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Smear and Culture (only) of Acid Fast Bacilli

Test Code

AFB7

Description

This test includes AFB smear and culture from a clinical specimen. Growth of acid-fast bacilli is reported but full identification is not performed.

The AFB smear is a direct fluorescent stain from the specimen and can be used to quickly establish the presence of mycobacteria. The AFB culture is the inoculation of a clinical specimen onto multiple media types followed by monitoring for six weeks. Growth of any AFB (i.e. mycobacteria) or partially acid fast organisms (e.g. aerobic actinomycetes) is reported.

This test order is typically a component of other workup algorithms (e.g. AFB1 and AFB3). It is used on its own only in specific circumstances and after discussion with the laboratory.

Collection/Transport

Collect

Specimen	Preferred Volume	Unacceptable Volume	Collection Container	Total stability time, including transport
Sputum (expectorated or induced)	5-10 mL	<3 mL	Sterile, leak-proof container.	7 days refrigerated; 72 hours ambient.
Lower respiratory tract (e.g. bronchoalveolar lavage, bronchial washes etc.)	5-10 mL	<3 mL	Collect washing and aspirates in a sputum trap. Place brushes in a sterile, leak-proof container with up to 5 mL sterile non-bacteriostatic saline.
Body Fluids (pericardial, synovial, pleural etc.)	2-4 mL	<2 mL	Sterile, leak-proof container.
Cerebrospinal fluid (CSF)	2-4 mL	<2 mL refrigerated/frozen CSF.	Sterile, leak-proof container.	72 hours ambient. This source should not be refrigerated.
Fresh Tissue	1-2 g	<1 g or tissue submitted on a dry swab or fixed in formalin or other preservatives.	Sterile, leak-proof container with tissue submerged in sterile non-bacteriostatic saline.
Blood	5-10 mL	<5 mL or blood collected in a red-top, EDTA (purple-top) or ACD (yellow-top) tubes.	Sterile, leak-proof blood collection green (heparin) or yellow (SPS) top tube.
Gastric lavage or wash	10 mL required	<10 mL or a specimen that has not been neutralized within 1 hour of collection.	Sterile, leak-proof container. Neutralize specimen within 4 hours of collection with 100 mg of sodium carbonate.
Urine	5-10 mL required	<3 mL, Pooled urine specimen, or a urine specimen that has been mixed with preservatives.	Sterile, leak-proof container.	7 days refrigerated.
Stool	1-2 g	<1 g or a stool specimen in PVA, formalin, or other preservative, rectal swabs.	Sterile, leak-proof container.	7 days refrigerated.

Unacceptable Conditions

Samples collected in wax containers are not acceptable. Wax containers may produce false-positive smear results.
Swabs are not recommended for the isolation of mycobacteria, since they provide limited material and the hydrophobicity of the mycobacterial cell envelop often compromises a transfer from the swabs onto solid media or into broth media.
Specimen received in the lab 14 days post-collection

Notes

Stool cultures for mycobacteria are not encouraged.
AFB smear is not performed for urine, stool, or blood.

Test Detail

Performed

Typically all days.

Methodology

When appropriate, specimens are processed using a standard digestion/decontamination procedure. An acid fast smear is performed from the processed specimen using a florescent auramine stain. Specimens are cultured on three solid and one liquid media then incubated for 6 weeks.

Turnaround Time

AFB Smear reported within 24 hours. Note that AFB smears are not performed for urine, stool, or blood.
The final report for the AFB culture is issued at 6 weeks. Solid media cultures are read at 1, 3, and 6 weeks. Liquid media cultures are continuously monitored. Positive cultures are reported at the time of positivity and negative cultures are reported at 1, 3, and 6 weeks. In some cases, media may be incubated for up to 8 weeks and if positive, a supplemental report will be issued.

Lab Department

Infectious Disease Laboratory, Mycobacteriology

Synonyms

AFB7, mycobacterial smear and culture

Reference method, no special licensing required

Result Interpretation

Reference Interval

Negative for acid fast bacilli.

Interpretive Data

Test	Interpretations
AFB Smear	Fluorochrome stain read at 400X No AFB found Doubtful: Repeat specimen recommended 1 to 2 AFB seen/ 70 fields observed 1+= 2-18 AFB/ 50 fields observed 2+= 4 to 36 AFB/ 10 fields observed 3+= 4-36 AFB/field observed 4+= >36 AFB/field observed
AFB Culture	Negative cultures are reported as negative for growth Positive cultures are reported as organisms recovered with a colony count where possible (CFU/mL)

Fees/Coding

CPT Code

This is a test algorithm. When it is ordered, smear and culture are typically performed.

Test	Method	CPT code	Billing code	When will this be applied?
AFB Smear	Fluorchrome stain	87206	CXAFB1	All samples, except blood, stool and urine
AFB Culture	Specimen processing	87015	CXAFB2	All samples
AFB Culture and Presumptive ID	Culture	87116	CXAFB3	All samples

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Smear and Culture (only) of Acid Fast Bacilli

Test Code

Description

Collection/Transport

Collect

Unacceptable Conditions

Notes

Test Detail

Performed

Methodology

Turnaround Time

Lab Department

Synonyms

Result Interpretation

Reference Interval

Interpretive Data

Fees/Coding

CPT Code

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Advanced Diagnostic Laboratories

Overview Search Tests

Smear and Culture (only) of Acid Fast Bacilli

Test Code

Description

Collection/Transport

Collect

Unacceptable Conditions

Notes

Test Detail

Performed

Methodology

Turnaround Time

Lab Department

Synonyms

Result Interpretation

Reference Interval

Interpretive Data

Fees/Coding

CPT Code

Recently Viewed Tests

Overview

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