In humans, the gene ABCB1 encodes MDR1(p-glycoprotein) which is a key transporter of medications on the cellular level. If MDR1 is overexpressed,<unk>  increases. Therefore, ABCB1 levels can be monitored. In patients with high levels of ABCB1 expression, the use of secondary treatments, like metformin, have been used in conjunction with the primary<unk> ug treatment with some success. For antibiotic<unk> , which represents a widespread problem nowadays,<unk> ugs designed to block the mechanisms of bacterial antibiotic<unk>  are used. For example, bacterial<unk>  against beta-lactam antibiotics (such as penicillin and cephalosporins) can be circumvented by using antibiotics such as nafcillin that are not susceptible to destruction by certain beta-lactamases (the group of enzymes responsible for breaking down beta-lactams). Beta-lactam bacterial<unk>  can also be dealt with by administering beta-lactam antibiotics with<unk> ugs that block beta-lactamases such as clavulanic acid so that the antibiotics can work without getting destroyed by the bacteria first. Recently, researchers have recognized the need for new<unk> ugs that inhibit bacterial efflux pumps, which cause<unk>  to multiple antibiotics such as beta-lactams, quinolones, chloramphenicol, and trimethoprim by sending molecules of those antibiotics out of the bacterial cell. Sometimes a combination of different classes of antibiotics may be used synergistically; that is, they work together to effectively fight bacteria that may be resistant to one of the antibiotics alone. Destruction of the resistant bacteria can also be achieved by phage therapy, in which a specific bacteriophage (virus that kills bacteria) is used.
Drug resistance
Multiple drug resistance
Antimicrobial resistance
Antibiotic synergy
Resistance 
Vaccine resistance
Infectivity
Host adaptation