Chapter 22: Infectious Diseases I Flashcards
Infectious diseases can be caused by the following pathogens:
- Viruses
- Bacteria
- Protozoa
- Fungi
- Parasites
- Infectious proteins (Prions)
Infectious diseases that can be spread through contact between people is known as what?
Communicable or contagious
When making a treatment decision regarding an infectious disease, what is considered?
- The bug (pathogen)
- The drug (antibiotic)
3, The patient (host)
What are the characteristics of an infection?
- Site of infection
- Severity of infection
- Whether it is community acquired or hospital acquired (Hospital acquired infections usually involves multidrug resistant organisms)
How is an infection diagnosed?
The main thing you look at is symptoms, not just the urine culture. You look at both.
What are the characteristics of an antibiotic that we should consider for treatment?
- Spectrum of activity
2. Ability to penetrate the site of infection
What are patient characteristics we consider for antibiotic selection?
- Age
- Weight
- Hepatic function
- Renal function
- Allergies
What is empiric treatment?
Before we even identify what the microorganism is, we want to give broad spectrum antibiotic treatment. This is giving a group of antibiotics that provide a broad coverage of organisms to make sure we treat whatever it could possibly be.
What is the gram stain?
When treating an infected patient, we obtain bodily fluids that contain the bacteria such as urine, lung sputum, etc… We send it to the microbiology lab to identify the strain of bacteria that the patient is infected with. The gram stain is a process that doesn’t completely identify the bacteria strain but it does give a clue as to what it could be in order to fight against it based on its characteristics. Gram positive cells have a thick cell wall and stain purple when stained with crystal violet. Gram negative cells have a thin cell wall and turn pink when stained with safranin concentration. Atypical cells do not have a cell wall and do not stain well.
What is the Culture and Susceptibility Report?
This is the report that the microbiology lab gives back after they were given the bacterium source from the patient. It tells you what the bacteria is and what antibiotics it is susceptible and resistant to. With this, you have to make the decision on what is the best antibiotic to give to the patient.
What is the minimum inhibitory concentration?
This is the minimum amount of the antibiotic needed to prevent growth of the bacterium. This is provided on the C&S Report.
What is synergy?
Synergy is using two-antibiotics of different classes together to provide a much stronger effect upon the bacteria. Using the two together provides a much larger effect than if they were used solely. A good example is aminoglycosides and beta-lactams. Beta-lactams allow the aminoglycosides to reach and attack the bacterium’s ribosomes a lot more clearly.
What are the Folic Acid Synthesis Inhibitors?
- Sulfonamides
- Trimethoprim
- Dapsone
What are the Cell Wall Inhibitors?
- Beta-Lactams (Penicillins, Cephalosporins, Carbapenems)
- Monobactams (Aztreonam)
- Vancomycin, Dalbovancin, Oritavancin, Telavancin
What are the DNA/RNA Synthesis Inhibitors?
Quinolones
Metronidazole, Tinidazole
Rifampin
What are the Protein Synthesis Inhibitors?
Aminoglycosides Macrolides Tetracyclines Clindamycin Linezolid, Tedizolid Quinupristin/Dalfopristin
What things do we monitor when treating a patient with an antibiotic?
- Fever
- WBC trend
- Signs and symptoms
These 3 things can tell us how effectively they are responding to treatment
What are reasons for lack of response to an antibiotic?
- The pathogen (It could be developing resistance, be a different , stronger strain, etc…)
- The drug (It could be at an insufficient dose strength, having a drug interaction with something else, etc…)
- The patient (The patient could be fighting another infection, be immunocompromised, etc…)
Organisms can develop resistance to fight back against antibiotics. What are some methods of resistance?
- Intrinsic Resistance: The pathogen has a natural resistance to the antibiotic. An example would be E. Coli towards Vancomycin. Vancomycin is too big to properly tear down the walls of the E. Coli. Therefore, the E. Coli thrives
- Susceptible Pressure. There are strains that are killed by the antibiotic but the resistant group of it will survive and thrive. An example would be enterococcus towards Vancomycin. When Vancomycin is taken, it will kill a lot of the enterrococcus that is naturally in the gut but there are groups of enterococcus resistant to the Vancomycin that will survive and thrive. This is natural selection.
- Acquired Resistance: This is when bacteria obtain resistant genes from other bacteria or by picking them up from the environment.
- Enzyme Inactivation: There are bacteria that contain enzymes capable of breaking down the antibiotic. There are many bacteria that contain beta-lactamases that break down beta-lactams (Penicillins, Cephalosporins, and Carbapenems). Through this, the bacteria survives. This is why beta-lactamase inhibitors are added to beta-lactams (Clavulanate, sulbactam, tazobactam).
Common Resistant Pathogens
Klebsiella Escherichia coli Acinetobacter Enterococcus Staphylococcus Pseudomonas
(Kill each and every strong pathogen)
What is Clostroides difficile infection?
This is another example of natural selection. Antibiotics kill of normal GI flora along with the bacteria that they are targeting. Inactive C. dificcile are usually sitting in the gut but once the active ones are wiped out, these inactive ones activate and thrive in the gut. The symptoms can then be mild or severe.
What needs to be considered with dose optimization?
We have to consider whether the antibiotic is time dependent or concentration dependent. If it is concentration dependent (Aminoglycosides, quinolones) then big doses of them should be given. If the antibiotic is time dependent (Beta-lactams) they should be given for a long period of time to keep them above the MIC.
What are Beta-Lactams?
These are drugs that contain a beta-lactam ring in their molecular structure. They bind to peptidoglycan binding proteins which then prevents the formation of cell walls.
What are penicillins?
These are Beta-Lactams. There are many subtypes of penicillins that cover different types of bacteria. However, for the most part, they cover gram positive bacteria. They do not cover MRSA or atypical bacteria.
