Cephalosporins Flashcards
Name a common cephalosporin?
Cephradine
What type of antibiotic are cephalosporins?
Beta Lactams
What spectrum do cephalosporins have?
Extremely Broad Spec (more than penicillins)
What are cephalosporins derived from?
Naturally occurring antimicrobials produced by fungi and bacteria
How do cephalosporins work?
Like penicillins they inhibit the enzyme responsible for peptidoglycan cross linking in the bacterial cell wall.
This lack of cross linking weakens the cell wall structure.
The weakening of the cell wall means they cannot maintain their osmotic gradient therefore water gets into the cell.
Water enetering the cell causes cell swelling –> Cell lysis –> Cell death
How many generations of cephalosporins are there?
5
What are the differences between the generations of cephalosporins?
As generations have continued they have gained more resitsance against beta lactase enzymes so are good agaisnt resistant bacteria
They have increased their spectrum against gram negative bacteria
They have less oral activity (later generations are usually given IV)
What is the addition to the beta lactam group in cephalosporins and penicillins?
Penicillins: amino group
Cephalosporins: dihydrothaizine ring
What are the common uses for cephalosporins?
- Gram negative and gram positive infections: severe complicated and resistant organisms
- Surgical Prophylaxis
- Second and third line for UTI and resp tract infections
What are the contraindications of using cephalosporins?
Those at risk of C.Diff (elderly and hospital)
Those with penicillin/cephalosporin allergies
When should cephalosporins be used with caution?
Renal impairment
Epilepsy
Are Cephalosporins and penicillins good at penetrating CSF?
No
What are the common interactions with cephalosporins?
Warfarin - kill of bacteria that help synthesise vitamin K therefore increase bleeding risk
Aminoglycoside antibiotics - can increase nephrotoxity
Valporate: can reduce the plasma levels and decrease efficacy
OCP
What are the side effects of cephalosporins?
GI Upset (nausea and diarrhoea) Antibiotic associated colitis Skin rash Anaphylactic reactions CNS toxicity
When are cephalosporins more likely to cause CNS toxicity?
When high doses are given to those with renal impairment
