Application of a nested, multiplex PCR to psittacosis outbreaks

Area of Science:

• Microbiology
• Molecular Biology
• Veterinary Medicine

Background:

• Chlamydiae are significant bacterial pathogens affecting both humans and animals.
• Accurate and sensitive detection methods are crucial for diagnosing and controlling chlamydial infections.
• Existing diagnostic methods may face limitations with sensitivity and inhibitors in clinical specimens.

Purpose of the Study:

• To develop a highly sensitive, nested, multiplex PCR assay for the simultaneous detection of three Chlamydia species.
• To differentiate between *Chlamydia pneumoniae*, *Chlamydia psittaci*, and *Chlamydia trachomatis*.
• To improve the detection rate of *Chlamydia psittaci* in avian specimens.

Main Methods:

• Development of a two-step nested, multiplex PCR targeting the 16S rRNA gene.
• The first PCR step was genus-specific for Chlamydiae.
• The second PCR step was multiplexed to differentiate between *C. pneumoniae*, *C. psittaci*, and *C. trachomatis* based on amplicon size.

Main Results:

• The assay demonstrated a limit of detection of 5 inclusion-forming units for each PCR step.
• The method successfully identified *C. psittaci* transmission from pet store birds to humans during an outbreak.
• PCR application to avian specimens significantly increased the detection rate of *C. psittaci* compared to traditional culture methods.

Conclusions:

• The developed nested, multiplex PCR is a sensitive and specific tool for simultaneous detection of three chlamydiae species.
• This assay is effective in identifying *C. psittaci* in both human and avian samples, aiding in outbreak investigations.
• The method offers improved diagnostic capabilities for chlamydial infections, particularly in avian populations.