Antimicrobial resistance a global issue

Antibiotic use in agriculture is increasing, but research into alternative medicines is costly.
|  File photo

QUEBEC CITY, Que. — Resistance to antimicrobials has turned into a major health crisis, says the head of the centre for disease dynamics, economics and policy.

“We have not seen a problem of this magnitude that encompasses the world since HIV,” said Ramana Laxminarayan, who is also affiliated with Princeton University.

Bacterial resistance to antimicrobials became a significant problem at about 2000. Today, serious medical problems have developed over the issue, such as when hospitalized patients develop infections and no antibiotic can cure them.

Various types of bacteria are showing high levels of antimicrobial resistance in many parts of the world.

African studies have shown newborns with resistant infections are far more likely to die.

“A 50 percent chance of a newborn dying of infection seems unacceptable to me,” he said.

Countries in the Far East report the highest number of resistant bacteria. About 58,000 deaths in India have been attributed to resistant bacteria.

However, probably more people will die because they did not have access to antibiotics versus those who faced drug resistance, said Laxminarayan.

Infectious diseases are declining but not fast enough. Most of the improvement is attributed to better hygiene, sanitation and water treatment, as well as active public health departments.

Antibiotic use in the agriculture sector is increasing globally, particularly in places like India and China.

Antibiotic use for livestock is increasing around the world with the top 10 consumers being China, United States, Brazil, Germany, India, Spain, Russia, Mexico, France and Canada.

Too often these drugs are used as a substitute for sanitation and hygiene rather than as a complementary product, said Laxminarayan. Consequently, there are diverse and abundant antibiotic resistant genes in Chinese swine farms, he said.

“There are alternatives for antibiotics but we haven’t really got very far.”

Tim McAllister of Agriculture Canada at Lethbridge said people must accept that microbes are part of the natural world and will never be eliminated.

Antimicrobial products are used for production of animals, aquaculture, seed crops, fruit, companion animals, industrial and household chemicals, as well as to treat humans.

Most of the push to get rid of antibiotics comes from consumers who fear residues and resistance.

“Removing antimicrobials in terms of their use is not a guarantee you will eliminate antimicrobial resistance,” McAllister said.

“Antimicrobial resistance may go down but it is unlikely it will ever go to zero,” he said.

The problem comes down to the bacteria themselves.

They are masters of adaptation and can take in new information into their chromosomes to protect themselves against a host of threats. Finding new products to stay ahead of resistance is time consuming and expensive.

There are 37 new antibiotics in development among 34 companies. Only five of those developers are from the top pharmaceutical companies.

Probably 80 percent of products in development are pursued by small companies, many of which are venture capitalists hoping to be taken over by a larger corporation.

New products focus on the basic premise of figuring out how to kill the bacteria.

Some work by destroying the bacterial cell wall or impairing its ability to synthesize protein.

However, the target bacteria may have already integrated several different ways to resist an antibiotic.

Further, most bacteria grow in biofilms that offers a protective layer to prevent outside attacks.

Vaccines present a promising alternative, but most operate in traditional ways. Currently, the best vaccines are only about 70 percent effective.

Plant extracts like tannins and essential oils, as well as organic acids, probiotics, prebiotics, bacteriocins and bacteriophages have all been considered.

Probiotics may occupy the binding sites on the epithelium and prevent pathogens from attaching in the guts. They may also reduce inflammation. However, probiotics have to be administered every day.

Bacteriocins are toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strains.

Bacteriophages overtake bacterial cells as a form of biocontrol but they kill only a precise bacterial strain and do not have a broad spectrum application.

McAllister said research into antimicrobial resistance and alternatives to antibiotics needs to grow into a major science if it is to deliver innovative therapies. However, it is very costly, he said.

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