Understanding Bacterial Mutation and Antibiotic Resistance: A Quizlet Review

Introduction


bacterial mutations

Bacterial infections have been effectively treated with antibiotics for many decades. Antibiotics work by attacking and destroying the cell wall or metabolic machinery of bacteria. However, in recent years, the increasing incidence of antibiotic-resistant bacteria has become a major threat to public health. Antibiotic resistance occurs when bacteria acquire the ability to resist the effects of antibiotics. One of the primary mechanisms by which bacteria develop antibiotic resistance is through mutations.

In this article, we will discuss how bacterial mutations make bacteria resistant to antibiotics. We will examine the different types of mutations that occur in bacteria and how they confer resistance to antibiotics.

Bacteria are constantly exposed to antibiotics. When a bacterium is exposed to an antibiotic, the antibiotic works by interfering with the biochemical processes within the bacterium, ultimately leading to its death. However, some bacteria may escape this fate by developing mutations that enable them to survive in the presence of the antibiotic.

Mutations are changes in the DNA sequence of a bacterium that arise spontaneously or as a result of exposure to environmental factors such as UV radiation or chemicals. Mutations can occur in any part of the bacterial genome, including genes that are involved in antibiotic resistance. When a mutation occurs in an antibiotic resistance gene, it can lead to changes in the protein structure or function encoded by the gene. This, in turn, can make the bacterium resistant to the antibiotic.

One of the ways in which bacteria acquire resistance to antibiotics is through the acquisition of plasmids. Plasmids are small, circular DNA molecules that are capable of replicating independently of the bacterial genome. They can carry genes that confer resistance to antibiotics, including genes that encode enzymes that degrade antibiotics, or genes that modify the targets of antibiotics so that they are no longer affected.

Another mechanism by which mutations can lead to antibiotic resistance is through changes in the structure of the bacterial cell wall. Some antibiotics work by binding to specific targets on the bacterial cell wall, leading to the disruption of the wall and eventual death of the bacterial cell. However, mutations can occur in the genes that encode enzymes involved in cell wall biosynthesis, leading to changes in the structure of the cell wall. This can make it more difficult for antibiotics to bind to the cell wall targets, leading to resistance to the antibiotic.

Furthermore, mutations can occur in the genes that encode antibiotic transporters, which are responsible for pumping antibiotics out of the bacterial cell. When these genes mutate, they can result in the overexpression of the transporter protein, leading to increased export of the antibiotic and reduced effectiveness of the drug.

In conclusion, bacterial mutations can lead to antibiotic resistance by a variety of mechanisms. These include changes in the structure or function of antibiotic targets, acquisition of plasmids carrying resistance genes, and mutations in genes encoding antibiotic transporters. Understanding the mechanisms behind antibiotic resistance is critical in the development of new strategies to combat antibiotic-resistant bacteria.

What are bacterial mutations?

bacterial mutations

Bacterial mutations refer to changes in the DNA sequence of bacterial cells. These changes can occur naturally or be induced by external factors such as exposure to radiation, chemicals or antibiotics. Mutations can lead to variations in the traits of bacteria, such as their ability to metabolize nutrients, reproduce, and interact with their environment.

Most mutations are harmless and do not affect the function of bacterial cells. However, some mutations can have a significant impact on bacterial survival and their interactions with other organisms. One of the most important consequences of bacterial mutations is the emergence of antibiotic-resistant strains.

How do bacterial mutations make bacteria resistant to antibiotics?

bacterial mutations antibiotics

Antibiotics are drugs used to kill or inhibit the growth of bacterial cells. They work by targeting specific components of bacterial cells, such as the cell wall, membrane, or metabolic pathways. However, some bacteria have developed mechanisms to resist antibiotics and continue to thrive despite exposure to these drugs.

Resistance to antibiotics is often caused by bacterial mutations that alter the structure or function of the targeted components. For example, mutations can lead to changes in the shape or composition of the cell wall or membrane, which can prevent antibiotics from binding to their targets. Mutations can also lead to changes in the expression of genes involved in metabolic pathways, making bacteria less susceptible to the effects of antibiotics.

In addition to genetic mutations, bacteria can also acquire resistance to antibiotics through horizontal gene transfer. This process involves the exchange of genetic material between bacteria, either through direct contact or the transfer of plasmids – circular pieces of DNA that can replicate independently of the bacterial chromosome.

