Streptococcal pharyngitis

Streptococcal pharyngitis
Classification and external resources

Note the petechiae, or small red spots, on the soft palate. This is an uncommon but highly specific finding in streptococcal pharyngitis.[1]
ICD-10 J02.0
ICD-9 034.0
DiseasesDB 12507
MedlinePlus 000639
eMedicine med/1811

Streptococcal pharyngitis or streptococcal sore throat (known colloquially as strep throat) is a form of group A streptococcal infection[2] that affects the pharynx and possibly the larynx. Common symptoms include fever, sore throat, and enlarged lymph nodes. It is a contagious infection, spread through close contact with an infected individual. A definitive diagnosis is made based on the results of a throat culture however this is not always needed as treatment may be decided based on symptoms. In highly likely or confirmed cases antibiotics are useful to both prevent complications and speed recovery.[1]

Contents

Signs and symptoms

The typical symptoms of streptococcal pharyngitis are a sore throat, fever of greater than 38 °C (100 °F), tonsillar exudates (pus on the tonsils), and large cervical lymph nodes.[1]

Others symptoms include:

The incubation period and thus the start of symptoms for strep throat is between one to three days post contact.[1]

Cause

Strep throat is caused by group A beta-hemolytic streptococcus (GAS).[5] Other bacteria such as non–group A beta-hemolytic streptococci and fusobacterium may also cause pharyngitis.[1][4] It is spread by direct, close contact with an infected person and thus crowding as may be found in the military and schools increases the rate of transmission.[6][4] It has been found that dried bacteria in dust are not infectious, although moist bacteria on toothbrushes or similar items can persist for up to fifteen days.[4] Rarely, contaminated food can result in outbreaks.[4]

Diagnosis

Modified Centor score
Points Probability of Strep Management
1 or less <10% No antibiotic or culture needed
2 11—17% Antibiotic based on culture or RADT
3 28—35%
4 or 5 52% Empiric antibiotics

The modified Centor score is used to determine the management of people with pharyngitis. Based on 5 clinical criteria, it indicates the probability of a streptococcal infection.[1]

One point is given for each of the criteria:[1]

Laboratory testing

A throat culture is the gold standard[7] for the diagnosis of streptococcal pharyngitis with a sensitivity of 90—95%.[1] A rapid strep test (also called rapid antigen detection testing or RADT) may also be used. While the rapid strep test is quicker, it has a lower sensitivity (70%) and statistically equal specificity (98%) as throat culture.[1]

A positive throat culture or RADT in association with symptoms establishes a positive diagnosis in those in which the diagnosis is in doubt.[8] Asymptomatic individuals should not be routinely tested with a throat culture or RADT because a certain percentage of the population persistently "carries" the streptococcal bacteria in their throat without any harmful results.[8]

Differential diagnosis

See also: Acute pharyngitis

As the symptoms of streptococcal pharyngitis overlap with other conditions it can be difficult to make the diagnosis clinically.[1] Coughing, nasal discharge, diarrhea, and red, irritated eyes in addition to fever and sore throat are more indicative of a viral sore throat than of strep throat.[1] The presence of marked lymph node enlargement along with sore throat, fever and tonsillar enlargement may also occur in infectious mononucleosis.[9]

Prevention

Tonsillectomy may be a reasonable preventative measure in those with frequent throat infections.[10][11] Three or more a year was seen as sufficient in 2003.[12] Watchful waiting is also appropriate.[10]

Treatment

Untreated streptococcal pharyngitis usually resolves within a few days.[1] Treatment with antibiotics shortens the duration of the acute illness by about 16 hours.[1] The primary reason for treatment with antibiotics is to reduce the risk of complications such as rheumatic fever and retropharyngeal abscesses[1] and they are effective if given within 9 days of the onset of symptoms.[5]

Analgesics

Analgesics such as non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol (acetaminophen) help significantly in the management of pain associated with strep throat.[13] Steroids are also useful in this respect[14][5] as is viscous lidocaine.[15] Aspirin may be used in adults but is not recommended in children due to the risk of Reye's syndrome.[5]

