7 of the deadliest superbugs

Approximately 3-5% of the population carry Klebsiella pneumoniae. But most people can carry it without becoming sick. It's different for those with a weakened immune system or acute infections. They could suffer severe gastrointestinal infections, pneumonia, blood poisoning — it depends on where the bacteria settles. Klebsiella pneumoniae is a critical-priority drug-resistant bug, says the WHO.

Making headlines in the US at the moment, Candida auris is an emerging fungus that's proving multidrug-resistant to antifungal medication commonly used to treat Candida infections. It's appeared on five continents so far and been so hard to get rid of some hospitals have had to close down to eliminate it. Healthy people aren't usually infected, but those who are unwell or need surgery are at risk.

This highly resistant, "nightmare bug" has been classified by the WHO as one of the biggest threats to human health. Thriving in wet or moist places, it's one of the hardest bacteria to eradicate. It's usually only seen in people with weakened immune systems, but healthy people can also get ear and skin infections if they come into contact with it, especially after being around contaminated water.

There's no vaccine for gonorrhea, so antibiotics are the only option for treating infections. But this sexually-transmitted disease is increasingly resistant to the drugs — azithromycin, cefixime and ceftriaxone — normally used to treat it. Two cases of so-called super gonorrhea were reported in Australia in 2018 and another two in the UK in early 2019. Another good reason to always wear a condom!

This bug is best known for causing non-typhoidal foodborne infections, but it can also cause typhoid fever in humans. In the last few decades, a highly virulant, antibiotic-resistant strain has emerged. Spread through contaminated food and water, regions including Asia and Africa are experiencing epidemics of the drug-resistant bacteria.

Ranked in the highest-risk category of pathogens by the WHO, this bug is commonly found in soil and water and can take on genes from other resistant bacteria. It's able to survive in healthy patients without causing symptoms, but can cause deadly lung, blood and wound infections in unwell patients. This is why outbreaks of Acinetobacter infections are usually seen in intensive care units.

Myobacterium tuberculosis is one of the world's leading infectious diseases, causing more than 1.7 million deaths each year. It's estimated that up to 13 percent of all new tuberculosis cases are multidrug-resistant — unresponsive to two of the most potent treatments — and six percent are extensively drug-resistant, unresponsive to even more. These sufferers are more likely to get diseases or die.