Diagnostic Tests for Strep throat
Strep throat: Diagnostic Tests
The list of diagnostic tests
mentioned in various sources as
used in the diagnosis of Strep throat
includes:
- Throat swab
- Rapid strep test (10-20 minutes)
- Throat swab culture
Strep throat Tests: Book Excerpts
Home Diagnostic Testing
These home medical tests may be relevant to Strep throat:
- Lung & Respiratory Health Tests:
- Cold & Flu: Home Testing:
Strep throat Diagnosis: Book Excerpts
Tests and diagnosis discussion for Strep throat:
Throat
is swabbed for culture or for a rapid strep test (10-20 minutes)
which can be done in the doctor's office. If the rapid test is
negative, a follow-up culture (which takes 24-48 hrs.) may be
performed. A negative culture suggests a viral infection, in which
case antibiotic treatment should be withheld or discontinued. (Source: excerpt from Group A Streptococcal Infections, NIAID Fact Sheet: NIAID)
Diagnostic Tests for Strep throat: Online Medical Books
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SORE THROAT:
DIAGNOSTIC WORKUP
(Algorithmic Diagnosis of Symptoms and Signs)
In a sore throat with typical exudates very suggestive of streptococcal pharyngitis, a throat culture may be all one needs before starting definitive antibiotic therapy. In the more difficult cases, screening for streptococcal antigens (streptozyme test and ASO titer) might be indicated. An ASO titer is particularly important when one suspects rheumatic fever. If the patient's streptococcal sore throat persists, a Monospot test and a culture for gonorrhea should be done. Although there are hardly any false-negative Monospot tests, there are 10% false positives, and that should be kept in mind. A blood smear for atypical lymphocytes may be helpful, as well as a heterophile antibody titer in those cases.
» READ BOOK EXCERPT ONLINE »
Source: Algorithmic Diagnosis of Symptoms and Signs, 2003
Mouth lesions:
History and physical examination
(Handbook of Signs & Symptoms (Third Edition))
Begin your evaluation with a thorough history. Ask the patient when the lesions appeared and whether he has noticed pain, odor, or drainage. Also ask about associated complaints, particularly skin lesions. Obtain a complete drug history, including drug allergies and antibiotic use, and a complete medical history. Note especially malignancy, sexually transmitted disease, I.V. drug use, recent infection, or trauma. Ask about his dental history, including oral hygiene habits, the frequency of dental examinations, and the date of his most recent dental visit.
Next, perform a complete oral examination, noting lesion sites and character. Examine the patient’s lips for color and texture. Inspect and palpate the buccal mucosa and tongue for color, texture, and contour; note especially painless ulcers on the sides or base of the tongue. Hold the tongue with a piece of gauze, lift it, and examine its underside and the floor of the mouth. Depress the tongue with a tongue blade, and examine the oropharynx. Inspect the teeth and gums, noting missing, broken, or discolored teeth; dental caries; excessive debris; and bleeding, inflamed, swollen, or discolored gums.
Palpate the neck for adenopathy, especially in patients who smoke tobacco or use alcohol excessively.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Signs & Symptoms (Third Edition), 2006
Throat pain:
History and physical examination
(Handbook of Signs & Symptoms (Third Edition))
Ask the patient when he first noticed the pain, and have him describe it. Has he had throat pain before? Is it accompanied by fever, ear pain, or dysphagia? Review the patient’s medical history for throat problems, allergies, and systemic disorders.
Next, carefully examine the pharynx, noting redness, exudate, or swelling. Examine the oropharynx, using a warmed metal spatula or tongue blade, and the nasopharynx, using a warmed laryngeal mirror or a fiber-optic nasopharyngoscope. Laryngoscopic examination of the hypopharynx may be required. (If necessary, spray the soft palate and pharyngeal wall with a local anesthetic to prevent gagging.) Observe the tonsils for redness, swelling, or exudate. Obtain an exudate specimen for culture. Then examine the nose, using a nasal speculum. Also, check the patient’s ears, especially if he reports ear pain. Finally, palpate the neck and oropharynx for nodules or lymph node enlargement.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Signs & Symptoms (Third Edition), 2006
Gag reflex abnormalities [Pharyngeal reflex abnormalities]:
History and physical examination
(Handbook of Signs & Symptoms (Third Edition))
Ask the patient (or a family member if the patient can’t communicate) about the onset and duration of swallowing difficulties, if any. Are liquids more difficult to swallow than solids? Is swallowing more difficult at certain times of the day (as occurs in the bulbar palsy associated with myasthenia gravis)? If the patient also has trouble chewing, suspect more widespread neurologic involvement because chewing involves different CNs.
