When penicillin was discovered in 1928 it brought about a revolution in the treatment of bacterial infection. Wounds and illnesses that before would likely have resulted in death or serious disability could now be treated with this new wonder-drug. However, bacteria developed their own defenses in the war with antibiotics, giving rise to pathogens that were not as easily defeated by these drugs. Today, scientists are in a race against bacterial evolution to contain these lethal super bugs and find new methods of curing the diseases they cause. We list ten of the deadliest such super bugs.
Multi-drug resistant Staphylococcus aureus is perhaps the most famous of the super bugs. First discovered in 1961, it is not always a particularly virulent bacterium, but in those who are already unwell or with open wounds it can easily take hold. This makes it both prevalent and dangerous in hospitals and nursing homes, where it can have devastating consequences. Most commonly, MRSA causes skin infections such as abscesses and necrotizing fasciitis, a flesh-eating disease where the bacteria penetrates under the skin and within hours can cause death of tissues. Up to 73 percent of patients may die from NF if it is left untreated. Particularly in those with weakened immune systems, MRSA can also cause infections throughout the body such as respiratory and urinary tract infections. In 2005 alone, the CDC estimates that 18,650 deaths in US hospitals were due to infection by MRSA.
9. Streptococcus pneumoniae
Not only does Streptococcus pneumoniae cause the condition for which it is named, pneumonia, it is also one of the leading causes of bacterial meningitis in young people and adults and can also be responsible for such dangerous conditions as pericarditis, brain abscesses and osteomyelitis. It is a bacteria which is normally found in the upper respiratory tract of healthy people, but when the immune system becomes compromised it can quickly turn pathogenic, and if it is resistant to antibiotics, treatment can be difficult. Historically, it was treated with beta-lactam antibiotics such as penicillin, but resistance to this and other antibiotics is becoming more and more common.
8. Pseudomonas aeruginosa
Pseudomonas aeruginosa uses multiple methods to resist the effect of antibiotics, including pumping the drugs out of its cell matrix, and it is constantly evolving new methods of resistance. The bacteria are highly common, living in water, the earth, man-made surfaces and even in our skin! When tissue is damaged or the immune system is not working well, the bacteria strikes, infecting the body and causing sepsis and inflammation. It can survive on medical equipment such as catheters, and the bacteria are often found on to have aggressively remained on other hospital supplies – even after cleaning – leading to its transmission from patient to patient. If the bacteria colonize vital body organs such as the lungs, death can occur. All in all, one in every ten infections acquired in hospitals are due to P. aeruginosa.
7. Clostridium difficile
Antibiotic use is particularly tricky with Clostridium difficile. The normal human body has many different species of bacteria happily living in the gut. When antibiotic use has destroyed these normal bacteria, C. difficile moves in, overrunning the gut and causing bloating, diarrhea and pain. In severe cases it can result in life-threatening toxic megacolon. Recent years have seen reports of resistant strains, and various serious outbreaks were reported throughout the 2000s. C. difficile infection can be treated with three antibiotics, but there are worries that the use of one of these drugs, vancomycin, could lead to the creation of even more antibiotic-resistant organisms. Even worse, C. difficile infection commonly recurs after treatment: about 20 percent of patients will have to suffer through the disease again.
6. Neisseria gonorrhoeae
Gonorrhea is one of the horror stories of sexually transmitted infections, causing a discharge of pus from the delicate areas of our bodies as well as inflammation and swelling. It can also cause conjunctivitis and inflammation of the urethra, prostate and testicles. Tragically, when newborn babies are exposed to gonorrhea while being born, they can contract conjunctivitis, which can lead to blindness. In severe cases it can spread throughout the body, causing arthritis, endocarditis and meningitis. Up to 80% of women who are infected with gonorrhea show no symptoms, leaving the bacteria to be passed on to others. Up to 20% of women with this infection can be rendered infertile. This disease was commonly treated with penicillin, but resistance to these antibiotics means that cephalosporins (another form of antibiotic) must often be used. Scarily, in 2011 scientists found a strain of the bacteria in Japan that has developed a resistance to these cephalosporins, too.
5. Acinetobacter baumannii
According to some scientists, Acinetobacter baumannii kills tens of thousands of hospital patients in the US every year. Unlike other bacteria that have evolved resistance in response to our use of antibiotics, this bacterium possesses an inherent level of resistance. While healthy individuals will not notice its presence, if they become ill or it passes to those who are already sick or with weakened immune systems, it can cause serious, life-threatening infections. Able to live for five months in the environment, it is a serious and growing cause of hospital-acquired infections and pneumonia. Such was its prevalence among wounded American soldiers in field hospitals in Iraq that the disease became known as “Iraqibacter.” Some strains are resistant to practically all antibiotics, and treatment can cost almost $100,000 more per patient compared to those who have identical wounds without this bacteria present.
4. Mycobacterium tuberculosis
In the Western world, tuberculosis is a disease most commonly associated with the past, but Mycobacterium tuberculosis has not gone away. It can survive in the environment for weeks before infecting the respiratory system and causing lethal infection. While there is a vaccine, it is not completely effective and is not commonly used in the US as it can interfere with screening tests. The bacterium’s resistance to antibiotics is growing, with some strains resistant to the two most effective first-line treatments, isoniazid and rifampicin. Four percent of those who develop tuberculosis will die from the disease, and every second someone across the world develops an infection – even though not all will develop a symptomatic disease.
3. Vancomycin-resistant Enterococcus (VRE)
Enterococcus can cause a variety of illnesses, including meningitis, endocarditis and urinary tract infections. It is naturally highly resistant to antibiotics, with vancomycin and ampicillin the most effective treatments. However, strains of the bacteria that are resistant to vancomycin are becoming increasingly common, especially in hospital environments, where sick patients are most at risk. Between January of 2006 and October of 2007, a vancomycin-resistant strain of Enterococcus faecalis was found in 4 percent of US patients who acquired an infection in hospital.
Every year thousands of people die from infections caused by ingesting pathogenic strains of Salmonella. With over 2,500 different types of Salmonella, it causes a serious medical challenge to doctors, veterinarians and public health officials across the globe. Salmonella is easily transmitted from animals to humans through the ingestion of foods contaminated with feces. Infection can cause severe diarrhea leading to dehydration and toxicosis. It can also cause meningitis. In the very young, very old, or those with suppressed immune systems it can even be fatal. With over 40,000 cases of Salmonella reported in the USA every year, the development of resistance is a concern. From 1990 to 2006, over 1,300 US citizens died from Salmonella infections.
1. E. coli
Pathogenic variants of E. coli are commonly acquired by the contamination of food with feces. These pathogenic strains can cause serious urinary tract infections, gastroenteritis and meningitis in newborn babies. With many different types of E. coli, there is a wide variation in their sensitivity to antibiotics. The resistance of E. coli to sophisticated antibiotics such as fluoroquinolones is rising, and worryingly, antibiotic-resistant E. coli is often responsible for passing on genes that help other species of bacteria resist antibiotics!