Question

1. Your 5-month-old son wakes up this morning with a high fever and hoarse cry, with what looks like a highly inflamed throat.  You decide to take him in for an examination.  The doctor believes he has a bacterial infection, likely Streptococcus.
   1. What three considerations should the doctor take before prescribing an antimicrobial drug?
   2. Describe the five sites of drug action.  Give an example of a drug that affects each site and explain the mode of action for each.
   3. When the doctor asks if you or your son have been exposed to the same disease recently, you recall that you’d seen something very similar at the healthcare clinic you work at just a few days prior.  Alarmingly, you also remember that some of the patients in your clinic were testing positive for MRSA.  
      1. What are the mechanisms of drug resistance and how are each acquired?
      2. How can the doctor determine the resistance of your son’s pathogen (Kirby Bauer)?

Answer 1

The 5-month-old son wakes up with an extremely high fever and a hoarse cry. he also shows signs of throat inflammation. The doctor is guessing that is is a Strep infection. The following answers are as follows.

a. The doctor should understand what is the primary cause of the symptoms before prescribing antimicrobial medicine to the child. Also, due to his age, extra precautionary measures are to be taken because prescribing any medicine. The doctor should assess the benefits which the medicine might cause on his body, keeping in mind that it should not be prone to causing resistance. Cost-effectiveness should also be considered.

b.Drugs have their respective target sites. These target sites are exclusive to only particular drugs. The drugs are designed in a way such that it targets only that particular site. Thus, the sites of drug action are receptors, enzymes, ion channels, and carrier molecules. Drugs targeting receptors is the easiest and most widely used system in the field of pharmacodynamics and pharmacokinetics. Enzymes and ion channels are usually blocked by drugs and they are used as a negative target.

c.As the woman works at a healthcare clinic, she is exposed to various microbes. There is a very high chance that she has been infected with a community transferrable disease, but due to her age and the strong immune system, she could overcome it without any alarming symptoms. But as she is the primary caregiver to her five-month-old son, the son has a chance to get infected. In the place she works, there have been cases of MRSA( Methicillin-resistant Staphylococcus aureus). This strain belongs to the Staph category of bacteria which over the period of time has developed resistant characteristics that have lead to a deadly situation.

i. There are several ways in which the microbe acquires a resistance towards the drug. This usually happens when the microbe is present in the body over a very long period of time. This is a survival strategy for the microbe. The ways in which they acquire resistance are many. These are mentioned as follows-

Firstly, there can be situations where the drug cannot get access to the microbe. Modification of the drug can result in its inactivation. There are efflux methods by which the microbe gets rid of the drug from its body, thus surviving. In cases of modification of the target, the drug cannot bind and thus fails to act. There can be situations where the drug has been inactivated with the help of enzymes. Lastly, there can be the development of a metabolic pathway which results in the resistance.

ii. After identifcation of the pathogen which is present in the body of the child, the next function is to identify which drugs are resistant to the pathogen. For this the doctor and his team of technicians need to use the disk diffusion method aka Kirby Bauer method. Here the pathogen needs to be plated and disks of different drugs are to be placed over it. After incubation, the disks which have a zone of diffusion will be potent agaisnt the microbe. For the remaining drugs, the pathogen is resistant.