Cephalosporins – Cell Wall Synthesis Inhibitors (Antibiotics)

00:00 Let's talk about cephalosporins.

00:03 Now we divide the cephalosporins into first, second, third and fourth generations.

00:08 And in general the first generation are more gram positive active.

00:11 And the fourth generation tend to be more gram negative.

00:14 And there is a spectrum in between.

00:16 Now cefazolin and cephalexin are first generation agents.

00:20 They are gram positive active.

00:22 And they are very useful in surgical infections because a lot of surgical infections come from Staphylococcus aureus and other skin surface agents.

00:31 There's minimal effectiveness of these drugs against gram negative bacteria.

00:38 The second generation, the probably typical agent is cefotetan.

00:42 They are much more active against gram negative.

00:45 And what's interesting is they'll often work again, also work against haemophillus influenzae which is one of the major causes of pneumonia in many of our patients.

00:53 Other agents are in this group include, cefuroxine.

00:58 Now if you notice very carefully, I've underlined two of the agents.

01:01 I've underlined cefotetan and I underlined cefuroxine.

01:05 These are the drugs you need to know.

01:07 Cefuroxine is commonly used in pneumonia treatment.

01:13 The third generation agents are more gram negative active.

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

01:19 Cefotaxine and ceftriaxone.

01:21 Cefotaxine is kind of our go to drug.

01:24 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.

01:34 And in general they're only available in intravenous form.

01:39 Let's move on to the fourth generation cephalosporins.

01:44 So cefepime is your prototypical agent.

01:46 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.

01:53 And they're also active against Entrobacter, Haemophillus and Neisseria.

01:58 Ceftaroline has activity in infections caused by methicillin resistant staphylococci.

02:04 So we sometimes use it in that case.

02:06 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 Other beta lactamases drug include aztreonam.

02:24 Now this is not commonly used in clinical practice.

02:27 And you don't hear much about it.

02:29 It is a drug that you need to know.

02:31 Why? Because it's resistant to beta lactamases which is huge.

02:34 There is no activity against gram positive drugs with this particular agent.

02:39 It binds to penicillin binding protein type 3 or PBP3.

02:45 The half life is prolonged in renal failure.

02:48 So you can adjust your medication accordingly.

02:51 Adverse events include GI upset, vertigo, headache.

02:56 But the nice thing is once again, it's resistant to beta lactamases and there's no cross out allergy with the penicillins.