In January, a coalition of 85 biotechnology, pharmaceutical and diagnostics companies, including Johnson & Johnson and Pfizer, came together at the World Economic Forum in Davos to form a landmark agreement to help combat antibiotic resistance. The companies have called on governments to help fund research and aid in developing a “sustainable and predictable” market for new drugs.

It’s a promising step, but there’s still a long way to go. Even when new antibiotics are discovered, developing them for use in the marketplace remains a big challenge. According to a May 2015 review on antimicrobial resistance, it’s often more profitable for pharmaceutical companies to pay to develop drugs intended for long term use, like medication to treat diabetes or heart disease, rather than antibiotics, typically used for a few days.

Drug-resistant infections currently kill an estimated 700,000 people worldwide each year. If efforts to curb antibiotic resistance fail, this number could increase to 10 million by 2050, surpassing the 8.2 million deaths a year caused by cancer,according to a global report commissioned by the UK government. The economic impact would also be devastating: the report estimates a cost of $100tn of global GDP over the next 35 years.

“It’s no wonder resistance continues with the sheer mass of antibiotics that we dump into the environment each year,” said Dr Brad Spellberg, an infectious disease specialist and author of Rising Plague, which outlines the problem of antibiotic resistance. “The low-hanging fruit has been plucked, and the stuff that’s easy to be discovered has been.”

As the pharmaceutical sector plays catch up, we take a look at how three industries – health, agriculture and tourism – are affected by antibiotic resistance.

Healthcare

For physicians, a reality in which antibiotics no longer work has already begun.

“We’re already in a post-antibiotic world,” said Spellberg. “We already have patients who are untreatable.”

Without effective antibiotics, many aspects of modern medical care would not be possible, said Spellberg, particularly treatments that put the patient at risk for serious infection, such as complicated surgeries, chemotherapy, organ transplants, and care for premature babies.

Even some commonplace illnesses are starting to show resistance to previously simple antibiotic treatments. Increasingly, patients with staph infections of the skin can no longer be treated with conventional oral antibiotics such as penicillin because of a resistant bacteria, or “superbug”, called MRSA. Another superbug, costridium difficile (C diff) colitis, is a normal bacteria in the gut that is kept in check by other bacteria. Antibiotic use wipes out those other bacteria, which sometimes allows the C diff bacteria to proliferate. The condition used to be treated with more antibiotics, but resistance has resulted in more people having their colon removed to treat the illness, according to Sarath Malepati, a Los Angeles surgeon.

“I remember a professor in medical school explaining that I may see a handful of cases of [toxic megacolon, or the end stage of C diff], which can be a lethal condition, over the course of my entire career,” he said. “I probably see one to three cases of it a year.”

Urinary tract infections are also an area of particular concern, said Dr Barbara Murray, chief of infectious diseases at University of Texas Health Sciences Center and former president of the Infectious Diseases Society of America. Infections like cystitis, which some women experience multiple times a year, are usually treated with an oral antibiotic, but resistance is increasing to even the fallback drugs, said Murray. Now, treatment often involves a shot daily over the course of three days, or a patient may even have to go to hospital and be hooked up to an IV, she said.

“It’s more inconvenient and uncomfortable,” said Murray. “And the cost of it compared to giving a pill is huge.”

Murray said she recently treated a woman in her thirties with gallbladder infection, but it showed resistance to all antibiotic treatment, and surgery wasn’t an option. There was nothing left to do. The infection spread to her bloodstream, and she passed away.

Another scenario that will become increasingly common is the nursing home patient with a now drug-resistant bronchial infection or pneumonia, said Malepati. The patient will be put on multiple rounds of antibiotics, both in the senior facility and then again in the emergency room and ward, only to end up requiring even stronger antibiotics or getting a more serious infection in the process.

“Many of these patients do not have the health reserve to withstand multiple disease ‘hits’ and sadly end up dying for what was once a routine treatable upper respiratory infection,” said Malepati.

Food production

The food sector, primarily livestock production, is already grappling with a post-antibiotic reality. The meat industry is facing increased pressure, from both the public and the private sector, to phase out the routine use of these drugs.

