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Responsible Editor | xi Healthy human skin has many different types of microorganisms colonized on the surface of the skin.
One of the most common types of bacteria exists in almost everyone's skin and even in the nasal cavity, so it is named "Staphylococcus epidermidis".
Staphylococcus epidermidis is generally considered to be a friendly and mild bacteria that can promote the development and maturity of the human immune system and secrete antibiotics to inhibit harmful pathogens.
However, more and more evidences show that Staphylococcus epidermidis is an important pathogen of hospital infections related to medical devices.
Staphylococcus epidermidis infection is extremely difficult to treat because of its high drug resistance rate, and up to 90% of the strains are highly resistant bacteria.
Staphylococcus epidermidis is also considered to be a drug-resistant gene pool.
For its close relatives, the more lethal Staphylococcus aureus called "super bacteria" provides different types of drug-resistant genes to successfully adapt to multiple drugs in the hospital.
Disinfectant environment.
So which strains of Staphylococcus epidermidis are friendly, and which ones have become enemies? In the past two decades, research on the mechanism of Staphylococcus epidermidis infection has always been around the formation and structure of its biofilm.
New infection mechanisms need to be discovered and explored urgently to develop new and effective drugs and vaccines to combat the infections caused by them.
On May 24, 2021, the team of Andreas Peschel from the Institute of Infection Biology, University of Tubingen, Germany (first author: Du Xin) published an article in the journal Nature Microbiology Staphylococcus epidermidis clones express Staphylococcus aureus-type wall teichoic acid to shift from a commensal to pathogen life>
In this work, the research team collected 277 strains of Staphylococcus epidermidis (infectious bacteria) from infected sites in the University Hospital of Tubingen, University Hospital of Hamburg, and Renji Hospital Affiliated to Shanghai Jiaotong University, and also collected health volunteers.
680 strains of Staphylococcus epidermidis (colonizing bacteria) from the inside of the arm and the nasal cavity.
Screening of these strains revealed that about 10% of the infectious bacteria can be infected by phages that usually only infect Staphylococcus aureus.
Bacteriophages are specific to bacterial infections.
Specific bacteriophages recognize specific wall teichoic acid structures on the surface of bacteria to determine whether they are infected, just like the relationship between antigens and antibodies.
The wall teichoic acid structure on the surface of Staphylococcus aureus is poly-Rbop, while the wall teichoic acid structure on the surface of Staphylococcus epidermidis has been reported as poly-Grop.
After analyzing the structure of the wall teichoic acid extracted from these 10% of the infectious bacteria, it was found that they had both the structure of polyribitol phosphate and polyglycerol phosphate.
Therefore, the double-walled teichoic acid structure of Staphylococcus epidermidis can be recognized and infected by more types of bacteriophages, and the phages can spread its genes to other more types of bacteria.
After genome sequencing, it was found that the double-wall teichoic acid structure of Staphylococcus epidermidis had an extra section of the wall teichoic acid structure-encoding gene tarIJLM2 (Figure 1).
Interestingly, this gene is similar to another unsuccessfully expressed gene in itself, but it is closer to the wall teichoic acid structure-encoding gene in Staphylococcus aureus in the genetic tree.
Therefore, it may be derived from Staphylococcus aureus in the process of evolution, or Staphylococcus aureus obtained this gene from it.
But this gene was not found in colonizing bacteria derived from healthy people.
Therefore, the researchers concluded that this new gene tarIJLM2 may be related to the pathogenicity of Staphylococcus epidermidis.
The pathogenicity of Staphylococcus epidermidis is generally considered to be related to the formation of biofilms.
However, experiments have shown that these double-walled teichoic acid structures of Staphylococcus epidermidis cannot form biofilms.
Figure 1 used nasal cavity cells and endothelial cells to carry out in vitro bacterial adhesion experiments.
The results showed that the adhesion ability of tarIJLM2 knockout bacteria to nasal cavity cells increased, but the adhesion ability to endothelial cells decreased.
Animal experiments confirmed this result.
The number of colonizations in the mouse nasal cavity increased with the knockout of tarIJLM2, and the knockout of tarIJLM2 in the bacteremia model reduced the mortality of mice and the number of bacteria in the blood.
Analyzing all the Staphylococcus epidermidis genomes in the GenBank gene bank, the researchers found that 100% of the ST23 Staphylococcus epidermidis that began to spread in hospitals only 15 years ago contains this new gene sequence, and is the most common infection.