Horizontal gene transfer can occur through several mechanisms, such as conjugation (cell-to-cell transfer), transduction (transfer via viruses), or transformation (uptake of DNA from the environment). The acquisition of resistance genes through horizontal gene transfer can allow bacteria to rapidly develop resistance to multiple antibiotics, making treatment more challenging and increasing the risk of infection.

In summary, bacterial mutations can lead to the emergence of antibiotic-resistant strains by altering the structure or function of bacterial cells, or by facilitating the acquisition of resistance genes through horizontal gene transfer. This highlights the importance of using antibiotics judiciously and developing new strategies to combat antibiotic resistance.

How do bacterial mutations occur?


Bacterial Mutations

Bacterial mutations occur spontaneously through various mechanisms such as DNA replication errors, exposure to radiation, or the presence of mutagens in the environment. Mutations can also arise through horizontal gene transfer, where bacteria exchange genetic material with each other, which can result in the acquisition of new genes containing antibiotic resistance mechanisms. These mutations can lead to changes in the genetic material of bacteria that allow them to resist the effects of antibiotics and become resistant to treatment.

How do mutations contribute to antibiotic resistance?


Antibiotic Resistance

The development of antibiotic resistance through mutation occurs when bacteria undergo genetic changes that alter or eliminate the target of the antibiotic or produce enzymes that degrade the antibiotic. This alteration or elimination of the target site occurs when the bacteria’s DNA mutates, allowing them to produce a modified target that is no longer affected by the antibiotic. Furthermore, some bacteria can produce enzymes that break down antibiotics before they can take effect. Mutations can also allow bacteria to increase the production of efflux pumps that rapidly expel antibiotics from the cell, reducing their effectiveness.

Mutation and survival of antibiotic-resistant bacteria can be considered to be a form of natural selection, where only bacteria with advantageous traits are able to survive in the presence of antibiotics. The overuse and misuse of antibiotics in human and veterinary medicine has led to the increase in selective pressure for the growth of antibiotic-resistant bacteria, which has resulted in the development of new mutation resistance mechanisms in some strains.

What are some examples of bacterial mutations leading to antibiotic resistance?


Mutation Bacterial antibiotics

One example of bacterial mutation that resulted in antibiotic resistance is the mutation of the fluoroquinolone-resistant strain of Salmonella Typhimurium. The mutation occurred in the target site of the antibiotic fluoroquinolone, causing it to no longer bind to, and inhibit, DNA gyrase, which is essential to bacterial replication. This mutation allows Salmonella Typhimurium to survive fluoroquinolone treatment, rendering the antibiotic ineffective.

Another example is the mutation of E. coli, one of the most common causes of urinary tract infections, leading to resistance to beta-lactam antibiotics. This mutation caused E. coli to produce an enzyme that could break down beta-lactam antibiotics, such as penicillin and amoxicillin, before they could be effective in treating the infection.

In conclusion, bacterial mutation is a significant factor in the development of antibiotic resistance in bacteria. It can lead to the acquisition of new genes or the alteration of existing genes, and the end result is resistance to antibiotics. The growing phenomenon of antibiotic resistance emphasizes the importance of responsible antibiotic use and research into developing new types of antibiotics to overcome this problem effectively.

What are the types of mutations?


Types of Mutations

Bacterial mutations are changes that occur in the DNA sequences of bacterial cells. These changes may be spontaneous or induced, leading to different types of mutations. The two primary types of mutations that occur in bacteria are spontaneous mutations and induced mutations.

Spontaneous mutations occur without any external influences or factors. These mutations occur randomly due to the errors that occur in DNA replication, repair mechanisms, or other internal processes. Spontaneous mutations may lead to changes in the amino acid sequence of proteins, thus affecting the normal cellular processes and leading to antibiotic resistance.

Induced mutations, on the other hand, occur due to the exposure of bacteria to external environmental factors such as UV radiation, chemical mutagens, or antibiotics. Exposure to such factors may damage the DNA of bacterial cells, thus leading to changes in their genetic sequences that result in antibiotic resistance.

How do bacterial mutations make bacteria resistant to antibiotics?


