Infections and antibiotics (1) Flashcards
B-lactams
- characteristic feature
- examples
- MoA
Beta-lactams
Characteristic: all contain beta-lactam ring
Examples: Penicillins such as amoxicillin and flucloxacillin; Cephalosporins such as cefalexin
MoA: Inhibit bacteria cell wall biosynthesis
Aminoglycosides
- characteristic feature
- examples
- MoA
Aminoglycosides
Characteristic: all contain aminosugar sunstructures
Examples: streptomycin, neomycin, kanamycin, paromomycin
MoA: Inhibit the synthesis of proteins by bacteria, leading to cell death
Chloramphenicol
- characteristic feature
- MoA
Chloramphenicol
Characteristic: chloramphenicol is a distinct individual compound; it’s commonly used in low-income countries
MoA: Inhibit synthesis of proteins, preventing growth.
*No longer a first line drug in any developed nation due to increased resistance and worries about safety.
Glycopeptides
- characteristics
- examples
- MoA
Glycopeptides
*drugs of last resort
Characteristics: consist of carbohydrate linked to a peptide formed of amino acids
Examples: Vancomycin, teicoplanin
MoA: Inhibit bacteria cell wall biosynthesis
Ansamycins
- characteristics
- examples
- MoA
Ansamycins
Characteristics: all contain an aromatic ring bridged by an aliphatic chain; can also exhibit anti-viral activity
Examples: Geldanamycin, rifamycin, naphthomycin
MoA: Inhibit the synthesis of RNA by bacteria, leading to cell death.
Streptogramins
- characteristics
- examples
- MoA
Streptogramins
Characteristics: Combination of two groups of antibiotics that act synergistically; two structurally differing compounds, from groups denoted A & B T
Examples: Pristinamycin IIA, Pristinamycin IA
MoA: Inhibit the synthesis of proteins by bacteria, leading to cell death.
Sulfonamides
- characteristics
- examples
- MoA
Sulfonamides
(first commercial antibiotic)
Characteristic: all contain sulfonamide group
Examples: Prontosil, sulfanilamide, sulfadiazine, sulfisoxazole
MoA: do not kill bacteria but prevent their growth and multiplication.
*Cause allergic reactions in some patients.
Tetracyclines
- characteristics
- examples
- MoA
Tetracyclines
Characteristics: all contain 4 adjacent hydrocarbon rings
Examples: Tetracycline, doxycycline, limecycline, oxytetracycline
MoA: Inhibit synthesis of proteins by bacteria, preventing growth
*use becomes less popular due to developing resistance
Macrolides
- characteristics
- examples
- MoA
Macrolides
Characteristics: all contain macrolide ring
Examples: Erythromycin, clarithromycin, azithromycin
MoA: Inhibit protein synthesis by bacteria, occasionally leading to cell death
Oxazolidinones
- characteristics
- examples
- MoA
Oxazolidinones
Characteristics: all contain 2-oxazolidone somewhere in their structure
Examples: Linezolid, posizolid, tedizolid, cycloserine. MoA: Inhibit synthesis of proteins by bacteria, preventing growth.
*very potent antibiotics, often used as ‘last resort’
Quinolones
- characteristics
- examples
- MoA
Quinolones
Characteristics: all contain fused aromatic ring with a carboxylic acid group attached
Examples: Ciprofloxacin, levofloxacin, trovafloxacin. MoA: Interfere with bacteria DNA replication and transcription.
Lipopeptides
- characteristics
- examples
- MoA
Lipopeptides
Characteristics: all contain lipid bounded to peptide
Examples: Daptomycin, surfactin
MoA: Disrupt multiple cell membrane functions, leading to cell death.
A 24 year old girl presents with a sore throat for the past 5 days – examination of her throat is shown on the picture.
What other information would you like to know that would aid in your decision to prescribe antibiotics?
Centor criteria:
- tonsillar exudates
- tender anterior cervical lymphadenopathy
- absence of cough
- history of fever >38C
If 3 or more of the criteria are present there is a 40-60% chance the sore throat is caused by Group A beta-haemolytic Streptococcus
Recommendation to treat if 3-4/4.
Absence of ¾ has NPV of 80%
Also if at risk of immunosuppression – chemotherapy, carbamazepine etc.
A 24-year-old girl presents with a sore throat for the past 5 days – examination of her throat is shown on the picture.
You decide to treat this lady with antibiotics – give the name, dose and duration of treatment? (two options if allergic to penicillin and if not)
- Penicillin V 500mg PO qds for 10 days
- Clarithromycin 500mg PO bd for 5 days