Cephalosporins – Cell Wall Synthesis Inhibitors (Antibiotics)

00:01 Let’s talk about cephalosporins.

00:03 Now, we divide the cephalosporins into first, second, third, and fourth generation and in general the first generation are more gram-positive active and the fourth generation tend to be more gram negative and there's a spectrum in between.

00:17 Now cefazolin and cefalexin are first generation agents, they're gram positive active and they're very useful in surgical infections because a lot of surgical infections come from staph aureus and other skin surface agents.

00:32 There's minimal effectiveness of these drugs against gram-negative bacteria.

00:36 The second generations, the prototypical agent is cefotetan.

00:42 They are much more active against gram-negative and what's interesting is they’ll often work again - also work against haemophilus enfluenzae which is one of the major causes of pneumonia in many of our patients.

00:54 Other agents are in this group include cefuroxime.

00:58 Now if you notice very carefully I've underlined two of the agents, I've underlined cefotetan and I underlined cefuroxime, these are the drugs you need to know.

01:07 Cefuroxime is commonly used in pneumonia treatment.

01:10 The third generation agents are more gram-negative active.

01:17 Once again I've underlined two of them: cefotaxime and ceftriaxone.

01:21 Cefotaxime is kind of our go to drug - it's a very, very, good gram-negative agent.

01:27 It will often work against organisms that are resistant to penicillin.

01:31 We only use these drugs in serious infections and in general they are only available in intravenous form.

01:38 Let's move on to the fourth generation cephalosporins. Cefepime is your prototypical agent and notice that I've underlined it because it's a drug that I want you to know.

01:50 These are more resistant to the beta lactamases and they are also active against the enterobacter, haemophilus, and neisseria.

01:58 Ceftaroline has activity in infections caused by methicillin resistant staphylococci so we sometimes use it in that case.

02:07 Now, remember that the cephalosporins are less likely to cause rashes and allergic reactions when compared to the penicillins.

02:14 Penicillins seems to be associated quite heavily with rash and other allergic activity.

02:21 There are two new fifth generation cephalosporins called ceftaroline and ceftobiprole.

02:28 Please note that ceftaroline used to be called an unclassified cephalosporin.

02:34 I mentioned it in the fourth generation segment. These drugs are not yet available in all countries.

02:40 The definition of the fifth generation is not agreed upon by all countries, but in the USA it is commonly accepted.

02:48 These drugs are similar to the third generation cephalosporins with respect to a broad spectrum activity against gram-negative bacteria.

02:57 They are as good as the third generation cephalosporins in this regard.

03:02 They have activity against gram-postive bacteria including MRSA as good as vancomycin or aztreonam.

03:11 Ceftaroline is approved for use in community-acquired pneumonia and skin and skin structure infections.

03:19 Ceftobiprole binds to PBP2b in MRSA.

03:24 It is approved for use in hospital-acquired pneumonia and community-acquired pneumonia.

03:30 It is an intravenous drug only.

03:33 Other betalactam drugs include aztreonam.

03:37 Now, this is not commonly used in clinical practice, and you don’t hear much about it.

03:42 It is a drug that you need to know. Why? Because it's resistant to beta lactamases which is huge.

03:47 There is no activity against gram-positive drugs with this particular agent.

03:52 It binds the penicillin binding protein type 3 or PBP3.

03:58 The half-life is prolonged in renal failure so you can adjust your medication accordingly.

04:04 Adverse events include GI upset, vertigo, headache; but the nice thing is, is once again, it's resistant to beta lactamases and there is no cross-allergy with the penicillins.