Throat (Swab and Washing) Culture- Procedure, Interpretation and Clinical Implications
- Throat cultures are important for diagnosis of the following conditions:
- Streptococcal sore throat
- Diphtheriae obtain both throat and nasopharyngeal cultures
- Thrush (candidal infection)
- Viral infection
- Tonsillar infection
- Gonococcal pharyngitis
- Bordetella pertussis
- Throat cultures can establish the focus of infection in:
- Scarlet fever
- Rheumatic fever
- Acute hemorrhagic glomerulonephritis
Throat cultures can be used to detect the carrier state of persons harboring such organisms as:
- β-Hemolytic streptococcus
- Neisseria meningitidis
- Corynebacterium diphtheriae
- S. aureus
- Gram Negative Bacilli
- Yeast Cells
Negative: Normal oral flora
Positive findings are associated with infection in the presence of:
- Group A hemolytic streptococci
- N. gonorrhoeae
- C. diphtheriae
- B. pertussis
- Adenovirus and herpesvirus
- Mycoplasma and Chlamydia
Throat Swab Culture Procedure
- For adult patients:
- Place the patient’s mouth in good visual light.
- Use a sterile throat culture kit with a polyester-tipped applicator or swab and a sterile container or tube of culture medium.
- Tilt head back. Depress the patient’s tongue with a tongue blade and visualize the throat as well as possible. Rotate the swab firmly and gently over the back of the throat, around both tonsils or fossae, and on areas of inflammation, exudation, or ulceration.
- Avoid touching the tongue or lips with the swab.
- Because most patients gag or cough, the collector should wear a facemask for protection.
- Place the swab into the designated receptacle so that it comes in contact with the culture medium. Immediately send the specimen to the laboratory.
- Refrigerate the throat culture if examination is delayed.
- For pediatric patients:
- Seat the patient in the adult’s lap.
- Have the adult encircle the child’s arms and chest to prevent the child from moving.
- Place one hand on the child’s forehead to stabilize the head and to prevent movement.
- Proceed with the technique used for collection of the throat and nose culture as described for adults.
- For throat washings:
- Have the patient gargle with 5 to 10 mL of sterile saline solution and then expectorate it into a sterile cup.
- Remember that this method provides more specimen than a throat swab and is more definitive for viral isolation.