Chlamydia psittaci and Chlamydia pecorum are successful widespread veterinary pathogens. In Australia, the diagnosis of these organisms is costly and laborious, challenging efforts to manage and treat infected hosts. While the options for Point-of-care (POC) testing are limited, the ability to provide rapid detection becomes of increasing significance when zoonotic transmission is suspected, such is the case for C. psittaci. POC testing is also attractive for Chlamydia detection in wild animals due to logistical challenges posed by field sampling and treatment. The latter problem is particularly acute for diagnosing infections in the native Australian marsupial, the koala. In the present study, we describe the development and evaluation of rapid and robust C. psittaci- and C. pecorum-specific Loop Mediated Isothermal Amplification (LAMP) assays for detection and diagnosis of these organisms in either laboratory or POC settings.
For LAMP assays, we targeted a 262bp region of the C. psittaci-specific Cps_0607 gene; and 209bp region of a C. pecorum-specific conserved gene CpecG_0573, respectively. LAMP assays were performed in a portable Real-Time Fluorometer Genie III, ideal for use at POC.
Both LAMP assays had analytical sensitivities of ten genome copies, comparable to that of currently used qPCR assays and were species-specific. The mean amplification time was 14.23 min compared to 90 - 120 min for qPCR. When testing clinical samples, the concordance between the qPCR assays with the newly developed LAMPs was 89% for C. psittaci with 92% sensitivity, and 83% for C. pecorum with 93.1% sensitivity. We also showed that a rapid processing method allows for chlamydial DNA detection using LAMP.
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.