Cephalosporins

Question 1

cephalosporins are similar to that of the penicillins, excretion being principally renal. what can they be used in the treatment of ?

Answer 1

1) Septicaemia
2) Pneumonia
3) Meningitis
4) Biliary-tract infections
5) Peritonitis
6) Urinary-tract infections

Question 2

Cephalosporins penetrate the cerebrospinal fluid poorly unless the meninges are inflamed. in this case which cephalosporins can be used for infections of the CNS e.g. meningitis

Answer 2

cefotaxime and ceftriaxone

Question 3

what is the main side effects of cephalosporins?

Answer 3

Hypersensitivity 0.5–6.5% of penicillin-sensitive patients will also be allergic to the cephalosporins

Question 4

If a cephalosporin is essential in patients with a history of immediate hypersensitivity to penicillin then which ones can be used with caution, and which ones should be avoided?

Answer 4

1) caution: ceftriaxone, cefixime, cefotaxime, ceftazidime , or cefuroxime
2) Avoid: cefalexin, cefaclor, cefadroxil, cefradine, and ceftaroline fosamil

Question 5

cephalosporins can be grouped into 5 classes. list 2 of the first generation drugs

Answer 5

1) CEFLAXIN, cefradine

2) cefadroxil- long duration of action and can be given twice daily; it has poor activity against H. influenzae.

Question 6

List a second generation cephalosorins and outline its characteristics

Answer 6

1) CEFACLOR- useful for UTI infection in pregnancy, respiratory-tract infections, otitis media, and skin and soft-tissue infections.
2) Cefuroxime

Question 7

Cefuroxime is a second generation drug. what key counselling advice needs to be given with this drug?

Answer 7

1) it is poorly absorbed and needs to be given with food to maximise absorption
2) less susceptible to inactivation by beta-lactamases

Question 8

list 4 ‘third generation’ cephalosporins

Answer 8

1) Ceftriaxone, cefotaxime, ceftazidime- greater activity than the 2nd gen against certain Gram-ve
2) Cefixime- is orally active, It has a longer duration of action than the other cephalosporins that are active by mouth.

Question 9

what is ceftriaxone (3rd gen) used to treat and what are its properties?

Answer 9

1) Ceftriaxone has a longer half-life- once daily
2) septicaemia, pneumonia, and meningitis. T
3) The calcium salt of ceftriaxone forms a precipitate in the gall bladder which may rarely cause symptoms but these usually resolve when the antibiotic is stopped.

Question 10

Ceftaroline fosamil is a fifth generation cephalosporins. what are the characteristics of this drug?

Answer 10

1) extended spectrum of activity against Gram-positive bacteria that includes MRSA and multi-drug resistant Streptococcus pneumoniae.
2) CAP, complicated skin and soft-tissue infections

Question 11

what is the MoA of cephalosporins?

Answer 11

Bind to penicillin binding proteins (enzymes) → Prevent cell wall synthesis

Question 12

what are the general indications for cephalosporins?

Answer 12

Pneumonia, Meningitis, UTIs, Gonorrhea

Question 13

Antibiotic associated colitis is more common with which cephalosporins?

Answer 13

cefuroxime & ceftriaxone (are also less susceptible to inactivation by beta lactamases)

Question 14

what are the import interactions with regards to cephalosporins?

Answer 14

1) Cephalosporins and carbapenems can enhance the anticoagulant effect of warfarin by killing normal gut flora that synthesise vitamin K.
2) Cephalosporins may increase nephrotoxicity of aminoglycosides.