A cold actually attracted super bacteria! How should I deal with you?

Author: Zhan Yu (Institute of Subtropical Agriculture Ecology, Chinese Academy of Sciences)

The article comes from the Science Academy official account (ID: kexuedayuan)

As the big brother of antibiotics, penicillin is very worried recently:

"On November 29, 2017, Luo Dipeng from Sichuan High School was in a coma for more than ten days due to infection with the super bacteria MRSA. Even my subordinates - vancomycin, teicoplanin and other attacks had little effect."

Although the ranks of antibiotics are expanding, their prestige has greatly decreased. Big Brother Penicillin recalled:

“

"When I was discovered in 1928, I could be said to be fighting a group of people alone. Streptococci, actinomycetes, diphtheria bacteria, etc. were no match for me. As long as their cell walls were destroyed, they would be helpless against me, not to mention the small fry like Staphylococcus aureus.

"During World War II, I saved so many soldiers' lives. So many people were so grateful to me that they would rather spend all their money to buy me.

"But now, since their new leader, the 'super bacteria', appeared, my position has obviously declined. The big bad guy, Methicillin-resistant Staphylococcus aureus (MRSA), is actually ineffective against my special moves."

”

What are superbugs?

Superbug does not refer to a specific type of bacteria, but rather refers to bacteria that are resistant to multiple antibiotics. Its correct name should be "multidrug-resistant bacteria."

This type of title first appeared in a report by British scientist Jevom in 1961, when he first called the methicillin-resistant Staphylococcus aureus (MRSA) he discovered a "superbug."

Multidrug-resistant Streptococcus pneumoniae (MDRSP), vancomycin-resistant Enterococcus (VRE), multidrug-resistant Mycobacterium tuberculosis (MDR-TB), and the newly discovered Escherichia coli and Klebsiella pneumoniae carrying the NDM-1 gene, etc., are all super bacteria.

If the discovery of superbugs is not enough to cause a strong response, after all, many pathogens have been discovered but may not necessarily cause harm to the human body, then the death due to infection with superbugs has made many people feel uneasy. The world's first case of death due to infection with superbugs occurred in Belgium in 2010, when a man was injured in a car accident while traveling in Pakistan. He was first treated in Pakistan and later sent back to Belgium, where he was found to have been infected with "superbugs". Although the doctor used powerful antibiotics such as Christian, he was unable to save his life.

Do antibiotics give rise to superbugs?

The emergence of bacterial resistance is the result of the widespread use of antibiotics in clinical practice, and the abuse of antibiotics has accelerated this process. In order to survive, the emergence of drug resistance is one of the inevitable ways for microorganisms to mutate. The first appearance of "super bacteria" means that more "super bacteria" will surely be discovered in the future.

Gene mutation is the root cause of super bacteria. MRSA resistance mainly has two forms: intrinsic resistance mediated by chromosomes and acquired resistance mediated by plasmids.

Intrinsic drug resistance: The penicillin binding protein (PBP) produced by Staphylococcus aureus has the function of synthesizing bacterial cell walls. The original PBP has a high affinity for β-lactam antibiotics and can covalently bind to the active sites of β-lactam drugs, causing the bacteria to lose their activity and die. However, MRSA produces a special PBP2a encoded by the foreign inserted gene mecA, which has a very low affinity for β-lactam antibiotics and is rarely or not bound by β-lactam drugs. However, PBP2a can still synthesize bacterial cell walls, showing drug resistance.

Methicillin resistance and ability to express different virulence factors in Staphylococcus aureus

Acquired drug resistance: Drug resistance factors can be transferred between species, so that some strains carry more than one drug resistance, which may lead to the emergence of so-called "super bacteria". Zhu Baoli, a researcher at the Institute of Microbiology, Chinese Academy of Sciences, is the corresponding author of an article published in the journal Applied and Environmental Microbiology, which reveals the transmission network of drug resistance genes with horizontal transfer ability in bacteria, humans and animals.

