Streptococcal pharyngitis | |
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Other names | Streptococcal sore throat, strep throat |
A culture positive case of streptococcal pharyngitis with typical tonsillar exudate in a 16-year-old. | |
Specialty | Infectious disease |
Symptoms | Fever, sore throat, enlarged lymph nodes [1] |
Usual onset | 1–3 days after exposure [2] [3] |
Duration | 7–10 days [2] [3] |
Causes | Group A streptococcus [1] |
Risk factors | Sharing drinks or eating utensils [4] |
Diagnostic method | Throat culture, strep test [1] |
Differential diagnosis | Epiglottitis, infectious mononucleosis, Ludwig's angina, peritonsillar abscess, retropharyngeal abscess, viral pharyngitis [5] |
Prevention | Airborne precautions, [6] Handwashing, [1] covering coughs [4] |
Treatment | Paracetamol (acetaminophen), NSAIDs, antibiotics [1] [7] |
Frequency | 5 to 40% of sore throats [8] [9] |
Streptococcal pharyngitis, also known as streptococcal sore throat (strep throat), is pharyngitis (an infection of the pharynx, the back of the throat) caused by Streptococcus pyogenes , a gram-positive, group A streptococcus. [10] [11] Common symptoms include fever, sore throat, red tonsils, and enlarged lymph nodes in the front of the neck. A headache and nausea or vomiting may also occur. [12] Some develop a sandpaper-like rash which is known as scarlet fever. [2] Symptoms typically begin one to three days after exposure and last seven to ten days. [2] [3] [12]
Strep throat is spread by respiratory droplets from an infected person, spread by talking, coughing or sneezing, or by touching something that has droplets on it and then touching the mouth, nose, or eyes. As with all respiratory pathogens once presumed to transmit via respiratory droplets, it is highly likely to be carried by the aerosols generated during routine breathing, talking, and even singing. [6] It may be spread directly through touching infected sores. It may also be spread by contact with skin infected with group A strep. The diagnosis is made based on the results of a rapid antigen detection test or throat culture. Some people may carry the bacteria without symptoms. [12]
Prevention is with airborne precautions, [6] frequent hand washing, and not sharing eating utensils. [12] There is no vaccine for the disease. [1] Treatment with antibiotics is only recommended in those with a confirmed diagnosis. [13] Those infected should stay away from other people until fever is gone and for at least 12 hours after starting treatment. [1] Pain can be treated with paracetamol (acetaminophen) and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. [7]
Strep throat is a common bacterial infection in children. [2] It is the cause of 15–40% of sore throats among children [8] [14] and 5–15% among adults. [9] Cases are more common in late winter and early spring. [14] Potential complications include rheumatic fever and peritonsillar abscess. [1] [2]
The typical signs and symptoms of streptococcal pharyngitis are a sore throat, fever of greater than 38 °C (100 °F), tonsillar exudates (pus on the tonsils), and large cervical lymph nodes. [14]
Other symptoms include: headache, nausea and vomiting, abdominal pain, [15] muscle pain, [16] or a scarlatiniform rash or palatal petechiae, the latter being an uncommon but highly specific finding. [14]
Symptoms typically begin one to three days after exposure and last seven to ten days. [3] [14]
Strep throat is unlikely when any of the symptoms of red eyes, hoarseness, runny nose, or mouth ulcers are present. It is also unlikely when there is no fever. [9]
Strep throat is caused by group A β-hemolytic Streptococcus (GAS or S. pyogenes). [17] Humans are the primary natural reservoir for group A streptococcus. [18] Other bacteria such as non–group A β-hemolytic streptococci and fusobacterium may also cause pharyngitis. [14] [16] It is spread by direct, close contact with an infected person; thus crowding, as may be found in the military and schools, increases the rate of transmission. [16] [19] Dried bacteria in dust are not infectious, although moist bacteria on toothbrushes or similar items can persist for up to fifteen days. [16] Contaminated food can result in outbreaks, but this is rare. [16] Of children with no signs or symptoms, 12% carry GAS in their pharynx, [8] and, after treatment, approximately 15% of those remain positive, and are true "carriers". [20]
Points | Probability of Strep | Management |
---|---|---|
1 or fewer | <10% | No antibiotic or culture needed |
2 | 11–17% | Antibiotic based on culture or RADT |
3 | 28–35% | |
4 or 5 | 52% | Empiric antibiotics |
A number of scoring systems exist to help with diagnosis; however, their use is controversial due to insufficient accuracy. [21] The modified Centor criteria are a set of five criteria; the total score indicates the probability of a streptococcal infection. [14]
One point is given for each of the criteria: [14]
A score of one may indicate no treatment or culture is needed or it may indicate the need to perform further testing if other high risk factors exist, such as a family member having the disease. [14]
The Infectious Disease Society of America recommends against routine antibiotic treatment and considers antibiotics only appropriate when given after a positive test. [9] Testing is not needed in children under three as both group A strep and rheumatic fever are rare, unless a child has a sibling with the disease. [9]
A throat culture is the gold standard [22] for the diagnosis of streptococcal pharyngitis, with a sensitivity of 90–95%. [14] A rapid strep test (also called rapid antigen detection testing or RADT) may also be used. While the rapid strep test is quicker, it has a lower sensitivity (70%) and statistically equal specificity (98%) as a throat culture. [14] In areas of the world where rheumatic fever is uncommon, a negative rapid strep test is sufficient to rule out the disease. [23]
