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Baker, S., Scott, T. A. (2023). Antimicrobial-resistant Shigella: where do we go next? Nature Reviews. https://www.nature.com/articles/s41579-023-00906-1
Antimicrobial resistance is when microorganisms develop traits that help them survive antibiotic treatment. Resistance can be built either through selection or interactions with environments. Selection can be thought of as survival of the fittest. In any group of microorganisms of the same species, there is a portion of the population that has the desired genes to be able to survive treatment with antibiotics. These remaining microorganisms reproduce, passing on their traits and creating a population of microorganisms with a greater ability to survive a particular treatment. Today, antimicrobial resistance is one of the greatest challenges facing humanity. One bacteria that this can be seen in is Shigella.
Shigella is a type of what is called Gram-negative bacteria. These types of bacteria have an outer membrane. When humans are infected with Shigella, they develop Shigellosis, an intestinal infection that causes diarrhea, stomach cramps, abdominal pain, and fever. Recently, Shigella has developed into strains that are sexually transmitted between men.
Unlike less resistant bacteria, Shigella is skilled at surviving and reproducing despite antibiotic treatment. Instead of acquiring antimicrobial resistance through selection, they also acquire it by interacting with their environment. When coming close to other Gram-negative bacteria, Shigella incorporates other bacterias’ genes, including antimicrobial resistance genes that give it immunity. Furthermore, through selection, they inherit mutations in the genes that are meant to be targeted by the antibiotics, making the bacteria resistant.
In the past when Shigella began to become resistant to antibiotics used at the time, scientists simply opted to research alternative antibiotics that could replace the old ones. However, now scientists have exhausted the different antibiotics that can possibly be used and Shigella has developed resistance to most drugs available.
The solution in the future will likely be vaccines. Scientists have had the technological ability to develop a Shigella vaccine for a long time. Still, due to gaps in knowledge and improper animal testing models, one has not been developed. However, the World Health Organization (WHO) has recently announced plans to develop a Shigella vaccine for children under 5 years old. One concept being researched right now is a vaccine with proteins common to every single strain of the Shigella bacteria, which would provide immunity for all Shigella and lower production costs. Another potential method is a vaccine with monoclonal antibodies, which are proteins that help the immune system fight off disease. Although as of right now, monoclonal antibodies are mainly used to treat viral diseases and cancer, in the future, scientists believe they can be applied to also treat antibiotic-resistant bacteria like Shigella.
Summarized by Jeannine Yu
References:
“Antimicrobial Resistance.” World Health Organization, 17 Nov. 2021, www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance.
“Point Mutation.” Genome.Gov, 16 June 2023, www.genome.gov/genetics-glossary/Point-Mutation#:~:text=Definition&text=A%20point%20mutation%20occurs%20in,or%20alterations%20in%20encoded%20proteins.
“Shigellosis (Shigella) Fact Sheet.” Shigellosis (Shigella) Fact Sheet - MN Dept. of Health, May 2009, www.health.state.mn.us/diseases/shigellosis/shigella.html#:~:text=What%20are%20the%20symptoms%3F,after%20being%20exposed%20to%20Shigella.
Silhavy, Thomas J, et al. “The Bacterial Cell Envelope.” Cold Spring Harbor Perspectives in Biology, May 2010, www.ncbi.nlm.nih.gov/pmc/articles/PMC2857177/#:~:text=Gram%2Dnegative%20bacteria%20are%20surrounded,found%20in%20the%20Gram%2Dnegatives.
“Treatment for Covid-19.” COVID, covid-19.acgov.org/treatment.page#:~:text=Monoclonal%20antibodies%20are%20proteins%20that,monoclonal%20antibodies%20authorized%20for%20prevention. Accessed 19 June 2023.
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