10 Interesting Facts About Antibiotics

Posted on December 23, 2025

Infectious disease was never my favorite subject --- I actually avoided it. It wasn’t until I built lessons for my NAPLEX tutoring service that things finally clicked. Along the way, I came across some surprisingly interesting antibiotic facts that made studying more memorable. Below is a short quiz highlighting a few of those tidbits.

Part I: 10 Antibiotic Questions

1. Which combination beta-lactam antibiotic does not include a beta-lactamase inhibitor?
2. Which cephalosporin can cause a disulfiram-like reaction similar to metronidazole?
3. Which antibiotic causes orange-red discoloration of bodily fluids, including urine and tears?
4. What infusion-related reaction occurs when IV vancomycin is given too quickly?
5. What antibiotic was withheld from research participants in the Tuskegee Syphilis Study?
6. Which antibiotic is the drug of choice for early Lyme disease in adults and children over 8, but should generally be avoided in younger children due to the risk of tooth discoloration?
7. Which antibiotic can be given as a single-dose regimen to treat Chlamydia, one of the most common sexually transmitted infections?
8. Which two antibiotics --- one beta-lactam and one combination drug --- both cover MRSA?
9. What is the drug of choice for uncomplicated UTIs in pregnancy for most of gestation?
10. Which IV antibiotic (also available orally) does not require renal dose adjustment?

Part II:

How did you do? More importantly, do you know why each answer is correct? Below, you’ll find the same questions --- this time with answers and brief explanations. These memorable details are what made studying antibiotics more engaging and easier to retain for me.

Questions + Answers and Explanations

1. Which combination beta-lactam antibiotic does not include a beta-lactamase inhibitor?

Answer: Imipenem/cilastatin (Primaxin®)

Explanation:
Most beta-lactam “combination” products pair an antibiotic with a beta-lactamase inhibitor (e.g., amoxicillin/clavulanate). Cilastatin is different --- it is not a beta-lactamase inhibitor. Instead, it inhibits renal dehydropeptidase I, preventing imipenem degradation in the kidneys and reducing nephrotoxicity.

2. Which cephalosporin can cause a disulfiram-like reaction?

Answer: Cefotetan

Explanation:
Cefotetan (a second-generation cephalosporin with anaerobic coverage) contains an N-methylthiotetrazole (NMTT) side chain, which interferes with alcohol metabolism --- similar to metronidazole. Patients may experience flushing, nausea, vomiting, and hypotension if alcohol is consumed.

3. Which antibiotic causes orange-red discoloration of bodily fluids?

Answer: Rifampin

Explanation:
Rifampin induces hepatic enzymes and is well known for discoloring urine, sweat, saliva, and tears. This is harmless but important to counsel patients about --- especially contact lens wearers. It can stain the lens bright orange-red. Although rifampin is not commonly used for routine infections, it is frequently tested on exams due to its characteristic orange-red discoloration of bodily fluids and its clinically significant drug–drug interactions.

4. What infusion-related reaction occurs when IV vancomycin is infused too quickly?

Answer: Red Man Syndrome

Explanation:
Red Man Syndrome is caused by histamine release, not an IgE-mediated allergy. Symptoms include flushing, pruritus, and hypotension. This reaction is most often prevented by slowing the infusion (≥60 minutes, often longer for higher doses) rate. This distinction matters clinically because you don’t want it misclassified as an allergy.

5. What antibiotic was withheld in the Tuskegee Syphilis Study?

Answer: Penicillin

Explanation:
Despite penicillin being recognized as a curative therapy for syphilis, it was deliberately withheld from participants. This tragic study is a cornerstone of medical ethics education and underscores the importance of informed consent and equitable care.

6. Which antibiotic is the drug of choice for early Lyme disease in adults and children over 8, but should generally be avoided in younger children due to the risk of tooth discoloration?

Answer: Doxycycline

Explanation:
Doxycycline is the first-line treatment for early Lyme disease in adults and children ≥8 years old. In children under 8, it is generally avoided because tetracyclines can bind to developing teeth and bones, potentially causing permanent tooth discoloration. For younger children with Lyme disease, amoxicillin is typically used instead.

7. Which antibiotic can be given as a single-dose regimen to treat Chlamydia, one of the most common sexually transmitted infections?

Answer: Azithromycin

Explanation:
Azithromycin is effective as a single-dose treatment for uncomplicated Chlamydia infections, making it both convenient and reliable. Chlamydia is considered one of the most common bacterial STIs, so this fact comes up often on exams.

8. Which two antibiotics --- one beta-lactam and one combination drug --- both cover MRSA?

Answer: Ceftaroline and trimethoprim/sulfamethoxazole (TMP-SMX)

Explanation:
Ceftaroline (a fifth generation cephalosporin) is unique as the only cephalosporin with MRSA coverage, while TMP-SMX is a common oral option for skin and soft tissue infections. This pairing highlights how MRSA coverage spans multiple drug classes with very different mechanisms.

9. What is the drug of choice for UTIs in pregnancy for most of gestation?

Answer: Nitrofurantoin

Explanation:
Nitrofurantoin is effective, well-tolerated, and concentrates in the urine. It is generally avoided at term (38–42 weeks) due to the risk of neonatal hemolytic anemia, but remains a first-line option during most of pregnancy --- an important nuance that often confuses learners. Additionally, nitrofurantoin should be avoided in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, because it can trigger oxidative stress that leads to hemolytic anemia.

10. Which antibiotic (IV and oral) does not require renal dose adjustment?

Answer: Linezolid

Explanation:
Linezolid is metabolized non-renally, making it especially useful in patients with renal impairment. However, it carries other important risks --- myelosuppression, optic neuropathy, and serotonin syndrome --- reinforcing that every antibiotic trade-off is about balancing risks and benefits.

Final Thought

Learning antibiotics doesn’t have to be dry memorization. These interesting facts serve as memorable anchors that make the material more engaging and easier to recall. By focusing on these small but striking points --- like unusual side effects, unique coverage, or historical context --- you can make studying infectious disease more enjoyable and the information more likely to stick.

How many of these facts were new to you? Reach out to study with me, and I’ll help you dig deeper, understand the “why,” and make the material truly memorable.

💡 Learn more about our services: PD Tutoring Services, LLC 

💡 Get started: Tutoring Inquiry Form