Bacterial Mutations and Antibiotic Resistance

Bacterial mutations play a crucial role in making bacteria resistant to antibiotics. These mutations often lead to changes in the cell’s genetic sequence, resulting in the production of modified proteins that cannot be targeted by antibiotics. Consequently, these mutated bacteria can survive and multiply even in the presence of antibiotics, leading to antibiotic resistance.

One of the most common ways that mutations lead to antibiotic resistance is by altering the bacterial cell’s outer membrane’s permeability. The outer membrane acts as a barrier to protect the bacterial cell from harmful substances, including antibiotics. By mutating the genes responsible for the production of the outer membrane proteins, bacteria can reduce the entry of antibiotics into the cell, thus becoming resistant to them.

Another way through which bacterial mutations confer drug resistance is by altering the target site of antibiotics. Antibiotics target specific proteins or enzymes required for the bacteria to grow and replicate. By mutating these target proteins, bacteria can modify their structure in such a way that antibiotics cannot bind to them and inhibit their function. As a result, the bacteria become resistant to the antibiotics.

What are the consequences of bacterial mutations?


Consequences of Bacterial Mutations

Bacterial mutations can have significant consequences both for the individual cell and the community of bacteria as a whole. In most cases, bacterial mutations lead to adaptive changes that increase the organism’s chances of survival and reproduction, leading to the emergence of antibiotic resistance.

However, bacterial mutations can also have detrimental effects on the bacteria, leading to reduced fitness and survival rates. For instance, mutations that disrupt essential cellular functions may result in the accumulation of toxic substances that can be harmful to the bacteria. Bacterial mutations may also interfere with the regulation of gene expression, leading to the over or underproduction of specific proteins that disrupt the normal cellular processes.

Furthermore, bacterial mutations can have broader implications for the environment and human populations. Antibiotic resistance is a severe global health crisis, with the World Health Organization indicating that it is one of the most significant threats to public health today. Bacterial mutations play a fundamental role in the development and spread of antibiotic-resistant infections, leading to increased morbidity and mortality rates across the world.

How can we limit the consequences of bacterial mutations?


Limiting the Consequences of Bacterial Mutations

The development and spread of antibiotic resistance are complex issues that require multifaceted approaches to address. The most effective ways of limiting the consequences of bacterial mutations are:

1. Rational use of antibiotics: Healthcare practitioners should prescribe antibiotics accurately and appropriately to patients to minimize the chances of developing antibiotic resistance.

2. Antibiotic stewardship: This involves implementing policies and procedures aimed at promoting the responsible use of antibiotics. This can include monitoring antibiotic prescribing practices and drug resistance patterns and providing guidance on the appropriate use of antibiotics.

3. Public education: Educating the general public on the appropriate use of antibiotics and the risks associated with antibiotic resistance can increase awareness and promote behavior changes that minimize the risks of developing antibiotic resistance.

4. Development of new antibiotics: Developing new antibiotics that target different mechanisms and pathways can provide alternative treatment options for antibiotic-resistant infections and reduce the risks associated with bacterial mutations.

In conclusion, bacterial mutations play a crucial role in the development of antibiotic resistance and pose significant challenges to global public health. Understanding the types of mutations that occur in bacteria, how they lead to drug resistance, and their consequences is critical in developing effective strategies for minimizing the development and spread of antibiotic resistance.

What are the causes of mutations?


Causes of mutations

Mutations are sudden genetic changes that can occur within an organism. These genetic changes are often responsible for evolution, but they can also lead to the development of antibiotic resistance in bacteria. The following are the main causes of mutations:

1. Environmental factors

Environmental factors

Environmental factors such as radiation, certain chemicals, and pollutants can cause mutations in bacteria. Radiation can cause damage to the DNA molecules in bacteria, causing them to change and mutate. Similarly, exposure to certain chemicals can also cause mutations in bacteria. Pollutants like heavy metals, pesticides, and other toxins can also cause mutations as they can cause damage to the genetic material.

2. Errors during genetic replication

Errors during genetic replication

Errors can happen during DNA replication. During cell division, DNA is replicated in the cell’s nucleus. Sometimes errors in the replication can occur, leading to mutations. These errors can include deletions, insertions, or substitutions of a single nucleotide or even much larger sections of DNA. The substitutions of nucleotides will cause changes in the genetic code which may lead to antibiotic resistance in bacteria.

