of susceptible patients are low.”
The researchers also said that while MRSA outside hospitals and clinics is a growing concern—cases are still very rare.
In fact, the lab study did not in any way research the transmission or number of cases of community-acquired MRSA—as opposed to what the tabloids claimed.
“This intriguing lab study did not investigate the transmission, effects or number of cases of community-acquired MRSA in the UK,” the National Health Service pointed out in an article released on the same day news of the “superbug” hogged tabloid headlines.
U.K.’s provider of public healthcare was quick to point out that the reports as “alarmist” and “overblown,” inaccurate and had no basis.
“The research itself doesn’t support the claims that we are under siege from an ‘airborne, bacteria-resistant, flesh-eating superbug’, as newspapers have today suggested,” the NHS concluded.
The study upon which the alarmist tabloid reports were spun was carried out by researchers from five universities—the University of Bath and the University of Nottingham in the UK, the University College Dublin in Ireland, and the United States’ University of Texas and Texas A&M Health Science Center. It was funded by the UK Medical Research Council and a Biotechnology and Biological Sciences Research Council Studentship.
Probing the resistance mechanism
To understand why healthcare-acquired MRSA infections are rarely found in healthy individuals, the UK-U.S. team of researcher began by probing the nature of MRSA and how it resists certain types of antibiotics.
First, the researchers reviewed what’s already known about MRSA:
• Many staphylococcus aureus bacteria have now developed resistance to the penicillin group of antibiotics because they produce enzymes that can make penicillin inactive.
• But they are usually still susceptible to the antibiotic flucloxacillin.
• MRSA, however, doesn’t have this susceptibility to flucloxacillin, and is, therefore, harder to treat than most staphylococci bacteria, needing stronger antibiotics.
• MRSA is resistant to the antibiotics meticillin and oxacillin because it has acquired a piece of DNA called a ‘mobile genetic element’.
• Bacteria have in their cell wall PBPs—or penicillin binding proteins—and many antibiotics work by deactivating PBPs, causing the bacteria to die.