Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2018

Diagnosing Chlamydia psittaci and Chlamydia pecorum in less than an hour using rapid novel isothermal amplification assays (#160)

Martina Jelocnik 1 , Mominul Islam 1 , Danielle Madden 1 , Cheryl Jenkins 2 , James Branley 3 , Scott Carver 4 , Adam Polkinghorne 1
  1. University of Sunshine Coast, BRISBANE, QLD, Australia
  2. Elizabeth Macarthur Agricultural Institute, NSW Department of Primary Industries, Menangle, NSW, Australia
  3. Nepean Hospital, Penrith, NSW, Australia
  4. University of Tasmania, Hobart, Tasmania, Australia

Chlamydia psittaci and Chlamydia pecorum are important veterinary pathogens, with the former also being responsible for zoonoses, and the latter adversely affecting koala populations in Australia and livestock globally. In Australia, the diagnosis and detection of these organisms is costly, laborious, not standardised and mainly restricted to research, challenging efforts to manage and treat infected hosts. The ability to provide a rapid detection of such infections becomes of increasing significance when zoonotic transmission is suspected for C. psittaci, and is also attractive for Chlamydia detection in wild animals such as koala due to the typical logistics associated with field sampling and treatment. Loop Mediated Isothermal Amplification (LAMP) assays are popular for use in pathogen diagnostics. We have developed and evaluated rapid and robust C. psittaci-specific and C. pecorum-specific LAMP assays for detection of these organisms in either laboratory or POC settings.

LAMP assays, run in a Fluorometer as well as thermal block targeted a (i) C. psittaci-specific Cps_0607 gene; and (ii) 209bp region of a C. pecorum-specific gene CpecG_0573, respectively, and were evaluated using a range of samples previously screened using species-specific qPCRs. Both LAMP assays were demonstrated to species-specific, highly reproducible and to be able to detect as little as 10 genome copy number/reaction, with a mean amplification time of 14 and 24 min for C. psittaci and C. pecorum, respectively. When testing clinical samples, the overall congruence between the newly developed LAMP assays and qPCR was 92.3% for C. psittaci (91.7% sensitivity and 92.9% specificity); and 84.1% for C. pecorum (90.6% sensitivity and 77.4% specificity). We also performed a pilot study using the C. psittaci LAMP assay at the Scone Equine Hospital where we demonstrated utility of the LAMP tests.

A recent Australian equine C. psittaci epizootic (with documented zoonotic events) and rampantly spreading chlamydiosis in koalas further demonstrates the need for POC assays to rapidly diagnose these pathogens. With further development and a focus on the preparation of these assays at the POC, it is anticipated that both tests may fill an important niche in the repertoire of ancillary diagnostic tools available to clinicians.