Bloodstream Infections Vary by Geography

Leonard A. Mermel DO FACP, FIDSA, FSHEA Professor of Medicine, Warren Alpert Medical School of Brown University and Division of Infectious Diseases, Rhode Island Hospital Providence, Rhode IslandMedicalResearch.com Interview with:
Leonard A. Mermel DO FACP, FIDSA, FSHEA
Professor of Medicine,
Warren Alpert Medical School of Brown University and Division of Infectious Diseases,
Rhode Island Hospital Providence, Rhode Island

Medical Research: What is the background for this study? What are the main findings?

Dr. Mermel: While talking to infectious diseases physicians some years ago in Israel, Greece, and Thailand, I learned that unlike my experiene here in the US, most of the bloodstream infections they see are far and away due to Gram-negative bacteria.  So, a hypothesis was generated, namely that the likelihood of Gram-negative bacteremia compared to Gram-positive bacteremia was greater the closer to the equator.  A writing group was formed, colleagues around the world graciously shared their data.  The main finding is that in fact, we unequivocally found that the likelihood of Gram-negative, compared to Gram-positive bacteremia is more common closer to the equator.  This difference was greatest during the warmer months of the year.  We also found that the % GDP spent on healthcare in a given country is also associated with more Gram-negative than Gram-positive bacteremia.  These findings may reflect differences in the human microbiome as one gets closer or farther from the equator as has been recently demonstrated, differences in survival of Gram-negative compared to Gram-positive bacteria under certain environmental conditions, and likely reflects differences in public health and other factors.

Medical Research: What should clinicians and patients take away from your report?

Dr. Mermel: Since the types of bacteria that cause bloodstream infections differs depending on latitude (and inevitably multiple other factors), the choice of empiric antibiotics used for such suspected infections should take our findings into consideration.  Researchers should also take such differences into account when planning international studies that involve bloodstream infections.  Patients should know that we’re a living microcosm of bacteria and the types of microbes that can breach nature’s barriers and cause serious infection vary depending on where you live.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Mermel: As above regarding research design.  I hope future research will help further elucidate the variables that lead to such differences in the types of microbes causing infections and ways to mitigate such infectious risk

Citation:
Geographical Variability in the Likelihood of Bloodstream Infections Due to Gram-Negative Bacteria: Correlation with Proximity to the Equator and Health Care Expenditure
David Fisman , Eleni Patrozou Yehuda Carmeli, Eli Perencevich, Ashleigh R. Tuite, Leonard A. Mermel, the Geographical Variability of Bacteremia Study Group

PLoS One Published: December 18, 2014 DOI: 10.1371/journal.pone.01145

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