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At Home Strep Test

Getting to the Bottom of At-Home Strep Tests

Tired of waiting in long lines at urgent care? Wondering if that sore throat is something more serious? At-home strep tests offer a convenient way to check for strep throat from the comfort of your own home. This comprehensive guide tells you everything you need to know about at home strep test.

Strep throat, caused by group A Streptococcus bacteria, affects millions each year. This common bacterial infection often causes throat pain, fever, inflammation, and pus on the tonsils. While strep throat usually resolves on its own, antibiotics are often prescribed to prevent rare complications like rheumatic fever. Traditionally, diagnosing strep requires a somewhat invasive throat culture at the doctor’s office. However, at-home rapid antigen detection tests have exploded in popularity due to their simplicity and convenience.

Keep reading to learn how at home strep test work, their accuracy compared to lab cultures, proper testing techniques, and what to do with positive or negative results. With this handy guide, you’ll have the confidence to test and treat strep throat at home.

The Basics of At Home Strep Testing

Most at-home rapid strep tests involve using a cotton swab to collect a throat sample, and then exposing it to an extractant solution. The extractant causes the release of strep cell components. These components migrate along a test strip containing anti-strep antibodies. If strep antigens are present, they’ll bind to the test line antibodies and become visible within 5 to 10 minutes, indicating a positive result.

At-home strep tests are antigen detection tests, not cultures. Whereas cultures directly look for viable bacteria, antigen tests detect cell parts. This means antigen tests don’t require lab equipment or days to incubate samples. Most deliver straightforward positive, negative, or invalid results within minutes. Many retail for $15 to $30 over the counter or online. Popular options include the Quidel QuickVue test, the BD Veritor System, and Abbot’s BinaxNOW.

Strep Testing
Strep Testing

Accuracy Compared to Cultures

The key advantage of rapid antigen testing is convenience and speed. However, they tend to be less accurate than lab cultures. According to a 2017 meta-analysis in the Journal of Clinical Microbiology, rapid antigen tests demonstrate:

  • Sensitivity of 80-90%: Proportion of positive strep cases correctly detected
  • Specificity of 95%+ Proportion of negative results that are truly not strep

Since cultures directly look for viable bacteria, they remain the clinical diagnostic gold standard with near 100% accuracy. However, cultures must be incubated for 1 to 2 days before reading results. Doctors also use a more invasive tongue depressor to swab the throat for cultures rather than a nasal swab. Due to improved convenience and reasonably high accuracy, most medical guidelines support using rapid tests to guide antibiotic treatment for likely strep cases. Negative rapid test results should be confirmed with a follow-up culture.

How to Properly Administer Rapid Strep Tests

While at-home strep tests seem simple, improper testing techniques can compromise results. Follow these steps when testing yourself or family members:

  1. Carefully read and follow all instructions in your test kit. Note any expiration dates printed on the package.
  2. Use soap and water to wash your hands thoroughly before testing.
  3. Start by inspecting the throat under a light for signs of strep: swollen tonsils with white streaks or tiny red spots on the area behind the tongue.
  4. Carefully swab the inflamed areas of the throat, avoiding the cheeks, gums, and tongue. Note that it’s important to swab both tonsils and far back enough to reach areas where the oral cavity and nasal passages meet.
  5. Promptly insert the saturated swab into the extractant solution. Agitate the swab for the directed time to allow maximal antigen transfer.
  6. Start test timer. Wait a full 10 minutes before interpreting results for maximal accuracy.
  7. Read positive test results right away. However, wait the full directed time before calling a negative test definitive, as faint lines can develop over time.
  8. Photograph ambiguous or borderline results to show your doctor.
  9. Consider testing again in 1-2 days if the first test was negative but symptoms persist or get worse.
Rapid Strep Tests
Rapid Strep Tests

What Positive Results Mean

The signature red line indicating a positive at-home test reflects the detection of Group A strep antigens in a throat sample. Positive rapid antigen results exhibit 80-90% correlation with true strep infections. Most doctors thus recommend promptly starting antibiotics when facing a positive at-home strep test coupled with supportive clinical symptoms like fever, throat swelling, or pus on the tonsils.