3. Exposure to mutagens

Exposure to mutagens

Mutagens are agents that promote mutations in organisms. Some mutagens are naturally occurring, while others are man-made. Exposure to mutagens can lead to genetic changes in bacteria that may result in antibiotic resistance. Some common mutagens include certain chemicals, radiation, and certain drugs.

4. Horizontal gene transfer

Horizontal gene transfer

Horizontal gene transfer is the process by which bacteria can exchange genetic material with other bacteria. This can occur through the transfer of plasmids, transposons or bacteriophages. If a bacterium acquires a plasmid containing an antibiotic resistance gene, it can then become resistant to that antibiotic. The ability to transfer genetic material horizontally between species is one of the key factors that the evolution of antibiotic resistance.

5. Random mutation events

Random mutation events

Bacteria can also acquire antibiotic resistance due to random mutation events. These mutations can happen spontaneously and are unpredictable. Even if a bacterium is not exposed to antibiotics, it can still acquire mutations that result in resistance to antibiotics. As these mutations are random, they can result in a wide variety of mutations and molecular mechanisms for resistance.

In conclusion, bacterial mutations are one of the key factors which lead to antibiotic resistance. These mutations can occur due to various environmental factors such as exposure to mutagens and horizontal gene transfer. Errors during replication and random mutation events can also lead to antibiotic resistance. Developing a deeper understanding of the causes of bacterial mutations that lead to antibiotic resistance is crucial to finding new and effective ways to combat bacterial infections.

What are antibiotic-resistant bacteria?


Antibiotic-resistant bacteria

Antibiotic-resistant bacteria are strains of bacteria that are no longer susceptible to the effects of antibiotics. Antibiotics are drugs used to kill or inhibit the growth of bacteria, but some strains are able to resist the drugs. These strains continue to survive, replicate, and cause infections, which can lead to serious health consequences. Antibiotic resistance has become a global health threat, and it is important to understand how and why bacteria become resistant to antibiotics.

How do bacterial mutations occur?


Bacterial mutations

Bacterial mutations occur when there is a change in the DNA of bacteria. DNA is the genetic material that controls the structure, function, and behavior of cells. Mutations can happen spontaneously due to errors in DNA replication, exposure to mutagenic agents, or through horizontal gene transfer. Horizontal gene transfer is the transfer of genes between different bacteria, which can occur through mechanisms such as conjugation, transformation, and transduction. These mechanisms can introduce new traits or genes into bacterial populations, which can lead to antibiotic resistance.

How do bacterial mutations make bacteria resistant to antibiotics?


Bacterial mutations and antibiotic resistance

Bacterial mutations can lead to antibiotic resistance in several ways. For example, mutations can occur in genes that control the production or regulation of antibiotic targets, such as enzymes, receptors, or transporters. These mutations can decrease the binding or uptake of antibiotics, preventing them from inhibiting bacterial growth. Mutations can also occur in genes that control drug efflux pumps, which are proteins that pump antibiotics out of the bacterial cell. Mutations in these genes can increase the expression or activity of efflux pumps, making it harder for antibiotics to reach their targets. In addition, mutations can occur in genes that control alternative metabolic pathways or stress responses, allowing bacteria to survive and reproduce in the presence of antibiotics.

What factors contribute to bacterial mutations and antibiotic resistance?


Bacterial mutations and antibiotic resistance factors

Several factors contribute to bacterial mutations and antibiotic resistance. One of the main factors is the overuse and misuse of antibiotics, which can create selective pressure for resistant strains to thrive. Antibiotics are often prescribed when they are not needed, or they are not taken as directed, which can promote the survival of resistant bacteria. In addition, antibiotic use in agriculture, animal husbandry, and aquaculture can also contribute to the spread of antibiotic-resistant bacteria. Other factors include poor infection control practices, lack of sanitation and hygiene, and inadequate surveillance and monitoring of antibiotic resistance.

How can we prevent and control antibiotic-resistant bacteria?


Prevention and control of antibiotic-resistant bacteria

Preventing and controlling antibiotic-resistant bacteria requires a comprehensive and coordinated approach. This includes reducing the inappropriate use of antibiotics, practicing good infection prevention and control, promoting hygiene and sanitation, and investing in research and development of new antibiotics and alternative therapies. Health care workers, patients, and their families can play a critical role in preventing and controlling antibiotic-resistant bacteria by following appropriate hand hygiene, getting vaccinated, and using antibiotics only when they are prescribed by a health care provider. Governments and international organizations also play a crucial role in addressing the global threat of antibiotic resistance through policy development, regulation, and surveillance.