A positive throat culture or RADT in association with symptoms establishes a positive diagnosis in those in which the diagnosis is in doubt. [24] In adults, a negative RADT is sufficient to rule out the diagnosis. However, in children a throat culture is recommended to confirm the result. [9] Asymptomatic individuals should not be routinely tested with a throat culture or RADT because a certain percentage of the population persistently "carries" the streptococcal bacteria in their throat without any harmful results. [24]
As the symptoms of streptococcal pharyngitis overlap with other conditions, it can be difficult to make the diagnosis clinically. [14] Coughing, nasal discharge, diarrhea, and red, irritated eyes in addition to fever and sore throat are more indicative of a viral sore throat than of strep throat. [14] The presence of marked lymph node enlargement along with sore throat, fever, and tonsillar enlargement may also occur in infectious mononucleosis. [25] Other conditions that may present similarly include epiglottitis, Kawasaki disease, acute retroviral syndrome, Lemierre's syndrome, Ludwig's angina, peritonsillar abscess, and retropharyngeal abscess. [5]
Tonsillectomy may be a reasonable preventive measure in those with frequent throat infections (more than three a year). [26] However, the benefits are small and episodes typically lessen in time regardless of measures taken. [27] [28] [29] Recurrent episodes of pharyngitis which test positive for GAS may also represent a person who is a chronic carrier of GAS who is getting recurrent viral infections. [9] Treating people who have been exposed but who are without symptoms is not recommended. [9] Treating people who are carriers of GAS is not recommended as the risk of spread and complications is low. [9]
Untreated streptococcal pharyngitis usually resolves within a few days. [14] Treatment with antibiotics shortens the duration of the acute illness by about 16 hours. [14] The primary reason for treatment with antibiotics is to reduce the risk of complications such as rheumatic fever and retropharyngeal abscesses. [14] Antibiotics prevent acute rheumatic fever if given within 9 days of the onset of symptoms. [17]
Pain medication such as NSAIDs and paracetamol (acetaminophen) helps in the management of pain associated with strep throat. [30] Viscous lidocaine may also be useful. [31] While steroids may help with the pain, [17] [32] they are not routinely recommended. [9] Aspirin may be used in adults but is not recommended in children due to the risk of Reye syndrome. [17]
The antibiotic of choice in the United States for streptococcal pharyngitis is penicillin V, due to safety, cost, and effectiveness. [14] Amoxicillin is preferred in Europe. [33] In India, where the risk of rheumatic fever is higher, intramuscular benzathine penicillin G is the first choice for treatment. [17]
Appropriate antibiotics decrease the average 3–5 day duration of symptoms by about one day, and also reduce contagiousness. [24] They are primarily prescribed to reduce rare complications such as rheumatic fever and peritonsillar abscess. [34] The arguments in favor of antibiotic treatment should be balanced by the consideration of possible side effects, [16] and it is reasonable to suggest that no antimicrobial treatment be given to healthy adults who have adverse reactions to medication or those at low risk of complications. [34] [35] Antibiotics are prescribed for strep throat at a higher rate than would be expected from how common it is. [36]
Erythromycin and other macrolides or clindamycin are recommended for people with severe penicillin allergies. [14] [9] First-generation cephalosporins may be used in those with less severe allergies [14] and some low-certainty evidence suggest cephalosporins are superior to penicillin. [37] [38] These late-generation antibiotics show a similar effect when prescribed for 3–7 days in comparison to the standard ten days of penicillin when used in areas of low rheumatic heart disease. [39] Streptococcal infections may also lead to acute glomerulonephritis; however, the incidence of this side effect is not reduced by the use of antibiotics. [17]
The symptoms of strep throat usually improve within three to five days, irrespective of treatment. [24] Treatment with antibiotics reduces the risk of complications and transmission; children may return to school 24 hours after antibiotics are administered. [14] The risk of complications in adults is low. [9] In children, acute rheumatic fever is rare in most of the developed world. It is, however, the leading cause of acquired heart disease in India, sub-Saharan Africa, and some parts of Australia. [9]
Complications arising from streptococcal throat infections include:
The economic cost of the disease in the United States in children is approximately $350 million annually. [9]
Pharyngitis, the broader category into which Streptococcal pharyngitis falls, is diagnosed in 11 million people annually in the United States. [14] It is the cause of 15–40% of sore throats among children [8] [14] and 5–15% in adults. [9] Cases usually occur in late winter and early spring. [14]
Streptococcus is a genus of gram-positive coccus or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales, in the phylum Bacillota. Cell division in streptococci occurs along a single axis, thus when growing they tend to form pairs or chains, which may appear bent or twisted. This differs from staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells. Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes.
