Beta Haemolytic Streptococcal Infection

Beta haemolytic streptococcal infections are caused by bacteria that can lead to illnesses ranging from a simple sore throat to severe, life-threatening conditions affecting multiple organs.

Table of contents

• What is beta haemolytic streptococcal infection
• Types of infections
• Signs and symptoms
• Who is at risk
• How the infection spreads
• Diagnosis and testing
• Treatment
• Prevention

What is beta haemolytic streptococcal infection

Beta haemolytic streptococcal infections are illnesses caused by specific types of bacteria that belong to the Streptococcus family. The term “beta haemolytic” refers to how these bacteria break down red blood cells when grown in laboratory conditions^[5]. These bacteria commonly live in the human body, particularly in the respiratory system, throat, and on the skin, without causing any harm^[4].

The most important groups are Group A and Group B streptococci. Group A Streptococcus (also called Streptococcus pyogenes) is the most common bacterial cause of throat infections, accounting for 15 to 30 percent of cases in children and 5 to 10 percent in adults^[9]. Group B streptococcus (also known as Streptococcus agalactiae) is usually harmless in healthy adults but can cause serious illness in newborn babies and people with certain health conditions^[1].

• Throat
• Skin
• Respiratory tract
• Intestines
• Genital tract
• Blood
• Bones and joints
• Heart

Types of infections

Beta haemolytic streptococci can cause many different types of infections. The severity ranges from mild conditions that can be treated easily to severe diseases that require urgent medical attention^[6].

Mild infections caused by Group A streptococcus include strep throat, which causes a sore, red throat with white spots on the tonsils. The bacteria can also cause skin infections such as impetigo, which produces sores and blisters near the mouth and nose or on the arms and legs. Another skin condition called cellulitis affects the deeper layers of skin tissue^[6].

Some strains of Group A strep produce a toxin that causes scarlet fever. This condition combines strep throat symptoms with a distinctive red, sandpaper-like rash that spreads across the body. The tongue may become bright red and bumpy, often described as looking like a strawberry^[21].

Severe infections occur when the bacteria invade normally sterile parts of the body, such as the blood, deep muscles, or lungs. These invasive infections include bacteremia (infection of the bloodstream), pneumonia (lung infection), sepsis (the body’s extreme response to infection), and meningitis (infection of the lining around the brain and spinal cord)^[3].

Two particularly severe forms of invasive disease are necrotizing fasciitis, sometimes called flesh-eating disease, which destroys muscle and fat tissue, and toxic shock syndrome, a rapidly progressing infection that causes dangerously low blood pressure and damage to multiple organs. Approximately 20 percent of patients with necrotizing fasciitis and 60 percent with toxic shock syndrome die from these conditions^[25].

Group B streptococcus most commonly causes bloodstream infections, pneumonia, and meningitis in newborn babies. In adults, it typically causes urinary tract infections, bloodstream infections, skin infections, and pneumonia, especially in older people or those with chronic health conditions^[3].

Signs and symptoms

The symptoms of beta haemolytic streptococcal infection depend on which part of the body is affected and how severe the infection is^[6].

When Group A strep causes throat infection, symptoms include sudden onset of sore throat, pain when swallowing, fever (often above 38.5°C or 101.3°F), headache, stomach pain, and swollen lymph nodes in the neck. Small red spots may appear on the roof of the mouth. The tonsils often look red and swollen and may be covered with white patches or pus^[10]. Children may also experience nausea, vomiting, or abdominal pain^[14].

Skin infections produce different symptoms. Impetigo causes small, red to purple sores that leak clear or yellow fluid and form crusty yellow scabs. Cellulitis makes the skin red, swollen, warm to touch, and painful. When scarlet fever develops, a pink or red rash appears, usually starting on the face and neck before spreading to the rest of the body. The rash feels rough like sandpaper and is often more noticeable in skin folds such as the armpits and groin^[21].

Severe invasive infections cause more alarming symptoms including high fever, severe pain that spreads beyond the wound, large wounds or black spots on the skin, skin that changes color from red to purple, extreme swelling, dizziness, confusion, nausea, vomiting, and diarrhea^[6].

In newborn babies with Group B strep infection, symptoms may include fever or unusually low body temperature, trouble feeding, sluggishness or weak muscle tone, trouble breathing, irritability, jittery movements, seizures, rash, or jaundice (yellowing of the skin). The illness can start within the first six hours after birth (called early onset disease) or appear weeks to months later (late onset disease)^[1].

Who is at risk

Anyone can get beta haemolytic streptococcal infections since the bacteria spread easily from person to person^[6].

Strep throat is most common in children between 5 and 15 years of age, though it can occur at any age. During winter and spring months in areas with temperate climates, up to 20 percent of school-aged children without symptoms may carry Group A strep bacteria in their throats^[9]. The illness spreads more easily in crowded settings such as schools, daycare centers, military facilities, and institutions^[14].

Certain people face higher risk for severe invasive infections. Adults who are 65 years or older, people with chronic health conditions such as diabetes, cancer, kidney disease, or liver disease, and those taking medications that weaken the immune system (such as steroids) are more vulnerable to serious complications^[8].

