Question

A 10-year-old girl presents with a sore throat and fever that has lasted 1 day. She appears flushed and moderately ill. Physical examination reveals a temperature of 39°C, tender bilateral anterior cervical lymph nodes that are 1 to 2 cm in the greatest dimension, and erythema and whitish-yellow exudate over enlarged tonsils and the posterior pharynx.

Diagnostic Testing Results:

Fever: 39°C

Cough: No cough present in patient

Cervical nodes: Swollen and tender

Tonsils: Tonsillar swelling or exudate

Patient Referral:

Due to symptoms, patient had their throat swabbed.

1. Based on what you know about GAS, would you have been able to diagnose her quickly from the clinical symptoms only?

2. Assume a Rapid-antigen test was ordered. What is this test detecting? In what situation would a culture be ordered?

Answer 1

Tonsilitis: Inflammation of the Tonsils . Tonsils are a pair of small masses of lymphoid tissue that lie on each side of the throat and that help to protect the body against infection.

1. GAS : Group A Streptococci.

Streprpcoccus is a spherical Gram positive bacterium of the genus Streptococcus . Although commonly found in human mouth and gut. Even though many of the species are non pathogenic, other specious can cause disease including Strep throat and other more serious conditions.

Clinical symptoms that she presented, makes the diagnosis easy for her condition. As the knowledge gained from the academic lessons regarding Acute tonsilitis and Strep throat that primarily caused by GAS.   

GAS or Group A Streptococcus   mainly causes Strep throat or Acute pharyngitis , an Inflammation of oropharynx. The main causative agent might be Steptococcus Pyogenes . The main clinical features are sudden onset of sore throat , fever , enlargement of tonsils with or without exudate ,  erythema of oro- pharynx , enlargement and tenderness of bilateral , anterior cervical lymph nodes etc. These symptoms all are present in the girl.

2. Rapid Antigen test: A rapid antigen detection test ( RADT) in GAS susceptible case is called a Rapid strep test ( RST) and is used in the diagnosis of bacterial pharyngitis caused by Group A Streptococci. A throat swab is the sample used for RST. A visible reaction will takes place , when the mucous from the throat is mixed with a reagent thst containing specific antibodies , that have an affinity to the strep antigens . A positive result may get based on the visible reaction.  

The test is detecting the presence of Antigen ( bacteria)in the sample fro the throat.

A culture can be ordered, if there is a time availability . It will take 1 or two days to get the culture results, whereas a RST results can get within 10 minutes. Throat culture helps the physician to differentiate the presence of infection, wheather it is a strep throat, thrush , Diphtheria or scarlet fever. It helps to identify the causative agent correctl. In case the Rapid Strep Test ( RST) is negative , the Doctor can order for a throat swab culture.