Bacterial Infection

Bacterial infections are illnesses caused by tiny single-celled organisms that enter and multiply in your body. While most bacteria around us are harmless or even helpful, some can cause diseases ranging from minor skin problems to life-threatening conditions affecting the blood, lungs, or brain.

Table of contents

• What Are Bacterial Infections
• Understanding Bacteria
• Difference Between Bacterial and Viral Infections
• Types and Examples of Bacterial Infections
• How Bacterial Infections Spread
• Symptoms of Bacterial Infections
• Diagnosis
• Treatment
• Prevention

What Are Bacterial Infections

Bacterial infections are any illness or condition caused by bacterial growth or toxins (poisons that bacteria produce). You can get sick from harmful bacteria entering your skin, gut (the digestive system or GI tract), lungs, heart, brain, blood, or anywhere else in your body.^[1]

Disease can occur when bacteria multiply in your body or release toxins that damage your cells and tissues. Harmful bacteria from the environment, an infected person or animal, a bug bite, or something contaminated like food, water, or surfaces can cause infections. Even bacteria that normally live harmlessly on your body can cause infections if they get into places where they shouldn’t be.^[1]

Understanding Bacteria

Bacteria are living things with only a single cell that can reproduce quickly. There are millions of bacteria that live all around us—in soil or water and on surfaces in our homes and workplaces. There are even millions of bacteria that live on your skin and inside your body.^[1]

Under a microscope, bacteria look like balls, rods, or spirals. They can be found almost everywhere on Earth. In fact, your body has about 10 times more bacteria cells than human cells.^[3]

Most bacteria aren’t harmful, and many are even helpful. They can help you digest food, produce vitamins and minerals that your body needs, and kill off other harmful forms of bacteria that try to invade your body. For example, “good” bacteria in your digestive system can help your body digest food and absorb vitamins and minerals. They can help protect you from getting sick. Bacteria are also used in making foods like yogurt and cheese.^[1][3]

Only a small percentage of bacteria cause infections and disease. These are called infectious bacteria. These bacteria can reproduce quickly in your body, and many of them give off toxins that can damage your cells and make you sick. Other types can move into and damage your tissues.^[3]

Difference Between Bacterial and Viral Infections

Living, single-celled organisms that can reproduce on their own cause bacterial infections. Only a few types of bacteria cause illness in people.^[1]

An organism that’s not made up of cells causes viral infections. Viruses always need to infect humans or other living things to create more copies of themselves.^[1]

The most important difference for treatment is that antibiotics can treat most bacterial infections, but only a few viral infections have medications that treat them. Antibiotics do not work on viruses.^[1][14]

Types and Examples of Bacterial Infections

Bacteria can cause many types of infections, depending on how you’re exposed and what part of your body becomes infected.^[1]

Some common types of bacterial infections include:^[1]

• Food poisoning (gastroenteritis)
• Some skin, ear, or sinus infections
• Some sexually transmitted infections (STIs)
• Bacterial pneumonia
• Most urinary tract infections (UTIs)

Common bacterial infections include:^[1]

• Campylobacter and Salmonella infections, common types of food poisoning
• Cellulitis, boils, and impetigo, which are skin infections
• Pneumococcal disease, including ear and sinus infections and some types of pneumonia
• Lyme disease, a disease spread by ticks
• Bacterial vaginosis, an overgrowth of bacteria in the vagina
• Chlamydia and gonorrhea, sexually transmitted infections
• Strep throat, a bacterial infection common in children that causes a sore throat
• C. diff, an infection in the intestines
• E. coli, a common cause of urinary tract infection (UTI)

Other bacterial infections that can occur include Legionnaires’ disease, meningococcal disease, Q fever, tuberculosis (TB), and whooping cough (pertussis).^[2]

There are many bacterial infections that aren’t usually serious or can be treated easily with antibiotics. Impetigo and boils are examples. However, any bacterial infection that gets deep into your body, like in your blood, heart, lungs, or brain, can be life-threatening.^[1]

How Bacterial Infections Spread

Bacterial infections can spread through droplets or dust in the air, direct or indirect contact, a vector (like a tick or mosquito), or contaminated food or water.^[1]

There are different ways that bacterial infections may spread:^[3]

• Through droplets and particles that are breathed out by someone who has the infection. You might breathe in the droplets or particles, or they could land on your mouth, nose, or eyes
• By touching surfaces or objects that have the bacteria on them and then touching your mouth, nose, or eyes
• Through cuts, scrapes, and skin-to-skin contact with someone who has the infection
• From the pregnant parent to the baby during pregnancy
• Through contaminated food or water
• By being bitten by an infected insect or animal
• Through sexual contact with someone who has the infection

Bacteria can enter your body through a wound, cut, or bite that breaks the skin, or when bacteria that usually live on your skin or inside your body start to multiply uncontrollably, causing an infection.^[2]

You can get bacterial infections through the air from contaminated dust or droplets of water or mucus. These droplets can be released when an infected person coughs or sneezes.^[1]

Symptoms of Bacterial Infections

The symptoms of a bacterial infection depend on where the infection is in your body and the type of bacteria. Common symptoms of bacterial infection include:^[2]

