Streptococcalpharyngitis, also known as strep throat, is most often caused bacterially byStreptococcus pyogenes, also known as part of group A Streptococcus, or GAS(CDC, 2016). This type of bacteria isbeta-hemolytic that belongs to the Lancefield serogroup A (Medscape, 2017). Acute pharyngitis accounts for about 12million ambulatory calls in the United States and is extremely common,especially in the winter and early spring (Medscape, 2017). Clinically,strep pharyngitis presents with a common set of symptoms, which are oftendiagnosed based on symptoms in association with in-office lab tests. The condition is spread directly from personto person, especially in places such as schools, child daycares or large publicspaces (CDC, 2016).
The common symptomsinclude sore throat, fever over 100.4 degrees F, exudates noted on the tonsilsand adenopathy of cervical nodes (Choby,2009). Some patients also presentwith a scalatiniform rash which will begin within the first couple days of theinfections and causes an erythematous rash on the neck and limbs (Medscape). Sincesome of symptoms can create an extensive differential, a diagnostic test ofGroup A step bacteria can be confirmed by a rapid antigen detection test (RADT)or a throat culture (CDC, 2016).
RADTsare speedy and allow for a clinician to know whether or not antibiotics are thecorrect line of treatment for each patient. However, RADTs can be higher in cost and are reported to have a lowersensitivity compared with other cultures (Medscape, 2017). RADT ranges from 90%-99% specificity, andapproximately 70% sensitive, but the AAP recommends that a negative RADT resultneeds to be confirmed with a throat culture (Choby, 2009). Theease of a throat culture or RADT allow for clinicians to differentiate thecauses of a sore throat in many different settings, such as Urgent Care or aprimary care setting. The sample isobtained from the posterior pharynx or tonsils (Medscape, 2017).
In the 1950s, acute rheumatic fever was themain focus of treating pharyngitis. Since the incidence of rheumatic fever has substantially decreased, thefocus was shifted to treating GAS infections with tests such as RADT (Stewart, 2014). Today, newer RADT uses what is called opticalimmunoassay (OIA) technology to find the carbohydrates in the cell wall. This allows for a sensitivity that is muchcloser to that of a throat culture (Medscape, 2017). Even beyond thistechnology is a test which uses nucleic acid to identify the bacteria, and issaid to be about 95%-100% specific and 86%-95% sensitive (Medscape, 2017). GroupA strep pharyngitis is very prevalent in children, which makes a quickdiagnosis extremely important to keep the infection from spreading from childto child. Although throat culture isconsidered to be the gold standard for diagnosis of bacterial strep, the rapidtest is much quicker, as the throat culture has a 24-48 hour turn around(Medscape, 2017). Often, clinicians areguilty of prescribing antibiotics based on a false positive RADT test withoutconfirming with a throat culture.
Thisis a large component in the overuse of antibiotics in a clinical setting. With the help of both critical physicians andother staff, these types of errors can be decreased and more correct diagnosis’and treatments will become ubiquitous. Bacterial Pharyngitis Workup. (2017, November 17).Retrieved January 21, 2018, from https://emedicine.
medscape.com/article/225243-workup Choby, B.A. (2009, March 01). Diagnosis and Treatment ofStreptococcal Pharyngitis. Retrieved January 21, 2018, from https://www.aafp.org/afp/2009/0301/p383.
htmlPharyngitis (Strep Throat). (2016, September 16).Retrieved January 21, 2018, from https://www.cdc.gov/groupastrep/diseases-hcp/strep-throat.
html Stewart, E.H., Davis, B., Clemans-Taylor, B.L.,Littenberg, B., Estrada, C.
A., & Centor, R.M. (2014). Rapid Antigen Group A Streptococcus Test to DiagnosePharyngitis: A Systemic Review and Meta- Analysis.
Retireved January 21, 2018, from medhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC4219770/