Tag Archives: Staphylococcus

Staphylococcus epidermidis biofilm.

One bacteria lives on everybody’s skin — and it’s becoming resistant to antibiotics

Researchers at the University of Bath, UK, report that an extremely common bacterium is developing antibiotic resistance.

Staphylococcus epidermidis biofilm.

A Staphylococcus epidermidis biofilm formed on a titanium substrate.

MRSA, E. coli, they’re all very scary. But new research says there’s a newcomer to the Scary Table: Staphylococcus epidermidis, a widespread species that lives on our skins. A close relative of MRSA, this bacteria is a leading cause of infections (some of them life-threatening) following surgery.

It’s abundant, widespread, generally overlooked — and rapidly becoming resistant to antibiotics, warn researchers at the Milner Centre for Evolution at the University of Bath.

Staphil-oh no no no.

The team says we should take the threat posed by S. epidermidis much more seriously than we do today. They recommend taking extra precautions especially in the case of patients with heightened risk of infection that are due to undergo surgery.

The researchers started by retrieving samples of the bacteria from patients who developed infections following following hip replacement, knee joint replacement, and fracture fixation operations. Then, they compared the genetic material of these strains with those in swab samples harvested from the skin of healthy volunteers.

They report identifying a set of 61 genes that allow some strains of S. epidermidis to cause life-threatening infection. These genes help the bacterium grow in the bloodstream, avoid the host’s immune response, make the cell surface sticky so that the organisms can form biofilms, and make the bug resistant to antibiotics, they write. This finding, the team hopes, will further our understanding of why some strains can become infectious — in the future, this should help us keep the risk of post-surgery infection with S. epidermidis at bay.

The team also found that a small number of (healthy) individuals carry a much more deadly strain of the bacteria on their skin. Determining which strain (relatively harmless, dangerous, or one of these very dangerous ones) a potential patient carries on their skin before surgery would help doctors prepare extra hygiene precautions as needed.

“[S. epidermidis has] 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,” says  Professor Sam Sheppard, Director of Bioinformatics at the Milner Centre for Evolution at the University of Bath and the study’s lead author. “Post-surgical infections can be incredibly serious and can be fatal. Infection accounts for almost a third of deaths in the UK so I believe we should be doing more to reduce the risk if we possibly can.

“Because the bug is so abundant, they can evolve very fast by swapping genes with each other,” he explains. “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.”

The paper “Disease-associated genotypes of the commensal skin bacterium Staphylococcus epidermidis” has been published in the journal Nature Communications.

Brown bear.

Brown bear saliva kills a bacteria that current antibiotics are unable to treat

An international research team reports that the saliva of a Siberian brown bear (Ursus arctos collaris) subspecies can kill Staphylococcus aureus bacteria, a strain that is rapidly becoming resistant to all current antibiotics.

Brown bear.

Image credits Oksanna Briere.

One subspecies of the Siberian brown bear can kill S.aureus with its bare saliva, a new paper reports. The animal’s range includes Mongolia, Siberia, and parts of northern China. While generally vegetarian, the bears also dine on caribou, elk, and fish. This wide menu has a profound impact on the subspecies’ microbiome, the team writes — including its surprising disinfectant ability.

‘Drool over this, please’

The discovery comes as part of a larger project aiming to study the microbiome of several wild animals. The project’s goal is to find naturally-occurring chemicals which can kill bacteria that also infect humans, especially the strains that are becoming or have become resistant to antibiotic treatments.

The team captured several specimens of the bear subspecies in the taiga — the forested parts of Siberia — and harvested saliva swabs for analysis. Using “state of the art screening techniques,” the team was able to identify the chemical make-up and microbiota of the samples.

One bacteria swimming its merry way in that saliva is Bacillus pumilus, a strain that secretes an antibiotic compound known as amicoumacin A. The team believes the bears obtain this bacterium when they munch on certain types of vegetation.

After finding B.pumilus in the saliva samples, the team looked to see how it interacts with other antibiotic-resistant bacteria such as S.aureus — which is associated with skin infections in humans. That’s how they discovered that the strain can effectively deal with the staphylococcus.

The findings could go a long way in hospitals and other healthcare facilities, which are struggling to remove the deadly bacteria. A naturally-occurring chemical that can help us fight staph would be quite valuable.

The team plans to continue the project in hopes of finding even more new compounds that can help us keep bacteria at bay.

The paper “Ultrahigh-throughput functional profiling of microbiota communities” has been published in the journal PNAS.