The clonotypes ST2, ST5, ST10 and ST87 also obtained this new gene to varying degrees.
In addition, the researchers also found more similar genes, named tarIJLM3, tarIJLM4 and tarIJL5.
After analysis, the fifth type only exists in animal infection strains, and the third and fourth types exist in human strains.
The gene functions of tarIJLM3 and tarIJLM4 are the same as tarIJLM2, and they can also express additional polyribitol phosphate on the surface of Staphylococcus epidermidis and are recognized by Staphylococcus aureus phage.
The researchers also tried to introduce this new gene tarIJLM2 into common single-walled teichoic acid Staphylococcus epidermidis.
Staphylococcus epidermidis that has obtained the new gene of single-wall teichoic acid also expresses additional polyribitol phosphate on the surface of its cells, which can be recognized by Staphylococcus aureus phage and has corresponding changes in cell experiments.
SaPI (Staphylococcus aureus pathogenicity islands) is a 15 kb polygene sequence containing multiple pathogenic factors that can be transferred by phage.
This sequence can be found in many Staphylococcus aureus bacteria.
Experiments have shown that Staphylococcus epidermidis with double-wall teichoic acid can obtain this pathogenic factor island through horizontal gene transfer of Staphylococcus aureus phage with extremely high efficiency.
This result shows that the polyribitol phosphate structure additionally expressed by the tarIJLM2 gene can promote the sharing of genes between different staphylococci to enhance the bacteria's ability to adapt to different environments.
In summary, this study found a new wall teichoic acid structure on the surface of Staphylococcus epidermidis, and revealed the important role of this structure in bacterial pathogenicity and horizontal gene transfer, suggesting that the structure of polyribitol phosphate can prevent Staphylococcus aureus infection is also a good vaccine target for infectious Staphylococcus epidermidis.
Dr.
Du Xin, a postdoctoral fellow at the Institute of Infectious Biology, University of Tubingen School of Medicine, Germany, is the first author of the paper, and Professor Andreas Peschel is the corresponding author.
Original link: https://doi.
org/10.
1038/s41564-021-00913-z Platemaker: Notes for reprinting on the 11th [Non-original article] The copyright of this article belongs to the author of the article.
Personal forwarding and sharing are welcome.
Reprinting without permission is prohibited.
The author has all legal rights, and offenders must be investigated.
One of the most common types of bacteria exists in almost everyone's skin and even in the nasal cavity, so it is named "Staphylococcus epidermidis".
Staphylococcus epidermidis is generally considered to be a friendly and mild bacteria that can promote the development and maturity of the human immune system and secrete antibiotics to inhibit harmful pathogens.
However, more and more evidences show that Staphylococcus epidermidis is an important pathogen of hospital infections related to medical devices.
Staphylococcus epidermidis infection is extremely difficult to treat because of its high drug resistance rate, and up to 90% of the strains are highly resistant bacteria.
Staphylococcus epidermidis is also considered to be a drug-resistant gene pool.
For its close relatives, the more lethal Staphylococcus aureus called "super bacteria" provides different types of drug-resistant genes to successfully adapt to multiple drugs in the hospital.
Disinfectant environment.
So which strains of Staphylococcus epidermidis are friendly, and which ones have become enemies? In the past two decades, research on the mechanism of Staphylococcus epidermidis infection has always been around the formation and structure of its biofilm.
New infection mechanisms need to be discovered and explored urgently to develop new and effective drugs and vaccines to combat the infections caused by them.
On May 24, 2021, the team of Andreas Peschel from the Institute of Infection Biology, University of Tubingen, Germany (first author: Du Xin) published an article in the journal Nature Microbiology Staphylococcus epidermidis clones express Staphylococcus aureus-type wall teichoic acid to shift from a commensal to pathogen life>
In this work, the research team collected 277 strains of Staphylococcus epidermidis (infectious bacteria) from infected sites in the University Hospital of Tubingen, University Hospital of Hamburg, and Renji Hospital Affiliated to Shanghai Jiaotong University, and also collected health volunteers.
680 strains of Staphylococcus epidermidis (colonizing bacteria) from the inside of the arm and the nasal cavity.
Screening of these strains revealed that about 10% of the infectious bacteria can be infected by phages that usually only infect Staphylococcus aureus.
Bacteriophages are specific to bacterial infections.
Specific bacteriophages recognize specific wall teichoic acid structures on the surface of bacteria to determine whether they are infected, just like the relationship between antigens and antibodies.