Explore the patient’s medical history for vascular and degenerative disorders. Then assess his respiratory status for evidence of aspiration, and perform a neurologic examination.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Signs & Symptoms (Third Edition), 2006
Mouth lesions:
History and physical examination
(Professional Guide to Signs & Symptoms (Fifth Edition))
Begin your evaluation with a thorough history. Ask the patient when the lesions appeared and whether he has noticed any pain, odor, or drainage. Also ask about associated complaints, particularly skin lesions. Obtain a complete drug history, including drug allergies and antibiotic use, and a complete medical history. Note especially any malignancy, sexually transmitted disease, I.V. drug use, recent infection, or trauma. Ask about his dental history, including oral hygiene habits, frequency of dental examinations, and the date of his most recent dental visit.
Next, perform a complete oral examination, noting lesion sites and character. Examine the patient’s lips for color and texture. Inspect and palpate the buccal mucosa and tongue for color, texture, and contour; note especially any painless ulcers on the sides or base of the tongue. Hold the tongue with a piece of gauze, lift it, and examine its underside and the floor of the mouth. Depress the tongue with a tongue blade, and examine the oropharynx. Inspect the teeth and gums, noting missing, broken, or discolored teeth; dental caries; excessive debris; and bleeding, inflamed, swollen, or discolored gums.
Palpate the neck for adenopathy, especially in patients who smoke tobacco or use alcohol excessively.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Signs & Symptoms (Fifth Edition), 2006
Throat pain:
History and physical examination
(Professional Guide to Signs & Symptoms (Fifth Edition))
Ask the patient when he first noticed the pain and have him describe it. Has he had throat pain before? Is it accompanied by fever, ear pain, or dysphagia? Review the patient’s medical history for throat problems, allergies, and systemic disorders.
Next, carefully examine the pharynx, noting redness, exudate, or swelling. Examine the oropharynx, using a warmed metal spatula or tongue blade, and the nasopharynx, using a warmed laryngeal mirror or a fiber-optic nasopharyngoscope. Laryngoscopic examination of the hypopharynx may be required. (If necessary, spray the soft palate and pharyngeal wall with a local anesthetic to prevent gagging.) Observe the tonsils for redness, swelling, or exudate; if exudate is present, obtain a specimen for culture. Then examine the nose, using a nasal speculum. Also, check the patient’s ears, especially if he reports ear pain. Finally, palpate the neck and oropharynx for nodules or lymph node enlargement.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Signs & Symptoms (Fifth Edition), 2006
Gag reflex abnormalities [Pharyngeal reflex abnormalities]:
History and physical examination
(Professional Guide to Signs & Symptoms (Fifth Edition))
Ask the patient (or a family member if the patient can’t communicate) about the onset and duration of swallowing difficulties, if any. Are liquids more difficult to swallow than solids? Is swallowing more difficult at certain times of the day (as occurs in the bulbar palsy associated with myasthenia gravis)? If the patient also has trouble chewing, suspect more widespread neurologic involvement because chewing involves different cranial nerves.
Explore the patient’s medical history for vascular and degenerative disorders. Then assess his respiratory status for evidence of aspiration, and perform a neurologic examination.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Signs & Symptoms (Fifth Edition), 2006
Pharyngitis:
Physical examination
(The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter)
A. Focused physical examination (PE). This should include assessing vital signs (especially temperature) and examining the head, eyes, ears, nose, throat, neck, and skin. Findings classically associated with GABHS infection include palatal petechiae, intense (“beefy red”) tonsillopharyngeal erythema with exudates, tender anterior cervical adenopathy, and a scarlatiniform rash (Chapter 13.5). Conversely, absence of these features together with the presence of rhinitis, hoarseness, conjunctivitis, stomatitis, discrete ulcerative lesions, or a typical viral exanthem point toward a viral cause. In IM, the classic GABHS features are often combined with posterior cervical or generalized lymphadenopathy and hepatosplenomegaly. However, once again none of these physical findings in and of themselves have sufficiently high sensitivity and specificity to rely on for accurate diagnosis (2–4).
B. Additional PE. Abdominal examination is dictated by either gastrointestinal symptoms or the presence of severe fatigue with posterior cervical adenopathy (suggesting IM). Cough or fever should lead to pulmonary examination. Cardiac examination is important for toxic appearing patients.
Testing
A. Clinical laboratory tests. Because even experienced clinicians are unable to use the clinical presentation of pharyngitis to reliably predict the causative agent (because of inadequate sensitivity and specificity), accurate diagnosis should be based on results of a throat culture (TC) or rapid streptococcal antigen detection test (RSADT). In an untreated patient with streptococcal pharyngitis, a properly obtained (vigorously swabbing both tonsils and posterior pharynx) TC is almost always positive (sensitivity 90% to 95%) (3,4). Unfortunately, the culture does not reliably distinguish between acute GABHS infection and streptococcal carriers with concomitant viral infection. Streptococcal pharyngeal carriage, unfortunately, is a common finding particularly in school-aged children (20% to 30%) (2,3,5). A negative TC does permit the withholding of antimicrobial therapy (i.e., specificity = 0.99) (3–5).
