Clinics and Departments

Laboratory Services

Lab Dept:

Microbiology/Virology

Test Name:

THROAT CULTURE, ROUTINE

General Information

Lab Order Codes:

TC

Synonyms:

Culture, Throat (Routine); Culture, Throat (Cystic Fibrosis); Culture, Throat for Diphtheria; Culture, Throat for N. meningitidis; Diphtheria Culture; Throat Culture, Cystic Fibrosis; Cystic Fibrosis Culture, Throat

CPT Codes:

87070 – Culture, bacterial; any other source except urine, blood or stool, with isolation and presumptive identification of isolates

The following testing may be added if appropriate based on findings for organism identification (multiple additions are possible if more than one organism is identified) and to aid in patient treatment management.

87077 – Aerobic isolate, additional methods required for definitive identification, each isolate (if appropriate)
87106 – Culture, fungi, definitive identification, each organism, yeast (if appropriate)
87107 – Culture, mold, definitive identification, each organism, mold (if appropriate)
87206 – Smear, primary source with interpretation, fluorescent and/or acid fast stain for bacteria, fungi or cell types (if appropriate)
87184 – Susceptibility studies, disk method, per plate (if appropriate)
87185 – Enzyme detection (eg, beta lactamase), per enzyme (if appropriate)
87186 – Susceptibility studies, microdilution or agar dilution, each multi-antimicrobial, per plate (if appropriate)

Test Includes:

Culture for routine aerobic flora and Streptococcus pyogenes (group A streptococci).

Logistics

Lab Testing Sections:

Microbiology

Phone Numbers:

MIN Lab: 612-813-5866

STP Lab: 651-220-6555

Test Availability:

Daily, 24 hours

Turnaround Time:

Preliminary report available at 1 day, final report within 2 - 5 days.

Special Instructions:

Specimen site and date/time of collection are required for processing.
● Cultures suspecting C. diphtheriae, N. menigitidis and N. gonorrhoeae must be specified since special isolation procedures are required.
● Cultures from cystic fibrosis patients must be specified since special isolation procedures are required.
● If Candida sp. or viruses are suspected, refer to Yeast Culture Only and Viral Culture.
● Note if specimen is from a peritonsillar abscess.

Specimen

Specimen Type:

Throat swab

Container:

Swab transport medium

Collection:

1. Depress tongue with tongue depressor.
2.
Sample the posterior pharynx, tonsils, and inflamed areas with a sterile swab.
3.
Place swab in transport medium.

Transport/Storage:

Transport to the Microbiology Laboratory immediately at room temperature.

Sample Rejection:

Specimen with a transit time exceeding 2 hours after collection; specimen not submitted in appropriate transport container; improperly labeled specimen. If an unacceptable specimen is received, the physician or nursing station will be notified and another specimen will be requested before the specimen is discarded.

Interpretive

Reference Range:

Usual upper respiratory flora

Alert Value:

● Gram-negative rods identified as ESBL or Carbapenemase producers will be called to the physician or patient’s nurse. Infection Prevention will be notified.
● If MRSA is isolated for the first time, and the patient location is not Emergency department, the result will be called to the physician or patient’s nurse.
● If Group A Streptococcus or Burkholderia are isolated from a patient with CF, the result will be called to the physician or patient’s nurse.
● If Corynebacterium diphtheria is isolated, the result will be called to the physician or patient’s nurse.

Limitations:

● Special media is required for the isolation of Corynebacterium diphtheriae, N. meningitidis and N. gonorrhoeae.
● Use of throat cultures to aid in diagnosis of lower respiratory tract disease is not recommended since the results of such cultures often produce dangerously misleading information.

Methodology:

Culture

Contraindications:

Throat cultures are not advised for patients with inflamed epiglottis. Swabbing the epiglottis may precipitate acute respiratory obstruction.

Additional Information:

Usual upper respiratory tract flora includes alpha and non-hemolytic streptococci, micrococci, Corynebacterium sp., coagulase-negative staphylococci, Neisseria sp., Lactobacillus sp., Stomatococcus sp., S. pneumoniae, Actinomyces sp, Haemophilus sp., M. catarrhalis, and a few colonies of S. aureus, Gram-negative rods, and yeast. If present in significant numbers, H. influenzae, S. pneumoniae, S. aureus, and M. catarrhalis will be identified. Mucoid strains of P. aeruginosa are generally associated with cystic fibrosis.

The majority of cases of pharyngitis are of viral etiology. At least 9 different viruses have been implicated, some of them producing symptoms indistinguishable from those of streptococcal infection such as severe sore throat with ulceration, exudate, and fever. Most cases of bacterial pharyngitis (up to 98%) are caused by beta-hemolytic streptococci, primarily those in group A. There is some evidence that other beta-hemolytic streptococci, especially groups C and G and Arcanobacterium haemolyticum (Corynebacterium) may occasionally cause pharyngitis. These organisms are thought to be self-limiting and so far have not been associated with serious sequelae as seen with group A.

References:

Cook, JH, and M Pezzlo (1992). Specimen receipt and accessioning. Section 1. Aerobic bacteriology, 1.2.1-4. In HD Isenberg (ed) Clinical Microbiology Procedures Handbook. American Society for Microbiology, Washington DC

Miller, J Michael (1999) A Guide To Specimen Management in Clinical Microbiology, American Society for Microbiology, Washington DC

Miller, J Michael, and HT Holmes (1999) Specimen Collection, Transport, and Storage In PR Murray et al, (ed), Manual of Clinical Microbiology, 7th edition, American Society for Microbiology, Washington DC, pp 33-104

Updated:

3/23/2010: CPT Update
3/7/2011: CPT Update
6/20/2012: Alert value added



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