Vancomycin: An Update

A formula has been developed to predict creatinine clearance (C cr ) from serum creatinine (S cr ) in adult males: Ccr = (140 – age) (wt kg)/72 × S cr (mg/100ml) (15% less in females). Derivation included the relationship found between age and 24-hour creatinine excretion/kg in 249 patients aged 18–92. Values for C cr were predicted by this formula and four other methods and the results compared with the means of two 24-hour C cr’s measured in 236 patients. The above formula gave a correlation coefficient between predicted and mean measured Ccr·s of 0.83; on average, the difference between predicted and mean measured values was no greater than that between paired clearances. Factors for age and body weight must be included for reasonable prediction.

It has been shown that after more than two decades of work on the structure and mode of action of the vancomycin group of antibiotics we have quite a detailed picture of aspects of their binding in vitro. Our introduction has indicated that these antibiotics are of continuing practical importance, whether in clinical use or animal husbandry. It is clear, however, that if one desires to modify these compounds to produce more effective antibiotic agents, more work is required--particularly to understand better the role of the sugar moieties. Nevertheless, with our present knowledge of the structure and mode of action of the antibiotics we can be fairly confident that they represent a group of compounds specifically evolved to aid the survival of the producing organisms by killing or inactivating competing gram-positive bacteria.

Vancomycin is a unique glycopeptide structurally unrelated to any currently available antibiotic. It also has a unique mode of action inhibiting the second stage of cell wall synthesis of susceptible bacteria. There is also evidence that vancomycin alters the permeability of the cell membrane and selectively inhibits ribonucleic acid synthesis. Induction of bacterial L-phase variants from susceptible organisms with vancomycin is extremely difficult, and such variants are unstable. Stable L-phase variants induced by other agents are susceptible to vancomycin. Vancomycin is active against a large number of species of Gram-positive bacteria, such as Staphylococcus aureus (including methicillin-resistant strains), Staph. epidermidis (including multiple-resistant strains), Streptococcus pneumoniae (including multiple-resistant strains), Str. pyogenes, Str. agalactiae, Str. bovis, Str. mutans, viridans streptococci, enterococci, Clostridium species, diphtheroids, Listeria monocytogenes, Actinomyces species and Lactobacillus species. There has been no increase in resistance to vancomycin during the past three decades. Enhancement of antimicrobial activity has been demonstrated with the combination of vancomycin and an aminoglycoside against Staph. aureus, Str. bovis, enterococci and viridans streptococci. The combination of vancomycin and rifampicin are antagonistic to most strains of Staph. aureus, though indifference and occasionally synergism have been shown, but is synergistic against strains of Staph. epidermidis. It shows indifference against enterococci. Vancomycin and fusidic acid are indifferent against Staph. aureus.