Antibiotics Flashcards
Uses of Nitrofurantoin
Lower UTI (cystitis)
Prophylaxis of UTIs
What is the mechanism of action of Nitrofurantoin?
- affects bacterial protein synthesis, DNA + RNA
What are the adverse effects of Nitrofurantoin?
- brown/orange urine
- pulmonary fibrosis
- hepatic disorders
- anaemia
- peripheral neuropathy
Uses of trimethoprim
Lower UTI (cystitis)
Prophylaxis of UTIs
What is the mechanism of action of trimethoprim/?
- Folate antagonist
- inhibits bacterial dihydrofolate reductase > inhibits tetrahydrofolate production needed for RNA, DNA + protein synthesis
What are the adverse drug reactions of trimethoprim?
Life threatening hyperkalaemia
What are the contraindications of trimethoprim?
Risk of teratogenicity in first trimester of pregnancy
Examples of aminoglycosides
- gentamicin
- vancomycin
- streptomycin
What class of drug is gentamicin?
Aminoglycoside
What are the uses of gentamicin?
- sepsis
- otitis externa
- endocarditis
- meningitis
- biliary tract infection
- pneumonia
- prostatitis
What are the adverse drug reactions of gentamicin?
Nephrotoxicity
Ototoxicity
What are the important drug drug interaction of trimethoprim?
methotrexate
- both folate antagonists
- both inhibit dihydrofolate reductase
- consequence of severe bone marrow suppression
What is co-amoxiclav composed of?
Why is the addition useful?
Amoxicillin + clavulanic acid
- addition of beta lactamase inhibitor to overcome resistance in beta lactamase secreting bacteria
Examples of penicillins
- Amoxicillin
- Flucolaxacillin
- Co-amoxiclav
- phenoxymethylpenicillin
What class of drugs are penicillins?
Beta lactams
What is the mechanism of action of beta lactams?
Cell wall synthesis inhibitors
What are the uses of penicillins?
- bacterial meningitis
- bone, joint, skin + soft tissue infections
- otitis media
- CAP (amoxicillin)
- UTIs
- STIs
- cellulitis (flucloxacillin)
- tonsillitis (phenoxymethylpenicillin)
What factor is the most important for determining when to change IV antibitoics to enteral route?
Overall clinical picture + patient improvement
How does antibiotic resistance occur?
- antibitoics kill bacteria but resistant strains remain due to not finishing course
- antibiotic resistant bacteria multiply
- antibitoic resistance spreads
What are the first line antibitoics based on CURB-65 score?
- 0-1 low severity: amoxicillin PO
- 2 mild severity: amoxicillin PO AND clarithromycin PO
- 3-5 severe: co amoxiclav IV AND clarithromycin PO or IV
Examples of macrolides
Clarithromycin
Erythromycin
Azithromycin
What is the mechanism of action of macrolides?
Protein synthesis inhibition 50S
What are the important drug drug interactions of macrolides?
They are CYP3A4 inhibitors: risk of overdose with verapamil + simvastatin
Types of beta lactams
- penicillins
- cephalosporins
- carbapenems
- monobactams
What are the uses of aciclovir?
- Herpes simplex infection (gential herpes, encephalitis)
- varicella zoster infection (chicken pox + shingles)
What is the mechanism of action of aciclovir?
DNA polymerase inhibitor
Examples of cephalosporins
- cefalexin
- Ceftriaxone
What is the mechanism of action of cephalosporins?
Beta lactam so inhibits cell wall synthesis
Examples of tetracyclines
Tetracycline
Doxycycline
What is the mechanism of action of tetracyclines
Protein synthesis inhibitors 30s
What are the uses of tetracyclines
- atypical respiratory tract infections
- acne
- chlamydia
- Lyme disease
Treatment of pyelonephritis
- co-amoxiclav
- cefalexin
- trimethoprim
- Ciprofloxacin
When can aciclovir be used in treatment of HSV?
Against HSV1+2 ??
When should antibiotics prescriptions be reviewed?
- after senior review of patients
- after any change in clinical condition
- daily during ward round
- after receipt of relevant investigations
