General
Description & Use
Used
to treat impetigo as well as other skin infections caused by bacteria.
Mupirocin (Bactroban or Centany) is an antibiotic originally isolated
from Pseudomonas fluorescens. Mupirocin is bacteriostatic at low
concentrations and bactericidal at high concentrations. It is
used topically and effective against Gram-positive bacteria, including
methicillin-resistant Staphylococcus aureus. Mupirocin is a mixture
of several pseudomonic acids, with pseudomonic acid A (PA-A) constituting
greater than 90% of the mixture. Also present in mupirocin are
pseudomonic acid B with an additional hydroxyl group at C8, pseudomonic
acid C with a double bond between C10 and C11, instead of the
epoxide of PA-A, and pseudomonic acid D with a double bond at
C4` and C5` in the 9-hydroxy-nonanoic acid portion of mupirocin[6].
Mupirocin
has been shown to strongly inhibit protein and RNA synthesis in
Staphylococcus aureus while DNA and cell wall formation are also
negatively impacted a lesser degree. The inhibition of RNA synthesis
was shown to be a protective mechanism in response to a lack of
one amino acid, isoleucine. In vivo studies in Escherichia coli
demonstrated that pseudomonic acid inhibits isoleucine t-RNA synthetase
(IleRS). This mechanism of action is shared with furanomycin,
an analog of isoleucine.
Uses
Mupirocin is used as a topical treatment for bacterial skin infections,
for example, furuncle, impetigo, open wounds etc. It is also useful
in the treatment of methicillin-resistant Staphyolococcus aureus
(MRSA), which is a significant cause of death in hospitalized
patients who have received systemic antibiotic therapy. It is
suggested, however, that mupirocin not be used for extended periods
of time, or indiscriminately, as resistance does develop, and
could, if it becomes widespread, destroy mupirocin's value as
a treatment for MRSA. It may also result in overgrowth of non-susceptible
organisms.
