Vancomycin, derived from Nocardia orientalis, belongs
to the tricyclic glycopeptide antibiotic type. It is
indicated to kill gram-positive cocci and bacilli. The
bacterial cell wall faces drastic changes between intra- and
extracellular pressure. The strict structure of peptidoglycan
composing the cell wall prevents the cell from lysing and
collapsing.
Having a chemistry of amphoteric glycopeptide antibiotic
(chemical formula C66H75CL2N9O24), vancomycin
causes major damage to the infection organisms by binding
to the carboxyl terminal D-Ala-D-Ala sequence of peptidoglycan
intermediates produced during bacterial cell wall
synthesis. This action leads to the inhibition of the formation
of cross-links in peptidoglycan. Once the peptidoglycan
is not structurally formed correctly, it loses the ability to
prevent the bacterial cell wall from collapsing, and the cells
basically explode under the pressure.
Vancomycin comes in powder form in injection vials and
in capsule form for oral use. Some hospital personnel compound
vancomycin oral solution, using the powder for
injection and vancomycin enema. Because of the relatively
high cost of vancomycin, it is important that the medication
is utilized only when necessary and with the correct
route of administration. I would like to bring to the attention
of my colleagues and pharmacists the appropriate treatment
of methicillin-resistant Staphylococcus aureus (MRSA)
and Pseudomonas colitis caused by Clostridium difficile.
It is very important for a pharmacist to correctly advise a
physician about the proper route of administration of an
antibiotic. For a systemic infection such as MRSA, the use of
oral vancomycin is not recommended because of the low
absorption and low serum concentrations. Likewise, intravenous
(IV) administration of vancomycin is not indicated for
the treatment of Pseudomonas colitis caused by Clostridium
difficile, due to the low concentrations achieved in the colon,
which are not enough to show an infection-killing effect.
Therefore, a pharmacist should advise the following:
For the treatment of MRSA infection, IV vancomycin
should be used.
For the treatment of Pseudomonas colitis caused by
Clostridium difficile, the oral and rectal (enema) forms
of vancomycin should be used.
Dr. Motylev is a pharmacy manager in the hospital setting.
