Date Published: January 12, 2010
Publisher: Public Library of Science
Author(s): Franklin D. Lowy
Abstract: Franklin Lowy discusses a new study in PLoS Medicine in which the investigators developed an interactive tool for analyzing the spatial distribution of invasive Staphylococcus aureus.
Partial Text: Understanding the geographic distribution of microbial pathogens such as Mycobacterium tuberculosis, Salmonella spp., or Staphylococcus aureus is critical to developing strategies to reduce their transmission. Varied approaches have been used to track their spread including the use of national surveillance networks, multinational strain collections, or more targeted strategies that track social networks within high-risk populations –. The integration of molecular techniques with these surveillance strategies helps identify specific bacterial strains or clones and potentially provides further insight into strain transmission and virulence.
In a new study by Hajo Grundmann and colleagues in this issue of PLoS Medicine, the investigators describe the development of an interactive tool for analyzing the spatial distribution of invasive S. aureus. The authors assembled a large group of collaborators throughout much of Europe including 450 hospitals from 26 countries. They then standardized strain collection and typing procedures. This arduous start-up process is likely to provide payoffs well beyond this initial study. Over a 6-month period, from 2006–2007, participating hospitals provided five successive methicillin-resistant and methicillin-susceptible S. aureus (MSSA) isolates collected from patients with invasive infections. Most of these isolates were from bacteremias. These isolates were characterized using a sequence-based approach, spa typing (based on the polymorphic protein A gene that is uniformly found in S. aureus), which allows for identification of specific strains. The strain spa types were assigned to their original hospital collection site and the spatial analytic tools were then used to map common spa types both by their regional proximity and their country of origin.
The major strength of Grundmann and colleague’s proof of principle study is that it shows the potential value of this integrated approach. By establishing a large collaborative network and then combining molecular and spatial analytic techniques, the authors illustrate the ability to map specific strains across large geographic regions. At its most basic, the study provides information on whether clones of S. aureus are randomly distributed or clustered. The authors however also illustrate that there are many other potential applications of this approach.