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I have completed bits of my EM training from India. Currently I am boarded with credentials from Christian Medical College, Vellore and also from the prestigious Royal College of Emergency Medicine, UK.  I am currently working in London as an A&E doctor, trying to appreciate the differences in the practise and culture of Emergency Medicine across different healthcare systems. I have always been an avid FOAMed supporter because FOAMed played an indispensable role during the days of my initial training. Through this blog, I aspire to disseminate knowledge and stay up to date with the EM literature. 

Monday, May 7, 2018

GABHS Pharyngitis - Strep throat

Group A β-hemolytic Streptococcus pharyngitis is the most commonly occurring form of acute bacterial pharyngitis primarily affecting children age 5-15 years old. It is typically a self-limited disease where symptoms diminish markedly at days 3 and 4 after symptom onset, and antibiotics only decrease the duration of symptoms by approximately 16 hours. Use of antibiotics for everyone with strep throat is controversial with but most physicians are not comfortable withholding antibiotics. Read this post on REBEL EM questioning the use Abx in strep throat. 

Symptoms of acute pharyngitis:
  • Sore throat, cough, hoarseness, coryza
  • Odynophagia
  • Fever
  • Headache, abdominal pain, nausea and vomiting, diarrhea
  • Arthralgias, myalgias,lethargy

Symptoms suggestive of viral infection:
  • Conjunctivitis, Coryza, Cough
  • Diarrhea, Hoarseness, Viral Exanthem
Physical examination findings:
  • Tonsillopharyngeal erythema and/or exudates
  • Soft palate petechiae, uvulitis
  • Anterior cervical lymphadenitis



It is difficult to distinguish between viral and bacterial causes based on physical examination alone, and tonsillar exudate does not imply bacterial etiology. Bacterial etiology is often overdiagnosed and unnecessary antibiotic treatment is given. 




Several clinical prediction rules have been created to identify cases of GABHS pharyngitis, and a commonly used rule is FeverPAIN score (recommended by NICE guidelines). 

Diagnosis

Performing diagnostic testing depends on local protocols but it is generally done by obtaining a swab from the throat and doing rapid antigen detection test (RADT) and/or culture because the clinical features alone do not reliably discriminate between GAS and viral pharyngitis. Routine use of backup throat cultures for those with a negative RADT is not necessary for adults. Anti-streptococcal antibody titers are not recommended in the routine diagnosis of acute pharyngitis as they reflect past but not current events. 
  • Gold standard for diagnosis - Bacterial culture (sensitivity of 90% to 95%)
  • Rapid antigen detection (highly specific, sensitivity 80% to 90%) 



Current American guidelines recommend confirmatory throat culture for all patients with a negative antigen test. The antibiotic treatment of GABHS pharyngitis shortens the duration of illness, prevents transmission, prevent suppurative complications (acute otitis media, acute sinusitis, and peritonsillar abscess), and prevent systemic illness such as rheumatic fever, rheumatic heart disease, and post-streptococcal glomerulonephritis. Antibiotics for the treatment of GABHS pharyngitis should be reserved for those patients with a positive antigen test or culture, or those meeting clinical criteria for diagnosis. 


Here is a summary of NICE guidelines:



Decision Rules 

FeverPAIN score 
Centor Criteria 



Treatment
  • Symptom relief with NSAIDs
  • Local Anethetics sprays 
  • Antibiotics (Her is another perspective on Abx use in Strep throat)
  • Steroids - Emerging evidence to achieve better symptoms relief 
Antibiotic treatment can be delayed safely for a few days after symptom onset and still prevent major nonsuppurative sequelae. This provides us time to get confirmatory cultures. Also, there is no definitive evidence that antibiotic use can prevent acute glomerulonephritis. 

Penicillin remains the treatment of choice. A course of 10 days of oral therapy with twice-a-day dosing is recommended for complete pharyngeal eradication; similar efficacy is achieved with once-daily dosing of amoxicillin for 10 days. Clarithromycin and first-generation cephalosporins are alternatives in penicillin-allergic patients. Clindamycin may be required for macrolide-resistant GABHS in the penicillin-allergic patient. 


Take Home:
  • Know your local protocols about diagnostic testing and indications for antibiotics. 
  • Strep throat is typically a self-limited disease where symptoms diminish markedly at days 3 and 4
  • There is no definitive evidence that antibiotic use can prevent acute glomerulonephritis
  • It is difficult to distinguish between viral and bacterial causes based on physical examination alone.

References and Further Reading:
  1. Shaikh N, Swaminathan N, Hooper EG: Accuracy and precision of the signs and symp- toms of streptococcal pharyngitis in children: a systematic review. J Pediatr 160: 487, 2012. [PMID: 22048053]
  2. Bisno AL: Acute pharyngitis. N Engl J Med 344: 205, 2001. [PMID: 11172144]
  3. Centor RM, Witherspoon JM, Dalton HP, et al: The diagnosis of strep throat in adults in the emergency room. Med Decis Making 1: 239, 1981. [PMID: 6763125]
  4. Wong DM, Blumberg DA, Lowe LG: Guidelines for the use of antibiotics in acute upper respiratory tract infections. Am Fam Physician 74: 956, 2006. [PMID: 17002029]
  5. Shulman ST, Bisno AL, Clegg HW, et al: Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clin Infect Dis 55: e91, 2012. [PMID: 23091044]
  6. https://www.nice.org.uk/guidance/ng84/documents/draft-guidance
  7. https://academic.oup.com/cid/article/55/10/e86/321183
  8. https://www.nice.org.uk/guidance/ng84/chapter/summary-of-the-evidence#corticosteroids
  9. http://www.idsociety.org/uploadedFiles/IDSA/Guidelines-Patient_Care/PDF_Library/Strep.pdf

Posted by:

              
     Lakshay Chanana
     
     Speciality Doctor
     Northwick Park Hospital
     Department of Emergency Medicine
     England

     @EMDidactic



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