Positive rapid antigen results are sufficient evidence to begin antibiotics without immediately confirming via throat culture. However, consider additional testing if symptoms do not improve on antibiotics within 1 to 3 days. Rarely, misleading positive results occur due to the detection of different bacteria like group C or G strep. Clinicians can perform cultures and strain identification in cases of suspected inaccurate rapid test results.

Interpreting Negative Test Results

The lack of a red test line signifies a negative result, suggesting strep throat is doubtful. However, false negative rapid antigen test results occur up to 20% of the time compared to cultures. Thus, negative rapid antigen results should undergo supplementary confirmation by culture—especially when symptoms strongly indicate strep.

Ideally, every negative rapid test would be followed up by a backup culture. However, this isn’t always practical. Reasons to get a follow-up throat culture after a negative rapid antigen test include:

  • Symptoms strongly suggestive of strep like fever, throat exudate, swollen lymph nodes or tonsils
  • Exposure to confirmed strep cases within the past week
  • Underlying conditions like rheumatic heart disease requiring maximal diagnostic certainty

In cases with low clinical suspicion of strep, it is reasonable to forego confirmatory cultures after negative rapid tests in favor of symptomatic relief measures instead. Ultimately, whether or not to seek secondary testing should incorporate both test results and clinical judgment.

What Do Invalid Results Mean?

Rapid test kits with broken parts, missing reagents, or incomplete lines should be discarded and repeated. However, faint test lines adjacent to clearly negative results are not considered invalid. Even faint lines indicate detection of strep antigen and should prompt further testing.

If multiple tests continue yielding fully invalid results, it is reasonable to suspect technique errors rather than faulty kits. Seek in-person testing assistance from a healthcare professional after three consecutive invalid rapid antigen test attempts.

Treating Strep Throat

Doctors tailor antibiotic selection and duration for strep throat based on patient age, medical history, potential side effects, and regional resistance patterns.

First-Line Antibiotic Options

Penicillins:

  • Amoxicillin: Generic beta-lactam antibiotic, often prescribed 500mg capsules or liquid suspension 1-2 times per day for 10 days. Ideal first choice for non-allergic patients due to proven efficacy, safety, affordability, and low resistance.
  • Penicillin V: Narrow spectrum beta-lactam is less prone to cause antibiotic resistance compared to broader agents, especially effective against streptococci. Typically prescribed 250mg tablets 2 times per day for 10 days. The go-to option for those at high risk of adverse reactions.

Macrolides:

  • Azithromycin: A macrolide with a long tissue half-life allowing short 3-5 day courses. Second-line option for penicillin-allergic patients or when resistance is a concern.

Cephalosporins:

  • Cephalexin: Broad spectrum first-generation cephalosporin. Second or third-tier option for those with severe amoxicillin allergies and inability to take macrolides.

Anti-inflammatories like ibuprofen or acetaminophen manage sore throat, headache, and fever while antibiotics control the root infection. Throat lozenges temporarily ease discomfort. Stay well hydrated and get ample rest until completing antibiotic therapy.

Alternative Antibiotics

Certain scenarios warrant alternative antibiotic therapy:

  • Documented localized penicillin-resistant strep calls for newer macrolides, fluoroquinolones, or latest-generation cephalosporins.
  • Recurrent strep infections failing amoxicillin suggest an underlying reservoir of bacteria; combination therapy with rifampin or testing family members to identify chronic carriers may be appropriate.
  • Allergy to first-line agents drives the selection of second-tier macrolides, clindamycin, or cephalosporins based on sensitivities.

Consulting doctors helps select suitable alternatives and proper doses/durations when standard first-line options get ruled out.

Resolution Confirmation

Schedule a revisit 3-7 days after completing therapy to confirm strep and symptoms have fully resolved through repeat rapid testing or cultures. Persistent positive tests after treatment warrant analysis for resistant organisms and investigation for retained infection sources.

Rarely, severe strep complications like peritonsillar abscesses require more aggressive interventions beyond antibiotics like hospitalization, steroids, or surgical drainage. Immediately consult emergency care for dangerously worsening throat swelling, breathing difficulties, high fevers, or dehydration despite home treatment.

