Antimicrobials Flashcards
Generally, discuss how bacteria differ from human cells
Bacteria have no nucleus
Ribosomes are the only internal organelles
Rapidly reproduce –> binary fission, recombination
Explain Obligate aerobes
Only aerobic growth, req O2
Only grow in areas where large [O2] have fused into medium
Explain facultative anaerobes
Both aerobic and anaerobic growth
Grow best when O2 is present but can grow in absence
Explain obligate anaerobes
Obligate anaerobes can only grow in the absence of O2
Explain Aerotolerant anaerobes
Only anaerobic growth but continues in the presence of oxygen
Where would you find aerobic bacteria on the body?
Skin
Some parts of the respiratory system
Where would you commonly find anaerobic bacteria?
Found in mucosal membranes and soils
Skin, brain, blood, intrabdominal, pelvic, skin and soft tissue
They’re unable to deal with the O2 radicals such as peroxides
Discuss the difference between Gram +ve and Gram -ve bacteria
Gram +ve (STaph, STrep) have a thick peptidoglycan layer whilst Gram -ve bacteria dont have a thick peptidoglycan layer on the surface of the cell
Which antibiotic mechanism would work better on Gram +ve bacteria compared to Gram -ve? Why?
Gram +ve bacteria are prone to cell wall disruption due to thick peptidoglycan layers in comparison to Gram -ve bacteria
Name some Gram+ve Cocci aerobic bacteria
staphylococci
streptococci
Enterococci
Name some Gram+ve rod-shaped anaerobic bacteria
Acintomyces
Clostridium
Name some Gram-ve Cocci aerobic facultative anaerobic bacteria
Neisseria
List the mechanistic targets of antibacterials (generally)
Nucleic acid synthesis (DNA gyrase)
RNA polymerase
Folate synthesis
Protein synthesis (50s and 30s subunits)
Cell wall synthesis
What factors influence the pharmacokinetics of antibiotics?
Bioavailability, clearance, vol of dist, ability to reach infection site and have desired concentration in target tissue
Which antibiotics target nucleic acid synthesis?
Quinolones
Which antibiotics target RNA polymerase?
Rifamyxins
Which antibiotics target folate synthesis?
Sulfonamides
trimethoprim
Which antibiotics target cell wall synthesis?
Penicillins
Cephalosporins
Carbapenems
Monobactams
Glycopeptides
Which antibiotics target Protein synthesis?
50s = macrolides, chloramphenicol
30s = aminoglycosides, tetracyclines
What do bactericidal antibiotics do?
Kill the bacteria, is bacteriocidal at low doses
e.g. penicillin, cephalosporins, monobactams, carbapenems, glycopeptides
What do bacteriostatic antibacterials do
Prevent the replication/duplication of bacteria
e.g.Tetracycline, spectinomycin, macrolides, trimethoprim, chrloamphenicol
Outline the principles of the antimicrobial creed
(Hint: MIND ME)
M = microbiology guides therapy wherever possible
I = indication should be evidence-based
N = narrowest spectrum therapy required
D = dosage individualised to patient and site/type of infection
M = minimise therapy duration
E = ensure oral therapy used where clinically possible
Describe prophylactic antibiotic use
Aims to prevent infection when significant risk of developing infection is present, basing antimicrobial choice on likely pathogen
Restrict only to indications for which there is evidence of efficacy/consequences of infection are sig
Discuss empirical antibiotic therapy
Treats an established infection when causative organism has not been identified, treatment guided by clinical presentation (most likely cause)
Restricted to clear indication and clinical benefit, using narrowest therapy possible , review after 28-72 hrs
