How Do Bacteria Become Resistant To Antibiotics

Mechanisms Of Antibiotic Resistance

There are a number of mechanisms that bacterial cells use to thwart the efforts of antibiotics. Some bacteria are naturally resistant due to an unusually impermeable cell membrane or a lack of the target that the antibiotic attacks. Other bacteria are capable of producing enzymes that can inactivate antibiotics upon contact. In some cases, bacteria can modify the antibiotics target, rendering the antibiotic ineffective. Bacteria can also produce efflux pumps, which can transport antibiotics out of the bacterial cell before they can take effect.

Can Antimicrobial Resistance Move From Animals To Humans

There is a substantial body of evidence to support the view that theemergence of antimicrobialresistance in bacteria in livestockpopulations is connected tothe emergence of resistance in bacterial populations that colonize andinfect humans.

However, it seems that the majority of the emergence of resistance inbacteria in humansoriginate from other bacteria in humans while the resistance in animalsoriginate from bacteria in livestock. In most cases, in both animals andhumans, a positive association was found between the volume ofantimicrobial consumptionand the prevalence of resistance in the exposed bacterialpopulations.

Nevertheless, there is consensus within the scientific literature thatthere are routes for spillover of resistance between the bacterialpopulations of humans andfood-producing animals in both directions.

How Worried Should We Be

Pretty worried! Many strains of bacteria have acquired resistance to more than one type of antibiotic.

These strains of bacteria, known as multidrug resistant organisms or superbugs, are already putting a strain on the worlds healthcare systems. Prof Dame Sally Davies, former chief medical officer for the UK, said that the golden era of ever-increasing life expectancy may soon give way to an era where mortality rates start to increase.

She told a government inquiry on antibiotic resistance that she was far more worried about dying in an operating theatre during a routine operation than climate change.

Hospitals are struggling to rid wards of multi-drug resistant bacteria such as MRSA , while extensively drug-resistant tuberculosis has now been identified in 100 countries, causing over 200,000 deaths each year.

In E. coli bacteria, a common cause of food poisoning, resistance to antibiotics is now so widespread that conventional treatment is ineffective in more than half of patients.

And strains of bacteria have been found that are resistant to our last resort antibiotics.

Treating patients who have these dangerous bacteria is difficult, hazardous and expensive. Experts have predicted that if trends continue, existing antibiotics could be almost useless in as little as 20 years.

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What Is An Antibiotic

Antibiotics, also known as antimicrobial drugs, are drugs that fight infections caused by bacteria. Alexander Fleming discovered the first antibiotic, penicillin, in 1927. After the first use of antibiotics in the 1940s, they transformed medical care and dramatically reduced illness and death from infectious diseases.

The term “antibiotic” originally referred to a natural compound produced by a fungus or another microorganism that kills bacteria which cause disease in humans or animals. Some antibiotics may be synthetic compounds that can also kill or inhibit the growth of microbes. Technically, the term “antimicrobial agent” refers to both natural and synthetic compounds however, many people use the word “antibiotic” to refer to both. Although antibiotics have many beneficial effects, their use has contributed to the problem of antibiotic resistance.

Poor Hygiene And Infection Prevention And Control

Poor hygiene and poor infection prevention and control can:

• provide more opportunity for resistant bacteria and other germs to spread
• make more people sick and increase the need for antibiotics.

Hand hygiene is the most important way of preventing the spread of infections including antibiotic resistant infections.

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Antibiotic Resistance: Everything You Need To Know

If youre a fan of apocalyptic disaster movies, youll be familiar with all manner of things that might bring about the fall of civilisation: asteroid strikes, deadly viruses, alien invasions, nuclear armageddon. Perhaps even an outbreak of zombies.

Experts now believe that the spread of drug-resistant bacteria is probably the single greatest threat to society greater even than the dangers posed by global terrorism, climate change and anything youll see at the cinema.

There are signs that this antibiotic apocalypse is already upon us: in Europe and the US alone, at least 50,000 people die each year from infections that dont respond to conventional treatment.

Ways That Bacteria Acquire Resistance

There are two main ways that bacterial cells can acquire antibiotic resistance. One is through mutations that occur in the DNA of the cell during replication. The other way that bacteria acquire resistance is through horizontal gene transfer. There are three different ways in which this can occur, but in each case genetic material is transferred from antibiotic-resistant bacteria to other bacterial cells, making them resistant to antibiotics as well. Once bacterial cells acquire resistance, exposure to antibiotics kills off non-resistance bacteria, while the antibiotic-resistant bacteria proliferate.

To learn more about antibiotic resistance, check out The Antibiotic Resistance Action Center.

ARAC was created to preserve the effectiveness of antibiotics by engaging in research, advocacy and science-based policy. Follow ARAC on, and

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How Antibiotic Use Affects Resistance

Antibiotics save lives but their use can contribute to the development of resistant germs. Antibiotic resistance is accelerated when the presence of antibiotics pressure bacteria and fungi to adapt.

Antibiotics and antifungals kill some germs that cause infections, but they also kill helpful germs that protect our body from infection. The antibiotic-resistant germs survive and multiply. These surviving germs have resistance traits in their DNA that can spread to other germs.

