Residency Insight -- A PRESENT Podiatry eZine

Volume 4 - Issue 16

Know Your Antibiotics

Robert Frykberg,
DPM, MPH
PRESENT Editor,
Diabetic Limb Salvage

It always intrigues me how students and Residents are so ill-prepared for managing the patients they are expected to care for. Don't get me wrong — we have some very bright young men and women studying podiatry now in school and in their residencies. I honestly believe that they also receive much better training than I did so many years ago in a very prestigious hospital and residency program. Yet, I am dumbfounded so often when students and residents cannot be conversant in the various types, classes, and indications for the numerous antibiotics that they must be cognizant of. Many of my former students (you know who you are) remember the day that I asked them the very poignant question: "Give me five different antibiotics that I can treat Staphylococcus aureus with." Now, this is not an esoteric question, considering that the most common organism causing foot infections is indeed staph aureus. It is surprising how few fourth year students can actually come up with 5 correct choices. Penicillin, ampicillin, and ciprofloxacin are the perennial favorite incorrect choices in this regard! I really don't blame the students, but rather their long ingrained impression that surgery is the most important subject to master. I believe that this impression starts with their recruitment into Podiatry School and is fostered throughout their podiatric education. It is unfortunate that during school, more emphasis is not placed on the basics (as I have previously opined) and the implications of this lack of concentration on things that matter!

Interestingly, the very same students who cannot recall five possible antibiotic choices to treat a Staph infection can easily spew out 6,7, or ten different types of bunion operations! Now, what is wrong here? As I have stated before, there is too much of an emphasis on surgery in school. Everyone wants to be a surgeon when they graduate — before they even know how to treat the postoperative complications that they will surely face! I have been on this soapbox before, but it needs to be repeated. Learn the basics before you learn the advanced things. Learn how to be a doctor before you become a super podiatric surgeon!

With that said, it is important to give a basic primer on antibiotics and pathogens (remember that I took such courses 35 years ago or so). Know your antibiotics! Know those that can be used to treat Staphylococcus aureus (both methicillin sensitive as well as methicillin resistant strains) backwards and forwards. And, if it is easier, learn those that cannot be used — like Penicillin G, ampicillin, and ciprofloxacin! Which antibiotic is indicated (and is best) for Group B streptococcal infections? This is important to know on your first day of residency, when that patient with a necrotizing soft tissue infection is admitted from the ED. What also is the best agent to use for those persons with a beta-lactamase antibiotic allergy? Which one has protease activity that can directly act on bacterial exotoxins? Learn about Gram negative rods (GNR) and which antibiotics cover which pathogens. No, Pseudomonas is certainly not the most important GNR, especially for diabetic foot infections. Nonetheless, when you have a septic patient with Pseudomonas aeruginosa isolated from a valid culture (wound or blood) you must know how to treat it. Speaking of Pseudomonas, what oral agent is the only such oral antibiotic that can cover Stenotrophomonas maltophilia (previously Pseudomonas maltophilia)? If you said that it was the all powerful, wonder drug ciprofloxacin, you would be wrong.

Know your antibiotics! Know those that can be used to treat Staphylococcus aureus (both methicillin sensitive as well as methicillin resistant strains) backwards and forwards. And, if it is easier, learn those that cannot be used — like Penicillin G, ampicillin, and ciprofloxacin! Which antibiotic is indicated (and is best) for Group B streptococcal infections? This is important to know on your first day...

My former students and residents know the answer to this question after having had to answer it for me somewhere along the way. My last query about GNR pathogens concerns ESBL producers. Can you tell me what ESBL stands for and what the implications for antimicrobial management are? If not, you need to learn this! And my very last question: Please name the three antibiotics currently available that have an indication for diabetic foot infections? (I did not ask for the previous oral agent that was removed from the market due to concerns over hepatotoxicity).

Believe it or not, all the questions and scenarios posed are relevant and their answers are necessary for you to know- from now until you stop practicing. I purposely did not give answers so that you would need to search your own databases (minds) to answer the questions. If you do not recall these topics, then get used to researching them — and looking up the appropriate antibiotics for the appropriate pathogen and the appropriate patients. Remember, they call it a practice because you never quite get it all right all the time.

Too bad I don't write board exam questions anymore — these would be perfect, don't you think? I trust that my point did not escape your notice!

See you next time...