The Types of Streptococcal Infections

There are various types or species of Streptococci (“strep”) bacteria. The two groups briefly discussed here are from group AStreptococcus pyogenes GAS and group B Streptococcus agalactiae GBS. Nonpathogenic forms of strep bacteria normally live on the skin, inside the mouth, nose, throat, and inside the intestines. However, streptococcal bacteria can cause different types of noninvasive and invasive illnesses, directly or indirectly, when they enter the bloodstream. This may cause an array of infections or secondary complications such as bacteremia, cellulitis, endocarditis, erysipelas, glomerulonephritis, impetigo, meningitis, necrotizing fasciitis, pneumonia, rheumatic fever, scarlet fever, strep throat, and streptococcal toxic shock syndrome. The term streptococcus is often confused with Staphylococcus, or “staph”, or “staph aureus”. The Staphylococcus aureus species that affects man mirrors the strep range of diseases in many cases, but is especially known for causing skin infections such as cellulitis, and is most notorious for causing food poisoning.

Streptococcus bacteria

Streptococcus bacteria cause infections such as strep throat, cellulitis, meningitis, bacterial pneumonia, endocarditis, scarlet fever, and rheumatic fever. They grow in chains or pairs.

Streptococcal bacteria are not always the culprit

Streptococcal bacteria are not exclusive to all the types of diseases listed below. For example, endocarditis can also be caused by fungi or other germs. Another example is pneumonia, that may be caused by viruses, parasites, fungi, or noninfectious lung diseases. Also, streptococcal bacteria can be indirectly responsible for actual tissue damage or complications that occur during a bout of infection. An example is rheumatic fever and the body’s immune response to infection that ultimately causes lasting damage to tissue.

A listing of some types of streptococcal infections


Bacteremia sometimes referred to as “blood poisoning”, is the condition of having viable bacteria in the bloodstream. Typically, bacteria enter the blood through an injury such as a cut, puncture wound, burn, skin abrasion, through dental procedures, or surgical injection. The natural barriers within the body’s immune system tend to stave off a serious infection, and for the most part, it is considered clinically benign. Serious systemic infection can occur if left untreated especially in cases that involve a high volume of viable bacteria in the bloodstream that accumulate in certain tissues or organs, through extensive bacterial toxins, or for certain high-risk individuals. Examples of high-risk individuals may include people with heart valve defects, artificial joints, and having a weak immune system. Bacteremia can lead to sepsis and other serious infections if not monitored and treated effectively.




Cellulitis is a skin infection that can affect any part of the body and is caused by streptococcus, staphylococcus, and other types of bacteria. Early stages include symptoms such as red and tender areas that feel warm and may become swollen. Other symptoms may include pain in the affected area, fever, hair loss, nausea, sweating, swollen glands and more. It often occurs in regions of the skin that have been previously damaged. Cellulitis can also occur for individuals with a weak immune system, diabetes, and other conditions. Antibiotics are normally prescribed in minor cases and may take 7 – 10 days of treatment. More severe cases may require hospitalization. To learn more visit U.S. National Library of Medicine.

Endocarditis vegetations

Endocarditis vegetations


Endocarditis is an infection of the endocardium and heart valves caused by bacteria such as streptococcus, fungi, or other germs. The highest risk individuals tend to have prior heart defects, but aggressive forms of bacteria may infect a healthy heart. With endocarditis, clumps of bacteria and blood clots (vegetations) accumulate on the surface of heart valves causing damage and leakage ultimately leading to heart failure. Poor dental hygiene and unhealthy teeth and gums increase your risk of endocarditis. Most people who are immediately treated with the proper antibiotics recover. Learn more about endocarditis at U.S. DHHS: National Heart Lung and Blood Institute.


Erysipelas is a bacterial infection similar to cellulitis but tends to be less raised, and may appear at several separate locations on the body at the same time. Erysipelas is a potentially dangerous infection especially to children and the elderly. Left untreated, the bacteria can spread to the blood and cause infection to deeper tissues and vital organs like the heart. Erysipelas infections are commonly visible on the facial area such as the bridge of the nose, cheeks, and around eyes. Most people immediately treated with the proper antibiotics recover.


