Six Common Bad Bacteria that Cause Human Illness

Six Common Bad Bacteria that Cause Human Illness
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Although some forms of bacteria are good for you, other kinds of bacteria can cause serious illness. It’s not all black and white, though, when it comes to bacteria. Most bacteria known for wreaking havoc on human health has an essential purpose and function, such as E. coli, according to biology expert Doc Miller on Vimeo1. As long as E. coli stays in the intestines of animals and humans, where it belongs, the bacteria are useful and help with the function of the digestive system. Once E. coli is misplaced and gets into blood, however, it can lead to illness and even fatality, in some cases. With proper food handling and preparation, E. coli contamination and poisoning are often thwarted2. Learn the names of six bad bacteria and avoid coming into contact with infectious germs.


Anthrax falls into the proteobacteria category and causes the infection that leads to the disease anthrax1. The function of many types of Proteobacteria enables the process of nitrogen being converted to ammonia (essential for all forms of life). However, protobacteria also has a negative side. Anthrax bacteria are also bacilli and rod-shaped and can be transmitted to humans through wild animals and livestock.

Anthrax bacteria first lie dormant as spores, and when the right conditions occur, the spores comes to life3. The spores can lie dormant in soil for many years and still infect you. Initial symptoms of this disease include fever, sore throat and muscle ache, but as the disease progresses, breathing becomes difficult, and eventually death occurs.


Botulinum is also in the proteobacteria category and is rod-shaped. It causes botulism, a rare but deadly disease. The bacteria grows on food and creates toxins that cause paralysis, if ingested4. Some preliminary symptoms are nausea, vomiting, dizziness, fatigue and dry mouth. Eventually, swallowing becomes difficult, speech is slurred and breathing becomes impossible. Your chance of survival from a botulinum infection is likely, with proper treatment, usually an antitoxin. If left untreated however, those with botulism have a 35 to 64 percent chance of death4.

Avoid eating food that smells bad or is from damaged or bulging containers. Also, avoid storing garlic or oils with herbs at room temperature, as well as baked potatoes. Never give babies honey.

E. Coli

Characteristics of E. coli include proteobacteria categorization and rod shape, as bacilli bacteria. As of the beginning of the 21st century, E. coli infection is on the rise. Instead of relying on the government to keep you safe from infection, do what you can, by cooking meat well and thoroughly cleaning vegetables. Keep your hands and food preparation areas clean and disinfected. Don’t eat foods in damaged containers, never eat raw shellfish and only eat and drink pasteurized dairy products and juices3. Once you’re infected with E. coli bacteria, you can develop symptoms of vomiting, abdominal cramping and diarrhea5. Certain strains of E. coli can cause severe symptoms, such as intense abdominal cramps, bloody diarrhea and organ damage, including kidney failure.

Listeria Monocytogenes

Listeria monocytogenes are rod-shaped proteobacteria that cause the food borne illness listeriosis. Although listeriosis is rare, it is a potentially deadly disease. The bacteria are found in water, soil and in animals, and they can grow even in cold temperature environments, including your refrigerator3. You can get infected by eating contaminated foods, such as raw vegetables, meat and unpasteurized milk. Listeria can be serious, especially for those with a weakened immune system or women who are pregnant6.


Streptococci are sphere-shaped bacteria that are chains of cocci1. Group A streptococci bacteria cause cellulitis, impetigo, strep throat and scarlet fever and can lead to serious infection, such as blood infection, flesh eating disease and multiple organ infection3. Severe strep throat can turn into rheumatic fever. Symptoms include fever, dizziness, confusion and pain. Pregnant mothers infected with group B streptococci can transmit the infection to their babies. A newborn is then at risk for meningitis, pneumonia and blood infections3.


Staphylococci are clusters of cocci bacteria1 that are also sphere-shaped. Staphylococci are often found on skin or in the nose and usually don’t cause problems7. The bacteria may lead to minor skin infections, such as boils and impetigo. If staph bacteria are ingested, they can cause food poisoning. If, however, the bacteria get into the bloodstream, urinary tract, lung or heart, they can lead to serious health problems, such as blood poisoning and toxic shock syndrome.

One of the biggest concerns when it comes to staphylococci is when people are infected with methicillin-resistant staphylococcus aureus (MRSA), because it is antibiotic-resistant. People in hospitals and other health care facilities are more susceptible to MRSA. This is known as health care-associated MRSA, or HA-MRSA8.

Healthy people can also contract MRSA. This form of the disease is called community-associated MRSA, CA-MRSA, and it frequently starts with a painful boil on the skin and is spread by skin-to-skin contact8. Certain groups, such as kids on high school wrestling teams, daycare workers and those who live in populated conditions, are more at risk for contracting CA-MRSA.