Antibiotic Sensitivity and Resistance in Urinary Tract Infection (Nursing)

00:00 Now, I want to talk about minimum inhibitory concentration. Do you see that in the table there? Yeah, organism 1 MIC mcg/mL. That stands for minimum inhibitory concentration. The MIC, if you want to call it that, is the lowest concentration in micrograms per milliliter of an antibiotic that will inhibit the growth of a given strain of bacteria. Whoosh, mouthful. So, MIC is the lowest concentration of an antibiotic that will inhibit the growth of the given strain of bacteria. Hey, why don't we just kill it all? Well, remember that's the idea, is that we just want to to level the playing field. When you give an antibiotic to a patient who has an infection, the idea is you're trying to put the odds back in the patient's favor so their immune system can take over and finish the job. That's why we want to see what the MIC is, the M-I-C, because it inhibits the growth of the strain of bacteria that's been identified. So, "S" stands for sensitive. That means the organism is inhibited by a normal serum concentration of the drug. It means you're not having to go in red line to go to the max. "R" stands for resistant.

01:24 The organism is resistant to the usually achievable serum drug levels. Now, I know I started on the left and jumped to the right. I did that on purpose because sometimes when you mix things up as you're studying it makes a bigger impression on your brain; bigger impression, more effective encoding, better recall and retention. So, "S" stands for sensitive. That means if we have a normal blood level of the drug it's going to inhibit the growth of the bacteria. "R" resistant, the organism is resistant to the normal blood levels that we can achieve with that drug. Now, right in the middle is intermediate. That means it works but it's only inhibited if I get the maximum recommended dosing. Now, think about what you know about antibiotics.

02:13 They are the worst category of drugs for anaphylactic reactions. Right. They come with all kinds of side effects. They can be really hard on your GI system. So, we don't ever want to give a patient the max of any drug, and with antibiotics, that can be particularly problematic.

02:29 So we're looking for, in the best case scenario, drugs with an "S" by them. Okay, let's have some fun. Let's take a look at the sensitivity chart and look at the medications that are sensitive, this bug is sensitive to any drug that has an "S" by it. I want you to go ahead and draw a line through anything with an "R" by it. Okay, now I've got boxes around three of the medications because I just want to walk you through an example of how we select an antibiotic. So, I picked 3 drugs that are typical, things that we might give, this bug is sensitive to them, and now I want to show you how we compare it. Now you see on this chart I've got a list of items or criteria down the side, 5 things; efficacy, cost, risk of adverse effects, resistance, and drug availability. So, I picked these 3 drugs for you, right. Let's take a look at these and let's compare them. Let's look at efficacy first. Check, check, and check. We know from the sensitivity report that all three of these drugs the bug is sensitive to these drugs.

03:40 So, they're going to inhibit growth. Now, let's look at the cost of treatment. Sadly, this is a reality in healthcare. Look at the cost, $35, $18.50, $2.50, right. So, for wanting to be cost-effective and they all have strong efficacy, it seems like that might factor in to our decision. Now what about the risk of adverse effects? With the 1st one, let's call it nitro because it's easier to say. You want to avoid this in the elderly because they have age-related renal function that declines. Now, it's not nephrotoxic but as the renal function declines, it's going to be hard to keep a therapeutic level in their serum or their blood. So, we don't want to use this in elderly not because it's nephrotoxic but because of their renal function we're just not going to be able to keep a therapeutic level in their serum or their blood. Now, for TMP-SMX, I've got a risk for sulfa allergy but if the patient doesn't have a sulfa allergy, that's not a problem. Now, ciprofloxacin is in the fluoroquinolones. There's a slight chance of tendon rupture but really I'm more concerned with that with young clients and it doesn't happen very often. So, we've looked at efficacy, check, check, and check. We've looked at cost. There's definitely a difference there in cost. We looked at risk of adverse effects, and we would compare this risk of adverse effects with our particular patient. Now, next step we're going to look at resistance. We'll look at the patient history and see if they have had any issues of resistance with this medication. Have they been treated with this antibiotic before and it wasn't effective. Finally, drug availability. Well, that matches efficacy. Check, check, and check. All three of these are common medications available in the United States.

05:34 So now let's look at a bigger challenge. What do you do, how do we decide what we're going to treat if there's more than 1 organism? Do we give multiple meds? Do we try and give 1 med? I want to look at the culture report with 2 bugs again. So see the report. Look down at the bottom. We've got organism 1 and organism 2. Now, looking at the CFUs, we know we've got the 2 different numbers there, 10 to the 3rd and 10 to the 4th. So, think of this as 2 times the fun. We're trying to treat 2 bugs with 1 drug.