Tag Archives: Drug resistance

Global antibiotic resistance in food animals has become a major issue

A new report concludes that growing antibiotic resistance in animals threatens not only animal and human health — but even food security.

A simple explanation of how antibiotic resistance works. Image credits: NIAID.

In recent years, antibiotic resistance has emerged as one of the biggest threats to human health, with the World Health Organization (WHO) and the Center for Disease Control (CDC) both considering it tremendously dangerous. The world is not ready to deal with antibiotic resistance, and the prospect of having newly-untreatable pathogens running around is horrifying. Thankfully, many parts of the world are starting to take action, acknowledging the urgency and the scale of the problem.

But it’s not just humans that take antibiotics. Antibiotic-resistant bacteria are on the rise globally, and much of that comes from farm animals. Animals consume three times as many antibiotics as humans and meat consumption is growing globally (particularly in low-income or developing countries).

To be able to meet the growing demand for animal protein, most meat production systems routinely use antibiotics, not just for disease prevention, but also for growth promotion. In most parts of the world, veterinary antibiotic sales are unregulated, and people stock their animals up with antibiotics because, frankly, it’s simpler and more financially lucrative.

However, although this can be beneficial in the short-term, overconsumption of antibiotics can produce untreatable infections not only for animals, but also for the humans that consume the meat. This is understudied as most research is focused on antibiotic resistance in humans, and there are very few monitoring mechanisms for this issue in developing countries.

The proportion of microbial compounds with resistance higher than 50%, confidence interval 95%. Credits: Van Boeckel et al, Science.

To address this issue, researchers mapped developed a geospatial model starting from the reported rates of antibiotic resistance in animals and animal-based food products. They used 901 surveys carried out between 2000 and 2018, focusing on foodborne pathogens such as Escherichia coli, Campylobacter spp., non-typhoidal Salmonella, and Staphylococcus aureus. The results are concerning.

Antibiotic resistance has increased by more than 50% overall in the time interval. The highest rates of resistance were identified in antibiotics commonly used in food production, including tetracyclines, sulfonamides, and penicillins.

When looking at a map of the antibiotic resistance, researchers also found a few hotspots of multidrug-resistance: north-eastern India, north-eastern China, northern Pakistan, Iran, eastern Turkey, the south coast of Brazil, the Nile River delta, the Red River delta in Vietnam and the areas surrounding Mexico City and Johannesburg in South Africa seem to be the worst affected. While there is some uncertainty due to lack of data in some areas (particularly in rural areas), the data paints a compelling picture: antibiotic resistance in animals is on the rise, and it’s rising particularly fast in areas which are starting to eat more meat.

“Animal production is increasing worldwide and the consequences of intensive use of antibiotics on resistance in animals is amply clear from our analysis. We have a small window of opportunity to help low- and middle-income countries transition to more sustainable farming practices. High-income countries -where antimicrobials have been used since the 1950s- should support that transition,” said study author Ramanan Laxminarayan, director of CDDEP and senior research scholar at Princeton University.

This means that if current trends continue, antibiotic usage will become less and less effective, which is especially dangerous for the people and animals who are actually sick and need the antibiotics — but at a larger scale, it’s dangerous for all society.

Researchers also point out that although the hotspots are in developing parts of the world, developed countries have their fair share of the blame, and should contribute to solving this issue. This is a global issue that requires global action and if we don’t act, we will all suffer in the end.

“It is of particular concern that antibiotic resistance is rising in low- and middle-income countries because this is where meat consumption is growing the fastest while access to veterinary antimicrobials remains largely unregulated. Antibiotic resistance is a global problem, and there is little point of making considerable efforts to reduce resistance on one side of the world if it is increasing dramatically on the other side,” concludes study author Thomas Van Boeckel at ETH Zurich.

The study titled, “Global Trends in Antimicrobial Resistance in Animals in Low- and Middle-Income Countries,” has been published in Science.

New bacteria strain.

Irish dirt might cure the world of (most) multi-drug-resistant bacteria

Irish soil might win us the fight against drug-resistant superbugs. Literally!

New bacteria strain.

Growth of the newly discovered Streptomyces sp. myrophorea. Although superficially resembling fungi, Streptomyces are true bacteria and are the source of two-thirds of the various frontline antibiotics used in medicine.
Image credits G Quinn / Swansea University

An international team of researchers based at the Swansea University Medical School, UK, reports finding a new strain of bacteria that can murder pathogens that our antibiotics increasingly cannot. The bacteria has been found in soil samples recovered from an area of Fermanagh, Northern Ireland.