Although methods vary, RSADTs do have high degrees of specificity (92% to 95%) (3,4). Unfortunately, their sensitivity in routine clinical practice is unacceptably low (60% to 85%) (3,4). Therefore, a negative antigen test does not exclude GABHS and a back-up throat culture must be obtained. Also, RSADTs suffer the same limitation as TCs because of the presence of carrier states.
Streptococcal antibody titers are of no immediate value in the diagnosis of acute GABHS pharyngitis.
If IM is suspected, a complete blood count and heterophil antibody testing can confirm the diagnosis reliably if the patient is in the second week of illness.
B. Imaging studies. None are usually necessary unless a serious suppurative sequela is suspected (e.g., retropharyngeal abscess).
Diagnostic assessment
Researchers have tried to incorporate clinical and epidemiologic features of acute pharyngitis into scoring systems that attempt to predict the probability of GABHS (2–5). Unfortunately, even the best of these predict positive TCs less than 70% of the time. Most scoring systems have incorporated the cardinal features such as fever, tender cervical adenopathy, tonsillar exudates, and lack of cough or rhinitis. Patients, especially adults, who have none of these features have a very low (<5%) probability of GABHS and no further testing is advised. For most other patients, who have varying numbers of cardinal features, the probability of GABHS is either intermediate (10% to 30%) or high (40% to 60%) and further testing is necessary, usually first with a RSADT and, if negative, a follow-up TC. Only in patients, usually children, with all the cardinal features plus a history of recent GABHS exposure or culture-proved recurrent streptococcal illness, can further testing be eliminated and empiric therapy begun.
References
1. National Ambulatory Medical Care Survey. Hyattsville, MD: National Center for Health Statistics, 1993.
2. Ebell MH. Sore throat. In: Sloane PD, Slatt LM, Curtis P, et al., eds. Essentials of family medicine, 3rd ed. Baltimore: Williams & Wilkins, 1998:632–634.
3. Bisno AL, Gerber MA, Gwaltney JM, Kaplan EL, Schwartz RH. Diagnosis and management of group A Streptococcal pharyngitis: a practice guideline—Infectious Disease Society of America. Clin Infect Dis 1997;25:574–583.
4. Komaroff AL. Sore throat and acute infectious mononucleosis in adult patients. In: Black ER, Bordley DR, Tape TG, et al., eds. Diagnostic strategies for common medical problems, 2nd ed. Philadelphia: American College of Physicians, 1999:229–242.
5. Perkins A. An approach to diagnosing the acute sore throat. Am Fam Physician 1997;55:131–138.>>>>
» READ BOOK EXCERPT ONLINE »
Source: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, 2000
Sore Throat:
Diagnostic Approach
(Field Guide to Bedside Diagnosis)
The most important consideration is whether the patient has a group A strep infection because prompt treatment prevents rheumatic fever. The findings of fever, tender anterior cervical adenopathy, and tonsillar exudate can be combined to make the diagnosis more or less likely. Rapid antigen tests have a sensitivity of 80% to 90% and specificity of 95% to 100%, so give a reasonably accurate diagnosis. Because of limitations in sensitivity however, patients with a high suspicion on clinical grounds should have a backup culture taken.
Prior probability in an adult population with sore throat is 5% to 10%, and in a pediatric population 20% to 25%. A prominent sore throat out of proportion to the degree of pharyngeal inflammation should raise the possibility of acute epiglottitis and acutely impending airway compromise. Persistent unilateral tonsillar enlargement in a young adult without sore throat should raise the suspicion of lymphoma.
» READ BOOK EXCERPT ONLINE »
Source: Field Guide to Bedside Diagnosis, 2007
Mouth lesions:
Physical assessment
(Signs & Symptoms: A 2-in-1 Reference for Nurses)
Perform a complete oral examination, noting lesion sites and character. Examine the patient’s lips for color and texture. Inspect and palpate the buccal mucosa and tongue for color, texture, and contour; especially note any painless ulcers on the sides or base of the tongue. Hold the tongue with a piece of gauze, lift it, and examine its underside and the floor of the mouth. Depress the tongue with a tongue blade, and examine the oropharynx. Inspect the teeth and gums, noting missing, broken, or discolored teeth; dental caries; excessive debris; and bleeding, inflamed, swollen, or discolored gums.
Palpate the neck for adenopathy, especially in patients who smoke tobacco or use alcohol excessively.