What is the future of antibiotic resistance?


Future of antibiotic resistance

The future of antibiotic resistance is uncertain, but it is clear that the problem will continue to grow unless significant action is taken. The development of new antibiotics and alternative therapies is essential, but it is also important to improve existing antibiotics by optimizing their use and formulation. In addition, addressing the systemic factors that contribute to antibiotic resistance, such as poverty, lack of access to health care, and weak health systems, will require a multi-sectoral and collaborative approach. Ultimately, preventing and controlling antibiotic-resistant bacteria requires a global commitment to protecting public health, preserving the effectiveness of antibiotics, and promoting sustainable development.

Education and Awareness


Education and Awareness

The first step in tackling antibiotic resistance is to educate the public about the dangers of overusing antibiotics. Antibiotics save lives, but they should be used cautiously and only when necessary. Unfortunately, many people don’t understand the difference between a viral infection and a bacterial infection. They may demand antibiotics for a cold or the flu, without realizing that antibiotics don’t work against viruses. This overuse of antibiotics can lead to resistance.

Healthcare providers must also be educated about the appropriate use of antibiotics. They should only prescribe antibiotics when they’re needed and for the shortest possible time. They should also explain to their patients why they don’t always need antibiotics and what they can do to relieve symptoms and help their bodies fight off infections.

Education should also be targeted towards farmers and veterinarians, as the use of antibiotics in livestock can contribute to the development of antibiotic-resistant bacteria that can be transmitted to humans through food. Farmers should be encouraged to use alternative methods of disease prevention and treatment, such as better hygiene and vaccinations.

Finally, the general public should be educated about basic hygiene practices, such as washing hands regularly and covering their mouths when coughing or sneezing, which can help prevent the spread of infectious diseases.

Research and Development


Research and Development

The development of new antibiotics is essential in the fight against antibiotic resistance. However, the process of discovering and developing new antibiotics is long and expensive. Many pharmaceutical companies have stopped investing in antibiotic research because antibiotics are typically used for short periods and are not as profitable as drugs that are taken continuously.

To promote the development of new antibiotics, governments can provide funding and incentives to pharmaceutical companies, universities, and other researchers. This could include tax breaks, grants, and prizes for the development of new antibiotics.

Researchers need to think outside the box when it comes to discovering new antibiotics. They can look to nature for inspiration, studying the bacteria and other microorganisms that produce antibiotics to see how they work and how they can be modified to create new drugs. Researchers can also use computer modeling and artificial intelligence to predict and design new antibiotics.

Reducing Antibiotic Use in Agriculture


Reducing Antibiotic Use in Agriculture

The use of antibiotics in agriculture, especially in intensive farming, is a major contributor to the development of antibiotic-resistant bacteria. To reduce the use of antibiotics in agriculture, farmers can be encouraged to adopt more sustainable and organic practices that rely on natural and alternative means of pest and disease control.

Regulators can also take action to reduce the use of antibiotics in livestock. For example, the US Food and Drug Administration (FDA) has implemented a voluntary program to phase out the use of antibiotics for growth promotion in livestock. The European Union has banned the use of antibiotics as growth promoters, and the use of antibiotics for disease prevention in healthy animals is only allowed in exceptional cases.

Improving Hospital Infection Control


Improving Hospital Infection Control

Hospitals are a common breeding ground for antibiotic-resistant bacteria. Patients with weakened immune systems are particularly vulnerable to infections, and hospitals are often overcrowded, making it easier for infections to spread.

To reduce the risk of infections in hospitals, healthcare facilities should have strict infection control protocols in place. This includes isolating infected patients, enforcing hand hygiene, and regularly cleaning and disinfecting surfaces.

Healthcare providers should also adopt practices that reduce the use of antibiotics, such as prescribing antibiotics only when they’re needed and choosing antibiotics that are less likely to lead to resistance.

Alternative Treatments


Alternative Treatments

Alternative treatments, such as probiotics, prebiotics, and phage therapy, may offer new ways of treating infections without relying on antibiotics. Probiotics are live microorganisms that can help restore the natural balance of bacteria in the human gut, while prebiotics are substances that help promote the growth of good bacteria. Phage therapy involves using viruses that infect and kill bacteria to treat bacterial infections.

