Three main resistance variants have been characterised to date among resistant Enterococcus faecium and E. faecalis populations:

VanA - enterococcal resistance to vancomycin and teicoplanin; inducible on exposure to these agents
VanB - lower-level enterococcal resistance; inducible by vancomycin, but strains may remain susceptible to teicoplanin
VanC - least clinically important; enterococci resistant only to vancomycin; constitutive resistanceVariant of vancomycin has been tested that binds to the resistant D-lactic acid variation in vancomycin-resistant bacterial cell walls, and also binds well to the original target (vancomycin-susceptible bacteria). "Re-gained" vancomycin
In 2020 a team at the University Hospital Heidelberg (Germany) re-gained the antibacterial power of vancomycin by modifying the molecule with a cationic oligopeptide. The oligopeptide consists of six arginin units in Position VN. In comparison to the unmodified vancomycin the activity against vancomycin-resistant bacteria could be enhanced by a factor of 1 000. This pharmacon is still in preclinical development. Therefore, a potential approval will take several more years. History
Vancomycin was first isolated in 1953 by Edmund Kornfeld (working at Eli Lilly) from a soil sample collected from the interior jungles of Borneo by a missionary, Rev. William M. Bouw (1918-2006). The organism that produced it was eventually named Amycolatopsis orientalis. The original indication for vancomycin was for the treatment of penicillin-resistant Staphylococcus aureus.The compound was initially called compound 05865, but was eventually given the generic name vancomycin, derived from the term "vanquish". One advantage that was quickly apparent was that staphylococci did not develop significant resistance, despite serial passage in culture media containing vancomycin.
The quantitative allergy blood result can help determine what a patient is allergic to, help predict and follow the disease development, estimate the risk of a severe reaction, and explain cross-reactivity.A low total IgE level is not adequate to rule out sensitization to commonly inhaled allergens. Statistical methods, such as ROC curves, predictive value calculations, and likelihood ratios have been used to examine the relationship of various testing methods to each other. These methods have shown that patients with a high total IgE have a high probability of allergic sensitization, but further investigation with allergy tests for specific IgE antibodies for a carefully chosen of allergens is often warranted. Laboratory methods to measure specific IgE antibodies for allergy testing include enzyme-linked immunosorbent assay (ELISA, or EIA), radioallergosorbent test (RAST) and fluorescent enzyme immunoassay (FEIA). Other testing
Challenge testing: Challenge testing is when tiny amounts of a suspected allergen are introduced to the body orally, through inhalation, or via other routes. Except for testing food and medication allergies, challenges are rarely performed. When this type of testing is chosen, it must be closely supervised by an allergist. Elimination/challenge tests: This testing method is used most often with foods or medicines. A patient with a suspected allergen is instructed to modify his diet to totally avoid that allergen for a set time. If the patient experiences significant improvement, he may then be "challenged" by reintroducing the allergen, to see if symptoms are reproduced.