Tetracyclines – Bacterial Protein Synthesis Inhibitors (Antibiotics)

by Pravin Shukle, MD

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    00:00 Let's move on to the tetracyclines.

    00:03 Now tetracyclines are very commonly used.

    00:05 They are broad spectrum bacteriostatic medications that are used mostly orally.

    00:10 They work both through gram positive and gram negative bacteria.

    00:15 And they may actually work with some protozoan as well.

    00:19 There's widespread resistance with two big major mechanisms.

    00:24 The first one is through a development of an efflux pump.

    00:27 And that's often seen in the porteus and the pseudomonas species.

    00:33 And in fact porteus and pseudomonas are quite interesting because they have multidrug pumps.

    00:38 So they actually have these pumps that will eject the whole host of different medications.

    00:42 And the second mechanism of resistance is through ribosomal protection proteins that actually prevent binding.

    00:48 Almost like a little shield around the ribosome.

    00:51 The prototypical drug in the tetracycline family is actually doxycycline or tetracycline.

    00:59 Doxycycline is used long term in acne treatment.

    01:03 It has a very long duration of activity.

    01:07 And it's relatively non-toxic.

    01:09 It's also used in bronchitis, bronchitis prevention and leptospirosis.

    01:14 Minocycline is used almost exclusively in acne.

    01:18 Demeclocycline is useful in most infectious diseases.

    01:22 And also has a bit of a diuretic effect.

    01:25 So if you go back to hormonal lectures and the adrenal lectures that we've spoken about, you will see that we have talked about demeclocycline and antidiuretic hormones secreting tumors.

    01:37 In terms of the toxicity of tetracyclines.

    01:40 First of all GI symptoms and I think all tetracyclines are suspect with this.

    01:46 They have common but minor side effects, there is very rare episodes of life-threatening enterocolitis, but, it's certainly there.

    01:54 It does eliminate normal gut flora, so, you can be prone to bacterial overgrowth syndrome and candidiasis.

    02:03 Now, fetal exposure to this medication, results in dental enamel dysplasia.

    02:08 This is a common exam question, i do want you to remember this.

    02:12 So tetracyclines with fetal exposure, dental enamel dysplasia.

    02:19 In terms of other side effects, you can get hepatotoxicity, like most antibiotics, dizziness, vertigo and that's mostly with doxycycline.

    About the Lecture

    The lecture Tetracyclines – Bacterial Protein Synthesis Inhibitors (Antibiotics) by Pravin Shukle, MD is from the course Antimicrobial Pharmacology.

    Included Quiz Questions

    1. All members of the class are available orally.
    2. They have broad-spectrum bacteriostatic activity.
    3. Doxycycline and minocycline are often used in long term acne treatment.
    4. They may be effective against some protozoan infections.
    5. They bind the 30S subunit of the ribosome.
    1. Acne
    2. AIDS
    3. Rubella
    4. Hypertension
    5. Meningitis
    1. Anemia
    2. Bacterial overgrowth in the gut
    3. Dizziness, vertigo
    4. Hepatotoxicity
    5. Dental enamel dysplasia with fetal exposure

    Author of lecture Tetracyclines – Bacterial Protein Synthesis Inhibitors (Antibiotics)

     Pravin Shukle, MD

    Pravin Shukle, MD

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