Antibiotic Resistance

Introduction to Microorganisms

Microbes are microscopic organisms that reside in all environments and help shape the ecosystem that we live in. Microorganisms play a substantial role in clinical and scientific medicine. The foundation of how human cells work was first discovered in microorganisms, and bacteria are still often employed as model organisms for scientists aiming to learn more about human molecular biology.¹

Microbes have a complex relationship with humans. Microorganisms can be beneficial to human health and provide a variety of necessary functions, including digestion and disease suppression.² These organisms that reside in or on the body of a healthy patient are called normal flora. Unfortunately, microorganisms can also be disease-causing (pathogenic) and lead to infections. Three primary classifications of microorganisms are discussed in medicine: viruses, fungi, and bacteria.²

Viruses are extremely small microorganisms that are not true cells, but rather a piece of genetic material (RNA or DNA) that is encapsulated in a protein shell.² During infection, the virus enters the cells of another living organism (the host) and multiplies. The viral load is a term commonly used in the clinical setting to describe the concentration of the virus in the body.  Often, an increased viral load is associated with worsening disease severity and may be monitored in chronic infections or among particularly vulnerable patients. There are limited options available to treat viral infections once they occur, so prevention is key to reducing morbidity and mortality.² Vaccines are available for certain viruses and should be recommended to eligible patients.

Fungi are a classification of microorganisms that reproduce with spores and can be unicellular or complex organisms.³ Although fungus is a regular component of normal flora, disease can occur if the body is introduced to a pathogenic fungal species (ex, mold) or there is an overgrowth of fungus (ex, yeast).² Mycoses is the formal term for a fungal-caused infection.

Bacteria are single-celled organisms that are the primary component of the human microbiome. It is estimated that for every 1 human cell, there are 10 bacterial cells found in the body.⁴ Similar to fungus, when a patient is exposed to a pathogenic bacterium, or there is an overgrowth of the once normal bacteria, a bacterial infection can arise.² When patients present to the medical office with a suspected bacterial infection, providers will collect a sample of the affected region and run a laboratory test called a culture. A culture involves placing the collected specimen in an optimal environment for bacterial growth, and after a few days, the presence of bacterial colonies (a group of single-species bacteria) can be detected. If isolated colonies grow, a bacterial infection is present, and a laboratory staff member will visualize the bacteria under a microscope to identify the exact species causing the infection. In addition, a sensitivity analysis will be conducted to determine which antibiotics will effectively eradicate the infection.

 

An Overview of Antibiotics

The discovery of antibiotics occurred in 1928, after Alexander Fleming, a scientist studying staphylococcus variants, accidentally left his window open over a holiday break, during which fungal (Penicillium) spores blew through the window and landed on an open petri plate.⁵ Fleming noted that there were no bacterial colonies in the area surrounding the spores and deduced that the spores were responsible for eliminating the bacteria. Since 1928, more than 100 antibacterial agents have been discovered and manufactured.⁶ All antimicrobial agents are categorized into classes based on the mechanism of action and chemical structure.⁷ There are two primary mechanisms through which antibiotics function: bactericidal (kills bacteria) and bacteriostatic (inhibits bacterial growth and replication).⁸ The Medical Assistant should be familiar with frequently prescribed antibiotics, common side effects of the antibiotics, and recognize the major classes to minimize the risk of prescribing antibiotics to patients with a known allergy in the same class. In the clinical setting, providers may refer to antibiotics as broad-spectrum or narrow-spectrum. Broad-spectrum antibiotics target multiple types of bacteria and may be given as a prophylactic or while culture results are pending. Narrow-spectrum antibiotics target specific bacterial species and are often given once the pathogenic bacteria have been identified.

 

Antibiotic Resistance

Bacteria evolve rapidly and, as such, can develop traits that render antibiotics ineffective (ie, the bacteria become resistant to the antibiotic’s effects). These traits acquired by the bacteria are called resistance mechanisms and can manifest in the bacterial cells in a variety of ways, including limiting entry of the antibiotic into the bacterial cell, transforming, or removing the antibiotic to prevent it from causing cellular changes, and changing the antibiotic’s target points within the cell so that the medicine cannot properly bind to the cell.⁹ If a bacterium has resistant properties to a specific antibiotic, a new treatment option will need to be prescribed to clear the infection. This results in limited treatment options for patients with a resistant infection and causes providers to have to use more toxic antibiotics that increase a patient’s risk of adverse events. The risk of bacteria developing resistant properties increases when antibiotics are overprescribed or used improperly. There has been a shift in the medical practice to limit the use of unnecessary antibiotics. In the past, it was not uncommon for antibiotics to be prescribed for viral infections to help ease patients’ concerns. Antibiotic prescriptions are now more regulated, and governing organizations urge providers to only prescribe antibiotics when clinically indicated, regardless of patient attitudes.¹⁰ In addition, patient-level factors can increase one’s risk of developing a resistant infection. When educating patients on taking an antibiotic, it is essential to inform the patient to take all doses as scheduled and to finish the entire prescription even after their symptoms have resolved.⁹ Antibiotic resistance is a major public health concern and cannot be taken lightly.

 

References

1. Yilmaz, L. S., & Walhout, A. J. (2017). Metabolic network modeling with model organisms. Current opinion in chemical biology, 36, 32–39. https://doi.org/10.1016/j.cbpa.2016.12.025
2. InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. What are microbes? 2010 Oct 6 [Updated 2019 Aug 29].Available from: https://www.ncbi.nlm.nih.gov/books/NBK279387/
3. BYJU’s. Kingdom Fungi. BYJU’s. Retrieved January 12th, 2024 from https://byjus.com/biology/kingdom-fungi/
4. U.S. Department of Health and Human Services. (2015, August 31). NIH human microbiome project defines normal bacterial makeup of the body. National Institutes of Health. https://www.nih.gov/news- events/news-releases/nih-human-microbiome-project defines-normal-bacterial-makeup-body
5. American Chemical Society International Historic Chemical Landmarks. Discovery and Development of Penicillin. Retrieved January 12th, 2024 from http://www.acs.org/content/acs/en/education/whatischemistry/landmarks/flemingpenicillin.html.
6. EMedicine Health. Antibiotics. E.Medine Health. Retrieved January 12th, 2024 from https://www.emedicinehealth.com/antibiotics/article_em.htm.
7. Centers for Disease Control and Prevention. All Antibiotic Classes. (2022) Centers for Disease Control and Prevention. Retrieved January 12th 2024 from https://arpsp.cdc.gov/profile/antibiotic-use/all-classes
8. Patel P, Wermuth HR, Calhoun C, et al. Antibiotics. [Updated 2023 May 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535443/
9. Centers for Disease Control and Prevention. How Antimicrobial Resistance Happens. (October 5th, 2022). Centers for Disease Control and Prevention. Retrieved January 12th 2024 from https://www.cdc.gov/drugresistance/about/how-resistance-happens.html
10. U.S Food and Drug Administration. Combating Antibiotic Resistance. (October 10th, 2019). U.S Food and Drug Administration.  Retrieved January 12th, 2024 from https://www.fda.gov/consumers/consumer-updates/combating-antibiotic-resistance