Antibiotics Ellie Whittingham
Overview • Thinking about Abx
• Know your enemy
• Classes of Abx
• Resistance
• Quiz o’clock
How do we feel about answering questions on Abx?
This is how I feel…..
How might Abx come up in the exams?
Know your enemy…
10 4
9
8
6
5
7
2
3
1
Gram Positive
Cocci
•Staphlococci
•Steptococci
Bacilli
•Clostridium
•Bacillius
Filamentous
•Actinomyces
Gram Negative
Cocci
• Neisseria
Bacilli
• Enterobacteria
• Pseudomonas
• Campylobacter
Spirochetes
• Leptospirosis
• Syphylis
Intracellular
• Chlamydiae
What classes of Abx can you list?
Classes of ABx
ABx
Inhibit wall synthesis
Beta Lactams Carbopenems
Cephalosporins Glycopeptides
Inhibit bacterial protein
synthesis/ Messes with
ribosome
Aminoglycosides
Chloramphenicol
Clindamycin
Fusidic Acid
Macrolides
Tetracyclines
Inhibit nucleic acid synthesis/
Messes with DNA
Metronidazole
Nitrofurantoin
Quinolones
Rifampicin
Sulphonadmides
Bacteriocidal vs Bacteriostatic
Let’s break it down…
What can we target?
1
3
2
Must be a living
replicating bacteria
Inhibit Cell Wall Synthesis
Cell wall
Beta Lactams
Penicillin(s)
Many Gram Neg unaffected
e.g. Flucloxacillin, Amoxicillin, Piperacillin
(combined with Tazobactam)
Monobactams
Best coverage
e.g. Meropenem, Ertapenem
Cephalosporins
Subsequent generations
• Increasing Gram Neg cover
• Better CNS penetration
e.g. Cephalexin (1st), Cefuroxime (2nd), Ceftriaxone
(3rd)
Glycopeptides
Principally work against Gram positive cocci
Narrow spectrum
e.g. Vancomycin, Teicoplanin
Inhibit protein synthesis
Ribosomes
Messes with 50s Subunit
Chloram-phenicol
H. Influenzae
Macrolides
Erythromycin, Clarithromycin
Lincosamide
Clindamycin
Linezolid
Resistant Gram Positives
50s
30s
Messes with 30s Subunit
Aminoglycosides
Aerobic Gram Negatives
Gentamicin, Neomycin
Tetracyclines
Mycoplasma, Sprirochetes
Avoid in children <12 yrs
Tetracycline, Doxycyline
Inhibits nucleic acid synthesis (messes with DNA synthesis)
“Nucleus”
Messes with DNA Synthesis
DNA Synthesis Inhibitors
Fluoroquinolones
e.g. Ciprofloxacin, Levofloxacin,
Metronidazole
(Anaerobes)
RNA Synthesis Inhibitors
Rifampicin
Folic Acid Synthesis Inhibitors
Sulfonamides
Trimethoprim
Resistance • Intrinsic
• Abx doesn’t work for that bacteria – target not present or antibiotic cannot enter bacterium
• E.g. B-lactam agents have no effect against mycoplasma
• Acquired • Mutation • Transfer of genetic material from resistant
organisms
Quiz time!
Which class of bacteria have a thick
purple cell wall on staining?
Gram Positive
Quiz time!
What are the 3 main ways Abx work?
Inhibit Cell Wall
Synthesis
Mess with ribosomes to
inhibit protein
synthesis
Mess with DNA
synthesis
Quiz time!
Are B-Lactams bacteriostatic or
bacteriocidal?
Quiz time!
What Abx work via interfering with DNA
synthesis?
Rifampicin Fluoroquinolones e.g.
Ciprofloxacin
Trimethoprim
Quiz time!
What type of bacteria do Glycopeptides
principally work on?
Questions?
Resources used
• http://www.frcamindmaps.org/mindmaps/primarybits/antibiotics/antibiotics-assets/antibiotics.png
• https://academic.oup.com/bjaed/article/9/6/184/378495
• https://bjaed.org/article/S2058-5349(17)30054-9/abstract
• http://www.frca.co.uk/Documents/190%20Microbiology%20for%20anaesthetists%20part%201%20-%20Pharmacology%20of%20antibacterial%20and%20antiviral%20drugs.pdf
• https://www.orthobullets.com/basic-science/9059/antibiotic-classification-and-mechanism
Top Related