Sample Guide Index

Sampling Guide 1

Chlamydia - Felines and Avians.

DIAGNOSTIC TESTS

Confirmation of Chlamydia psittaci infection relies upon the detection of genus specific lipopolysaccharide antigen (immunochromatography) or species specific Chlamydia psittaci DNA (polymerase chain reaction - PCR).

ANTIGEN TEST

Samples:

Conjunctival swab, post mortem tissues.

 

Use dry cotton swabs on plastic, wire or paper sticks. Wood sticks must not be used. Transport medium is not required. Swabs are available free of charge on request.

Techniques:

Conjunctival swabs - reflect the eyelid and roll the swab across the conjunctiva to harvest cells.

 

PM tissues - sear the tissue surface and stab insert the swab, rotating to harvest cells. Suitable avian p.m. tissues are liver, spleen and lungs.

Comments:

Swabs from most sites can be processed but faecal swabs are not suitable and may give false positive results. A PCR test is recommended for this application. Samples should be dispatched promptly. If delayed then samples may be stored at 2-8 ° C for up to 48 hours.

PCR FOR CHLAMYDIAL DNA

Samples:

Conjunctival swab, faeces (birds only), tissue, blood.

 

Use dry cotton swabs on plastic, wire or paper sticks. Wood sticks must not be used (possible false negative results). Faeces and tissues should be submitted fresh, unfixed in a sterile container. Blood samples should be submitted in EDTA. Swabs, sterile universals and EDTA tubes are available free of charge on request.

Techniques:

Conjunctival swabs - reflect the eyelid and roll the swab across the conjunctiva to harvest cells.

 

Faeces - with an asymptomatic carrier bird, take faeces on days 1, 3, 10 and 12 and pool in a sterile container without fixative. 0.5g is the optimum amount (about 1/4 tsp) but smaller amounts will still be tested. A single sample from a diarrhoeic bird may be sufficient to demonstrate the organism.

 

PM tissues - sear the tissue surface and stab insert the swab, rotating to harvest cells Suitable avian p.m. tissues are liver, spleen and lungs. Alternatively whole unfixed tissues may be submitted.

Comments:

Faecal samples are the preferred samples in avian species. A virulent infection may kill the bird before colonisation of the intestines occurs therefore ocular or tracheal swabs should also be submitted from symptomatic birds. In cats ocular infections may not lead to colonisation of the intestines therefore ocular swabs should be submitted from symptomatic cases. PCR is more sensitive than the antigen ELISA. Samples are robust and there are no special handling requirements.


ZOONOTIC HAZARDS

To minimise the zoonotic hazards, carcases of potentially infected birds should be soaked in a quaternary ammonium compound disinfectant (1:1000 dilution) prior to post mortem or dispatch to the laboratory. Carcases that are dispatched to the laboratory should be placed in an inner polythene bag, dipped in disinfectant, labelled with a biohazard label and should then be sealed in an impervious outer container with sufficient absorbant material to absorb any leakage. Post mortem of a potentially infected bird should always be commenced in a microbiology safety cabinet in order to screen the bird for possible infection with Chlamydia psittaci . In this laboratory the immunochromatography antigen test is applied to a liver swab and, if a negative result is achieved, the carcase is removed to the post mortem facility for further investigation. This procedure is routinely followed for all carcases of cage birds or pigeons submitted to the laboratory for post mortem. Owners of cats in which chlamydial infection has been diagnosed should be advised to maintain hygienic precautions when handling the cat or litter tray.

Test Code

Test Name

Sample

CHLA

Chlamydial Antigen

See above

CHLB

Chlamydial DNA (PCR)

See above

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