Group A streptococcal infections are a number of infections with Streptococcus pyogenes, a group A streptococcus (GAS). S. pyogenes is a species of beta-hemolytic Gram-positive bacteria that is responsible for a wide range of infections that are mostly common and fairly mild. If the bacteria enter the bloodstream an infection can become severe and life-threatening, and is called an invasive GAS (iGAS).
Scarlet fever, also known as scarlatina, is an infectious disease caused by Streptococcus pyogenes, a Group A streptococcus (GAS). It most commonly affects children between five and 15 years of age. The signs and symptoms include a sore throat, fever, headache, swollen lymph nodes, and a characteristic rash. The face is flushed and the rash is red and blanching. It typically feels like sandpaper and the tongue may be red and bumpy. The rash occurs as a result of capillary damage by exotoxins produced by S.pyogenes. On darker-pigmented skin the rash may be hard to discern.
Lemierre's syndrome is infectious thrombophlebitis of the internal jugular vein. It most often develops as a complication of a bacterial sore throat infection in young, otherwise healthy adults. The thrombophlebitis is a serious condition and may lead to further systemic complications such as bacteria in the blood or septic emboli.
Infectious mononucleosis, also known as glandular fever, is an infection usually caused by the Epstein–Barr virus (EBV). Most people are infected by the virus as children, when the disease produces few or no symptoms. In young adults, the disease often results in fever, sore throat, enlarged lymph nodes in the neck, and fatigue. Most people recover in two to four weeks; however, feeling tired may last for months. The liver or spleen may also become swollen, and in less than one percent of cases splenic rupture may occur.
Pharyngitis is inflammation of the back of the throat, known as the pharynx. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, difficulty swallowing, swollen lymph nodes, and a hoarse voice. Symptoms usually last 3–5 days, but can be longer depending on cause. Complications can include sinusitis and acute otitis media. Pharyngitis is a type of upper respiratory tract infection.
Sore throat, also known as throat pain, is pain or irritation of the throat. Usually, causes of sore throat include:
Rheumatic fever (RF) is an inflammatory disease that can involve the heart, joints, skin, and brain. The disease typically develops two to four weeks after a streptococcal throat infection. Signs and symptoms include fever, multiple painful joints, involuntary muscle movements, and occasionally a characteristic non-itchy rash known as erythema marginatum. The heart is involved in about half of the cases. Damage to the heart valves, known as rheumatic heart disease (RHD), usually occurs after repeated attacks but can sometimes occur after one. The damaged valves may result in heart failure, atrial fibrillation and infection of the valves.
An upper respiratory tract infection (URTI) is an illness caused by an acute infection, which involves the upper respiratory tract, including the nose, sinuses, pharynx, larynx or trachea. This commonly includes nasal obstruction, sore throat, tonsillitis, pharyngitis, laryngitis, sinusitis, otitis media, and the common cold. Most infections are viral in nature, and in other instances, the cause is bacterial. URTIs can also be fungal or helminthic in origin, but these are less common.
Tonsillitis is inflammation of the tonsils in the upper part of the throat. It can be acute or chronic. Acute tonsillitis typically has a rapid onset. Symptoms may include sore throat, fever, enlargement of the tonsils, trouble swallowing, and enlarged lymph nodes around the neck. Complications include peritonsillar abscess (Quinsy).
Peritonsillar abscess (PTA), also known as quinsy, is an accumulation of pus due to an infection behind the tonsil. Symptoms include fever, throat pain, trouble opening the mouth, and a change to the voice. Pain is usually worse on one side. Complications may include blockage of the airway or aspiration pneumonitis.
Sydenham's chorea, also known as rheumatic chorea, is a disorder characterized by rapid, uncoordinated jerking movements primarily affecting the face, hands and feet. Sydenham's chorea is an autoimmune disease that results from childhood infection with Group A beta-haemolytic Streptococcus. It is reported to occur in 20–30% of people with acute rheumatic fever and is one of the major criteria for it, although it sometimes occurs in isolation. The disease occurs typically a few weeks, but up to 6 months, after the acute infection, which may have been a simple sore throat (pharyngitis).