The distribution of horizontal gene transfer in different classifications, from the inner circle to the outer circle, is phylum, class, order, tribe, genus and species.

Do super bacteria have “natural enemies”?

Science and technology are advancing, talents are innovating, and many anti-MRSA drugs are being developed. Commonly used anti-MRSA drugs include glycopeptide antibiotics such as vancomycin and teicoplanin, linezolid and the most effective aminoglycoside antibiotic arbekacin, in addition to tigecycline, daptomycin, etc.

However, it usually takes about 10 years for people to develop a new antibiotic for clinical application. However, super bacteria are constantly mutating and increasing, and their specific drug resistance mechanisms are becoming more complex, which forces people to look for new antibacterial agents.

Antimicrobial peptides (AMPs) that have emerged in recent years are a new type of antimicrobial drug with great development potential. Antimicrobial peptides are small molecule polypeptides with biological activity induced in the body. They are important effector molecules of the innate immune defense system and have broad-spectrum antimicrobial activity, especially against multidrug-resistant bacteria.

It is known that antimicrobial peptides destroy the integrity of bacterial cell membranes, causing the loss of intracellular and extracellular barriers, thereby killing cells, but the specific process of their action is still unclear. Antimicrobial peptides also have the advantages of good water solubility, thermal stability, almost no toxicity to normal cells of higher animals, and no drug resistance. Therefore, they are considered to have broad application prospects in the pharmaceutical industry. Currently, a variety of antimicrobial peptides are undergoing preclinical feasibility studies.

Multiple functions of antimicrobial peptides in host defense

What can we do?

Although the development of drug resistance is one of the inevitable ways for microbial mutation, the speed at which it develops depends on the concentration and frequency of contact with antibiotics.

Therefore, as human beings, we must use antibiotics rationally, not abuse them blindly, and take medicines according to the doctor's orders. For example, people often fall into the misunderstanding that once the antibiotics are effective, they stop taking them and frequently change antibiotics. But in fact, this is wrong. If you stop taking antibiotics after they have a little effect, it is easy to cause the pathogenic bacteria to revive, and the symptoms will recur and take the medicine again, which will cause drug resistance. In addition, each antibiotic has its own use cycle. Poor efficacy may also be a problem of insufficient medication time. Frequent changes of drugs will not only fail to cure the disease, but will cause bacterial resistance.

In addition, more importantly, we must strengthen our personal physique, exercise regularly, and develop good living habits so that all kinds of microorganisms have no way to invade. As long as we are "strong" enough, get sick less and use less medicine, then we can say goodbye to "super bacteria".

References

[1] Chen Binze, Li Zehui, Feng Qiangsheng, et al. Research progress on the resistance mechanism and molecular typing of methicillin-resistant Staphylococcus aureus[J]. Laboratory Medicine and Clinic, 2016, 13(19):2824-2827.

[2] He Zhesheng. The past, present and future of "super bacteria"[J]. International Journal of Epidemiology and Infectious Diseases, 2010, 37(5):289-290.

[3] Li Guanhong, Hong Zhimin, Jia Yongjie, et al. Antimicrobial effects and mechanisms of antimicrobial peptides[J]. Journal of Animal Nutrition, 2011, 23(4):546-555.

[4] Liao Yuanquan. Research progress on methicillin-resistant Staphylococcus aureus hospital infection[C]// Chinese Medical Association National Public Health Academic Conference. 2009:62-64.

[5] Shen Deli, Zhao Yonghong. Understanding the infection status and treatment progress of MRSA[C]// National Hospital Pharmacy. 2011.

[6] Hu Y, Xi Y, Jing L, et al. The Bacterial Mobile Resistome Transfer Network Connecting the Animal and Human Microbiomes[J]. Applied & Environmental Microbiology, 2011, 82(22):6672.

[7] Timothy J. Foster. The Staphylococcus aureus “superbug”. Citation Information: J Clin Invest. 2004;114(12):1693-1696. doi:10.1172/JCI23825.

Note: Some of the pictures in the article are from the Internet, and some are from references.