Sunday Article 08: What Are Superbugs?
WHAT ARE THEY?
Superbugs are strains of bacteria, viruses, parasites and fungi that are resistant to most antibiotics, even other medications that are available to treat the infections they cause. Most common and the deadliest of the superbugs are the resistant bacteria. These are difficult to control and treat, as the treatments cause no harm or changes to them.
Antibiotics made a major change in the previous century through their use in humans. Unfortunately, the growing resistance towards antibiotics in bacteria is rendering them ineffective, with the threat of catastrophic public health consequences if this trend continues.
WHERE DO SUPERBUGS COME FROM?
- Excessive or inappropriate prescription of antibiotics by health personnel- bacterial strains survive and propagates antibiotic-resistant bacteria.
- Poor regulation of the drug market- antibiotic can be accessed without a prescription.
- Standardise practices of agricultural and livestock production-cattle are provided with antibiotics which can be transferred directly to humans.
SUPERBUG PRIORITY LIST
MRSA SUPERBUG
MRSA (Methicillin-Resistant Staphylococcus aureus) is an antibiotic-resistant bacterial strain that caused a global epidemic in the 1950s and emerged again as community-acquired MRSA. In 2000, there was a major outbreak of MRSA in the UK and it has been prevalent since then.
Strains of Staphylococcus aureus developed multiple drug resistance to commonly used antibiotics through several ways to beta-lactam antibiotics. Beta-lactam antibiotics include penams (penicillin derivatives e.g. Methicillin and oxacillin), cephams, fluoroquinolones, tetracyclines, macrolides, lincosamides and aminoglycosides and specifically, penicillin class antibiotic, methicillin. These Gram-positive bacteria are genetically distinct from other strains, suggesting that different genetic material in the system might be causing this resistance.
The MRSA’s resistance to penicillin is mainly achieved by the alteration of the antibiotic’s target site. Beta-lactam antibiotics inactivate PBP enzymes permanently, needed for cell wall synthesis and bacterial life, by indelibly binding to their active sites. When the enzyme is antibiotic sensitive, the amino acids bind to the active site normally and then expels itself, leaving the β-lactam antibiotic to bind itself at the active site to the reactive serine. This allows the antibiotic to block the enzyme’s active site. Whereas, when the enzyme is antibiotic-resistant, the size and shape of the active site are altered, allowing the amino acids of the protein to bind perfectly, removing an alanine in the process. The binding of β-lactam antibiotic to the reactive serine then fails due to the alteration of the active site and change in shape. This leads to a working active site in the enzyme, allowing it to fully function and exhibit resistance to the antibiotic.
Researchers have discovered a new toxin produced in Staphylococcus aureus which has dual toxic and antibiotic properties. This new bacterial toxin was transformed into potent antibiotics, which are effective against both gram-positive and gram-negative bacteria. The challenge here was to separate these activities which will lead them to create new non-toxic antibiotics for the body.
IMPLICATIONS OF ANTIBIOTIC RESISTANCE ON GLOBAL HEALTH
Antibiotic resistance is a global threat to global health, food security and development. This can affect anyone at any age and community. Increase in antibiotic resistance can lead to higher medical costs, prolonged hospital stays and increased mortality. It is also proven that infections caused by resistant bacteria are much harder to treat than those caused by non-resistant bacteria. When infections cannot be treated by first-line antibiotics, more expensive medicines must be used. This then can lead to a longer duration of treatment in the hospital or elsewhere posing an economic burden on the family and society in general. Modern medicine such as organ transplantations, chemotherapy and surgeries (caesarean sections) are also at more risk due to the possible antibiotic resistance that can be dangerous without effective antibiotics for the prevention of infections.
ALTERNATIVES TO ANTIBIOTIC THERAPY
Bacteriophage therapy is the most researched alternative for antibiotic therapy where phage viruses infect bacteria and treat bacterial diseases. Few phage therapeutic products are available in Eastern Europe but the difference in efficacy has caused these products to not be displayed in the United States.
Advantage: Specificity of the target bacterium, effective on topical or mucosal infections.
Disadvantage: Requires knowledge on the target bacterium and sufficiently high populations of the target bacterium; which has a potential for resistance to develop.
Vaccination can and has been used for years rather than antibiotics for disease prevention as this is just as important as disease treatment. Vaccination reduces primary and secondary bacterial infections, replacing the use of antibiotics.
Immunotherapeutics are molecules that boost the body’s immune system to prevent diseases at an infection-susceptible time. Pegfilgrastim is one of the products used, where a granulocyte colony-stimulating factor (G-CSF) is used to induce neutrophils in certain types of cancer patients with a low count of neutrophils. Having a sufficient amount of neutrophils helps strengthen the immune system. In agriculture, pegbovigrastim, a bovine G-CSF is given to cattle before parturition to boost its immune system and decrease the occurrence of mastitis.
Advantage: A general boost of the immune system to prevent diseases.
Disadvantage: The need for precise timing of the administration; a challenge in the agricultural field.
Probiotics are living organisms where ‘good’ bacteria fed to hosts on purpose, prebiotics is molecular precursors that expand the count of ‘good’ gut microbiota of a host and synbiotics are a combination of both. These ‘-biotics’ are considered to be a good influence on the gut microbiota in a way that improves health. Though the mammal gut microbial community consists of more than 500 different bacterial species and researchers currently have a low level of knowledge on how each microorganism in the gut contributes to its host’s health. Research on how the gut bacteria and the animal hosts interact is currently being implemented worldwide.
WHAT MORE CAN BE DONE?
MRSA is currently ranked as a serious threat globally. Hence, the development of new drugs or an alternative is very important. Research on antibiotic resistance and alternative therapies should be funded more. Countries and organisations should also promote awareness about this threat and encourage innovative thinking amongst people in the scientific research sector. Governments in all countries should also look into implementing extreme measures of precaution in healthcare facilities, in social or public areas and in agricultural settings. The general public should be encouraged to practice good hygiene and to only use prescribed antibiotics as directed by health personnel.
References:
INSERM (Institut national de la santé et de la recherche médicale). (2019, July 9). New antibiotics effective without triggering resistance, mouse study shows. ScienceDaily from www.sciencedaily.com/releases/2019/07/190709141249.htm
Who.int. 2020. Antibiotic Resistance from https://www.who.int/news-room/fact-sheets/detail/antibiotic-resistance
Allen, H. K. 2017. Alternatives to antibiotics: Why and how. NAM Perspectives. Discussion Paper, National Academy of Medicine, Washington, DC from https://doi.org/10.31478/201707g
Munita, J. and Arias, C., 2020. Mechanisms Of Antibiotic Resistance. ASMscience. Retrieved October 11 2020 from https://www.asmscience.org/content/journal/microbiolspec/10.1128/microbiolspec.VMBF-0016-201
Roberts, M. (2017). World's most threatening superbugs ranked in new list. Retrieved from https://www.bbc.co.uk/news/health-39104411
McLaughlin, A. (2005). Community MRSA is re-emergence of 1950s pandemic, study suggests. Retrieved from https://www.eurekalert.org/pub_releases/2005-03/uob-cmi033105.php#:~:text=Community%20MRSA%20is%20re%2Demergence%20of%201950s%20pandemic%2C%20study%20suggests,University%20of%20Bath&text=An%20early%20type%20of%20antibiotic,(Saturday%202%20April%202005).
Guanais, F. (2021). Relationship between antibiotics and superbugs. Retrieved from https://blogs.iadb.org/salud/en/superbugs-and-antibiotics/
This article is prepared by Keshwiny Nathan.
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