Why Should I Be Concerned About Antibiotic Resistance

Antibiotic resistance has been called one of the world’s most pressing public health problems. Almost every type of bacteria has become stronger and less responsive to antibiotic treatment when it is really needed. These antibiotic-resistant bacteria can quickly spread to family members, schoolmates, and co-workers – threatening the community with a new strain of infectious disease that is more difficult to cure and more expensive to treat. For this reason, antibiotic resistance is among CDC‘s top concerns.

Antibiotic resistance can cause significant danger and suffering for children and adults who have common infections, once easily treatable with antibiotics. Microbes can develop resistance to specific medicines. A common misconception is that a person’s body becomes resistant to specific drugs. However, it is microbes, not people, that become resistant to the drugs.

If a microbe is resistant to many drugs, treating the infections it causes can become difficult or even impossible. Someone with an infection that is resistant to a certain medicine can pass that resistant infection to another person. In this way, a hard-to-treat illness can be spread from person to person. In some cases, the illness can lead to serious disability or even death.

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How Do Bacteria Become Resistant

Although it seems like bacteria are in some way learning how to fight back against us, the development of antibiotic resistance is an inevitable and natural part of bacterial evolution. Each time a bacterium multiplies, it divides into two and copies its DNA.

Imperfections in this process mean that in a population of millions, billions or even trillions of multiplying bacterial cells, there are lots of mistakes, know as mutations, in the DNA of each successive generation.

Owing to the sheer number of variants, over time a tiny proportion of individuals will, by chance, develop a quirk that means they are immune to certain antibiotics. A mutation may, for example, subtly change the structure of a key molecule that the antibiotic targets, rendering it ineffective. Or, it may mean the bacteria start producing a chemical that destroys the antibacterial properties of the drug.

In the case of penicillin, many bacteria have evolved to produce chemicals known as beta-lactamase enzymes, which neutralise the drugs effect.

Once it emerges, antibiotic resistance can jump from one species of bacteria to another. Microorganisms naturally exchange genetic material in a process called horizontal gene transfer either by close contact or by forming a sort of bridge between each other.

This helps bacteria shuffle their DNA and share useful genes, but often causes the genes responsible for antibacterial resistance to jump from harmless bacteria into more deadly types.

What Else Can We Do To Stop Antibiotic Resistance

Due to the ease with which people can travel around the world, containing the spread of antibiotic resistance requires coordinated global action. To preserve the potency of existing antibiotics, their use must be curbed: they must be prescribed only for bacterial infections, and in the proper dose, for the correct amount of time.

Read more about hygiene:

• Why does salt have antibacterial properties?

Lots of research is being directed at tests which will allow GPs to quickly diagnose whether an illness requires antibiotics or not, and this should help encourage more targeted use. Other research is looking at ways to interfere with how bacteria swap DNA, to try and eliminate the spread of resistance genes between bacteria.

On an individual level, regular hand-washing and general good hygiene helps reduce the spread of bacteria and therefore the need for antibiotics. People are encouraged not to pressure doctors or pharmacists into giving them antibiotics without knowing for sure what is causing their illness.

In short, the whole of society must start to appreciate these valuable drugs more. The more we use them, the less effective they are.

What we still dont know

How long do we have? As the development of antibiotic resistance is based on chance mutations and random transfer of genetic material, its hard to predict when and where resistance will emerge, and how much time we have left to find solutions.

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How Do Antibiotics Work

Antibiotics are chemicals that disrupt key processes in bacterial cells. To be safely used as a drug, they must specifically affect bacterial cells without damaging human tissue.

The first modern antibacterial, penicillin, was discovered in 1928 by Alexander Fleming. Produced by a fungus found in mould, penicillin causes the walls of bacterial cells to fail.

Human cells do not have these rigid cell walls, so are unaffected by penicillin, and many similar drugs have been developed over the decades.

Other antibiotics interfere with processes that are essential for bacteria to grow, such as the production of proteins, DNA, or energy.

Scientific terms explained

AMR AMR, or antimicrobial resistance, is a broad term that includes the emergence of resistance in bacteria, as well as in other microorganisms such as viruses and fungi.

Beta-lactamase Bacteria that can produce beta-lactamase are a major threat to healthcare systems worldwide. This chemical blocks the action of a key family of antibiotics that act on the bacterial cell wall.

Horizontal Gene Transfer As well as passing on DNA to successive generations, bacteria can also exchange DNA with unrelated microorganisms nearby. This allows them to share useful genes, helping resistance spread from one species to another.

MDROs Multi-drug resistant organisms are strains of bacteria that are resistant to lots of antibiotics. Some are resistant to last resort drugs.

When Are Antibiotics Needed

This complicated question, which should be answered by your healthcare provider, depends on the specific diagnosis. For example, there are several types of ear infectionsmost need antibiotics, but some do not. Most cases of sore throat are caused by viruses. One kind, strep throat, diagnosed by a lab test, needs antibiotics.

