Antibiotic-resistant bacteria have become a serious problem in recent years — particularly given the high prevalence of antibiotic medication misuse or overuse.
According to the Medline Plus magazine published by the National Institutes of Health, 2 million Americans become infected with antibiotic-resistant bacteria every year — with at least 23,000 of them losing their lives to untreatable bacterial infections.
Among the most well-known drug-resistant bacteria that can cause life-threatening infections are E. coli and MRSA — a strain of Staphylococcus aureus that is resistant to methicillin, a semisynthetic form of penicillin typically prescribed in the treatment of staph infections.
However, scientists warn that we should be paying closer attention to another type of staphylococcus as well — one that commonly lives on the human skin and which can pose a great threat to some people, particularly to those who are due to undergo surgery. The bacterium in question is Staphylococcus epidermidis — a MRSA-related organism that exists on the hair and skin, as well as in the mucous membranes of the throat and nose. Said bacterium is part of the normal bacterial flora of the human body, notes Science Direct.
Although this bacterium is typically harmless, some strains of Staphylococcus epidermidis cause disease in certain circumstances — and can lead to life-threatening infections after surgery.
Most Staphylococcus epidermidis infections usually occur in prosthetic joints, catheters, and large wounds, states the University of Connecticut. Nevertheless, they have also been associated with intravascular devices, such as prosthetic heart valves and shunts.
The reason why Staphylococcus epidermidis affects only certain patients is not yet completely understood. In an effort to get to the bottom of this, a team of researchers led by Prof. Samuel Sheppard, head of bioinformatics at the University of Bath’s Milner Centre for Evolution in the U.K., has conducted an investigation into the bacterium’s genome.
Their research revealed that Staphylococcus epidermidis has 61 genes that can turn the normally innocuous organism into a “potentially deadly bacterium,” reports Science Daily, citing the University of Bath.
“Staphlococcus epidermidis is a deadly pathogen in plain sight. It’s always been ignored clinically because it’s frequently been assumed that it was a contaminant in lab samples or it was simply accepted as a known risk of surgery,” said Sheppard.
In a study published today in the journal Nature Communications, his team argues that examining the organism’s genome could help pinpoint which patients are most susceptible to this MRSA-related staph — and thereby prevent infection.
“If we can identify who is most at risk of infection, we can target those patients with extra hygiene precautions before they undergo surgery.”
The scientists stumbled upon the 61 genes that seem to be responsible for the bug’s pathogenicity — meaning that they drive the bacterium to become infectious to humans — after analyzing samples taken from patients who contracted Staphlococcus epidermidis infections following fracture repair surgery, and hip or knee replacements.
The groups latest paper investigating Disease-associated genotypes of the commensal skin bacterium Staphylococcus epidermidis was published online today in @NatureComms https://t.co/4vVkEIwNAQ @phylogeo @LMageiros pic.twitter.com/f6BhKRWcP1— Sheppard Laboratory (@sheppard_lab) November 28, 2018
Their analysis determined that these disease-causing genes — which were not present in samples taken from healthy volunteers in the control group — help the bacterium grow in the bloodstream. These genes also enable the bacterium to produce a hydrophobic biofilm that attaches to prosthetics. This biofilm allows the staph to evade the immune system’s attack, and creates a barrier against antibiotics.
“Because the bug is so abundant, they can evolve very fast by swapping genes with each other. If we do nothing to control this, there’s a risk that these disease-causing genes could spread more widely, meaning post-operative infections that are resistant to antibiotics could become even more common.”
In a surprising twist of events, the study also uncovered that some of the healthy people in the control group actually carried a far more dangerous form of Staphlococcus epidermidis without even knowing it. These individuals, however, were unharmed by the bacterium, which hadn’t become pathogenic in their case.