Vancomycin is a glycopeptide antibiotic used in infections caused by gram + bacteria or in association with other types of antibiotics, such as aminoglycosides.
Vancomycin is a glycopeptide antibiotic indicated in the second-line treatment in patients who are allergic to penicillin or β-lactams.
In a natural antibiotic derived from gram + Nocardia orientalis bacteria effective against gram +, aerobic and anaerobic bacteria. Its use is totally contraindicated in those patients with a history or history of allergic reactions to this medication.
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Gram +ve or gram -ve bacteria ?
Depending on the structure of the cell wall of the bacteria, we can classify them into gram + and gram – . The first ones present a cellular membrane composed of peptidoglycan and an inner cytoplasmic membrane formed by a double layer of lipids.
On the other hand, the gram -, which in addition to the internal cytoplasmic membrane, have another bilayer of lipids in the outermost membrane . Between both membranes there is a space that is called periplasmic space.
This space of gram-bacteria is formed by peptidoglycan, which is much larger and wider than in gram + bacteria. As we can see, the cell membrane of the gram – is more complex than that of the opposite membrane .
To know if it is one type or another, a series of tests must be carried out in the laboratory that allow us to classify the bacteria. The best known technique is Gram stain .
Mechanism of action of vancomycin
Vancomycin owes its effect to its ability to inhibit the cell wall synthesis of gram + bacteria from the outside, that is, it does not need to penetrate the cell to develop its action.
It is a bactericidal antibiotic, which means that it causes the direct death of the microorganism , unlike the bacteriostatic ones, that what they do is inhibit the growth, without inducing death.
The bacterial cell wall is an element of bacteria cells essential for the life of these microorganisms.
It is effective against infections of anaerobic bacteria (those that can live in the absence of oxygen) and aerobic (require oxygen to live). When administered in an infection caused by a gram – bacterium, it will diminish the framework of peptidoglycan, favoring the action of the specific antibiotics of these bacteria.
That is why it is widely used in the hospital setting in association with active antibiotics against gram infections – such as aminoglycosides.
Normally vancomycin is administered intravenously . However, in certain circumstances, such as in the treatment of pseudomembranous colitis, it is used orally. Maximum concentrations in blood are usually observed in blood two hours after intravenous administration.
It is a drug that binds approximately 55% to plasma proteins in healthy patients . If the person suffers an infection, this degree of union decreases to approximately 30-40%, depending on the degree of renal dysfunction and the degree of hypoalbuminemia (low concentration of albumin, which is the main plasma protein).
Vancomycin is excreted by glomerular filtration in the unmetabolized kidney . However, when administered orally, due to its low bioavailability, most of this antibiotic is eliminated in the faeces.
It is a drug that has a high toxicity , with ototoxicity and nephrotoxicity being the two most serious adverse effects. The ototoxicity of vancomycin can be manifested through cochlear toxicity (tinnitus) or vestibular toxicity, which includes symptoms such as ataxia, vertigo, nausea and vomiting.
It is believed that this ototoxicity is due to the administration of a high dose, prolonged exposure to the drug , the concomitant use of other ototoxic drugs, excessive noise, dehydration and bacteremia, which is the presence of bacteria in the blood. .
As for nephrotoxicity, it usually appears in rare cases . The possibility of suffering this adverse effect is diminished when the plasma concentrations of vancomycin are below 10mg / ml.
However, nephrotoxic effects can be additive if it is administered in conjunction with other drugs that also have these characteristics. We have seen that a very typical association is to administer this drug with aminoglycosides. In this situation, the likelihood of suffering nephrotoxicity increases greatly, since aminoglycosides are a type of antibiotic that have a lot of toxicity in these organs.
Red neck syndrome
This syndrome is a characteristic adverse reaction of this antibiotic . It occurs when a rapid intravenous infusion of vancomycin has been carried out. This causes histamine to be released into the body. Histamine is the molecule responsible for producing anaphylactic reactions that are characterized by:
- Shaking chills
- Hot flushes
In addition to these symptoms, it produces a reddening on the face , neck and upper part of the patient’s trunk. This anaphylactic reaction, which encompasses all the above symptoms, is called “Red man syndrome”.