Neomycin is an aminoglycoside antibiotic discovered in 1949. It belongs to a class of antibiotics containing two or more aminosugars bonded together. Neomycin is commonly used topically in creams and eyedrops but can also be taken orally combined with other antibiotics. It works by binding to the 30S subunit of the ribosome to inhibit protein translation from mRNA. However, neomycin can cause ototoxicity and hearing loss.

1. • Neomycin is an aminoglycoside antibiotic
found in many topical medications such as
creams, ointments, and eyedrops.
• The discovery of neomycin dates back to
1949. It was discovered in the lab of Selman
Waksman.
• Neomycin belongs to aminoglycoside class
of antibiotics that contain two or more
aminosugars connected by glycosidic
bonds.
Neomycin

3. Uses
• Neomycin is typically used as a topical
preparation, such as Neosporin.
• It can also be given orally, where it is
usually combined with other antibiotics.
Neomycin is not absorbed from the
gastrointestinal tract and has been used
as a preventive measure for hepatic
encephalopathy and
hypercholesterolemia.

4. Molecular biology
• Neomycin resistance is conferred
by either one of two
aminoglycoside
phosphotransferase genes.
• Neomycin binds to the 30S
subunit of the ribosome and
inhibits translation of proteins
from mRNA.

5. Biosynthetic pathway
• Neomycin is a mixture of neomycin B
(framycetin); and its epimer neomycin C.
• Neomycin has good activity against Gram-
positive and Gram-negative bacteria, but is
very ototoxic.
• Neomycin B is composed of four linked parts:
D-neosamine,
• 2-deoxystreptamine (2-DOS),
• D-ribose, and L-neosamine.

6. Spectrum
• MIC susceptibility data for a few medically
significant Gram-negative bacteria.
• Enterobacter cloacae: >16
μg/ml
• Escherichia coli: 1 μg/ml
• Proteus vulgaris: 0.25 μg/ml

7. Safety
• Neomycin, like other aminoglycosides,
has been shown to be ototoxic causing
tinnitus, hearing loss, and vestibular
problems in a small number of patients.
• Patients with existing tinnitus or
sensorineural hearing loss should speak
with their doctor about the risks and side
effects prior to taking this medication.

8. DNA binding
•Aminoglycosides such
as neomycin are
known for their ability
to bind to duplex RNA
with high affinity.