Bad bugs get grounded

“This new strain of bacteria is effective against 4 of the top 6 pathogens that are resistant to antibiotics, including MRSA. Our discovery is an important step forward in the fight against antibiotic resistance,” says Professor Paul Dyson of Swansea University Medical School, paper co-author.

The finding is far from inconsequential. The World Health Organisation (WHO) describes rising antibiotic resistance as “one of the biggest threats to global health, food security, and development today”. Further research also estimated that antibiotic-resistant ‘superbugs’ could lead up to 1.3 million deaths in Europe alone by 2050.

The team named their discovery Streptomyces sp. myrophorea. It was discovered in the Boho Highlands, County Fermanagh, Northern Ireland, hiding in the soil. The researchers investigated the soils there as Dr. Gerry Quinn, a previous resident of the area, became curious to investigate local healing traditions.

Those traditions called for a small amount of soil to be wrapped up in cotton cloth and applied to cure ailments varying from toothaches to throat or neck infections. The team notes that the area has been inhabited for at least 4,000 years — first by Neolithic tribes and later druidic tribes — who may have started this tradition.

Lab tests later revealed the presence of the strain in local soils, and clued the team in on their impressive antibacterial properties. This bacteria inhibited the growth of four of the top six multi-resistant pathogens (those listed by the WHO as being responsible for healthcare-associated infections): Vancomycin-resistant Enterococcus faecium (VRE), methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumonia, and Carbenepenem-resistant Acinetobacter baumanii. It was also successful in inhibiting both gram positive and gram negative bacteria, which differ in the structure of their cell wall. Gram-negative bacteria are, generally speaking, more resistant to antibiotics.

It is not yet clear exactly how the bacteria do this, but the team is hard at work finding out.

New bacteria strain.

Zone of inhibition (light brown) produced by Streptomyces sp myrophorea (brown spot) on a lawn of MRSA.
Image credits G Quinn / Swansea University.

The active compounds secreted by Streptomyces sp.myrophorea could help create a new class of treatment against multi-drug resistant bacteria, the study reports. These pathogens are one of the most pressing threats to public health currently, as doctors are often left powerless to treat them. They’re especially dangerous in hospitals, where the large density of patients (often with weakened or compromised immune systems) means easy pickings for such pathogens.

“Our results show that folklore and traditional medicines are worth investigating in the search for new antibiotics,” Professor Dyson says. “Scientists, historians, and archaeologists can all have something to contribute to this task. It seems that part of the answer to this very modern problem might lie in the wisdom of the past.”

“We will now concentrate on the purification and identification of these antibiotics. We have also discovered additional antibacterial organisms from the same soil cure which may cover a broader spectrum of multi-resistant pathogens.”

The paper “A Novel Alkaliphilic Streptomyces Inhibits ESKAPE Pathogens” has been published in the journal Frontiers in Microbiology.

Livestock-MRSA found in British-sourced pork at Asda and Sainsbury’s

British-grown pork livestock has been tested positive for livestock associated MRSA, the Guardian reports. The tests were carried out by Dr Mark Holmes, director of studies in clinical veterinary medicine at Churchill College, Cambridge University, and commissioned by the Alliance to Save Our Antibiotics, founded by the Soil Association, Compassion in World Farming and Sustain.

Image credits Tanakawho / Flickr.

Out of a sample of 97 UK-grown-pork products purchased from British supermarkets, three items — sourced from Asda and Sainsbury’s — were contaminated with MRSA CC398, a livestock strain of the superbug, the publication reports. Working with the Bureau of Investigative Journalism (BIJ), the Guardian has identified the most likely source of the infection in import-legislature loopholes. Through these, pigs from countries where the bacteria is rampant, such as Denmark, have been imported to the UK without proper precautions.

And that’s really bad news.

While MRSA CC398 isn’t as harmful to us as the human-specific strains, it’s still a potentially deadly bacteria that can resist almost everything we can throw at it. Research has found that combining three previously-efficient drugs together can serve as a sort of stop-gap measure against the bacteria; there’s also a thousand year-old salve that’s shown some potential agains MRSA, and Canadian clay. And that’s it.

About 300 people die each year as result of MRSA infection in England and Wales alone, and the bug seriously threatens patients with weakened immune systems.

“MRSA infections kill 11,000 people each year in the United States, and the pathogen is considered one of the world’s worst drug-resistant microbes,” said Gautam Dantas, PhD, an associate professor of pathology and immunology at the Washington University School of Medicine, unaffiliated with the publication.

