Image created by Dr. Michael J. Miller
A team of researchers from Karadeniz Technical University, Turkey, in collaboration with research centres in Italy, Greece, and Spain, has developed a rapid technique for detecting lactococcosis, a bacterial disease caused by Lactococcus, which affects both freshwater species such as rainbow trout, as well as marine fish like gilthead sea bream and European sea bass.
This is a multiplex PCR assay, a technique that allows the simultaneous amplification and detection of multiple DNA sequences specific to the pathogens involved. Specifically, this technique allows researchers to simultaneously identify and differentiate between Lactococcus garvieae and Lactococcus petauri.
The method is fast, specific, and accurate, as it provides results in less than two hours. Moreover, it is highly sensitive, with detection limits of 5 CFU (colony-forming units, which measure the number of viable bacteria present) for Lactococcus garvieae and 4 CFU for Lactococcus petauri in pure cultures, making it suitable for routine diagnostic laboratories.
In addition to rapid detection of disease outbreaks, the technique can also be used as a preventative monitoring tool, allowing early detection of bacteria in asymptomatic fish before visible symptoms occur. This allows control measures to be implemented more quickly and significant economic losses to be avoided.
The use of this technique can also be useful for epidemiological research, contributing to a better understanding of how the disease spreads and the environmental factors that facilitate its occurrence.
Since lactococcosis affects both freshwater and marine species, the multiplex PCR assay can be applied to rainbow trout, gilthead sea bream, and European sea bass, making it a versatile tool for aquaculture health management.