Catching and measuring sexually transmitted bugs

A new automated system for testing sexually transmitted infections is proving highly accurate and very efficient.

In 2010, Aotea Pathology was one of the world's first laboratories to get the Roche Cobas 4800 system: a specialised machine that uses DNA from patient samples to diagnose Chlamydia trachomatis, a sexually transmitted infection, and human papillomavirus, a virus that may cause warts or cervical cancer.

Or, as Dr Collette Bromhead, our head of molecular biology, describes the work: "Bugs: we catch them, kill them, cook them and measure them!"

Each swab comes to us in a solution that kick starts the test by cracking the cells open to let out their DNA.

Our laboratory staff then load the samples into the Cobas 4800 for testing. In the first step, each patient sample is mixed with magnetic glass particles which attract the DNA and allow it to be “washed” clean before being mixed with test reagents.

After that the DNA is put through a complex process called Polymerase Chain Reaction or PCR which amplifies any bugs that are present.

Fluorescence generated by this process is measured to determine if a patient is infected. A computer compiles the result for each sample.

Using this system saves us a lot of manual work and we can rapidly test up to 400 specimens a day. The PCR test is also very sensitive and can detect right down to just one or two bugs so we can pick up more instances of infection.

It's proving to be a great system for enabling us to help doctors to better care for their patients.