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Nucleoside-nucleotide mixture and its components and response to methicillin-resistant Staphylococcus aureus
S Yamamoto1, A A Adjei, H Yokoyama
1School of Health Sciences, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan.
Abstract:
The effects of a nucleoside-nucleotide mixture and its individual components on response to methicillin-resistant Staphylococcus aureus (MRSA) strain 8985N were studied in mice. BALB/c mice were fed a nucleic-acid-free 20% casein diet and intraperitoneally administered a nucleoside-nucleotide mixture, its individual components (inosine, GMP2Na, uridine, thymidine, cytidine), or saline for 30 days. On the 10th day of this treatment, the mice were inoculated intravenously with the viable MRSA organisms. By the 20th day after inoculation, mice in the saline group showed 33% survival, whereas mice in the nucleoside-nucleotide mixture group showed 75% survival. The survival rates in the inosine (62%), GMP2Na (57%), uridine (54%), cytidine (50%), and thymidine (46%) groups were not significantly different. The survival rates of the individual-component groups tended to be higher than that of the saline group, but this was not statistically different. Furthermore, there was a greater reduction in viable organism recovery in the spleen and kidney of the surviving mice in the component groups than in the saline group. However, the survival rates in the individual-component groups did not exceed that of the nucleoside-nucleotide mixture group. This study suggests that intraperitoneal administration of a nucleoside-nucleotide mixture appears to be important in producing a high survival rate after challenge with MRSA. The effect cannot be achieved with the specific components of the mixture administered individually.
Insights
A nucleoside-nucleotide mixture significantly enhanced survival against methicillin-resistant Staphylococcus aureus (MRSA) in mice. Individual components did not provide the same protective effect, highlighting the importance of the complete mixture for MRSA response.
Area of Science:
- Immunology
- Microbiology
- Nutritional Science
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant public health threat.
- Understanding host-response modulators is crucial for developing novel therapeutic strategies against resistant bacterial infections.
Purpose of the Study:
- To investigate the efficacy of a nucleoside-nucleotide mixture and its individual components in enhancing host survival against MRSA infection in a murine model.
- To determine if the observed effects are attributable to the combined action of the mixture or individual nucleosides/nucleotides.
Main Methods:
- BALB/c mice were administered a nucleic-acid-free diet and treated with a nucleoside-nucleotide mixture, individual components (inosine, GMP2Na, uridine, thymidine, cytidine), or saline for 30 days.
- Mice were intravenously inoculated with MRSA strain 8985N on day 10 of treatment.
- Survival rates and bacterial load in spleen and kidney were assessed 20 days post-inoculation.
Main Results:
- The nucleoside-nucleotide mixture group exhibited a 75% survival rate, significantly higher than the saline control group (33%).
- Survival rates in groups receiving individual nucleosides/nucleotides (46-62%) were not significantly different from the saline group, though they tended to be higher.
- A greater reduction in viable MRSA was observed in the spleen and kidney of surviving mice treated with individual components compared to saline, but less than the mixture group.
Conclusions:
- A nucleoside-nucleotide mixture significantly improves survival rates in mice challenged with MRSA.
- The protective effect against MRSA is dependent on the complete nucleoside-nucleotide mixture and cannot be replicated by its individual components.
- This suggests a synergistic or complex interaction within the mixture is responsible for the enhanced immune response against MRSA.