Antimicrobials
3.1 Infection and Antimicrobials Introduction
- Identify the classifications and actions of antimicrobial medications
- Provide examples of when, how, and to whom antimicrobial drugs may be administered
- Identify the side effects and special considerations associated with antimicrobial therapy
- Explain considerations and implications of using antimicrobial medications across the lifespan
- Consider evidence-based concepts when using the nursing process, clinical reasoning and decision-making
Key Terms
- antagonistic interactions
- antifungal
- antiviral
- bactericidal
- bacteriostatic
- black box warnings
- broad-spectrum antimicrobial
- clostridium difficile (C diff)
- culture
- dose dependent
- gram + infection
- gram negative
- gram stain
- half-life
- indications
- mechanism of action
- methicillin-resistant S. aureus (MRSA)
- narrow-spectrum antimicrobial
- pathogen
- prototype
- resistance
- sensitivity analysis
- superinfection
- synergistic interaction
- time dependent
- trough
- vancomycin-resistant S. aureus (VRSA)
Have you ever been prescribed an antibiotic for an infection and asked, “Why do I have to finish taking all these pills when I already feel better”? Or, perhaps you wondered why the healthcare provider chose a certain medication over another or why the pharmacist told you to avoid certain foods when taking a certain antibiotic.
You may have had these questions in your own healthcare experiences. It is important to remember that if you have these questions, many of your patients will as well. Learning about the various types of antimicrobials and how they work will help you provide better health education to your patients.
Did you know that the use of antimicrobial agents dates back to ancient times?
Although the discovery of antimicrobials and their subsequent widespread use is commonly associated with modern medicine, there is evidence that humans have been exposed to antimicrobial compounds for millennia. Chemical analyses of the skeletal remains from between 350 and 550 AD of people living near the Nile River have shown residue of the antimicrobial agent tetracycline in high enough quantities to suggest the purposeful fermentation of tetracycline-producing Streptomyces during the beer-making process. The resulting beer, which was thick and gruel-like, was used to treat a variety of ailments, including gum disease and wounds, in both adults and children.
Additionally, the antimicrobial properties of plants and honey have been recognized by various cultures around the world, including Indian and Chinese herbalists who have long used plants for a wide variety of medical purposes. Healers of many cultures understood the antimicrobial properties of fungi, and their use of moldy bread or other mold-containing products to treat wounds has been well documented for centuries.
Attributions
- The section on the ancient use of antimicrobial agents was adapted from “History of Chemotherapy and Antimicrobial Discovery” in Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (© 2022 OpenStax), which is licened under a CC BY 4.0 licence.
Concurrent administration of two drugs causes harmful effects such as a decrease of drug activity, decreased therapeutic levels due to increased metabolism and elimination, or increased potential for toxicity due to decreased metabolism and elimination. An example of an antagonistic interaction is taking antacids with antibiotics, causing decreased absorption of the antibiotic.
Medications that are used to treat fungal infections. For example, nystatin is used to treat Candida Albicans, a fungal infection.
Medications used to treat viral infections. For example, Tamiflu is used to treat influenza.
Antimicrobial drugs that kill their target bacteria.
Antimicrobial drugs that cause bacteria to stop reproducing but may not ultimately kill the bacteria.
The strongest warnings issued by the Federal Drug Association (FDA) that signify a drug carries a significant risk of serious or life-threatening adverse effects.
An antibiotic that targets a wide variety of bacterial pathogens, including both gram-positive and gram-negative species.
Clostridium difficile causes pseudomembranous colitis, a superinfection that can be caused by broad spectrum antibiotic therapy.
A test performed to examine different body substances for the presence of bacteria or fungus.
A more significant response occurs in the body when the medication is administered in large doses to provide a large amount of medication to the site of infection for a short period of time.
Infections caused by Streptococcus and Staphylococcus bacteria are examples of gram + infection.
Infections that often grow between aerobic and anaerobic areas.
A test used to quickly diagnose bacterial infection .Identification of bacteria as gram + or gram - assists the healthcare provider in selecting an appropriate antibiotic to treat the infection.
The rate at which 50% of a drug is eliminated from the bloodstream.
The use of a drug for treating a particular condition or disease. The FDA determines if there is enough evidence for a labeled indication of a drug. Providers may also prescribe medications for off-label indications if there is reasonable scientific evidence that the drug is effective, but these uses have not been approved by the FDA.
How a medication works at a cellular level within the body.
An infection caused by Methicillin-resistant Staphylococcus aureus that is difficult to treat because it exhibits resistance to nearly all available antibiotics.
An antibiotic that targets only specific subsets of bacterial pathogens.
An organism causing disease to its host.
A common individual drug that represents a drug class or group of medications having similar chemical structures, mechanism of action and mode of action.
A characteristic of bacteria demonstrating lack of effective treatment by an antibiotic when a sensitivity analysis is performed.
A test performed in addition to a culture in order to select an effective antibiotic to treat the microorganism.
A secondary infection in a patient having a preexisting infection. C diff and yeast infections as a result of antibiotic therapy are examples of superinfections.
Concurrent drug administration producing a synergistic interaction that is better than the efficacy of either drug alone. An example of synergistic drug combinations is trimethoprim and sulfamethoxazole (Bactrim).
Time dependency occurs when greater therapeutic effects are seen with lower blood levels over a longer period of time.
The trough level of medication indicates the lowest concentration of that medication in a person's body. Troughs of medication concentration occur after the drug has been broken down and metabolized by the body.
An infection caused by Vancomycin-resistant Staphylococcus aureus that is difficult to treat because it exhibits resistance to nearly all available antibiotics.