• Fever
• Feeling tired or unwell
• Headache or muscle aches
• Skin changes or rashes
• Diarrhea or vomiting
• Wet cough or sore throat

The common element with most bacterial infections includes fever, chills, and pain or discomfort in the affected area. But if the infection is in a joint, that joint and the surrounding area will likely hurt. If you have a sinus infection, you will probably have a headache and foul nasal discharge.^[13]

If you have bacterial pneumonia, you may experience fever, cough with phlegm, shortness of breath, sweating, shaking chills, headache, muscle pain, fatigue, and chest pain with breathing.^[13]

If you have a urinary tract infection, you may experience sudden and extreme urges to pass urine, frequent urges to pass urine, burning or pain when passing urine, a feeling of not emptying your bladder completely, a feeling of pressure in your abdomen or lower back, thick or cloudy urine that may contain blood, and fever.^[13]

Diagnosis

A health care provider can diagnose bacterial infections based on symptoms and medical history. In some cases, lab tests such as blood tests, urine tests, or cultures may be needed to identify the specific bacteria causing the infection.^[6]

Doctors may use several tests to diagnose bacterial infections. These can include:^[3]

• Bacteria culture test
• Gram stain
• Blood tests
• Urine tests

Specialized tests can determine differences in the genetic makeup of bacteria, which helps doctors identify the specific type causing the infection.^[5]

Treatment

The most common and proven drugs for treating bacterial infections are antibiotics, sometimes called antibacterials. Antibiotics are chemical substances derived from bacteria, molds, and other microorganisms. Each antibiotic works against a specific bacteria species.^[11]

Antibiotics either kill the targeted bacteria or prevent them from reproducing, allowing the body’s immune system to destroy the pathogens. Antibiotic medicines take the form of pills that are swallowed or liquids that are swallowed or injected into the muscles or veins.^[11]

Sometimes your immune system may be able to fight off a bacterial infection on its own. For mild infections, home care such as increased fluid intake, proper nutrition, and rest can often suffice and allow the body’s natural defenses to fight the infection.^[11]

How a bacterial infection is treated varies based on its kind and how serious it is. Mild infections may improve with rest, fluids, and over-the-counter pain relievers. For more serious infections, doctors may prescribe antibiotics. Some infections, such as bacterial pneumonia or sepsis, may require hospitalization and IV antibiotics.^[6]

When you take antibiotics, follow the directions carefully. Take them exactly as prescribed. Do not share your antibiotics with others. Do not save them for later. Each time you take antibiotics, there is a risk that the bacteria will become resistant to the effects of the antibiotics. This is called antibiotic resistance. When this happens, the bacteria are not killed, and they continue to grow. They can cause resistant infections, which can be difficult, and sometimes impossible, to treat.^[3][14]

It’s important to take the full course of antibiotics as prescribed. You may start to feel better soon after the first few doses, but be sure to finish the full course. If you don’t, the bacteria might not be fully eliminated from your system.^[18]

Common side effects of antibiotics range from minor to very severe health problems and can include rash, dizziness, nausea, diarrhea, and yeast infections. More serious side effects can include C. diff infection, which causes diarrhea that can lead to severe colon damage.^[14]

Prevention

You can help prevent some bacterial infections by taking several important steps.^[3]

The first line of defense is to keep germs at bay by following good personal hygiene habits:^[19]

• Wash your hands well, especially after using the bathroom, before preparing or eating food, after blowing your nose, coughing, or sneezing, and after caring for a sick person. Wet your hands thoroughly, lather up with soap, and rub it into the palms and backs of your hands and your wrists. Be sure to clean your fingertips, under your nails, and between your fingers. Rinse under running water and dry thoroughly
• Cover your mouth and nose with a tissue when you sneeze or cough, then dispose of it. If no tissue is handy, cough or sneeze into your elbow rather than into your hands
• Wash and bandage all cuts. Any serious cut or animal or human bite should be examined by a doctor
• Do not pick at healing wounds or blemishes, or squeeze pimples
• Don’t share dishes, glasses, or eating utensils

Additional prevention measures include:^[2][3]

• Getting vaccines that protect against bacterial infections
• Paying attention to food safety. Rinse all meat, poultry, fish, fruits, and vegetables under running water before cooking or serving them. Wash your hands with soap and water before and after you handle raw meat. Separate raw foods and cooked foods. Don’t use the same utensils or cutting boards with cooked meat that were used to prepare raw meat without washing between uses
• Cleaning and disinfecting surfaces that you frequently touch
• Preventing insect bites by using insect repellent when you go outdoors. If you travel to an area that has a high risk of diseases from insect bites, also wear long pants, shirts, and socks
• Practicing safe sex by using a condom
• Avoiding close contact with people who are sick

If you are in an area affected by flooding, avoid contact with flood water or any contaminated water and practice good hand hygiene. Floods or environmental disruptions can bring harmful bacteria from soil to the surface.^[2]

You should see a health care provider if you experience a fever that does not improve or gets worse, persistent or severe pain, difficulty breathing, a wound that is not healing or is oozing pus, or symptoms lasting longer than expected or worsening over time.^[6]