Antibiotics

The antibiotic of choice in the United States for streptococcal pharyngitis is penicillin V due to safety, cost, and effectiveness.[1] Amoxicillin is preferred in Europe.[16] In India, where the risk of rheumatic fever is higher, intramuscular benzathine penicillin G is the first choice for treatment.[5] Appropriate antibiotics decrease the average 3-5 day duration of symptoms by about one day, and also reduce contagiousness.[8] They are primarily prescribed out of a motivation to reduce rare complications such as acute rheumatic fever and peritonsillar abscess.[17] The arguments in favour of antibiotic treatment should be balanced by the consideration of possible side effects,[4] and it is reasonable to suggest that no antimicrobial treatment be given to healthy adults who have adverse reactions to medication.[17] Antibiotics are prescribed for strep throat at a higher rate than would be expected from its prevalence.[18] Erythromycin and other macrolides are recommended for people with severe penicillin allergies.[1] First, general cephalosporins may be used in those with less severe allergies.[1] Streptococcal infections may also lead to acute glomerulonephritis, however the incidence of this side effect is not reduced by the use of antibiotics.[5]

Prognosis

The symptoms of strep throat usually improve irrespective of treatment within three to five days.[8] Treatment with antibiotics reduces the risk of complications and transmission; children may return to school 24 hours after antibiotics are administered.[1]

Complications arising from streptococcal throat infections include:

Epidemiology

Pharyngitis, the broader category into which Streptococcal pharyngitis falls, is diagnosed in 11 million people annually in the United States.[1] Although most cases are viral, group A beta-hemolytic streptococcus is the cause in 15—30% of the pharyngitis cases in children and 5—20% in adults.[1] Cases usually occur in late winter and early spring.[1]

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 Choby BA (March 2009). "Diagnosis and treatment of streptococcal pharyngitis". Am Fam Physician 79 (5): 383–90. PMID 19275067. 
  2. ↑ streptococcal pharyngitis at Dorland's Medical Dictionary
  3. ↑ 3.0 3.1 3.2 3.3 Brook I, Dohar JE (December 2006). "Management of group A beta-hemolytic streptococcal pharyngotonsillitis in children". J Fam Pract 55 (12): S1–11; quiz S12. PMID 17137534. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Hayes CS, Williamson H (April 2001). "Management of Group A beta-hemolytic streptococcal pharyngitis". Am Fam Physician 63 (8): 1557–64. PMID 11327431. http://www.aafp.org/afp/20010415/1557.html. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Baltimore RS (February 2010). "Re-evaluation of antibiotic treatment of streptococcal pharyngitis". Curr. Opin. Pediatr. 22 (1): 77–82. doi:10.1097/MOP.0b013e32833502e7. PMID 19996970. 
  6. ↑ Lindbaek M, Høiby EA, Lermark G, Steinsholt IM, Hjortdahl P (2004). "Predictors for spread of clinical group A streptococcal tonsillitis within the household". Scand J Prim Health Care 22 (4): 239–43. doi:10.1080/02813430410006729. PMID 15765640. 
  7. ↑ Smith, Ellen Reid; Kahan, Scott; Miller, Redonda G. (2008). In A Page Signs & Symptoms. In a Page Series. Hagerstown, Maryland: Lippincott Williams & Wilkins. pp. 312. ISBN 0-7817-7043-2. 
  8. ↑ 8.0 8.1 8.2 8.3 Bisno AL, Gerber MA, Gwaltney JM, Kaplan EL, Schwartz RH (July 2002). "Practice guidelines for the diagnosis and management of group A streptococcal pharyngitis. Infectious Diseases Society of America". Clin. Infect. Dis. 35 (2): 113–25. doi:10.1086/340949. PMID 12087516. http://www.journals.uchicago.edu/doi/abs/10.1086/340949. 
  9. ↑ Ebell MH (2004). "Epstein-Barr virus infectious mononucleosis". Am Fam Physician 70 (7): 1279–87. PMID 15508538. http://www.aafp.org/afp/20041001/1279.html. 
  10. ↑ 10.0 10.1 Paradise JL, Bluestone CD, Bachman RZ, et al. (March 1984). "Efficacy of tonsillectomy for recurrent throat infection in severely affected children. Results of parallel randomized and nonrandomized clinical trials". N. Engl. J. Med. 310 (11): 674–83. PMID 6700642. 
  11. ↑ Alho OP, Koivunen P, Penna T, Teppo H, Koskela M, Luotonen J (May 2007). "Tonsillectomy versus watchful waiting in recurrent streptococcal pharyngitis in adults: randomised controlled trial". BMJ 334 (7600): 939. doi:10.1136/bmj.39140.632604.55. PMID 17347187. 
  12. ↑ Johnson BC, Alvi A (March 2003). "Cost-effective workup for tonsillitis. Testing, treatment, and potential complications". Postgrad Med 113 (3): 115–8, 121. PMID 12647478. 
  13. ↑ Thomas M, Del Mar C, Glasziou P (October 2000). "How effective are treatments other than antibiotics for acute sore throat?". Br J Gen Pract 50 (459): 817–20. PMID 11127175. 
  14. ↑ "Effectiveness of Corticosteroid Treatment in Acute Pharyngitis: A Systematic Review of the Literature.". Andrew Wing. 2010; Academic Emergency Medicine. http://www3.interscience.wiley.com/journal/123372200/abstract. 
  15. ↑ "Generic Name: Lidocaine Viscous (Xylocaine Viscous) side effects, medical uses, and drug interactions". MedicineNet.com. http://www.medicinenet.com/lidocaine_viscous/article.htm. Retrieved 2010-05-07. 
  16. ↑ Bonsignori F, Chiappini E, De Martino M (2010). "The infections of the upper respiratory tract in children". Int J Immunopathol Pharmacol 23 (1 Suppl): 16–9. PMID 20152073. 
  17. ↑ 17.0 17.1 Snow V, Mottur-Pilson C, Cooper RJ, Hoffman JR (March 2001). "Principles of appropriate antibiotic use for acute pharyngitis in adults". Ann Intern Med 134 (6): 506–8. PMID 11255529. http://www.annals.org/cgi/reprint/134/6/506.pdf. 
  18. ↑ Linder JA, Bates DW, Lee GM, Finkelstein JA (November 2005). "Antibiotic treatment of children with sore throat". J Am Med Assoc 294 (18): 2315–22. doi:10.1001/jama.294.18.2315 (inactive 2009-11-10). PMID 16278359. http://jama.ama-assn.org/cgi/content/full/294/18/2315. 
  19. ↑ 19.0 19.1 "UpToDate Inc.". http://www.utdol.com/online/content/topic.do?topicKey=upp_resp/4610. 
  20. ↑ Stevens DL, Tanner MH, Winship J, et al. (July 1989). "Severe group A streptococcal infections associated with a toxic shock-like syndrome and scarlet fever toxin A". N. Engl. J. Med. 321 (1): 1–7. PMID 2659990. 
  21. ↑ 21.0 21.1 Hahn RG, Knox LM, Forman TA (May 2005). "Evaluation of poststreptococcal illness". Am Fam Physician 71 (10): 1949–54. PMID 15926411. 

