Scientists have carried out the largest ever genomic study of Cronobacter, paving the way for the development of new methods to rapidly detect the deadly infection-causing bacterium in food, clinical materials and the environment.
An international research team, led by Nottingham Trent University, has for the first time been able to DNA sequence strains across the entire Cronobacter genus, allowing them to determine and characterise a hugely diverse range of genes.
The researchers – writing for the science journal PLoS One - believe this data could prove crucial in the fight against Cronobacter. This opportunistic bacterial pathogen can occur in all age groups, but causes the most severe cases in new born babies, including necrotizing enterocolitis and meningitis. The vast majority of these cases lead to death or permanent brain damage.
As Cronobacter has only recently been recognised, knowledge of the bacterium – and therefore detection methods – have been relatively poor.
But now the research team has been able to investigate the DNA of Cronobacter genomes across all seven species – C. sakazakii, C. malonaticus, C. turicensis, C. dublinensis, C. muytjensii, C. universalis, and C. condimenti.
Considerable variations in traits were found among all the Cronobacter genomes. These included variations in secretion systems which serve to transport bacteria to the exterior of a cell, resistance to metals including tellurite, copper and silver, and adhesins, which allow bacteria to attach to other cells or inanimate surfaces.
The data generated is also the first to show the core genes in the Cronobacter genus and supports the hypothesis that the Cronobacter organism has evolved from growing on plants about 40 million years ago.
Scientists hope the gene sequence data can be used to design genus and species-specific detection methods.
The research team also involved the University of California, Irvine, in the United States – who used advanced computer analysis to identify the unique genes between each species and their relationships – and Life Technologies Corporation in the US and Germany, which funded and performed the genome sequencing.
The work follows recent studies at Nottingham Trent University, which revealed new previously unrecognised species of Cronobacter, and that neonatal meningitis was primarily associated with certain Cronobacter strains.
Stephen Forsythe, Professor in Microbiology and member of the Pathogen Research Group at Nottingham Trent University, said: “This study shows the significant diversity of the Cronobacter bacterium, but at the same time equips us with the tools to learn how to control it. Until recently the bacterium was poorly known and poorly understood, but in the last five to ten years the association with infections has been become more widely recognised.
“It’s very important that rapid and effective methods for identifying this organism are developed as quickly as possible, and this work is a step in the right direction.”
Professor Michael McClelland of the University of California, Irvine, said: “High-throughput sequencing has revolutionised our ability to perform comparative genomics within bacterial species and between related species.
“An understanding of genome sequence diversity greatly accelerates the identification of potential diagnostics in the short term, while contributing vital foundational information to the ultimate goal of reducing the burden of disease through prevention and therapeutics.”
“Comparative Analysis of Genome Sequences Covering the Seven Cronobacter Species”, Susan Joseph et al.
PLoS ONE 7(11): e49455. doi:10.1371/journal.pone.0049455