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Test Code CHLG Chlamydia IgG, Immunofluorescence, Serum


Ordering Guidance


For suspected Chlamydia trachomatis infection, order either CTRNA / Chlamydia trachomatis, Nucleic Acid Amplification, Varies or CGRNA / Chlamydia trachomatis and Neisseria gonorrhoeae, Nucleic Acid Amplification, Varies.



Specimen Required


Specimen Required

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.3 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Secondary ID

619389

Useful For

Assessing IgG antibody levels to aid in the clinical diagnosis of Chlamydia pneumoniae or Chlamydia psittaci infections

Testing Algorithm

This test includes testing for Chlamydia pneumoniae IgG and Chlamydia psittaci IgG.

Method Name

Micro-Immunofluorescent Antibody (MIF) Assay

Reporting Name

Chlamydia IgG, IFA, S

Specimen Type

Serum

Specimen Minimum Volume

0.15 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 30 days
  Frozen  30 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject
Heat-inactivated specimen Reject

Clinical Information

Members of the family Chlamydiaceae are small, nonmotile, gram-negative, obligate intracellular organisms that grow in the cytoplasm of host cells. While there are at least 9 species within the Chlamydia genus, 3 are clinically significant, including Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci.

 

The chlamydial life cycle can be divided into 2 distinct phases: an extracellular, nonreplicating, infectious stage and an obligate intracellular, replicating, noninfectious stage. The infectious form, or elementary body (EB), attaches to the target cell membrane and enters the cell via a phagosome. After cell entry, the EB reorganizes into reticulate particles (forming inclusion bodies) and binary fission begins. After 18 to 24 hours, reticulate particles condense to form EBs. These new EBs are released, beginning another infection cycle.

 

C psittaci is the causative agent of psittacosis, a disease characterized by pneumonia, headache, altered mentation, and hepatosplenomegaly. Psittacosis is acquired by airborne transmission from infected birds.

 

C pneumoniae (formerly known as Taiwan acute respiratory agent and, more recently, as Chlamydophila pneumoniae) causes pneumonia in humans. It is unique because it is a primary pathogen of humans, is spread from human to human, and apparently has no animal or bird host. C pneumoniae is responsible for approximately 10% of pneumonia cases.

Reference Values

Chlamydia pneumoniae

<1:64

 

Chlamydia psittaci

<1:64

Interpretation

Chlamydia pneumoniae

≥1:512

IgG endpoint titers of 1:512 or more are considered presumptive evidence of current infection.

 

≥1:64 and <1:512

A single specimen endpoint titer of 1:64 to 1:512 should be considered evidence of infection at an undetermined time. A second specimen collected 10 to 21 days after the original collection should be tested in parallel with the first. If the second specimen exhibits a titer 1:512 or more or a 4-fold increase over that of the initial specimen, current (acute) infection is indicated. Unchanging titers from 1:64 to 1:512 suggest past infection.

 

<1:64

IgG endpoint titers below 1:64 suggest that the patient does not have a current infection. These antibody levels may be found in patients with either no history of chlamydial infection or those with past infection whose antibody levels have dropped below detectable levels.

 

C pneumoniae antibody is detectable in 25% to 45% of adults tested.

 

Chlamydia psittaci

≥1:64

IgG endpoint titers of 1:64 or more are considered presumptive evidence of current infection.

 

<1:64

IgG endpoint titers below 1:64 suggest that the patient does not have a current infection. These antibody levels may be found in patients with either no history of chlamydial infection or those with past infection whose antibody levels have dropped below detectable levels.

CPT Code Information

86631 x 2

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CHLG Chlamydia IgG, IFA, S 10848-0

 

Result ID Test Result Name Result LOINC Value
619392 C. pneumoniae IgG In Process
619393 C. psittaci IgG In Process