Strep Throat

Overview

Strep throat, medically known as streptococcal pharyngitis, is a bacterial infection that causes inflammation and pain in the throat. Unlike most sore throats which are caused by viruses, strep throat is caused by group A Streptococcus bacteria (also known as Streptococcus pyogenes). This distinction is crucial because bacterial infections like strep throat require antibiotic treatment, while viral sore throats do not. Strep throat accounts for approximately 15-30% of sore throats in children and 5-15% in adults, making it one of the most common bacterial infections in outpatient settings.

The infection primarily affects the pharynx, including the back of the throat and the tonsils, causing significant inflammation and the characteristic symptoms of severe throat pain, difficulty swallowing, and fever. Strep throat is highly contagious and spreads through respiratory droplets when an infected person coughs, sneezes, or talks. It can also spread through shared food or drinks and by touching surfaces contaminated with the bacteria and then touching the mouth or nose. The incubation period is typically 2-5 days, and individuals are most contagious during the acute phase of illness and for up to 24 hours after starting antibiotic treatment.

While strep throat itself is usually not dangerous and responds well to antibiotic treatment, untreated strep throat can lead to serious complications. These include local complications such as peritonsillar abscess and systemic complications like rheumatic fever, which can damage the heart valves, and post-streptococcal glomerulonephritis, which affects the kidneys. These potential complications underscore the importance of proper diagnosis and treatment. Strep throat is most common in school-age children between 5 and 15 years old, particularly during the winter and early spring months when people spend more time indoors in close contact.

Symptoms

Strep throat symptoms typically develop suddenly and are often more severe than those of viral sore throats.

Primary Symptoms

Throat and Mouth Findings

• Red and swollen tonsils
• White patches or streaks of pus on tonsils
• Tiny red spots (petechiae) on the soft palate
• Swollen, tender lymph nodes in neck
• Bright red, swollen uvula
• Bad breath (halitosis)

Systemic Symptoms

• Body aches and general malaise
• Chills and sweating
• Loss of appetite
• Nausea or vomiting, especially in children
• Abdominal pain (more common in children)
• Fatigue and weakness

Associated Symptoms

• Ear pain (referred pain from throat)
• Skin rash (scarlet fever - sandpaper-like rash)
• Mild nasal congestion (less common than with viral infections)
• Joint pain (may indicate complications)

Symptoms Typically ABSENT in Strep Throat

• Cough (presence suggests viral cause)
• Hoarseness
• Conjunctivitis (pink eye)
• Significant runny nose
• Mouth ulcers
• Diarrhea

Age-Specific Presentations

Children (5-15 years)

• Classic presentation with severe symptoms
• Higher fever
• More likely to have nausea/vomiting
• Abdominal pain common
• May develop scarlet fever rash

Adults

• May have milder symptoms
• Less likely to have high fever
• Throat pain may be primary complaint
• Fatigue more prominent

Children Under 3

• Strep throat less common
• May present with fever and irritability
• Nasal discharge more common
• May refuse to eat

Scarlet Fever

When strep throat is accompanied by a characteristic rash:

• Fine, red, sandpaper-like rash
• Starts on chest/abdomen, spreads to limbs
• Flushed face with pale area around mouth
• "Strawberry tongue" - red with white coating
• Rash fades after 3-4 days with peeling

Causes

Strep throat is caused exclusively by bacteria, specifically group A Streptococcus, making it distinct from most sore throats which are viral in origin.

Primary Causative Agent

Group A Streptococcus (GAS)

• Scientific name: Streptococcus pyogenes
• Gram-positive bacteria in chains
• Beta-hemolytic (destroys red blood cells)
• Produces various toxins and enzymes
• Over 100 different strains (M-types)

Transmission Methods

Direct Transmission

• Respiratory droplets: Primary mode of spread
• Coughing and sneezing
• Talking closely with infected person
• Kissing or intimate contact
• Sharing food, drinks, or utensils

Indirect Transmission

• Touching contaminated surfaces
• Door handles, toys, shared items
• Bacteria survive on surfaces for short periods
• Hand-to-mouth contact after touching contaminated items

Bacterial Virulence Factors

• M protein: Helps bacteria evade immune system
• Streptolysins: Damage host cells
• Hyaluronidase: Helps spread through tissues
• Pyrogenic exotoxins: Cause fever and rash
• Streptokinase: Breaks down blood clots

Host Factors

Why Some People Get Infected

• Exposure to infected individuals
• Weakened immune system
• Damaged throat tissue (from viral infection, dry air)
• Lack of immunity to specific strain
• Genetic susceptibility

Environmental Factors

• Crowded conditions: Schools, daycare, military barracks
• Close contact: Household members, classmates
• Season: Winter and early spring peak
• Indoor activities: Increased during cold weather
• Poor ventilation: Facilitates transmission

Carrier State

• Some individuals carry GAS without symptoms
• Can transmit bacteria to others
• Up to 20% of school children may be carriers
• Carriers less likely to spread infection than acutely ill
• Usually don't require treatment

