Which of the following statements best reflects the key difference between bactericidal and bacteriostatic antibiotics?
Bacteriostatic antibiotics inhibit bacterial replication, whereas bactericidal antibiotics directly kill bacteria.
Bactericidal antibiotics allow the host immune system to combat bacteria, whereas bacteriostatc antibiotics rely less on host immunity for clearing infection.
Bacteriostatic antibiotics are the preferred treatment for infections at sites of poor penetration.
Bacteriostatic and bactericidal antibiotics are very similar and can be used interchangeably.
The primary mechanism of action of Tetracyclines and Clindamycin is to inhibit bacterial protein synthesis. Therefore, both of these agents are classified as...
The primary mechanism of action for Vancomycin and penicillins is to disrupt the bacterial cell wall. Therefore, these antibiotics are...
The primary mechanism of action for Fluoroquinolones is to inhibit bacterial DNA synthesis via DNA fragmentation. Therefore, this antibiotic is...
Which statement best describes the cellular wall structure of gram positive organisms?
A thick outer peptidoglycan layer with an inner lipid bilayer.
A thin outer peptidoglycan layer with an inner lipid bilayer.
An outer lipid bilayer containing porins. Lipoproteins attach the outer membrane to a middle peptidoglycan layer. The inner cytoplasmic membrane is a lipid bilayer.
An outer lipid bilayer. Lipoproteins attach the outer membrane to a middle peptidoglycan layer. The inner cytoplasmic membrane is a lipid bilayer that contains porins.
Select all the factors that make gram negative bacteria more difficult to kill:
Gram negative bacteria have a thicker peptidoglycan layer in the cell membrane than gram positive bacteria, which makes it more difficult for antibiotics to penetrate the cell.
Gram negative bacteria have porins embedded in the outer membrane, which can block out certain antibiotics.
In fact, gram positive bacteria are more difficult to treat than gram negative.
Gram negative bacteria have a strong outer membrane and a peptidolgycan layer protecting the cytoplasmic membrane, whereas gram positive bacteria only have peptidoglycan layers covering the cytoplasmic membrane. This makes it more difficult for antibiotics to penetrate gram negative bacteria.
Gram negative bacteria possess exotoxins and endotoxins, whereas gram positive bacteria only possess exotoxins.
Most bacteria are aerobic. Anaerobes are common in the bowel.
What is the purpose of ordering a C&S test?
To determine the antibiotics to which the bacteria is most sensitive
To determine whether the bacteria is gram negative or gram positive
To determine whether the bacteria is a rod or coccus form
To determine how the bacteria associate
What is the clinical significance of the concept of minimum inhibitory concentration (MIC)?
The MIC correlates to the dose that will be administered to the patient. We need serum and tissue concentrations to exceed the MIC to be effective.
The MIC will help to determine when therapy should begin and how long the course of treatment should be.
When calculating the MIC, you have to take into consideration the patient's age, disease state, previous antibiotic use, and other factors.
Immunosuppressed patients will always require a dose that is much lower than the MIC.
When should a patient be started on antibiotics?
Not until C&S results are available.
As soon as there is a clinical suspicion of infection.
As soon as staining results are available and the bacteria is confirmed as gram positive or negative.
Whenever a patient is admitted to hospital. All patients should receive antibiotics prophylactically.
Which statement is true about combining antibiotics?
Antibiotics should never be combined because it increases the risk of toxicity and developing resistance.
Combining antibiotics may result in either an additive, synergistic, or antagonistic response, depending on the agents used and the bacteria being targeted.
Combining antibiotics will result in a synergistic response, which is why it is standard practice to administer combination therapy.
Combinations should never be administered to an immunosuppressed patient.
What is the main reason for why beta-lactams (e.g. penicillins) are very safe antibiotic agents?
Beta-lactams target penicillin-binding proteins (PBPs), which are involved in the final stages of synthesis of peptidoglycan. Mammalian cells do not require this protein to synthesize cell wall components.
Beta-lactams are bacteriostatic so they do not actively kill cells.
Beta-lactams are quickly metabolized and excreted.
Certain bacteria that occur naturally in the body produce an enzyme that cleaves the beta-lactam ring, thereby inactivating the drug. This prevents levels of the drug from building up in the body and leading to toxicity.
With regard to cephalosporins, the newer generations have greater resistance to beta-lactamase (e.g. fourth generation is more resistant than first).
From the following, select all correct characteristics of beta-lactams:
Dosing is usually TID to QID because of short half-lives
Some have better absorption if taken on empty stomach (e.g. cloxacillin)
Most are renally excreted, therefore requiring dose adjustment in pts with renal impairment
Unlike many other antibiotics, they have no influence on the efficacy of oral contraceptives
Both beta-lactams and vancomycin inhibit cell wall biosynthesis. Therefore, both of these agents are...
You are caring for a patient who has been prescribed vancomycin. You started an IV infusion 20 minutes ago. The patient pressed the call bell and tells you that he is feeling itchy and his neck and face are flushed. What do you suspect is happening and what should you do?
You suspect an allergic reaction. You should stop the infusion immediately and notify the prescribing MD.
You suspect red man syndrome. You should slow the infusion rate and monitor the patient.
You suspect an allergic reaction. You should call the Rapid Response Team and document the event ASAP.
You suspect that these symptoms are caused by the infection. You should do nothing.
Aminoglycosides are one antibacterial agent that exhibits a post-antibiotic effect (PAE). What does this mean?
There is a continued inhibition of bacterial growth even when concentration falls below MIC
The patient may exhibit symptoms of toxicity even after the course of treatment has ended
The patient may experience adverse effects for days or weeks after treatment
The patient will experience GI troubles after a course of treatment because their gut flora is diminished
Why is it important to monitor trough concentrations in patients being administered either Vancomycin or Aminoglycosides?
Because both agents are nephrotoxic
Because both agents may cause Stevens-Johnson syndrome
Because both agents have a very narrow therapeutic index
Because monitoring peak concentrations will give you false results
Macrolides (e.g. erythromycin, clarithromycin, and azithromycin) inhibit bacterial protein synthesis. Therefore, this class of antibiotic is...
Fluoroquinolones inhibit bacterial DNA synthesis. Therefore, this class of antibiotic is...
Sulfonamides inhibit bacterial folate synthesis needed for making DNA, RNA, and protein. Therefore, this class of antibiotics is...
Which of the following antibiotics is highly protein bound and has many drug interactions?
Clindamycin inhibits bacterial protein synthesis. Therefore, it is...
Which of the following agents' main side effect is GI intolerance, including development of antibiotic-associated diarrhea due to overgrowth of C. difficile?
Which of the following agents should NOT be taken with alcohol?