What is Streptococcus?

The genus Streptococcus contains a large number of species, many of which have a huge impact on human health, infecting people of all ages and from all socio-economic groups. Diseases caused by streptococcus range from mild, but extremely widespread conditions, such as respiratory infections, inner ear infections, pharyngomyelitis, skin rash, also known as scarlet fever, skin infections, such as infectious wax and cellulitis, i.e. inflammation of the skin and subcutaneous fat, and dental diseases, up to severe, life-threatening conditions such as necrotizing encephalitis, rheumatic fever and pneumonia.

With increasing resistance to antibiotics, due to their excessive and inappropriate use, there is an urgent need for new strategies for the treatment of streptococcal infections. The development of these new strategies is based on improved knowledge of the ways in which streptococcus interacts and causes disease in humans.

Streptococcus A only infects humans, with around 10% of school-age children being carriers and causes more than half a million deaths worldwide per year.

We have known about bacteria for more than 100 years and they were a leading cause of childhood death in the 19th and early 20th centuries. But it is less of a threat to public health since antibiotic drugs were developed for treatment. In the 1980s, a type of streptococcus A strain called “M1” emerged as the leading cause of invasive streptococcus A infections in high-income settings.

In the last decade, a resurgence of streptococcus A infections has been reported in the UK and China.

Severe infection is rare but when it does occur, the mortality rate can be as high as 20%.

What is the most common strain of streptococcus for humans?

It is the Group A streptococci that are mostly associated with infections in humans. Acute group A streptococcal disease is most often a respiratory infection (pharyngitis or tonsillitis) or a skin infection (pyoderma).

Group A streptococcal bacteria cause diseases ranging from strep throat (strep throat) to necrotizing encephalitis (flesh-eating disease). They can also cause scarlet fever, rheumatic fever, postpartum (postnatal) fever and streptococcal toxic shock syndrome.

Are there new strains of streptococcus threatening to humans?

The M1UK variant of Streptococcus A was first reported in the UK in 2019 and was identified by studying the DNA sequence.

The British scientists found that the M1UK variant produces up to five times more streptococcus A-specific toxin than the previous M1 strain. This toxin is associated with the development of invasive Streptococcus A and may be more contagious.

At the same time, there is an increase in cases of invasive streptococcus A in New South Wales, Queensland and Western Australia, the Netherlands, Sweden.

Where is streptococcus found?

Streptococcus A is a common bacterium carried by people mainly in their throat. It can cause mild illnesses such as sore throat, scarlet fever, but it can also cause multiple infections of different organs and lead to sepsis. Repeated streptococcus A infections can lead to other serious conditions, such as acute rheumatic fever and rheumatic heart disease.

Streptococcus is found in the nasopharynx and on the skin. About 5% of healthy people have this microbe in their throat without infection (healthy carriers). In the winter months, healthy carriers reach 20%. Streptococcus does not survive in the external environment.

How is Streptococcus transmitted?

Group A streptococcus is transmitted via

• contaminated droplets from patient secretions
• contact with contaminated surfaces
• contact with infected wounds on the skin of patients; and
• from healthy carriers of the bacterium.

As EODY notes, group A streptococcus is much easier transmitted by people who are symptomatic and sick than by healthy carriers of the bacterium.

Symptoms of streptococcus

A sore throat caused by streptococcus A is different from a simple sore throat. Patients may experience severe pain when swallowing, but may also experience fever and swelling in their tonsils or have white patches or streaks of pus in the throat.

The first signs of strep throat can be flu-like symptoms such as high fever, sore throat and swollen glands in the throat. A rash appears 12 to 48 hours later, which starts in the chest and stomach and then spreads. A white coating also appears on the peeling tongue, leaving it red, swollen and covered with small bumps, which is often called “strawberry tongue”.

Rarely, streptococcus A can cause serious illness when the bacteria enter parts of the body that are usually free of it. This is called invasive group A streptococcal disease.

Diagnosis

There are several tests for the diagnosis of group A streptococcal infection depending on the symptoms of the patient. For example, streptococcal pharyngomyelitis can be quickly diagnosed by culture of pharyngeal swab as well as by a rapid test to detect the streptococcal antigen, known as a step test, and finally by using the sensitive PCR method for streptococcus.

Treatment

Penicillin is usually administered for the treatment of streptococcal tonsillitis. Alternatively, ampicillin or amoxicillin.
Sometimes treatment fails and other antibiotics get administered. The same is true when people are allergic to penicillin.

In any case you should consult your doctor.

Procautions

Protective antibodies are created after the infection. However, because there are many types of the microbe there is actually no complete immunity to new infections. However, with age, the frequency of streptococcal infections decreases significantly.

To date there is no vaccine, but efforts are underway to produce one. Personal hygiene measures must be taken for precaution. Using a handkerchief when coughing and sneezing reduces the chance of transmission of the germ.

Hands should be washed after sneezing or coughing, as well as before eating.
People with pharyngitis or skin infections should consult a physician immediately.