Group A Streptococcal Screen

Group A Streptococcal Screen

Synonym/acronym: Strep screen, rapid strep screen, direct strep screen.

Common use

To detect a group A streptococcal infection such as strep throat.


Throat swab (two swabs should be submitted so that a culture can be performed if the screen is negative).

Normal findings

(Method: Enzyme immunoassay or latex agglutination) Negative.


Rheumatic fever is a possible sequela to an untreated streptococcal infection. Early diagnosis and treatment appear to lessen the seriousness of symptoms during the acute phase and overall duration of the infection and sequelae. The onset of strep throat is sudden and includes symptoms such as chills, headache, sore throat, malaise, and exudative gray-white patches on the tonsils or pharynx. The group A streptococcal screen should not be ordered unless the results would be available within 1 to 2 hr of specimen collection to make rapid, effective therapeutic decisions. A positive result can be a reliable basis for the initiation of therapy. A negative result is presumptive for infection and should be backed up by culture results. In general, specimens showing growth of less than 10 colonies on culture yield negative results by the rapid screening method. Evidence of group A streptococci disappears rapidly after the initiation of antibiotic therapy. A nucleic acid probe method has also been developed for rapid detection of group A streptococci.

This procedure is contraindicated for



  • Assist in the rapid determination of the presence of group A streptococci

Potential diagnosis

Positive findings in:

  • Rheumatic fever
  • Scarlet fever
  • Strep throat
  • Streptococcal glomerulonephritis
  • Tonsillitis

Critical findings


Interfering factors

  • Polyester (rayon or Dacron) swabs are favored over cotton for best chance of detection. Fatty acids are created on cotton fibers during the sterilization process. Detectable target antigens on the streptococcal cell wall are destroyed without killing the organism when there is contact between the specimen and the fatty acids on the cotton collection swab. False-negative test results can be obtained on specimens collected with cotton tip swabs. Negative strep screens should always be followed with a traditional culture.
  • Sensitivity of the method varies among manufacturers.
  • Adequate specimen collection in children may be difficult to achieve, which explains the higher percentage of false-negative results in this age group.

Nursing Implications and Procedure

Potential nursing problems

ProblemSigns & SymptomsInterventions
Infection (Related to exposure to bacterial organisms secondary to, inadequate defense mechanism; insufficient nutrition; chronic disease)Temperature; increased heart rate; increased blood pressure; shaking; chills; mottled skin; lethargy; fatigue; swelling; pain; night sweats; confusion; positive Streptococcal throat swab; swollen tender lymph nodes in neck; headache; rash; vomiting; red, tender, pus-filled tonsilsPromote good hygiene; assist with hygiene as needed; administer prescribed antibiotics, antipyretics; provide cooling measures; monitor vital signs and trend temperatures; encourage oral fluids; adhere to standard or universal precautions; obtain cultures as ordered; assess nutritional status and provide supplements as needed
Airway (Related to infection; inflammation)Difficulty swallowing; tonsils that are red, swollen, with puss or white patches; swollen tender lymph nodes in neck; dyspnea; tachypneaAssess respiratory characteristics (rate, rhythm, depth, accessory muscle use); use pulse oximetry; administer prescribed oxygen; administer prescribed antibiotics; provide humidification of oxygen as appropriate
Fatigue (Related to infection and inflammation)Report of tiredness; inability to maintain activities of daily living at current level; inability to restore energy after rest or sleepDiscuss the implementation of energy conservation activities (even pace when working, frequent rest periods, items in easy reach, push items instead of pulling); limit naps to increase nighttime sleeping; set priorities for energy expenditures; administer ordered antibiotics
Health management (Related to inadequate access to care; low income; inadequate support systems; cultural influences)Unable to or fails to recognize or process information toward improving health and preventing illness with associated mental and physical effects; fails to keep appointments; fails to comply with recommended therapeutic regimeCollaborate with health-care provider to develop a plan of care that supports health; ensure patient adheres to recommended medication regime; ensure patient complies with health-care follow-up appointments; assess diet and lifestyle choices; assess health history; identify specific questions and reservations related to health management


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in identifying a streptococcal infection.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s immune and respiratory systems, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a history of prior antibiotic therapy.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Before specimen collection, verify with the laboratory whether wet or dry swabs are preferred for collection.
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the swabbing procedure.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.


  • Potential complications: N/A
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Vigorous swabbing of both tonsillar pillars and the posterior throat enhances the probability of streptococcal antigen detection.
  • Promptly transport the specimen to the laboratory for processing and analysis.


  • Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Administer antibiotics as ordered, and emphasize to the patient or caregiver the importance of completing the entire course of antibiotic therapy even if no symptoms are present.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
  • Patient Education

    • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
    • Answer any questions or address any concerns voiced by the patient or family.
  • Expected Patient Outcomes

    • Knowledge
    • Discusses the effects of noncompliance on overall health
    • States importance of completing antibiotic therapy to prevent infection recurrence
    • Skills
    • Demonstrates proficiency in self-administration of prescribed antibiotics
    • Relates symptoms of infection that should be reported to the HCP
    • Attitude
    • Recognizes the importance of accepting financial assistance as necessary to maintain health
    • Exhibits willingness to break long-held habits to improve health

Related Monographs

  • Related laboratory tests include analgesic and antipyretic drugs, antimicrobial drugs, ASO, chest x-ray, CBC, culture (throat, viral), and Gram stain.
  • Refer to the Immune and Respiratory systems tables at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners
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