10 most dangerous antibiotic-resistant bacteria

26 Aug 2014
Written by
Longitude team

The Longitude Prize aims to tackle growing levels of antimicrobial resistance, but what exactly are we up against?

The global problem of antibiotic resistance is fast becoming one of the major scientific issues of modern times. The development of new antibiotics is slow and difficult work but bacterial resistance is decreasing our arsenal of existing drugs posing a catastrophic threat as ordinary infections become untreatable.

Preventative action is needed to help reduce resistance. The Longitude Prize aims to improve our ability to target infections more precisely by encouraging the development of new tools.

The bacteria listed below cover a range of diseases and levels of resistance. All of them present a threat to humans in some way or another. Some, like tuberculosis for example, are already a huge challenge to overcome in their own right and will only become harder to control as their resistance to antibiotics grows.

Discover more about the challenge of tackling resistance

10. Streptococcus pyogenes

First Documented: 1884

Illness Caused: Sore throat, skin disorders

Antibiotic Resistance: Low

Virulence: Deadly

Like other potentially dangerous bacteria such as E.coli, Streptococcus pyogenes can be found in 5 per cent - 15 per cent of all humans, residing in the lungs or throat without causing any harm. Streptococcus pyogenes causes over 700 million infections globally every year and has a high mortality rate of 25 per cent in serious cases - once you have an infection the bacteria can cause a range of diseases ranging from sore throat and impetigo up to scarlet fever. Luckily, the bacteria is affected by penicillin so is treated easily in most cases - however several strains are building resistance to various other antibiotics.

9. Neisseria gonorrhoeae

First Documented: 1885

Illness Caused: Gonorrhoea

Antibiotic Resistance: Medium

Virulence: Worrying

Gonorrhoea is spread through sexual contact and causes various infections in both men and women. Certain strains of the bacteria have shown resistance to antibiotics and have mutated over the course of 50 years or so, slowly adapting different resistances as doctors change their approach by using different antibiotics to counter the disease. The small hairs or ‘pili’ on the bacteria act like hooks that are used to move the cell and attach it to other healthy cells. Using the pili the cell can exert a force 100,000 times its weight!

8. Mycobacterium tuberculosis

First Documented: 1882

Illness Caused: Tuberculosis

Antibiotic Resistance: Medium

Virulence: Deadly

Tuberculosis has been know by many names including scrofula and the White Plague and has been a huge cause of death and distraction throughout history, with evidence found in bodies estimated to be around 9,000 years old. It is believed that Nefertiti and her Pharaoh husband Akhenaten both died from tuberculosis in around 1330 BC, and documents remain from ancient Egypt that talk of the dangers of the disease. While instances of the disease reduced to only 5,000 a year in the UK in 1987, the increase in antibiotic resistance has seen a rise in cases in the early 90s.

7. Acinetobacter baumannii

First Documented: 1911

Illness Caused: Pneumonia, Meningitis, Urinary Tract Infection

Antibiotic Resistance: High

Virulence: Worrying

Acinetobacter baumannii have become resistant to many antibiotics and like other bacteria are currently being countered most effectively through thorough hygiene in healthcare situations. The bacteria can survive in harsh conditions for long periods of time so are often difficult to deal with in weaker patients, and coupled with increasing resistance presents a tough challenge when encountered by doctors. Sometimes called Iraqibacter, Acinetobacter baumannii became very prevalent during the Iraq war amongst injured soldiers who passed through several different medical facilities.

6. Escherichia coli (E.coli)

First Documented: 1895

Illness Caused: Diarrhoea, Urinary Tract Infection, Meningitis

Antibiotic Resistance: High

Virulence: Worrying

Most E.coli is completely harmless and survives happily in the human digestive system. However, some strains of E.coli can cause serious illness and most commonly lead to severe food poisoning as well as meningitis and infections. A high level of resistance to antibiotics has been found across several strains of E.coli and while it is rare to find these strains causing illness, it is another concerning example of a bacteria that has the potential to cause problems if our use of antibiotics goes unchecked.

5. Klebsiella pneumoniae

First Documented: 1886

Illness Caused: Lung infections, Pneumonia

Antibiotic Resistance: Medium

Virulence: Worrying

Klebsiella pneumoniae can cause a range of infections and has proven to be very resistance to a range of antibiotics. Primarily affecting middle-aged and older men with weakened immune systems, this bacteria can be dangerous but is mostly ‘opportunistic’ and is far less likely to affect healthy adults. Due to its high levels of resistance, it is common in the US to perform tests to identify which strain is present in a patient to better inform doctors of how to treat them. This is slowing the rate at which resistance is built up but this bacteria is still of concern across the globe.

4. Clostridium difficile

First Documented: 1935

Illness Caused: Diarrhoea

Antibiotic Resistance: Low

Virulence: Dangerous

One of the better known ‘superbugs’ because of a consistent presence in hospitals around the world, C.difficile is, primarily, an easily spread type of diarrhoea that can lead to complications in the colon. Several significant outbreaks of C.difficile have made the news in the UK and despite a major effort in improving hygiene in hospitals, the bacteria is responsible for a significant number of deaths globally. The chance of catching C. Difficile is actually increased by exposure to antibiotics - you are more likely to get ill from C.difficile if your internal balance has been upset and the bacteria can exploit this.

3. Pseudomonas aeruginosa

First Documented: 1872

Illness Caused: Pneumonia, Various Infections

Antibiotic Resistance: Medium

Virulence: Worrying

Quick to mutate and adapt to counter different antibiotic treatments, Pseudomonas aeruginosa shows an innate ability to develop resistance to antibiotics. Described as ‘opportunistic’ because it primarily affects humans that are already critically ill, this bacteria can cause serious complications in the treatment of AIDS, cancer or cystic fibrosis patients. While it isn’t a massive threat to humanity currently, this bacteria will become an increasing threat over the next few years.

2. Burkholderia cepacia

First Documented: 1949

Illness Caused: Pneumonia

Antibiotic Resistance: Low

Virulence: Worrying

Discovered in 1949 as the bacterium that causes onions to rot, Burkholderia cepacia can be very dangerous to humans in the worst cases. While it mostly responds well to treatment with a combination of antibiotics, it has been shown to have high levels of resistance to several types of antibiotics and is able to survive in extreme conditions. Particularly dangerous to humans with preexisting lung conditions such as Cystic Fibrosis, scientists have been developing new ways to fight the bacteria as it evolves an increasing resistance to antibiotics.

1. Staphylococcus aureus (MRSA)

First Documented: 1884

Illness Caused: Pneumonia, Flesh Eating Disease

Antibiotic Resistance: Medium

Virulence: Dangerous

More commonly known as MRSA (which stands for Methicillin-resistant Staphylococcus aureus), this ‘superbug’ is very easily spread through human contact and can cause a range of illnesses from skin disorders to deadly diseases like meningitis and pneumonia. Most often treated with Penicillin type antibiotics, by 1960, 80 per cent of hospital samples were antibiotic resistant. A concerted effort in tracking the disease and improving hygiene measures in hospitals has seen cases of MRSA fall by 84.7 per cent in the UK between 2003 and 2011, proving that prevention is often the best form of defence against bacteria.

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