Incubation and Contagious Period

• Incubation: 2-5 days after exposure
• Most contagious: During acute illness
• Remains contagious: Until 24 hours after antibiotics start
• Without treatment: Contagious for 2-3 weeks
• With treatment: Non-contagious after 24-48 hours

Risk Factors

Certain factors increase the likelihood of developing strep throat:

Age-Related Risk

• Highest risk: Children 5-15 years old
• School-age children: Peak incidence
• Adults with children: Increased exposure
• Less common: Children under 3 years
• Can occur: At any age

Environmental Factors

• Crowded living conditions
• Schools and daycare centers
• Military barracks
• Dormitories
• Nursing homes
• Poor ventilation

Seasonal Patterns

• Peak season: Late fall through early spring
• Winter months: Highest incidence
• Indoor crowding: Facilitates spread
• Dry air: May damage throat mucosa
• Can occur: Year-round in any climate

Exposure Risks

• Close contact with infected person
• Household members of infected individual
• Healthcare workers
• Teachers and childcare providers
• Parents of school-age children

Medical Conditions

• Weakened immune system
• Recent viral upper respiratory infection
• Chronic tonsillitis
• History of recurrent strep throat
• Diabetes
• HIV/AIDS

Behavioral Factors

• Poor hand hygiene
• Sharing personal items
• Touching face frequently
• Not covering coughs/sneezes
• Close physical contact (sports teams)

Risk for Complications

Higher risk of complications in:

• Untreated or inadequately treated cases
• History of rheumatic fever
• Family history of rheumatic fever
• Certain genetic factors
• Poor access to healthcare
• Non-compliance with antibiotic treatment

Diagnosis

Accurate diagnosis of strep throat is important to ensure appropriate antibiotic treatment and prevent complications.

Clinical Assessment

Centor Criteria

Scoring system to assess likelihood of strep throat:

• Fever over 100.4°F (38°C) - 1 point
• Absence of cough - 1 point
• Swollen, tender anterior cervical lymph nodes - 1 point
• Tonsillar swelling or exudate - 1 point
• Age adjustment:
  • 3-14 years: +1 point
  • 15-44 years: 0 points
  • 45+ years: -1 point

Score Interpretation

• 0-1 points: Low risk (1-10%), no testing needed
• 2-3 points: Moderate risk, testing recommended
• 4-5 points: High risk (51-53%), empiric treatment or testing

Diagnostic Tests

Rapid Antigen Detection Test (RADT)

• Results in 5-15 minutes
• Specificity: 95% (few false positives)
• Sensitivity: 70-90% (may miss some cases)
• Positive result confirms strep
• Negative result may need culture backup

Throat Culture

• Gold standard for diagnosis
• Takes 24-48 hours for results
• More sensitive than rapid test
• Can identify other bacteria
• Recommended after negative RADT in children

Testing Procedure

• Throat swab of posterior pharynx and tonsils
• Avoid touching tongue, teeth, or gums
• May cause gagging
• Quick and minimally uncomfortable
• Same swab can be used for both tests

Additional Tests

When Complications Suspected

• Complete blood count: If severe illness
• Mono spot test: If mononucleosis suspected
• ASO titers: For recent strep infection
• Blood cultures: If bacteremia suspected
• Imaging: For abscess evaluation

Differential Diagnosis

Conditions to distinguish from strep throat:

• Viral pharyngitis: Most common cause of sore throat
• Infectious mononucleosis: EBV infection
• Peritonsillar abscess: Complication of throat infection
• Diphtheria: Rare but serious
• Gonococcal pharyngitis: In sexually active patients
• Candidiasis: In immunocompromised
• Kawasaki disease: In young children

Testing Recommendations

• Test patients with 2+ Centor criteria
• Don't test patients with clear viral symptoms
• Consider empiric treatment for 4+ criteria
• Backup culture for negative RADT in children
• No routine testing for asymptomatic contacts

Treatment Options

Strep throat requires antibiotic treatment to eliminate the infection, reduce symptoms, prevent spread, and avoid complications.

Antibiotic Therapy

First-Line Antibiotics

• Penicillin V:
  • Children: 250mg 2-3 times daily for 10 days
  • Adults: 500mg 2-3 times daily for 10 days
  • Must complete full course
• Amoxicillin:
  • Often preferred for children (better taste)
  • Once or twice daily dosing
  • 50mg/kg/day for 10 days
• Benzathine penicillin G:
  • Single intramuscular injection
  • Ensures compliance
  • Painful injection

Alternative Antibiotics (Penicillin Allergy)

• Azithromycin (Z-pack): 5-day course
• Cephalexin: 10-day course
• Cefadroxil: 10-day course
• Clarithromycin: 10-day course
• Clindamycin: For severe allergy

Symptomatic Relief

Pain and Fever Management

• Acetaminophen: Every 4-6 hours as needed
• Ibuprofen: Every 6-8 hours with food
• Alternate medications for better control
• Follow age-appropriate dosing

