MIIM - Antibiotics II - Week 9 Flashcards
Name 3 nucleic acid pathways that can be targetted.
Inhibiting synthesis of precursors
Inhibiting DNA replication
Inhibiting RNA polymerase
What nucleic acid pathway do quinolones inhibit? What enzyme specifically?
Inhibits DNA replication
Affects DNA gyrase
What is the action of DNA gyrase?
Required to supercoil bacterial DNA
Are quinolones bactericidal or bacteriostatic?
Bactericidal
Name three reasons to use antibiotic combinations.
To cover a range of organisms which might reasonably be expected to be present
To achieve synergy
To cover the possibility of the presence of antibiotic resistant mutants
What is the therapeutic guideline for staph blepharitis?
Antibiotic efficacy uncertain - chloramphenicol 1% ointment 1-2x daily for 1 week
What is the therapeutic guideline for chronic blepharitis (rosacea)?
Doxycycline one daily for 8 weeks
What is the therapeutic guideline for conjunctivitis (empirical treatment) (2)?
Delayed prescription approach - chloramphenicol or framycetin
What is the therapeutic guideline for conjunctivitis (non-empirical treatment) (3)?
Gentamycin, tobramycin, or quinolone drops when indicated
What is the therapeutic guideline for conjunctivitis (chlamydia)?
Systemic therapy with azithromycin
What is the therapeutic guideline for HSV keratitis?
Acyclovir 3% 5x daily for 14 days
What should be done with bacterial keratitis?
Referral
Define minimal inhibitory concentration.
The lowest concentration of an antimicrobial agent that will inhibit the growth of an organism under test over a suitable defined time interval
Describe the tube method for determining minimal inhibitory concentration (3).
Serial dilutions of the antibiotic are made in a suitable broth and a standard number of bacteria from the patient is added.
After overnight incubation, the growth is scored.
The last dilution which inhibits growth is the minimal inhibitory concentration.
Define the term sensitive or susceptible.
An infection with that organism will respond to the usually recommended dose on an antimicrobial