Gram-negative bacteria are an especially resistant type of bacteria, able to fight off many antibiotics. They are particularly problematic in healthcare settings,where they can cause infections, pneumonia, meningitis, and other illnesses.
A recent study published in Molecular Immunology addressed the issue of gram-negative bacteria, titled “Comparison of the cytokine immune response to pathogenic Yersinia enterocolitica bioserotype 1B/O:8 and 2/0:9 in susceptible BALB/C and resistant C57BL/6 mice.”
This study examined the cytokines involved in the immune system response to infection by Y. enterocolitica. Cytokines are small molecules used by cells, particularly in the immune system, to send signals to one another. The researchers used two different bioserotypes of the bacterium (1B/O:8 and 2/0:9), and infected two different types of mice. BALB/C is a common albino laboratory-bred species of mouse, and C57BL/6 is a common black albino laboratory-bred mouse, and both have shown some resistance to the bacterium.
They began by testing the LD50 of Y. enterocolitica. This is a measure of the dosage at which half of the mice will die. For the 1B/O:8 strain, it was 103 cfu (colony-forming units) for each species of mouse. For the 2/O:9 strain, it was 108 cfu for BALB/C mice and 109 cfu for C57BL/6 mice. To examine the cytokine response to Y. enterocolitica, serum was collected from the mice at intervals following infection with the virus. Cytokines were measured with the Fluorokine® MAP Multiplex Mouse Cytokine Panel from R&D Systems Inc., using a Luminex® 100™ instrument with an XY plate handling platform. Luminex xMAP® Technology is capable of detecting the presence of dozens of substances simultaneously.
The following cytokines were found at elevated levels in the serum of BALB/C mice after infection:
- GM-CSF (granulocyte-macrophage colony-stimulating factor)
- IFN-gamma (interferon-gamma)
- TNF-alpha (tumor necrosis factor-alpha)
- IL-1 beta (interleukin-1 beta)
- IL-2
- IL-4
- IL-5
- IL-6
- IL-10
- IL-12
The authors stated that “the cytokines appeared as a cytokine storm in a short period, reached peak values, and then quickly decreased. This appeared important for the immune response and cytokine immunopathogenesis in pathogenic Y. enterocolitica infections.” In addition, cytokine levels were found to be higher for 1B/O:8, the more pathogenic strain of the bacterium, than 2/O:9.
The authors conclude that this research is important for understanding the immune response in humans to Y. enterocolitica, giving researchers insight into the nature of the infection and possible biomarkers to detect infection.
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