Subway announced last month that it was on track to start offering chicken raised without antibiotics at stores across the country starting in March, the latest sign that companies are recognizing the threat that overusing antibiotics poses to human health.

Subway’s announcement is just the start: the company has committed to eliminating antibiotics from all its chicken, turkey, pork and beef products by 2025. Other fast food chains are enacting similar policies. McDonald’s recently announced it would begin sourcing chicken without antibiotics that are important to human medicine, while Chick-fil-A took it a step further, committing to cutting out all antibiotics from its chicken supply by 2019.

Government is also taking steps to address the problem. By January 2017, it will be illegal in the US to use medically important antibiotics in livestock feed and water to treat and prevent disease, or to promote growth. If these drugs are used for this purpose, they will need to be administered under the supervision of a licensed veterinarian.

This could have a negative impact in situations where using an antibiotic to prevent illness may be the only effective way to treat the disease, said Dr Terry Lehenbauer, director of the Veterinary Medicine Teaching and Research Center at University of California, Davis. Since drug-resistant bacteria can spread, this could have a negative impact on food production.

For instance, anaplasmosis is an infectious blood disease in cattle that is commonly transmitted by insects. Currently, there isn’t a safe vaccine, and treatment of the disease is challenging, as mortality rates are high after signs of the disease start to appear, said Lehenbauer.

“Low-level feeding of a highly medically important antibiotic called chlortetracycline is an effective method of preventing anaplasmosis in cattle that may become exposed to that disease during the insect season,” said Lehenbauer. “If this preventive use were eliminated, many cattle would suffer and die.”

Antibiotics are most commonly given to cattle suffering from pneumonia, bovine respiratory disease, or mastitis – inflammation of the mammary gland – in lactating dairy cows. Resistance to antibiotics that treat these diseases does occur. In those cases, farmers switch to a different drug, but the success rate is usually lower, said Lehenbauer.

Farmers are exploring ways to keep their animals healthy so they have less need for medications, by working with veterinarians to improve sanitation and the nutritional health of their animals, and to develop new vaccines, he said.

Antibiotic resistance won’t have a big impact on crop production: just over one-tenth of 1% of all agricultural use in the US relies on antibiotics today. Pear and apple growers will likely suffer the most. Antibiotics are sprayed on pear and apple trees to prevent the spread of a bacterial infection called fire blight, which can destroy entire orchards. But resistance to the primary antibiotic used, called streptomycin, is growing, particularly in the Pacific Northwest.

Tourism

People who travel to other countries to receive medical care are especially at risk, said Michael Millar, a doctor at the Department of Infection, Barts Health NHS Trust in the UK.

In India, which is seeing a burgeoning health tourist market, limited regulation of antibiotics, the ready availability of antibiotics over the counter, overcrowding, poor sanitation around major cities, and poverty together contribute to antibiotic resistance.

If a healthy tourist acquires resistance while overseas, the effects could be insidious and only be felt years later. For example, a person might travel to another country to have cosmetic surgery, which typically has a low risk of infection, said Millar. However, while abroad, the patient’s gut is colonized with an organism such as Klebsiella pneumoniae, which is extremely resistant to antibiotics. The person returns home to the US or Europe, and months, or even years later, has to be hospitalized following a car accident, or needs to undergo major surgery or chemotherapy for cancer.

It’s at this point that the Klebsiella pneumoniae causes infection, said Millar, because the antibiotics used to treat the patient don’t work as they should. The patient ends up in intensive care and may die as a result.

No matter the industry, and no matter the disease, it’s going to take a concerted effort from both the public and private sector to ensure the future generation remains safe, and that the medicines we rely on for our first and last lines of defense remain strong, said Spellberg.

“Unless we do a much better job of protecting the antibiotics we already have, both in humans and livestock, and find alternative ways to treat infections, people are going to keep dying,” he said.

• This article was amended on 17 March 2016. An earlier version said that Dr Malepati only sees “a handful of cases of C diff”. He has contacted us subsequently to say that he meant he sees toxic megacolon, or end-stage cases of C diff, a few times a year.