Antibiotics Lecture Part 4 Flashcards by Kyle Tuttle

Quinolones spectrum of kill:
Bactericidal or Bacteriostatic
Narrow or Broad spectrum

Bactericidal
Broad spectrum

Like an explosive device! Kills everything

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Mechanism of action for quinolones

Inhibit DNA synthesis during bacterial replication

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T or F, human cells are unaffected by quinolones

True

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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

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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

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Two main drugs in Quinolone family

ciprofloxacin (Cipro)

levofloxacin (Levaquin)

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Describe the spectrum of kill for Metronidazole

Bactericidal
Broad spectrum
Synthetic drug

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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

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Metronidazole is used for what?

Used to supplement other antibiotics when periodontal condition is not responding

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Is metronidazole susceptible to penicillinase?

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metronidazole is very effective against what type of pathogens?

Periodontal pathogens

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What are the adverse events of metronidazole?

- Very important!

Hematopoietic system
- leukopenia, thrombocytopenia, aplastic anemia
Metallic taste
Circumoral paresthesia
Oral ulcerations

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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

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What should be avoided if a patient is on metronidazole

Alcohol-containing mouthwashes should be avoided

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Vancomycin belongs to what drug family

“miscellaneous” antibiotic

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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

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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.

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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

1. Chromosomal mutations - mutations in genes that code for the drug target; or in the genes that code for drug transport or metabolism 2. 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

1. developed mechanisms to inactivate drugs before drugs can bind to their targets 2. Can develop mutations that prevent the uptake of a drug into the cell 3. 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:

1. Achieve optimal clinical outcomes related to antimicrobial use 2. Minimize toxicity and other adverse events 3. Reduce the costs of health care for infections 4. Limit the selection for antimicrobial resistant strains

CDC Four Core actions to fight antibiotic resistance

1. Preventing infections, preventing the spread of resistance 2. Tracking resistance resistance patterns 3. Improving use of today's antibiotics (antibiotic stewardship) 4. Developing new antibiotics and diagnostic tests

What is most important action to for improving antibiotic use:

1. 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

1. Give an adequate dose 2. Take for an adequate duration 3. Avoid repeated administration 4. Avoid topical administration