External links

Firmicutes (low-G+C) Infectious diseases · Bacterial diseases: G+ (primarily A00–A79, 001–041, 080–109)
Bacilli
Lactobacillales
(Cat-)
optochin susceptible: S. pneumoniae (Pneumococcal infection)
optochin resistant: S. viridans (S. mitis, S. mutans, S. oralis, S. sanguinis, S. sobrinus, milleri group)

A, bacitracin susceptible: S. pyogenes (Scarlet fever, Erysipelas, Rheumatic fever, Streptococcal pharyngitis)

B, bacitracin resistant, CAMP test+: S. agalactiae
γ
D, BEA+: Streptococcus bovis
Enterococcus
BEA+: Enterococcus faecalis (Urinary tract infection) · Enterococcus faecium
Bacillales
(Cat+)
Staphylococcus

Cg+ S. aureus (Staphylococcal scalded skin syndrome, Toxic shock syndrome, MRSA)

Cg- novobiocin susceptible (S. epidermidis) · novobiocin resistant (S. saprophyticus)
Bacillus anthracis (Anthrax) · Bacillus cereus (Food poisoning)
Listeria
Listeria monocytogenes (Listeriosis)
Clostridia
Clostridium (spore-forming)

motile: Clostridium difficile (Pseudomembranous colitis) · Clostridium botulinum (Botulism) · Clostridium tetani (Tetanus)

nonmotile: Clostridium perfringens (Gas gangrene, Clostridial necrotizing enteritis)
Peptostreptococcus (non-spore forming)
Peptostreptococcus magnus
Mollicutes
Mycoplasmataceae
Ureaplasma urealyticum (Ureaplasma infection) · Mycoplasma genitalium · Mycoplasma pneumoniae (Mycoplasma pneumonia)
Anaeroplasmatales
Erysipelothrix rhusiopathiae (Erysipeloid)

: BAC

bact (clas)

gr+f/gr+a(t)/gr-p(c)/gr-o

drug(J1p, w, n, m, vacc)