A complication in medicine, or medical complication, is an unfavorable result of a disease, health condition, or treatment. Complications may adversely affect the prognosis, or outcome, of a disease. Complications generally involve a worsening in the severity of the disease or the development of new signs, symptoms, or pathological changes that may become widespread throughout the body and affect other organ systems. Thus, complications may lead to the development of new diseases resulting from previously existing diseases. Complications may also arise as a result of various treatments.
Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) is a controversial hypothetical diagnosis for a subset of children with rapid onset of obsessive-compulsive disorder (OCD) or tic disorders. Symptoms are proposed to be caused by group A streptococcal (GAS), and more specifically, group A beta-hemolytic streptococcal (GABHS) infections. OCD and tic disorders are hypothesized to arise in a subset of children as a result of a post-streptococcal autoimmune process. The proposed link between infection and these disorders is that an autoimmune reaction to infection produces antibodies that interfere with basal ganglia function, causing symptom exacerbations, and this autoimmune response results in a broad range of neuropsychiatric symptoms.
Acute proliferative glomerulonephritis is a disorder of the small blood vessels of the kidney. It is a common complication of bacterial infections, typically skin infection by Streptococcus bacteria types 12, 4 and 1 (impetigo) but also after streptococcal pharyngitis, for which it is also known as postinfectious glomerulonephritis (PIGN) or poststreptococcal glomerulonephritis (PSGN). It can be a risk factor for future albuminuria. In adults, the signs and symptoms of infection may still be present at the time when the kidney problems develop, and the terms infection-related glomerulonephritis or bacterial infection-related glomerulonephritis are also used. Acute glomerulonephritis resulted in 19,000 deaths in 2013, down from 24,000 deaths in 1990 worldwide.
The rapid strep test (RST) is a rapid antigen detection test (RADT) that is widely used in clinics to assist in the diagnosis of bacterial pharyngitis caused by group A streptococci (GAS), sometimes termed strep throat. There are currently several types of rapid strep test in use, each employing a distinct technology. However, they all work by detecting the presence of GAS in the throat of a person by responding to GAS-specific antigens on a throat swab.
The Centor criteria are a set of criteria which may be used to identify the likelihood of a bacterial infection in patients complaining of a sore throat. They were developed as a method to quickly diagnose the presence of Group A streptococcal infection or diagnosis of streptococcal pharyngitis in "adult patients who presented to an urban emergency room complaining of a sore throat." The Centor criteria are named after Robert M. Centor, an internist at the University of Alabama at Birmingham School of Medicine.
A throat culture is a laboratory diagnostic test that evaluates for the presence of a bacterial or fungal infection in the throat. A sample from the throat is collected by swabbing the throat and placing the sample into a special cup (culture) that allows infections to grow. If an organism grows, the culture is positive and the presence of an infection is confirmed. The type of infection is found using a microscope, chemical tests, or both. If no infection grows, the culture is negative. Common infectious organisms tested for by a throat culture include Candida albicans known for causing thrush and Group A streptococcus known for causing strep throat, scarlet fever, and rheumatic fever. Throat cultures are more sensitive than the rapid strep test (70%) for diagnosing strep throat, but are nearly equal in terms of specificity.
Perianal cellulitis, also known as perianitis or perianal streptococcal dermatitis, is a bacterial infection affecting the lower layers of the skin (cellulitis) around the anus. It presents as bright redness in the skin and can be accompanied by pain, difficulty defecating, itching, and bleeding. This disease is considered a complicated skin and soft tissue infection (cSSTI) because of the involvement of the deeper soft tissues.
Professor Asha Bowen is an Australian Paediatric Infectious Diseases clinician-scientist and a leading voice and advocate for children's health and well-being. She is Head of the Department of Infectious Diseases at Perth Children's Hospital, and Head of the Healthy Skin and ARF Prevention team at Telethon Kids Institute. She was the former Program Head of the End Rheumatic Heart Disease program (2022-2023) at the Telethon Kids Institute. Bowen leads a large body of skin health research in partnership with healthcare workers and community in the Kimberley while expanding her team and work to understand skin health in urban Aboriginal children better. She has been widely acknowledged and awarded for her contributions towards improving the health and well-being of Australian children, and addressing existing health inequities faced by First Nations Australian children and their families. Throughout the COVID-19 pandemic she contributed her knowledge and expertise to clinical research, guideline development and on several national and public health committees. She has published widely in the area of paediatric infectious diseases and is a recognized expert in the field who regularly contributes to popular Australian media sources such as The Conversation.