From the Royal College of Pathologists of Australasia
Medical microbiology is undergoing a revolution explains Dr Jenny Robson and Dr Michael Harrison, microbiology representatives from The Royal College of Pathologists of Australasia (RCPA). According to Dr Robson, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF MS) is the biggest thing to happen in microbiology laboratories in the past 50 years, offering improved testing and patient care.
"MALDI-TOF MS allows us [microbiologists] to identify bacteria using completely different principles through the analysis of the proteins that a bacterium produces. MALDI-TOF MS provides rapid organism identification and, in some cases, even susceptibility and resistance testing. This has the potential to provide quicker results to the clinician, enabling a targeted and timely antibiotic therapy. Organisms that have, in the past, been difficult to recognise can often be diagnosed much more rapidly.
Initially pioneered in the 1990's, MALDI-TOF MS has only become a reality in the past couple years with many large laboratories in Australia now using this advanced technology. Dr Robson explains that it has had a very positive impact when testing for those bacterial infections that require a rapid turn-around time, for example Vancomycin Resistant Enterococci (VRE), an increasingly common hospital pathogen that requires rapid infection control precautions to control its spread.
"Over the past 12 months, the introduction of these machines to laboratories for routine diagnostic work has provided a whole new mindset and has made the process more user friendly. Historically, it took a long time to identify bacteria and yeasts. Firstly, we had to grow these organisms on agar plates which can take some hours or even days, and then we use identification tests that take a similar length of time. Now, the diagnosis is almost immediate with the time of the entire process basically changing from as much as five days to less than five minutes," says Dr Robson.
In addition to the improved speed of testing, these tests are relatively inexpensive once the hardware has been purchased and cost a fraction of the tests they have replaced. This may allow more complete characterization of pathogens in a clinical setting. However, Dr Michael Harrison cautions that it is still early days in these new developments. There are still some deficiencies but the databases are improving all the time. Newer applications to directly identify organisms from samples such as blood cultures are also underway.
"Microbiology is a conservative area in terms of technology change. When looking at colonies, the judgment of an experienced microbiologist is still hugely significant whereas the results of MALDI-TOF MS are purely dependent on the computer database," says Dr Harrison.
Nevertheless, Dr Harrison rates the significance of MALDI-TOF MS in microbiology as equivalent to the invention of the combustion engine. He explains that young scientists who are new to the field will benefit from this technology.
"For the profession, it also offers vast training opportunities. As most of our work has been reliant upon the experience of individual microbiologists, in the future, it may be that we won't need to tell young scientists what we think about a sample in order to explain why we think that is the case. They can put it through the MALDI-TOF MS and see for themselves," says Dr Harrison.