Vol. 1, Issue 4, Part A (2016)

Author(s): Tesfaye Adeladlew, Wondmnew Taddie and Debeb Dessie

Abstract: Antibiotics are the substances that can be produced or developed by the microorganism, which selectively inhibit the generation (bacteriostatic) or kill (bactericida the microorganism (that are harmful for human and animal health) at very low concentrations. The mechanism of action of antibiotics can be categorized based on the function that is affected by the agents, these generally included the following: inhibition of the cell wall synthesis, inhibition of the nucleic acid synthesis, inhibition of ribosome function, cell membrane function and inhibition of folate metabolism. There are several ways of classifying antibiotics but the most common classification schemes are based on their molecular structures, mode of action and spectrum of activity. Others include route of administration (injectable, oral and topical). Antibiotics within the same structural class will generally show similar pattern of effectiveness, toxicity and allergic-potential side effects. Some common classes of antibiotics based on chemical or molecular structures include Beta-lactams, Macrolides, Tetracyclines, Quinolones, Aminoglycosides, Sulphonamides, Glycopeptides and Oxazolidinones. Resistance is the ability of a bacteria against the antagonizing effect of an antibacterial agent upon reproduction prevention or bactericidal. The developments of resistance to antibiotics in bacteria often develop as a result of unnecessary and inappropriate use of antibiotics. Several factors have been reported to be responsible to antibiotics resistance in bacterial. Some of the reasons includes: Reduced access to target due to slow porin channels; increased antibiotics expulsion due to multiple drug efflux pumps; inactivating enzymes due to B - lactamases, aminoglycoside-modifying enzymes; mutational resistance due to regulatory mutations that increases the expression of intrinsic genes and operons which is variable in certain circumstances.