MOA of Tetracycline Antibiotics
MOA of Tetracycline Antibiotics
Tetracycline Antibiotics
Discovered in
the late 1940s, tetracyclines are a
family of broad-spectrum antibiotics used to treat a wide range of bacterial
infections. The original tetracyclines were derived from Streptomyces bacteria, but the newer derivatives are semi-synthetic.
Some representative tetracyclines include:
·
tetracycline
·
doxycycline
·
minocycline
·
panmycin
·
terramycin
·
trimocycline
Tetracycline Mode of
Action
Tetracyclines
exert their bacteriostatic effect by inhibiting protein synthesis in bacteria.
This antibiotic
prevents transfer-RNA (tRNA)
molecules (a type of nucleic acids which
transport amino
acids) from binding to the 30S subunit of bacterial ribosomes.
It is possible
for tetracyclines to inhibit protein synthesis in the eukaryotic cells of the
host, but the drug is less likely to reach the required concentrations in
humans because eukaryotic cells do not have a tetracycline uptake mechanism.
Antimicrobial Spectrum of
Tetracyclines
Tetracyclines are broad-spectrum antibiotics which exhibit activity against a wide range of microbes including both Gram-positive (Gram+) and Gram-negative
(Gram-)
bacteria, chlamydias, mycoplasmas, rickettsiae, as well as some protozoan
parasites.
Type of Infections
Tetracyclines Are Used Against
Tetracycline is used to treat many different infections including respiratory tract infections caused by Hemophilus influenza, Streptococcus pneumonia, or Mycoplasma pneumoniae. It also is used for urinary tract infections (UTIs), Rocky Mountain spotted fever, typhus, chancroid, cholera, brucellosis, anthrax, syphilis, lyme disease, acne and may be used concomitantly with other medications against Helicobacter pylori, the bacteria associated with stomach ulcers.
Antibiotic Resistance
Because
tetracyclines have been around for so long, bacterial resistance is common, and
the presence of tetracycline-resistant pathogens limits the use of this class
of antibiotic.
Adverse Effects of Tetracyclines
Side effects may
include nausea, diarrhea, and sensitivity to light. Tetracyclines also form
complexes with calcium, which can stain the developing teeth of children and
affect the strength and shape of bones.
Since tetracyclines are active against such a wide range of microbes, destruction of normal intestinal flora often occurs, resulting in increased secondary infections.
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