Complications or Risk of At Home Strep Test

Here is a table summarizing the main complications and risks of at home strep testing:

Complication/Risk Description Impact Prevention
Inadequate swabbing technique Failing to reach infected throat areas leads to poor sample collection False-negative results missed diagnoses Closely follow instructions, have someone assist in testing children
Misreading results Misinterpreting faint lines or degraded tests Inappropriate antibiotic use missed diagnoses Carefully inspect test components before use, and get doctor input on confusing results
False negatives 20% false negative rate risks untreated infection, complications Disease spread, rare immune issues like rheumatic fever Seek confirmatory cultures with concerning symptoms despite negative rapid tests
False positives Misleading positives spur overtreatment of non-strep cases Wasted medications, antibiotic resistance Pursue confirmatory cultures following positive results with atypical symptoms

Precautions For At-Home Strep Testing

While at-home strep tests offer convenience, take the following precautions to maximize safe, effective use:

Precaution Description Rationale
Check expiration Don’t use expired tests Expired tests give inaccurate results
Follow instructions Closely adhere to provided directions on proper technique and interpretation Improper technique or misreading results reduces accuracy
Consider backup testing Pursue confirmatory cultures with concerning symptoms despite negative rapid tests False negative rapid tests miss some true strep cases
Don’t overtreat negative tests Avoid prescribing antibiotics based solely on symptoms if the rapid test is negative Inappropriate antibiotic use risks side effects and resistance
Avoid antibiotic overuse Don’t reuse leftover antibiotics without evaluation Promotes antibiotic resistance patterns

Self-testing requires thoughtful precautions to optimize safe use akin to home pregnancy tests, glucose monitors, or blood pressure cuffs. Carefully apply at-home strep kits as an adjunct but not a replacement for necessary clinical assessments when used judiciously.

FAQs

Can rapid tests distinguish between viral infections like COVID-19 or the common cold vs strep?

No. Rapid antigen tests only detect strep bacteria components. Negative rapid test results don’t rule out viral infections causing similar throat symptoms. Follow up with a PCR test or doctor visit to check for illnesses besides strep if throat symptoms persist after a negative at-home test.

Do negative rapid test results completely rule out strep throat?

Not necessarily. False negative rapid antigen test results occur up to 20% of the time compared to cultures. Consider getting a follow-up throat culture if your symptoms seem very indicative of strep despite a negative rapid result.

How long do you have to wait between repeat testing attempts?

It’s reasonable to re-test for strep 24 to 48 hours after prior rapid antigen testing if symptoms fail to improve. Testing again too soon increases the chances of detecting residuals rather than new infections.

Are rapid antigen test results reliable in young children?

Yes, the latest medical guidelines endorse using rapid antigen testing for diagnosing strep in children. However, exercise extra care by swabbing small throats fully to obtain adequate samples in young kids.

Can I transmit strep throat to others after starting antibiotics?

Yes, you can still transmit strep for the first 1-2 days on antibiotics until your infection clears. Avoid close contact like kissing and implement diligent hygiene measures during this time to protect your household.

Is it safe to use at-home strep testing while pregnant?

Yes, rapid antigen testing poses minimal risks during pregnancy and helps guide timely treatment. However, opt for additional confirmatory cultures after positive or negative rapid test results while expecting. Prompt and accurate diagnosis prevents putting unborn babies at risk.

Last Words

Rapid at-home testing empowers convenient strep throat diagnosis and management. However, carefully adhere to complete test instructions for optimal accuracy. Confirm negative results with culture follow-up when feasible. Promptly consult doctors for treatment guidance if tests read positive. While home testing continues gaining favor, gold-standard cultures retain an important role when definitive diagnoses are essential.

Equipped with the comprehensive details above, deciding when and how to best utilize at-home strep tests becomes much easier. Next time a sore throat strikes your household, you’ll have confidence in judiciously leveraging rapid antigen kits available at local pharmacies. Just don’t forget backup cultures for inconclusive or negative test lines if strep throat is strongly suspected!

Selina

My name is Selina, a medical specialist blogger helping people access treatment for 5+ years. Although blogging awhile, only recently deeply engaged. This past year my most productive, providing hospital reviews and info on symptoms, diagnoses and diseases. Also offer guidelines to help readers navigate healthcare. Goal to continue increased content pace to assist many. Aim to facilitate treatment and empower advocacy through writing.

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