The wall teichoic acid structure on the surface of Staphylococcus aureus is poly-Rbop, while the wall teichoic acid structure on the surface of Staphylococcus epidermidis has been reported as poly-Grop.
After analyzing the structure of the wall teichoic acid extracted from these 10% of the infectious bacteria, it was found that they had both the structure of polyribitol phosphate and polyglycerol phosphate.
Therefore, the double-walled teichoic acid structure of Staphylococcus epidermidis can be recognized and infected by more types of bacteriophages, and the phages can spread its genes to other more types of bacteria.
After genome sequencing, it was found that the double-wall teichoic acid structure of Staphylococcus epidermidis had an extra section of the wall teichoic acid structure-encoding gene tarIJLM2 (Figure 1).
Interestingly, this gene is similar to another unsuccessfully expressed gene in itself, but it is closer to the wall teichoic acid structure-encoding gene in Staphylococcus aureus in the genetic tree.
Therefore, it may be derived from Staphylococcus aureus in the process of evolution, or Staphylococcus aureus obtained this gene from it.
But this gene was not found in colonizing bacteria derived from healthy people.
Therefore, the researchers concluded that this new gene tarIJLM2 may be related to the pathogenicity of Staphylococcus epidermidis.
The pathogenicity of Staphylococcus epidermidis is generally considered to be related to the formation of biofilms.
However, experiments have shown that these double-walled teichoic acid structures of Staphylococcus epidermidis cannot form biofilms.
Figure 1 used nasal cavity cells and endothelial cells to carry out in vitro bacterial adhesion experiments.
The results showed that the adhesion ability of tarIJLM2 knockout bacteria to nasal cavity cells increased, but the adhesion ability to endothelial cells decreased.
Animal experiments confirmed this result.
The number of colonizations in the mouse nasal cavity increased with the knockout of tarIJLM2, and the knockout of tarIJLM2 in the bacteremia model reduced the mortality of mice and the number of bacteria in the blood.
Analyzing all the Staphylococcus epidermidis genomes in the GenBank gene bank, the researchers found that 100% of the ST23 Staphylococcus epidermidis that began to spread in hospitals only 15 years ago contains this new gene sequence, and is the most common infection.
The clonotypes ST2, ST5, ST10 and ST87 also obtained this new gene to varying degrees.
In addition, the researchers also found more similar genes, named tarIJLM3, tarIJLM4 and tarIJL5.
After analysis, the fifth type only exists in animal infection strains, and the third and fourth types exist in human strains.
The gene functions of tarIJLM3 and tarIJLM4 are the same as tarIJLM2, and they can also express additional polyribitol phosphate on the surface of Staphylococcus epidermidis and are recognized by Staphylococcus aureus phage.
The researchers also tried to introduce this new gene tarIJLM2 into common single-walled teichoic acid Staphylococcus epidermidis.
Staphylococcus epidermidis that has obtained the new gene of single-wall teichoic acid also expresses additional polyribitol phosphate on the surface of its cells, which can be recognized by Staphylococcus aureus phage and has corresponding changes in cell experiments.
SaPI (Staphylococcus aureus pathogenicity islands) is a 15 kb polygene sequence containing multiple pathogenic factors that can be transferred by phage.
This sequence can be found in many Staphylococcus aureus bacteria.
Experiments have shown that Staphylococcus epidermidis with double-wall teichoic acid can obtain this pathogenic factor island through horizontal gene transfer of Staphylococcus aureus phage with extremely high efficiency.
This result shows that the polyribitol phosphate structure additionally expressed by the tarIJLM2 gene can promote the sharing of genes between different staphylococci to enhance the bacteria's ability to adapt to different environments.
In summary, this study found a new wall teichoic acid structure on the surface of Staphylococcus epidermidis, and revealed the important role of this structure in bacterial pathogenicity and horizontal gene transfer, suggesting that the structure of polyribitol phosphate can prevent Staphylococcus aureus infection is also a good vaccine target for infectious Staphylococcus epidermidis.
Dr.
Du Xin, a postdoctoral fellow at the Institute of Infectious Biology, University of Tubingen School of Medicine, Germany, is the first author of the paper, and Professor Andreas Peschel is the corresponding author.
Original link: https://doi.
org/10.
1038/s41564-021-00913-z Platemaker: Notes for reprinting on the 11th [Non-original article] The copyright of this article belongs to the author of the article.
Personal forwarding and sharing are welcome.
Reprinting without permission is prohibited.
The author has all legal rights, and offenders must be investigated.