Common viral infections, like coughs or a cold, can sometimes become complicated and a bacterial infection can develop. However, treating viral infections with antibiotics in order to prevent bacterial infections is not recommended because of the risk of causing bacterial resistance:

• Remember that antibiotics do not work against viral colds and the flu, and that unnecessary antibiotics can be harmful.

• Talk with your healthcare provider about antibiotics and find out about the differences between viruses and bacteria, and when antibiotics should and should not be used.

• If your child receives an antibiotic, be sure to give it exactly as prescribed to decrease the development of resistant bacteria. Have your child finish the entire prescription. Don’t stop when the symptoms of infection go away.

• Never save the left over antibiotics to use “just in case.” This practice can also lead to bacterial resistance.

• Do not share your antibiotics with someone else or take an antibiotic that was prescribed for someone else.

• Antibiotic resistance is a problem in both children and adults.

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Mutation Rates And Bacterial Growth

Even if only a single S. aureuscell were to make its way into your wound, it would take only 10 generations for that single cell to grow into a colony of more than 1,000 , and just 10 more generations for it to erupt into a colony of more than 1 million . For a bacterium that divides about every half hour , that is a lot of bacteria in less than 12 hours. S. aureus has about 2.8 million nucleotide base pairs in its genome. At a rate of, say, 10-10 mutations per nucleotide base, that amounts to nearly 300 mutations in that population of bacteria within 10 hours!

To better understand the impact of this situation, think of it this way: With a genome size of 2.8 × 106 and a mutation rate of 1 mutation per 1010 base pairs, it would take a single bacterium 30 hours to grow into a population in which every single base pair in the genome will have mutated not once, but 30 times! Thus, any individual mutation that could theoretically occur in the bacteria will have occurred somewhere in that populationin just over a day.

How Does Resistance Spread

Antibiotic resistance becomes a big problem when antibiotics are overused. Using an antibiotic destroys a lot of bacteria in a persons body both good and bad strains.

This means bacteria that are resistant to the antibiotic are free to colonise that space and multiply without competition.

This can cause illnesses in the person affected, but also means they will be carrying huge numbers of antibiotic-resistant germs, which are then passed on to other people.

Hospitals act like a sort of transport hub for antibiotic-resistant genes: antibiotics are used heavily, concentrating resistance genes in the ward. These are then passed on to staff, other bacteria and patients.

In a nutshell

Life savers Antibiotics kill the bacteria that cause infections and diseases. Theyre used in billions of operations, and without them, an infection caused by something like a paper cut could prove fatal.

The drugs dont work As bacteria are constantly multiplying, a small number of cells will emerge now and again with a DNA mutation immunity to an antibiotic. The more drug-resistant bacteria there are, the more dangerous infections become.

The more often antibiotics are used, the more likely it is that drug-resistant bacteria will come to dominate in any given location. And its not just human medicine that helps spread antibiotic resistance.

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There are hundreds of different types of antibiotic, from creams to pills to injections, each developed to target different infections caused by different types of bacteria. Since their introduction around 75 years ago, antibiotics have added approximately 20 years to the average life expectancy across the globe.

Life before these wonder drugs was scary anything that caused an infection could kill you, even a paper cut. In the centuries before modern antibiotics, its believed that around 40 per cent of all deaths were caused by untreated infections. And if an infection didnt kill you, it could leave you scarred or disfigured.

Read more about bacteria:

• Am I more bacteria than human?

World Antimicrobial Awareness Week

Held annually since 2015, WAAW is a global campaign that aims to increase awareness of antimicrobial resistance worldwide and to encourage best practices among the general public, health workers and policy makers to avoid the further emergence and spread of drug-resistant infections. Antimicrobials are critical tools in helping to fight diseases in humans, animals and plants. They include antibiotics, antivirals, antifungals and antiprotozoa. WAAW takes place every year from 18 to 24 November. The slogan has previously been, Antibiotics: Handle with Care but changed to Antimicrobials: Handle with Care in 2020 to reflect the broadening scope of drug resistant infections.

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How Bacteria Resist Antibiotics

What methods do Bacteria use to resist antibiotics?

There are a few different methods that bacteria use to actively resist antibiotics. These natural defences are what cause the problem when treating patients for infections. If a patient is infected with bacteria that have these defences, then antibiotics are likely to be less effective because the bacteria have now become resistant to antibiotics. Here are three of the most common ways bacteria counter their antibiotic attackers:

Efflux Pump

This is a pump in the wall of the bacteria cell that simply ejects the antibiotics out of the cell, meaning that the antibiotics cant kill the bacteria.

Neutralisation

Enzymes in the bacteria breakdown the antibiotic compounds so they dont work properly to kill the bacteria.

Modification

Rather than destroy or breakdown the antibiotics, this method sees enzymes in the bacteria cell attach to the antibiotics to change their structure and make them ineffective against the bacteria.

What can we do?

Bacteria are constantly evolving and we can never stop bacteria from resisting antibiotics. The aim for the Longitude Prize is to produce a diagnostic to help us all use fewer antibiotics and slow down the rate at which bacteria evolve.

Were calling on people from all areas of innovation and from across the world to take part in the Longitude Prize and to come up with a solution to this problem. If resistance is slowed, antibiotics will have a fighting chance.