Still, six cases of MRSA CC398 death have been confirmed in Denmark so far, but there are probably a lot more, the Guardian reports. Animals can catch the bacteria from infected pigs, and people can contract it from eating infected meat or from working with infected animals. Thoroughly cooking it should destroy the germs, but a small risk remains.

The publication warns that UK pigs might be in for the same fate as Denmark’s, where MRSA CC389 spread over a decade ago and now afflicts two-thirds of farms. It’s a major health issue for the country, with some 12,000 people believed to have contracted it — and there are no screening programs set in place for danish pigs.

“If we don’t have tight infection control and we don’t try to control the movement of live animals, infection can spread. The British are up in arms about the movement of people, but the EU also has a large movement of animals,” said Prof Tim Lang from the Food Policy at City University, London.

“We need biosecurity, we need to tighten up this livestock movement. You may get cheap meat, but in the long term it’s going to add to your public health problems.”

The real issue here, just like with human-specific MRSA, is the drug resistance part. What most people don’t understand is that it’s not limited to humans — it’s happening in agriculture, too. The rise of the CC398 strain can in part be attributed to an overuse of antibiotics in factory farming, where cramped and dirty conditions allows disease to flourish. Farmers are left with little choice but feed their livestock huge amounts of antibiotics, promoting the rise of drug resistance at a much higher rate than those seen in humans. And if the bacteria gains a foothold in the UK (and there’s not much we can do to spot it apart from screenings) our drugs won’t be able to destroy it. So even such a low number of cases is worrying.

Where’s it coming from?

The Guardian reports that last year, out of 100 samples of pork from UK supermarkets, nine were found to contain MRSA. One of these was sourced from an Irish farm, and the others from pigs in Denmark. The findings marked the first confirmed occurrence of the superbug in the UK.

Image credits Tim Geers / Flickr.

While it’s impossible to determine if the meat tested now comes from UK or imported pigs, it does show that the bacteria is present in UK farms. Imports are likely the original source of the infection, The Guardian adds. At least one Danish farm has been found to be a regular supplier of importer pigs to the UK even if their pigs were contaminated with MRSA in 2014, the BIJ reported. The company, Breeding Centre Rønshauge A/S, refused to say how many pigs it had exported to the UK and whether they could have been contaminated. But official export figures show that the company supplied 41 pigs to the UK in July this year, 65 in 2013 and 16 in 2012. The UK government does not screen for the infection in imported animals, citing a low risk of serious illness.

“It is extremely worrying to find LA [livestock-associated]-MRSA in British-produced pork,” said Emma Rose, from the Alliance to Save Our Antibiotics.

“Scientists are now warning that the extensive MRSA reservoir in animals could ultimately lead to a pandemic spread in the human population. LA-MRSA is able to cause serious and potentially fatal infections in humans, and as the bacteria is resistant to antibiotics, it is extremely difficult to treat. What’s more, even more dangerous variations are emerging as the superbug evolves.”

The Department for Environment, Food and Rural Affairs (Defra) said that LA-MRSA “is not the same as MRSA strains that can cause healthcare-associated infections” if the meat isn’t properly cooked, and the risk to people is “low”. Defra and the National Pig Association recommend that all pigs imported to Britain be screened for the bacteria.

“The government is reviewing options for surveillance, which will be proportionate to the very low health risk posed by livestock-associated MRSA.”

When animals are imported, they’re screened for multiple diseases, but the one for CC398 is voluntary. So there’s no way to know how many infected pigs there are in UK right now. There have been two confirmed cases, one in Northern Ireland and one in eastern England, but without any systematic tests carried out in farms, all we’re left with are extremely rough estimations. The publication says that this and other health concerns related to UK meat come down to pressure towards factory farms producing the cheapest possible meat.

New star-shaped polymer can shred bacteria membranes to bits, offering alternative to antibiotics

A new class of star-shaped polymers has proven effective at killing drug-resistant bacteria, opening new potential treatment options in the future.

Neutrophil and Methicillin-resistant Staphylococccus aureus (MRSA) Bacteria.
Image credits NIAID / Flickr.

Bacteria are an adaptable lot. We’ve learned before just how incredibly fast these bugs can learn to thrive in antibiotics which took us decades to develop. A new approach in medicine is to use physical rather than chemical means of killing these single-cell organisms. And now we have another such weapon: a team from the Melbourne School of Engineering has developed a new class of star-like protein chains or “peptide polymers,” that can effectively kill bacteria which are impervious to current antibiotics.

