Computational methods reveal how hospital-acquired bacteria spread

January 16, 2013, Academy of Finland

Scientists at the Academy of Finland's Centre of Excellence in Computational Inference Research have developed novel computational methods that have yielded essential knowledge of how hospital-acquired bacteria spread and develop. These new methods, based on randomised algorithms, make it possible to analyse extensive genomic data significantly faster and more efficiently than previously. By applying these results, it is possible to better follow hospital-acquired infections in the future, or even fight them in real time.

The new methods are used to develop models of the evolution of bacteria and viruses. "Essential for the evolution of the bacteria that cause hospital-acquired infections is the . It means that several different transfer genes between the lineages of the same and different species so that the bacterium becomes resistant to antibiotics and the virulence factor rapidly spreads in the population," explains group leader, Professor Jukka Corander. Corander's group is part of the Centre of Excellence in Computational Inference Research.

This so-called recombination of bacteria makes it much more complicated to carry out evolution analyses. To facilitate such analyses, Corander's group in cooperation with researchers from Harvard University and the Wellcome Trust Sanger Institute has developed a number of methods based on smart randomised algorithms. These methods facilitate efficient and reliable analyses of extensive . With the current, most commonly used this work would take several months or even several years.

Two of the group's methods have recently been applied by an international study. This study demonstrated that more than half of the of the MRSA bacteria (i.e. methicillin-resistant strains of ) is caused by horizontal genomic transfer. This shows that the of the strains of bacteria are necessary when investigating the spread of bacteria in a host population. This horizontal variation significantly distorts the results received from normal evolutionary analyses.

"On the basis of the results from these analyses, i.e. the evolutionary variation, we're able to estimate when a certain strain of the MRSA bacterium has entered a country and started to spread to hospitals. This is the first time we have been able to prove that the interplay between the horizontal genomic variation and the mutational genomic variation may vary significantly across geographical locations and even between individual hospitals," Corander says. According to Corander, these insights open up new opportunities for in-depth studies on the spread and variation of MRSA and related causalities.

In another recently published study, Corander's group investigated the origin and evolution of the Enterococcus faecium bacterium that has adapted to survive in hospital environments. By using its analysis methods, the group found out that the forms of the bacteria originate from several independent sources, which is contrary to previous knowledge. In the nuclear genome of hospital strains of E. faecium, fewer signs of horizontal transfer were found than expected. This discovery led to a hypothesis that strains of bacteria that have adapted to survive in hospital environments may become either genetically or ecologically more isolated after horizontal transfer.

MRSA is a globally spread bacterium that is especially troublesome in hospitals. It is resistant to most antibiotics and annually causes the death of tens of thousands of people in the US, for instance. According to cautious estimates, the annual costs incurred by MRSA infections amount to several billion US dollars. In recent years, the E. faecium has become one of the major causes of hospital-acquired infections and its antibiotic- have caused severe hospital epidemics worldwide.

Explore further: How one strain of MRSA becomes resistant to last-line antibiotic

More information: Santiago Castillo-Ramirez, Jukka Corander, Pekka Marttinen, Mona Aldeljawi, William P Hanage, Henrik Westh, Kit Boye, Zeynep Gulay, Stephen D Bentley, Julian Parkhill, Matthew T Holden and Edward J Feil (2012) Phylogeographic variation in recombination rates within a global clone of Methicillin-Resistant Staphylococcus aureus (MRSA) Genome Biology, 13:R126 doi:10.1186/gb-2012-13-12-r126.
genomebiology.com/2012/13/12/R126/abstract

Rob J. L. Willems, Janetta Top, Willem van Schaik, Helen Leavis, Marc Bonten, Jukka Sirén, William P Hanage and Jukka Corander (2012) Restricted gene flow among hospital subpopulations of Enterococcus faecium. mBio, 3, e00151-12.
mbio.asm.org/content/3/4/e00151-12.full.html#

Related Stories

How one strain of MRSA becomes resistant to last-line antibiotic

May 22, 2012
Researchers have uncovered what makes one particular strain of methicillin-resistant Staphylococcus aureus (MRSA) so proficient at picking up resistance genes, such as the one that makes it resistant to vancomycin, the last ...

Scientist warns of new MRSA threat

February 2, 2012
(Medical Xpress) -- An MRSA expert from the University’s Department of Biology & Biochemistry has warned that a new, more toxic strain of the disease poses a serious threat to people in Britain as it migrates from the ...

Scientists link quickly spreading gene to Asian MRSA epidemic

April 22, 2012
National Institutes of Health (NIH) scientists and their colleagues in China have described a rapidly emerging Staphylococcus aureus gene, called sasX, which plays a pivotal role in establishing methicillin-resistant S. aureus ...

MRSA superbug spreads from big city hospitals to regional health centers, study suggests

May 14, 2012
Hospitals in large cities act as breeding grounds for the superbug MRSA prior to it spreading to smaller hospitals, a study suggests.

Recommended for you

Study ends debate over role of steroids in treating septic shock

January 19, 2018
The results from the largest ever study of septic shock could improve treatment for critically ill patients and save health systems worldwide hundreds of millions of dollars each year.

New approach could help curtail hospitalizations due to influenza infection

January 18, 2018
More than 700,000 Americans were hospitalized due to illnesses associated with the seasonal flu during the 2014-15 flu season, according to federal estimates. A radical new approach to vaccine development at UCLA may help ...

Zika virus damages placenta, which may explain malformed babies

January 18, 2018
Though the Zika virus is widely known for a recent outbreak that caused children to be born with microencephaly, or having a small head, and other malformations, scientists have struggled to explain how the virus affects ...

Certain flu virus mutations may compensate for fitness costs of other mutations

January 18, 2018
Seasonal flu viruses continually undergo mutations that help them evade the human immune system, but some of these mutations can reduce a virus's potency. According to new research published in PLOS Pathogens, certain mutations ...

Study reveals how MRSA infection compromises lymphatic function

January 17, 2018
Infections of the skin or other soft tissues with the hard-to-treat MRSA (methicillin-resistant Staphylococcus aureus) bacteria appear to permanently compromise the lymphatic system, which is crucial to immune system function. ...

Fresh approach to tuberculosis vaccine offers better protection

January 17, 2018
A unique platform that resulted in a promising HIV vaccine has also led to a new, highly effective vaccine against tuberculosis that is moving toward testing in humans.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.