Antimicrobials
3.2 Infection Concepts
Concepts Related to Infection
For the purposes of this concept discussion, the Concept of Infection is defined as “the invasion and multiplication of microorganisms in body tissues, which may be clinically unapparent or result in local cellular injury”[1]. This resource provides a basic introduction to the concept of infection as it relates to pharmacology. The example concept map below provides a summary of the key information necessary to understand infection. You can revisit this map after you have completed the chapter. The information for the map was informed by several resources. [2]
Before learning about medications that are used to treat infections in our clients, it is important for nurses to first understand the basics of microbiology. Bacteria are found in nearly every habitat on earth, including within and on humans. Most bacteria are harmless or considered helpful, but some are pathogens. A pathogen is defined as an organism causing disease to its host. Pathogens, when overgrown, can cause significant health problems or even death for your clients.
Bacteria may be identified when a client has an infection by using a culture and sensitivity test or a gram stain test. Antimicrobials may be classified as broad-spectrum or narrow-spectrum, based on the variety of bacteria they effectively treat. Additionally, antibiotics may be bacteriostatic or bactericidal in terms of how they target the bacteria. Finally, the mechanism of action is also considered in the selection of an antibiotic.
In addition to antibiotics, antimicrobials also include medications used to treat viruses and fungi. Each of these topics will be discussed in more detail below, along with the issue of drug resistance.
Concepts Related to Bacterial Infections
Culture and Sensitivity
When a client presents signs or symptoms of an infection, healthcare providers will begin the detective work needed to identify the source of the infection. A culture is a test performed to examine different body substances for the presence of bacteria or fungus. These culture samples are commonly collected from a client’s blood, urine, sputum, wound bed, etc. Nurses are commonly responsible for the collection of culture samples and must be conscientious to collect the sample prior to the administration of antibiotics. Antibiotic administration prior to a culture can result in a delayed identification of the organism and complicate the client’s recovery. Once culture samples are collected, they are then incubated in a solution that promotes bacterial or fungal growth and spread onto a special culture plate.[3] Clinical microbiologists subsequently monitor the culture for signs of organism growth to aid in the diagnosis of the infectious pathogen. A sensitivity analysis is often performed to select an effective antibiotic to treat the microorganism. If the organism shows resistance to the antibiotics used in the test, those antibiotics will not provide effec