Glomerulonephritis, sometimes referred to as “nephritis”, is an infection of the glomeruli. The glomerulus are tiny, tubular tufts of capillaries in the kidneys that filter blood by removing waste.

When infected, the filtering capabilities are greatly hindered resulting in protein and red blood cells passing into the urine. This loss of protein in the bloodstream may result in edema (fluid buildup) throughout the body. This condition is called nephrotic syndrome. Left untreated, chronic glomerulonephritis symptoms may have a slow onset of symptoms, may come-and-go for months at a time, but ultimately can lead to kidney failure. Acute cases will produce extreme symptoms that require immediate medical attention.


Impetigo is a bacterial infection that is highly contagious and usually found in children. It usually begins with a reddening of the skin typically around the nose and mouth. This is followed by tiny bumps or blisters that are sometimes hard to distinguish. Complications may include inflammation of the kidneys, blood infection, and lymphatic damage if not treated. Care should be taken not to touch the infected areas to avoid spreading the infection to yourself or others. Children with impetigo should be separated from other children until the infection is treated. It’s recommended to wash all linens and clothing frequently until the infection is eradicated. Personal hygiene items, like the child’s soap, should be kept away from others. Talk to a doctor immediately in order to discuss treatment options.


Bacterial meningitis is a serious, potentially life-threatening infection of the triple layer of protective tissue which envelops the central nervous system. These membranes are collectively called meninges. The three layers of the meninges are called dura mater, arachnoid, and pia mater [see illustration]. Approximately 80 percent of all meningitis cases are identified as acute bacterial meningitis. Most cases of meningitis can be treated and people will see a full recovery. If left untreated, more serious complications are likely to occur such as hearing loss, brain damage, and other brain disorders. Infants are at higher risk for bacterial meningitis as well as people with weakened immune systems. The hallmark symptoms include sudden onset of a headache, fever and a stiff neck. Other symptoms may include nausea, vomiting, photophobia (a sensitivity to light), bulging fontanelle (in infants), abnormal reflex response, and confusion. The more severe cases of untreated bacterial meningitis can lead to seizures, coma, and death. Antibiotics can help prevent severe illness and reduce the spread of infection. Sometimes the exact causes of certain meningitis cases remain a mystery. Other times infections can occur due to a weakened immune system, from pneumococcal pneumonia, through alcohol abuse, serious blood infection, chronic nose and ear infections, brain or spinal surgery complications, or from a head injury.

Meninges of a normal brain in contrast to bacterial meningitis infected meninges.


Necrotizing Fasciitis (NF)

Necrotizing Fasciitis (NF) is a medical emergency also known as flesh-eating disease or flesh-eating bacteria syndrome. Necrotizing fasciitis spreads quickly, destroying (necrotizing) the body’s soft tissue and fascia (a structure of connective tissue covering muscle). Necrotizing fasciitis is very rare but it’s a serious condition because of the toxic properties and enzymes produced by the bacteria. These toxins and enzymes rapidly destroy tissue and can lead to secondary systemic shock resulting in respiratory failure, heart failure, and renal failure. Death occurs in about 1/4 of acute cases according to the CDC but this number may be higher according to the NNFF. Necrotizing fasciitis bacteria can enter a wound, insect bite, wounds that contact sea water, raw seafood such as oysters or crabs, from C-section or vaginal birth, intestinal wounds, muscle strain or bruise (even if internal), a burn, a cut, or just about any type of trauma. However, spontaneous cases where no apparent injury can be found, are also reported according to the National Necrotizing Fasciitis Foundation. Necrotizing fasciitis can be spread from person-to-person through close contact usually by touching an open wound, respiratory droplets, or direct contact with secretions of someone carrying Strep A. Prompt diagnosis is crucial to decrease the risk of disfigurement or death.