Throat Comfort Measures

• Warm salt water gargles (½ tsp salt in 1 cup warm water)
• Throat lozenges (for children over 4)
• Warm liquids (tea, soup, honey water)
• Cold foods (ice cream, popsicles)
• Throat sprays with numbing agents
• Humidifier to add moisture to air

General Care

• Rest: Stay home until fever-free for 24 hours
• Hydration: Drink plenty of fluids
• Soft diet: Easy-to-swallow foods
• Avoid irritants: Smoke, strong odors
• Replace toothbrush: After 24 hours of antibiotics

Treatment Timeline

• First 24-48 hours: Begin feeling better
• 24 hours after antibiotics: No longer contagious
• 2-3 days: Significant symptom improvement
• 10 days: Complete antibiotic course
• 1-2 weeks: Full recovery

Important Treatment Considerations

• Complete full antibiotic course even if feeling better
• Don't share antibiotics with others
• Take antibiotics as prescribed
• Report any allergic reactions immediately
• Follow up if not improving after 48 hours

Managing Recurrent Strep Throat

For frequent episodes (>3-4 per year):

• Evaluate for carrier state
• Consider different antibiotic
• Treat close contacts
• Environmental cleaning
• Consider tonsillectomy referral

When Surgery May Be Considered

Tonsillectomy indications:

• 7+ episodes in one year
• 5+ episodes per year for two years
• 3+ episodes per year for three years
• Recurrent peritonsillar abscess
• Significant sleep-disordered breathing

Prevention

Preventing strep throat involves reducing exposure to the bacteria and maintaining good hygiene practices.

Personal Hygiene

• Hand washing: Most important prevention method
• Wash hands frequently with soap and water
• Use alcohol-based hand sanitizer when soap unavailable
• Avoid touching face, especially mouth and nose
• Cover mouth when coughing or sneezing
• Use tissues and dispose properly

Avoiding Transmission

• Stay home when sick (at least 24 hours after starting antibiotics)
• Avoid close contact with infected individuals
• Don't share personal items (cups, utensils, toothbrushes)
• Avoid sharing food or drinks
• Maintain distance from people who are coughing/sneezing

Environmental Measures

• Disinfect commonly touched surfaces
• Clean doorknobs, light switches, phones
• Wash dishes in hot, soapy water
• Don't share towels or washcloths
• Ensure good ventilation in living spaces
• Use humidifiers to prevent throat dryness

In Schools and Daycare

• Teach children proper hand washing
• Encourage covering coughs and sneezes
• Regular cleaning of toys and surfaces
• Exclude sick children until treated
• Notify parents of strep outbreaks
• Promote not sharing personal items

Family Prevention

When someone in household has strep:

• Isolate sick family member when possible
• Use separate eating utensils
• Wash hands after contact with sick person
• Don't share bedding or towels
• Consider prophylactic antibiotics for high-risk contacts
• Monitor family members for symptoms

Preventing Recurrence

• Complete full course of antibiotics
• Replace toothbrush after starting treatment
• Wash bedding and towels in hot water
• Identify and treat carriers in household
• Address underlying health issues
• Consider environmental factors

Special Considerations

• No vaccine currently available for group A strep
• Previous infection doesn't provide lasting immunity
• Multiple strains mean reinfection possible
• Prophylactic antibiotics only in special circumstances
• Tonsillectomy doesn't eliminate all risk

When to See a Doctor

Timely medical evaluation is important for proper diagnosis and treatment of strep throat.

See a Doctor Promptly For

• Severe sore throat lasting more than 2 days
• Sore throat with fever over 101°F (38.3°C)
• Sore throat without cold symptoms (runny nose, cough)
• Difficulty swallowing liquids or saliva
• Swollen, tender lymph nodes in neck
• Red rash accompanying sore throat
• Known exposure to someone with strep throat

Seek Emergency Care For

• Difficulty breathing or swallowing
• Drooling (unable to swallow saliva)
• Severe dehydration signs
• Stiff neck with fever
• Confusion or altered mental state
• Inability to open mouth fully
• Muffled or "hot potato" voice
• Severe headache with high fever

Follow-up Care Needed If

• Symptoms not improving after 48 hours of antibiotics
• Fever persists beyond 3 days of treatment
• New symptoms develop during treatment
• Rash appears after starting antibiotics
• Joint pain or swelling develops
• Dark urine or decreased urination
• Recurring strep throat infections

Signs of Complications

Seek immediate care for:

• One-sided throat swelling (peritonsillar abscess)
• Difficulty opening mouth (trismus)
• Chest pain or heart palpitations
• Joint pain and swelling
• Blood in urine
• Facial swelling
• Severe abdominal pain

Special Populations

Lower threshold for medical evaluation in:

• Children under 3 years old
• Elderly adults
• Pregnant women
• Immunocompromised individuals
• People with chronic medical conditions
• History of rheumatic fever

What to Tell Your Doctor

• Duration and severity of symptoms
• Associated symptoms (fever, rash, etc.)
• Recent sick contacts
• Previous strep throat episodes
• Antibiotic allergies
• Current medications
• Compliance with previous treatments

Related Conditions

Frequently Asked Questions