A vicious organism so “armed to the teeth” it can dodge most drugs thrown at it and a fungus with a kill rate of up to 60 percent lead a new list of pathogens federal health officials say pose the greatest threats to Canadians.
The updated list of “high impact” superbugs making people sick, sometimes fatally sick, includes a family of bacteria that cause E. Coli and Salmonella, as well as extremely drug-resistant gonorrhea.
All in, 29 pathogens made the watchlist, whittled down from 68 initially flagged by Public Health Agency of Canada expert working and advisory groups.
Those selected were scored and ranked based on their treatability (or lack thereof), transmission, case fatality ratio — the proportion of confirmed cases that are fatal — and the impact on marginalized groups like Indigenous communities, people who inject drugs, gay, bisexual and other men who have sex with men, the homeless and new immigrants and refugees from conflict or disaster-affected regions.
It’s the first update since an initial list was published a decade ago, in 2015. Since then, new threats have emerged, including Candida auris, a drug-resistant fungus spreading in hospitals that can cause infections of the blood, heart, nervous system and organs, and Mycoplasma genitalium, a sexually transmitted infection.
Resistance is also rising in already known bugs, including Streptococcus pneumoniae, a serious infection that can lead to life-threatening meningitis, pneumonia or sepsis, with kids and the elderly at greatest risk.
The pathogen watchlist “reflects the current reality in Canada,” said Dr. Gerry Wright, a professor of biochemistry and biomedical sciences at McMaster University in Hamilton.
With no new drugs coming on the market, “things are going to get to the point that we’re going to be seeing a lot more people staying in hospital or even dying, because the antibiotics are not working.”
Antimicrobial resistance, a top global health threat, happens when infections caused by bacteria, viruses, fungi and parasites can’t be stopped by the antibiotics, antivirals and other drugs designed to kill them.
Infections get harder to treat, increasing the risk of the disease spreading, serious illness and death — an estimated 14,000 deaths in 2018 alone.
Canada’s “pathogen prioritization list” ranks organisms across four tiers, from high priority to low.
The high priority group includes carbapenem-resistant Enterobacterales, a family of bacteria that normally reside in the human gut but that can cause infections.
Enterobacterales, which include E. Coli and Salmonella, can cause urinary tract, abdominal and bloodstream infections. They’re spread via person-to-person contact (dirty hands, wounds, stool) or contaminated medical equipment and devices.
Carbapenems are powerful antibiotics — “the last station on the penicillin highway,” Wright said.
“If you look at your IV bag and you see the word carbapenem, you know you’re in trouble. It’s not something that’s given all the time, and resistance to that class of drugs has spread like wildfire over the last 20 years or so around the world.”
Second on the utmost priority list is highly drug-resistant gonorrhea, a sexually-transmitted infection that has become immune to nearly every antibiotic used against it.
In 2022, Canada’s national gonorrhae rate was three times what it was three decades ago, the highest recorded in 30 years. The rates are highest in males 20 to 39, and females 15 to 30. It spreads easily, is associated with travel-related sexual contact and increases the risk of HIV.
“If you can’t treat gonorrhea, it can lead to pelvic inflammatory disease or infertility in the future,” said Dr. Kanchana Amaratunga, medical advisor to Canada’s antimicrobial resistance task force.
Carbapenem-resistant Pseudomonas — another “super bad bug,” Wright said — was also ranked high priority.
“It’s a vicious organism, really intrinsically drug-resistant. It doesn’t seem to care too much about any antibiotics. It’s very well armed to the teeth and causes all sorts of things like pneumonia,” Wright said.
It’s also seriously problematic for people with cystic fibrosis who have a lot of mucus in their lungs. “It loves to hang out in those types of (moist) environments.”
Wright’s lab at McMaster is working hard at trying to kill Pseudomonas. “Because if you’ve got something that will kill Pseudomonas, it will probably kill everything else.”
Rounding out the high priority group are drug-resistant Acinetobacter — a bug that clings to materials like IV bags, IV poles and dialysis lines that causes blood, wound and other infections — and Candida auris, a deadly fungus that can colonize or get into the skin via needles or catheters and can linger on hospital sinks, bed rails and curtains. It severe cases, C. auris can cause organ failure. It’s particularly lethal for people with weak immune systems and has a death rate ranging from 30 to 60 percent.
It wasn’t included in the old list and has “now emerged as a critical public health threat” owing to its resistance to multiple anti-fungals, high morbidity and how easily it can spread in healthcare settings, according to the task force.
The new list relied on data from 2017 to 2022, which means a natural time lag, the team said. It’s urging updates every three to five years, not once a decade.
Microbes can evolve rapidly, within hours. However, unlike the heydays of the 80s, “It’s now a completely different kettle of fish,” Wright said. “There are very few drug companies working in the field.”
“They can’t make money on it,” he said. “Antibiotics cure disease. If you’re a large pharma company, you like to be controlling chronic diseases, because then people take your drugs for a very long time,” meaning a guaranteed revenue stream, he said.
In work published recently in the journal Nature, Wright’s lab isolated a protein from a bacterium taken from a soil sample collected from his technician’s backyard in Hamilton. In lab mice, “It has activity against almost all of the pathogens that we care about on that list.” He’s now trying to develop it into a drug candidate.
That’s going to take time, and a lot of money. “And no matter what drug you bring into the country, resistance is inevitable,” Amaratunga said.
Both she and Wright emphasized the need for prevention, including judicious and appropriate use of antibiotics, beefed up surveillance, early detection and vaccines.
Nearly all (68 percent) of cases of invasive pneumococcal disease in Canada, which soared by 82 per cent between 2021 and 2022, are caused by vaccine-preventable strains.
National Post
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