However, much more research is needed to understand the effectiveness and safety of these alternative treatments before they can be used as mainstream treatments.

Clean Water and Sanitation


Clean Water and Sanitation

Access to clean water and sanitation is essential for preventing the spread of bacterial infections. In many parts of the world, people don’t have access to safe drinking water or proper sanitation facilities. This can lead to the spread of infectious diseases, which in turn can lead to the overuse of antibiotics.

To reduce the need for antibiotics in these areas, governments and non-governmental organizations should prioritize improving access to clean water and sanitation facilities. This includes building wells, water treatment plants, and toilets, as well as educating people about the importance of good hygiene practices.

Collaboration and Coordination


Collaboration and Coordination

Tackling antibiotic resistance requires a collaborative and coordinated effort from governments, healthcare providers, the pharmaceutical industry, scientists, and the public. This includes sharing data and resources, promoting best practices, and working together to develop new antibiotics and alternative treatments.

International organizations such as the World Health Organization (WHO) and the World Organisation for Animal Health (OIE) play an important role in providing leadership and coordinating efforts to tackle antibiotic resistance on a global scale.

Ultimately, everyone has a role to play in addressing antibiotic resistance. By taking action to reduce the overuse of antibiotics and promoting sustainable practices in agriculture, healthcare, and everyday life, we can help protect the effectiveness of antibiotics and save lives for generations to come.

Mutations and Antibiotic Resistance


Antibiotic Resistance

Bacterial mutations are the driving force behind the development of antibiotic resistance. Antibiotics function by targeting bacterial functions and preventing them from replicating effectively, ultimately leading to bacterial death. However, bacteria can mutate, or change in their genetic makeup, in response to external pressures such as antibiotics. These mutations that occur within the bacterial DNA can ultimately change the way the bacteria functions. In some cases, mutations can cause the bacteria to become tolerant, or resistant, to antibiotics.

When bacteria mutate in a way that makes them resistant to antibiotics, it poses a serious threat to human health. Bacterial infections that were once easily treatable with antibiotics can now be persistent and even fatal. For this reason, it is crucial that we take necessary measures in the fight against antibiotic resistance.

The Spread of Antibiotic Resistance


Spread of Antibiotic Resistance

Antibiotic resistance can spread rapidly among bacterial populations through the transfer of genetic material. Bacteria can share DNA in several ways, including through the formation of biofilms and by exchanging genetic material through structures called plasmids. Plasmids are small, circular pieces of DNA that can replicate independently from the parent bacterial genome.

When bacteria transfer genetic material between themselves, it can happen rapidly and on a large scale. This means that even if a small population of bacteria has developed antibiotic resistance, it can transfer that resistance to other bacteria. This genetic transfer can happen between bacteria of the same species, as well as across different species. This means that antibiotic-resistant bacteria can quickly spread and infect humans, making the consequences of antibiotic resistance even more severe.

Preventing Antibiotic Resistance


Preventing Antibiotic Resistance

Preventing antibiotic resistance requires a multi-faceted approach. One important strategy is to limit the use of antibiotics to only necessary cases. The misuse and overuse of antibiotics contributes to the development of antibiotic resistance by putting selective pressure on bacterial populations. This means that when antibiotics are used unnecessarily, they can select for antibiotic-resistant bacteria and promote the spread of resistant infections.

It is also important to continue developing new antibiotics to remain effective against bacteria that have developed resistance. Additionally, effective infection control measures can help limit the spread of antibiotic-resistant bacteria. Measures such as hand hygiene, proper disposal of biological waste, and proper cleaning and disinfection of healthcare facilities can help prevent the spread of resistant infections.

Conclusion


Conclusion

Bacterial mutations play a significant role in the development of antibiotic resistance, which can have serious consequences for human health. When bacteria mutate in a way that makes them resistant to antibiotics, it can lead to persistent and even fatal infections. For this reason, it is important that we take measures to prevent the development and spread of antibiotic-resistant bacteria. By limiting the use of antibiotics, developing new antibiotics, and implementing effective infection control measures, we can reduce the impact of antibiotic resistance and ensure that antibiotics remain an effective tool in the treatment of bacterial infections.

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