Professor Greg Qiao from the school’s Department of Chemical and Biomolecular Engineering and his team said that the only real avenue of treatment currently available for infections caused by bacteria is antibiotics. But he’s worried that if we continue the arms race with bacteria in this way, we will be left defenseless in a few decades.

“It is estimated that the rise of superbugs will cause up to ten million deaths a year by 2050. In addition, there have only been one or two new antibiotics developed in the last 30 years,” he said.

The team has been working with peptide polymers for the past few years, looking for a way to weaponize them in our favor. Recently, they developed a star-shaped polymer that might become one of the best foot-soldier in this fight. And the upshot is that the substance is harmless to the patient.

Tests undertaken on mice have shown that the polymer is extremely effective at killing Gram-negative bacteria — a class known for its propensity to develop antibiotic resistance. The bacteria showed no signs of resistance against the peptide polymers, and the little ninja stars have shown they can destroy bacteria through multiple pathways, unlike most antibiotics which kill with a single pathway — meaning they can be used to cure several types of bacteria.

“Comprehensive analyses using a range of microscopy and (bio)assay techniques revealed that the antimicrobial activity of SNAPPs [the polymers] proceeds via a multimodal mechanism of bacterial cell death by outer membrane destabilization, unregulated ion movement across the cytoplasmic membrane and induction of the apoptotic-like death pathway,” the paper reads.

One of these pathways includes ‘ripping apart’ the bacteria cell wall.
Image credits University of Melbourne.

They’ve also determined experimentally, by testing with red blood cells, that you’d have to pump 100 times the effective dosage into a patient for it to become toxic to the body. While more research is needed to bring the ninja stars of bactericide to market, Professor Qiao and his team believe that their discovery is the beginning of unlocking a new treatment for antibiotic-resistant pathogens.

The full paper, titled “Combating multidrug-resistant Gram-negative bacteria with structurally nanoengineered antimicrobial peptide polymers,” has been published in the journal Nature Microbiology.

Drug resistant Strep and the return of the scarlet fever

In a study published Monday in the journal Scientific Reports, researchers from the University of Queensland caution that the surge in scarlet fever cases may pose an unexpected threat.

Evolution is a wonderful thing — it brought us out of the primordial puddle and took us to the Moon, and will hopefully power us to even greater heights. It’s an awesome thing, and I’m a big fan of it. But evolution does tend to have one nasty habit — it never stops, not even for the bugs that are trying to kill us dead.

One of those bugs is group A Streptococcus; it’s the biological vector of scarlet fever, a condition that commonly affects children from 5 to 12. Most of those infected with this bacteria only develop strep throat, but in some cases it can escalate into a full-blown case of scarlet fever, thus named for the red, sandpaper-like rash it causes on the skin.

A scarlet fever rash.
Image via newsshopper

It used to be a deadly disease, but with the advent of modern antibiotics it’s just unpleasant — while there is no vaccine for it, medication can easily treat the condition.

But if the Streptococcus is easily kept in check with antibiotics, why the sudden increase in number of scarlet fever cases in the recent years? The answer is evolution — more to the point, evolution of drug-resisting bacteria.

“We now have a situation which may change the nature of the disease and make it resistant to broad-spectrum treatments normally prescribed for respiratory tract infections, such as in scarlet fever,” lead study author Nouri Ben Zakour said in a statement.

Ben Zakour’s team analyzed samples from 25 confirmed scarlet fever patients and 9 patients suffering from a number of group A strep infections from China and Hong Kong. They were able to confirm that a strain of group A strep that emerged in the 1980s was the common cause for all of the infections.

The usual treatment, penicillin, still works on this strain — other common antibiotics do not. The team found evidence of tetracycline, erythromycin and clindamycin resistance, raising immediate concerns for the patients who are allergic to penicillin. However, we’re all at risk here. Should a strain develop that also has resistance to penicillin, there will be few treatment options left for doctors.

The increase of antibiotic resistant bacteria should come as no surprise. As such substances become more and more common in the environment as consequence of human and agricultural use, more and more bacteria are exposed to them. Any that survive will multiply, and when they infect a human host they’ll be immune to one or more antibiotic substances. Antibiotic resistance causes an estimated 2 million illnesses and 23,000 deaths every year in the United States.

The findings, Ben Zakour said, suggest that monitoring the spread and evolution of this bacteria is of the utmost importance. The fact that penicillin still seems to work in most cases of scarlet fever means that it isn’t time to panic. But this is just the latest example of the ticking time bomb that is antibiotic resistance.