JAL L4 β-Lactams Flashcards
R group of penicillins determines…. (5)
Selectivity (small enough to reach g-ve through porins)
Solubility (Na+ and K+ salts more soluble)
Stability (degrades in stomach pH?)
Bioavailability
β-Lactamase resistance
e.g. of β-Lactamase sensitive? (2)
Pen G
Penicillin V
e.g. of β-Lactamase resistant? (2)
Flucloxacillin: co-fluampicil
&
Temocillin (also resistant to G-ves)
e.g. of broad spectrum (2)
amoxicillin
ampicillin
e.g. of antipseudomonal (2)
piperacillin + tazobactam: Tazocin
Pen G is also called
benzylpenicillin
Pen G is orally active?
No
Does pen G have good distribution?
Yes into tissues and fluids, not into CSF (unless meningitis)
Pen G lasts for a long time?
Rapid excretion into the urine but long post antibiotic effect
To maintain Pen G levels we might:
- give larger doses
- frequent dosing
- combine with slow IM (benzathine benzylpenicillin)
Uses of Pen G (6)
Throat infections Meningitis Pneumonia Cellulitis Osteomyelitis Endocarditis (high dose! therefore not toxic!)
If meningitis suspected use………………. immediately
Pen G
3 Causes of meningitis:
LEARN LEARN LEARN.
Neisseria meningitidis
Strep. pneumoniae
Haemophilus influenzae
Ampicillin is oral because….
stable under acid conditions.
PK of ampicillin….
=40% absorption
Good CSF levels in meningitis but usually IM or IV.
Is there resistance to ampicillin
Yes
40% E.coli
Most staphylcocci
What is ampicillin used to treat? (4)
Throat
Dental
Resp
UTI etc.
S/e of penicillins (4)
HYPERSENSITIVITY 1-10% rash 0.05% anaphylaxis ----- neurotoxicity renal failure oral can cause diarrhoea
How does superinfection occur?
Oral broad spectrum antibiotics kill gut bacteria, resistant bacteria cause superinfection.
>diarrhoea
> C. diff
Cephalosporins are resistant to β-Lactamases?
Yes, not ESBLs
Cephalosporins are active against gram +/-ve?
originally +ve
now also -ve
Cephalosporins treat:
similar to penicillins
PK of cephalosporins?
Mostly IM or IV, some oral.
Low penetration CSF (except meningitis)
Renal excretion.
Cephalosporins cause hypersensitivity in what % of penicillin allergic patients?
0.5-6%
S/e Cephalosporins
Diarrhoea, nausea, C. diff.
1st generation Cephalosporins such as ……….. have generally been replaced and are active against gram …
cefazolin, cefradine
MOST gram +ve
2nd gen Cephalosporins such as ………… have increased resistance to β-Lactamases
cefaclor
and increase gram -ve spectrum
2nd generation are used for…
severe infection & preventing infection after surgery
3rd generation cephalosporins such as ….. are used for….
ceftriaxone
Everything: CAP, hospital acquired infections etc.
Subset of 3rd generation such as ceftazidime are active against….
p. aeruginosa
4th generation cephalosporins are used for (2)
severe infections and p. aeruginosa
4th generation cephalosporins have broader spectrum but,…
more resistance to β-Lactamases
Carbapenems work by….
inhibiting cell wall synthesis
Carbapenems are resistant or not to β-Lactamases
Very resistant
Carbapenems have broad or narrow spectrum?
Broad. Including Ps. aeruginosa (but not against MRSA)
Carbapenems used for (5)
Use IV for: septicaemia HA pneumonia Intra-abdominal infections complicated UTI skin and soft tissue infections
Monobactams work by….
inhibiting cell wall synthesis
Monobactams have broad or narrow spectrum?
Narrow - only gram -ve aerobes
Monobactams are resistant or not to β-Lactamases?
Resistant
Monobactams are used for…
septicemia and complicated UTI
Monobactams cause penicillin allergy?
No, less likely
