Probiotic May Eliminate Staph Bacteria Colonizations

MedicalResearch.com Interview with:
"staph aureus on blood agar" by Iqbal Osman is licensed under CC BY 2.0Pipat Piewngam
Postdoctorol fellow
Pathogen Molecular Genetics Section,
Laboratory of Bacteriology,
NIAID/NIH
Bethesda, MD, USA 20892 

MedicalResearch.com: What is the background for this study? What are the main findings? 

Response: Our team at National Institutes of health, Mahidol University and Rajamangala University of Technology in Thailand has reported that the consumption of probiotic Bacillus bacteria comprehensively abolishes colonization with the dangerous pathogen, Staphylococcus aureus.

We hypothesized that the composition of the human gut microbiota affects intestinal colonization with S. aureus. We collected fecal samples from 200 healthy individuals from rural populations in Thailand and analyzed the composition of the gut microbiome by 16S rRNA sequencing. Surprisingly, we did not detect significant differences in the composition of the microbiome between S. aureus carriers and non-carriers. We then sampled the same 200 people for S. aureus in the gut (25 positive) and nose (26 positive). Strikingly, we found no S. aureus in any of the samples where Bacillus were present.

In mouse studies, we discovered S. aureus Agr quorum-sensing signaling system that must function for the bacteria to grow in the gut. Intriguingly, all of the more than 100 Bacillus isolates we had recovered from the human feces efficiently inhibited that system. Then, we discovered that the fengycin class of Bacillus lipopeptides achieves colonization resistance by inhibiting that system.

To further validate their findings, we colonized the gut of mice with S. aureus and fed them B. subtilis spores to mimic probiotic intake. Probiotic Bacillus given every two days eliminated S. aureus in the guts of the mice. The same test using Bacillus where fengycin production had been removed had no effect, and S. aureus grew as expected. This is one of the first study that provide human evidence supporting the biological significance of probiotic bacterial interference and show that such interference can be achieved by blocking a pathogen’s signaling system. Continue reading

Toxin-Producing Bacteria Staph Aureus Induces Skin Inflammation

MedicalResearch.com Interview with:

Lloyd S. Miller, M.D., Ph.D. Vice Chair for Research, Department of Dermatology Associate Professor of Dermatology, Infectious Diseases, Orthopaedic Surgery & Materials Science and Engineering Faculty Member, Cellular and Molecular Medicine (CMM) and Pathobiology Graduate Programs Johns Hopkins Department of Dermatology Baltimore, MD 21231

Dr. Miller

Lloyd S. Miller, M.D., Ph.D.
Vice Chair for Research, Department of Dermatology
Associate Professor of Dermatology, Infectious Diseases, Orthopaedic Surgery & Materials Science and Engineering
Faculty Member, Cellular and Molecular Medicine (CMM) and Pathobiology Graduate Programs
Johns Hopkins Department of Dermatology
Baltimore, MD 21231 

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Staphylococcus aureus is a common bacterial skin pathogen and its abundance is greatly increased on affected skin of eczema patients, especially during disease flares. However, how S. aureus induces skin inflammation and exacerbates the skin inflammation is incompletely understood.

In this study, we found that S. aureus exposure of mouse skin induced skin inflammation through an inflammatory mediator known as IL-36.

Continue reading

Bacterial Nitric Oxide Essential For Staph Bacteria To Colonize Nose

MedicalResearch.com Interview with:

Ferric C. Fang, M.D. Professor of Laboratory Medicine and Microbiology Adjunct Professor of Medicine (Infectious Diseases) Director, Harborview Medical Center Clinical Microbiology Laboratory University of Washington School of Medicine Seattle, WA

Dr. Ferric C. Fang

Ferric C. Fang, M.D.
Professor of Laboratory Medicine and Microbiology
Adjunct Professor of Medicine (Infectious Diseases)
Director, Harborview Medical Center Clinical Microbiology Laboratory
University of Washington School of Medicine
Seattle, WA

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: The Fang lab has a longstanding interest in the interaction between nitric oxide (NO·) and pathogenic bacteria. NO· is an important mediator of the host innate immune response that restricts the growth of invading bacterial pathogens. One of the known actions of NO· is the reversible inhibition of aerobic respiration that results from NO· binding to the heme centers of terminal oxidases.

Like mammalian hosts, many bacteria also possess the ability to enzymatically synthesize NO·. Our latest research investigated the physiological role of the Staphylococcus aureus nitric oxide synthase (saNOS). We discovered that endogenously produced NO· is able to target bacterial terminal oxidases under microaerobic conditions, allowing the bacteria to transition to nitrate respiration when oxygen concentrations are limited and helping to maintain the membrane potential. This process was found to be essential for S. aureus nasal colonization in a mouse model. Thus, a conserved mechanism is involved in both the antimicrobial actions of NO· and the physiological role of NO· in regulating bacterial electron transfer reactions. Interestingly, NO·-heme interactions have been shown to control mitochondrial respiration during hypoxia in mammalian cells.

Continue reading