Types of Bacterial Infections
Bacteria are single-cell germs that can only be seen under a microscope. Scientists name bacteria based on their family grouping. For example, Streptococcus (“strep”) is a family of bacteria whose members can cause infections like strep throat. Escherichia is another family of bacteria. Perhaps the most common bacterium of this family is E. coli, which can cause infections of the digestive tract.
Each of these germs can cause different symptoms of bacterial infection. Learn more about the types of bacterial infections and how treatment varies by the type and location of the infection.
Skin punctures or cuts can allow bacteria to enter and cause an infection. Some of the most common types of bacterial skin infections are:
- Abscesses: bacterial infections that cause pus-filled pockets to develop in the skin
- Carbuncles: a grouping of infections within the hair follicles
- Cellulitis: an infection of the lower layers of the skin
- Ecthyma and impetigo: skin infections caused by S. aureas or a germ of the Streptococcus family
- Folliculitis: another infection of the hair follicles
Many types of bacteria can cause skin infections, including Streptococcus and Staphylococcus. Doctors treat bacterial skin infections by determining which type of bacteria is causing the infection and then prescribing the appropriate antibiotic medication to destroy that particular bacterium. A bacterial culture test can diagnose the type of bacteria infection. Antibiotic creams and ointments applied to the skin may clear up the infection, or you may need to take an oral antibiotic. Severe skin infections may also require surgical draining of an abscess.
Bacterial lung infections often cause coughing and phlegm production. Many bacterial infections of the lungs are categorized as “pneumonias,” but pneumonia is not a single disease. Pneumonias can be caused by many different types of bacteria, including:
- Chlamydial pneumonias
- Haemophilus pneumonia
- Legionnaires’ disease, caused by Legionella pneumophila
- Mycoplasma pneumonia (also called “walking pneumonia”)
- Pneumococcal pneumonia (the most common type of bacterial lung infection)
- Pseudomonas pneumonia
Other important bacterial lung infections are tuberculosis, pertussis (whooping cough), pulmonary abscess, infectious bronchitis, and pleurisy. Some bacterial lung infections, such as pneumococcal pneumonia and pertussis, can be prevented by vaccination. Other types of bacterial lung infections require treatment with antibiotics.
Bacterial infections of the digestive tract can cause cramping, vomiting, diarrhea and fever. Infectious gastritis, duodenitis, ileitis, appendicitis, colitis, proctitis and diverticulitis are good examples. These infections occur when bacteria invade the tissues of the stomach or intestines. A great many types of bacteria can cause infections in the stomach and digestive tract. A few of the most common include:
- Clostridium difficile (C. diff): an infection that can occur after taking antibiotics
- E. coli: an infection often caused by eating undercooked meat
- H. pylori: a bacterium that causes stomach ulcers
- Listeria: another food-borne bacterium
- Salmonella: a bacterium that can be consumed in food or water
Many times, when a bacterium causes an infection of the gastrointestinal tract, we call it “food poisoning”—and that’s an apt description, because these bacteria can enter your body when you eat food that is undercooked, improperly preserved, or spoiled. You also can get a gastrointestinal infection by drinking unpurified water. You might have heard this called “traveler’s diarrhea.”
Mild forms of gastrointestinal infections caused by bacteria may not require treatment. They often clear up on their own after a few days. More serious infections, like C. diff, require medical intervention.
The symptoms of a bacterial infection can be very similar to the symptoms of an infection caused by a virus, fungus or parasite. Sometimes, the only way to say for sure that an infection is caused by bacteria is to examine samples of fluid and tissue from the site of the infection. Under a microscope, bacteria look different from other types of pathogens.
The most common symptoms related to bacterial infections of the skin, lungs, stomach and digestive tract can include:
- Abdominal cramping
- Coughing, especially a cough that produces sputum
- Enlarged lymph nodes
- Red, hot skin
- Visible pus
Symptoms will be specific to the location of the bacterial infection. For instance, a bacterial skin infection likely won’t cause coughing; a pneumonia won’t cause pus pockets on the skin.
You should seek medical attention for any illness that includes these symptoms:
- Bloody vomit or vomit that looks like coffee grounds
- Chest pain or pressure
- Difficulty breathing
- Fever over 101.4 degrees Fahrenheit in an adult
- Loss of consciousness or an altered mental status (such as delirium)
If your symptoms are caused by a bacterial infection, your doctor probably can treat the illness with antibiotics. Most bacteria can be eliminated by these drugs, but severe bacterial infections or those caused by antibiotic-resistant bacteria can require hospitalization coupled with various types of supportive care.