Antibiotics Lecture Part 4 Flashcards
Quinolones spectrum of kill:
Bactericidal or Bacteriostatic
Narrow or Broad spectrum
Bactericidal
Broad spectrum
- Like an explosive device! Kills everything
Mechanism of action for quinolones
Inhibit DNA synthesis during bacterial replication
T or F, human cells are unaffected by quinolones
True
Would drugs like Ciprofloxacin (Cipro), levofloxacin (Levaquin) and norfloxacin (Noroxin) be go-to drugs for orofacial infections?
No, these would be quite overkill for typical oral infections
Indications for Quinolones:
Medical: to treat resistant organisms
- Respiratory infections like Bronchitis, community-acquired pneumonia
- Urinary tract infections
Dentistry: Rarely used in dentistry
- Used to treat periodontal disease when other agents are not effective
Two main drugs in Quinolone family
ciprofloxacin (Cipro)
levofloxacin (Levaquin)
Describe the spectrum of kill for Metronidazole
Bactericidal
Broad spectrum
Synthetic drug
Why is metronidazole sometimes referred to as an antimicrobial rather than an antibiotic?
It is effective against other things than just bacteria.
- Effective as an antibiotic, amebicide, antiprotozoal
Metronidazole is used for what?
Used to supplement other antibiotics when periodontal condition is not responding
Is metronidazole susceptible to penicillinase?
No
metronidazole is very effective against what type of pathogens?
Periodontal pathogens
What are the adverse events of metronidazole?
- Very important!
- Hematopoietic system
- leukopenia, thrombocytopenia, aplastic anemia - Metallic taste
- Circumoral paresthesia
- Oral ulcerations
What is a very dangerous drug interaction with metronidazole?
Avoid drinking alcohol while taking metronidazole
- You will get a disulfiram-like reaction used to help people break desire to drink. Symptoms following include nausea, vomiting, flushing, headache, sweating, tachycardia
What should be avoided if a patient is on metronidazole
Alcohol-containing mouthwashes should be avoided
Vancomycin belongs to what drug family
“miscellaneous” antibiotic
Mechanism of action for Vancomycin
Inhibits bacterial cell wall synthesis, but with a different mechanism than the penicillin
- Used for resistant staph infections, strep infections, enterococcal infections
- Used to treat antibiotic-induced pseudomembranous colitis caused by C diff
What drug used to be considered one of the last lines of antibiotic defense?
Vancomycin
- This prompted the development of new classes of antibiotics in U.S.
Amino glycosides are used for what?
Used for severe hospital-acquired infections, antibiotic-resistant infections
Are ahminoglycosides used in dentistry?
No indication
Mechanism of Aminoglycosides
Bacterial ribosome is target. Bind to the 30S subunit of the bacterial ribosome and interfere with the formation of the initiation complex, and cause misreading of the mRNA
What are the issues with Clarithromycin/Azithromycin
- Caution in liver disease = hepatotoxic
2. Alters QT interval of the heart = caution with vasoconstrictor
Drugs that prolong the QT interval:
Fluoroquinolone antibiotics - moxifloxacin, ciprofloxacin, levofloxacin Macrolide antibiotics - azithromycin - clarithromycin Azole antifungals - fluconazole - ketoconazole - itraconazole Epinephrine
In children, most common medication errors occur how?
With incorrect dosing
- Must calculate dose based upon mg/kg body weight
What drug interaction should be avoided or wait a minimum of 2 hours between use with tetracycline?
Tetracyclines and iron/dairy/antacids
- Chelation reaction, both drugs will pass through GI tract unchanged; no clinical effects
Describe how you should respond when a women who is on a hormonal contraceptive needs antimicrobial therapy
Consider additional non-hormonal contraception at initiation and for duration of antimicrobial therapy (or for 14 days, which ever is longer), plus 7 more days after completion of antimicrobial therapy.
What is the mechanism of why oral contraceptives and antibiotic relationships may not always work together
Oral contraceptives are prodrugs. They are hormones activated by gut flora. If an antibiotic is taken and decreases flora, this decreases active hormone, and possible ovulation will occur
How common is antimicrobial-induced oral contraceptive failure?
in 1% to 3% normal rate of pregnancy. Very RARE
T or F, Most of the common drugs like tetracycline, doxycline, ampicillin, metronidazole, etc. do not affect OC steroid levels in women taking combination OC
True- but the carious approach is to recommend second form of contraception
Warfarin (Coumadin) competes with what in the body?
Vitamin K for synthesis of prothrombin or clotting factors in blood which takes place in the liver. Vitamin K is synthesized by gut bacteria.
Why is Coumadin not indicated with antimicrobials
Because vitamin K is synthesized by gut bacteria, antimicrobials will kill these bacteria, causing decreased levels of Vitamin K. Warfarin then has no competitor, and causes excessive anticoagulation (very thin blood)
What are red flag drugs
Macrolides
Azole antifungals
- Always check for compatibility prior to prescribing these drugs to medicated patients
60% of what infections are caused by drug-resistant microorganisms
Hospital-acquired infections or nosocomial infections
Genetic origin mechanisms of microbial resistance
- Chromosomal mutations
- mutations in genes that code for the drug target; or in the genes that code for drug transport or metabolism - Exchange of genetic material
- alterations in DNA are transferred from one organism to another
- occurs with organisms that are in close proximity to one another
What are some mechanisms that have been developed in pathogens for microbial resistance
- developed mechanisms to inactivate drugs before drugs can bind to their targets
- Can develop mutations that prevent the uptake of a drug into the cell
- Acquire ability to cause active drug efflux from the cell.; activates membrane pumps that push the drug out of the cell
T or F, People infected with drug-resistant organisms are less likely to have longer and more expensive hospital stays and less likely to die as a result of the infection
False, More likely
What is MRSA
Methicillin-resistant Staphylococcus aureus
- Resistant to certain antibiotics
- Observed with increasing frequency in persons with no links to healthcare systems
Name URGENT threat level resistant organisms
C difficile
N gonorrhoeae
Name SERIOUS threat level resistant organisms
azole resistant Candida MRSA S pneumoniae Salmonella multidrug resistant tuberculosis
Name CONCERNING threat level resistant organisms
Vancomcin resistant S aureus (VRSA)
Antimicrobial stewards seek to:
- Achieve optimal clinical outcomes related to antimicrobial use
- Minimize toxicity and other adverse events
- Reduce the costs of health care for infections
- Limit the selection for antimicrobial resistant strains
CDC Four Core actions to fight antibiotic resistance
- Preventing infections, preventing the spread of resistance
- Tracking resistance resistance patterns
- Improving use of today’s antibiotics (antibiotic stewardship)
- Developing new antibiotics and diagnostic tests
What is most important action to for improving antibiotic use:
- Change the way antibiotics are used.
- Up to 50% of all the antibiotics prescribed are not needed or are not prescribed appropriately
What are 4 ways we can minimize antibiotic resistance in dentistry
- Give an adequate dose
- Take for an adequate duration
- Avoid repeated administration
- Avoid topical administration