Group B strep poses particular risk to newborn babies. Most babies born to women carrying these bacteria remain healthy, but those who become infected during labor can develop severe illness. Pregnant women should be screened for Group B strep bacteria during the third trimester of pregnancy^[1].

How the infection spreads

Beta haemolytic streptococci spread primarily through direct person-to-person contact. The most common way is through respiratory droplets produced when an infected person coughs or sneezes. The bacteria can also spread through direct contact with infected skin sores or with secretions such as saliva, wound discharge, or nasal secretions from an infected person^[8].

People with active infection are most contagious while they are ill. Those who carry the bacteria without having symptoms are much less likely to spread the infection to others^[25].

Although less common, the bacteria can spread through contact with contaminated objects or surfaces. Rare outbreaks have occurred through contaminated food, particularly milk, milk products, and eggs that have been contaminated during preparation^[8].

Crowding increases the chance of transmission. Outbreaks commonly occur in institutional settings, schools, childcare centers, and among family members living in the same household^[10].

For Group B strep, pregnant women can pass the bacteria to their babies during delivery. This is how most babies who develop Group B strep disease in the first week of life become infected^[3].

Diagnosis and testing

Doctors cannot diagnose beta haemolytic streptococcal infections based on symptoms alone because viral infections often cause similar symptoms. Laboratory testing is necessary to confirm the presence of strep bacteria^[14].

For throat infections, the doctor takes a sample by swabbing both tonsils with a soft cotton swab. This may cause slight discomfort but takes only a moment^[2].

Two types of tests can detect Group A strep bacteria in the throat. The rapid antigen detection test (also called rapid strep test) provides results in 5 to 10 minutes while you wait in the doctor’s office. This test is very accurate when it shows a positive result, meaning you can begin treatment right away. However, if the rapid test is negative in children but the doctor still suspects strep throat, a throat culture should be performed to confirm the result^[10].

A throat culture is considered the gold standard test. The sample is sent to a laboratory where the bacteria are grown and identified. Results typically take 24 to 48 hours. Under ideal conditions, throat culture can detect strep bacteria in 90 percent of cases^[10].

For skin infections, the doctor may take a sample from the infected area. For suspected invasive infections, samples may be taken from blood, spinal fluid, or urine, depending on the type of infection. Healthcare providers may also order a chest x-ray to help determine if someone has strep pneumonia^[3].

Pregnant women are screened for Group B strep between 36 and 37 weeks of pregnancy. The test involves swabbing the vagina and rectum. Results help doctors determine if antibiotics are needed during labor to protect the baby^[3].

Treatment

Beta haemolytic streptococcal infections are treated with medicines called antibiotics, which kill the bacteria. Starting treatment as soon as possible is important to prevent complications and reduce the time you can spread the infection to others^[2].

For Group A strep throat infections, penicillin remains the most commonly recommended antibiotic. It can be given as pills taken by mouth for 10 days or as a single injection into the muscle. Another antibiotic called amoxicillin works equally well and may be easier for children to take because it tastes better^[10].

People who are allergic to penicillin can be treated with other antibiotics such as cephalosporins, clindamycin, or certain macrolides. However, some strep bacteria have developed resistance to certain antibiotics, so sensitivity testing may be needed to ensure the chosen antibiotic will work^[12].

It is very important to take the entire course of antibiotics as prescribed, even if you start feeling better after a few days. Most people feel better within 1 to 2 days after starting antibiotics^[2]. After taking antibiotics for 24 hours, you are no longer contagious and children can return to school or daycare, provided they feel well^[8].

For severe invasive infections, patients require high doses of antibiotics given through a vein in the hospital. Some patients may also need surgery. For example, necrotizing fasciitis often requires surgical removal of dead tissue, which can be lifesaving. Patients with severe infections may need intensive care and support for their breathing, blood pressure, and organ function^[17].

For Group B strep infections, high-dose penicillin or ampicillin given through a vein is the standard treatment. In patients allergic to penicillin, vancomycin may be used. Treatment duration varies depending on the type and severity of infection^[11].

Prevention

Several steps can help prevent beta haemolytic streptococcal infections and limit their spread^[3].

Good hygiene practices are important. Wash your hands frequently with soap and water, especially after coughing or sneezing. Cover your mouth and nose with a tissue when you cough or sneeze, then throw the tissue away. If you don’t have a tissue, cough or sneeze into your elbow rather than your hands^[8].

Do not share drinking glasses, eating utensils, or personal items such as toothbrushes with someone who is sick. If you have strep throat, replace your toothbrush after you have been taking antibiotics for 24 hours to avoid reinfecting yourself^[8].

People who are sick with a strep infection should stay home from work, school, or daycare until they have taken antibiotics for at least 24 hours and no longer have a fever. This helps prevent spreading the infection to others^[2].

For pregnant women, getting screened for Group B strep during the third trimester is crucial. If the test is positive, receiving antibiotics through a vein during labor can protect the baby from developing Group B strep disease. This preventive approach has significantly reduced the number of newborns who become seriously ill^[1].

Currently, there are no vaccines available to prevent Group A or Group B streptococcal infections, though vaccines are under development^[3].

If someone in your household has strep throat, wash dishes and utensils in hot, soapy water or in a dishwasher. This helps kill any bacteria that may be on these items^[8].