» READ BOOK EXCERPT ONLINE »
Source: Signs & Symptoms: A 2-in-1 Reference for Nurses, 2007
Throat pain:
Physical assessment
(Signs & Symptoms: A 2-in-1 Reference for Nurses)
Carefully examine the pharynx, noting redness, exudate, or swelling. Examine the oropharynx, using a warmed metal spatula or tongue blade, and the nasopharynx, using a warmed laryngeal mirror or a fiber-optic nasopharyngoscope. Laryngoscopic examination of the hypopharynx may be required. (If necessary, spray the soft palate and pharyngeal wall with a local anesthetic to prevent gagging.) Observe the tonsils for redness, swelling, or exudate. Obtain an exudate specimen for culture. Then examine the nose, using a nasal speculum. Also, check the patient’s ears, especially if he reports ear pain. Finally, palpate the neck and oropharynx for nodules or lymph node enlargement.
» READ BOOK EXCERPT ONLINE »
Source: Signs & Symptoms: A 2-in-1 Reference for Nurses, 2007
Sore Throat:
Diagnostic Approach
(The Diagnostic Approach to Symptoms and Signs in Pediatrics)
Historyand physical exam provide important clues for proper diagnosis ofsore throat.Most common clinical dilemma in childwith pharyngitis is whether pathogen is virus or group A Streptococcus.Tests to detect streptococcal antigen may be diagnostic, but ifresults of such tests are negative, throat culture should be performed.Because many cases of pharyngitis aredue to viruses, antibiotic use should be guided by antigen detectiontests or culture. Presence of conjunctivitis, cough, rhinitis, andhoarseness suggests viral etiology. Infectious mononucleosis isalso a consideration, especially in older children and adolescents.Neck radiography, flexible laryngoscopy,and CT are useful with suspected foreign body or retropharyngeal/lateralpharyngeal abscess.
» READ BOOK EXCERPT ONLINE »
Source: The Diagnostic Approach to Symptoms and Signs in Pediatrics, 2006
Mouth lesions:
History and physical examination
(Nursing: Interpreting Signs and Symptoms)
Begin your evaluation with a thorough history. Ask the patient when the lesions appeared and whether he has noticed odor or drainage or experienced pain. Also ask about associated complaints, particularly skin lesions. Obtain a complete drug history, including drug allergies and antibiotic use, and a complete medical history. Note especially malignancy, sexually transmitted disease, I.V. drug use, recent infection, or trauma. Ask about his dental history, including oral hygiene habits, the frequency of dental examinations, and the date of his most recent dental visit.
Next, perform a complete oral examination, noting lesion sites and character. Examine the patient's lips for color and texture. Inspect and palpate the buccal mucosa and tongue for color, texture, and contour; note especially painless ulcers on the sides or base of the tongue. Hold the tongue with a piece of gauze, lift it, and examine its underside and the floor of the mouth. Depress the tongue with a tongue blade, and examine the oropharynx. Inspect the teeth and gums, noting missing, broken, or discolored teeth; dental caries; excessive debris; and bleeding, inflamed, swollen, or discolored gums. Note any odor.
Palpate the neck for adenopathy, especially in patients who use tobacco or ingest alcohol excessively.
» READ BOOK EXCERPT ONLINE »
Source: Nursing: Interpreting Signs and Symptoms, 2007
Throat pain:
History and physical examination
(Nursing: Interpreting Signs and Symptoms)
Ask the patient when he first noticed the pain, and have him describe it. Has he had throat pain before? How was it treated? Is it accompanied by fever, ear pain, or dysphagia? Review the patient's medical history for throat problems, allergies, and systemic disorders.
Next, carefully examine the pharynx, noting redness, exudate, or swelling. Examine the oropharynx and the nasopharynx. Laryngoscopic examination of the hypopharynx may be required. (If necessary, spray the soft palate and pharyngeal wall with a local anesthetic to prevent gagging.) Observe the tonsils for redness, swelling, or exudate. Obtain an exudate specimen for culture. Then examine the nose. Also, check the patient's ears, especially if he reports ear pain. Finally, palpate the neck and oropharynx for nodules or lymph node enlargement.
» READ BOOK EXCERPT ONLINE »
Source: Nursing: Interpreting Signs and Symptoms, 2007
Gag reflex abnormalities [Pharyngeal reflex abnormalities]:
History and physical examination
(Nursing: Interpreting Signs and Symptoms)
Ask the patient (or a family member if the patient can't communicate) about the onset and duration of swallowing difficulties, if any. Are liquids more difficult to swallow than solids? Is swallowing more difficult at certain times of the day (as occurs in the bulbar palsy associated with myasthenia gravis)? If the patient also has trouble chewing, suspect more widespread neurologic involvement because chewing involves different CNs.
Explore the patient's medical history for vascular and degenerative disorders. Then assess his respiratory status for evidence of aspiration, and perform a neurologic examination.
» READ BOOK EXCERPT ONLINE »
Source: Nursing: Interpreting Signs and Symptoms, 2007
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