抗生素(英文)-Introduction-to-Lab-Ex-14-Antibiotic-Se.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,*,*,Introduction to Lab Ex.14:Antibiotic Sensitivity,Disc Diffusion Method,Introduction to Lab 10:Ex.Antibiotic Sensitivity,Antibiotics,are chemicals that are produced by other bacteria/fungi,that have the ability to prevent other organisms(bacteria),from growing or killing them.,These have been used widely in controlling bacterial infections,in humans that cause diseases in humans.,There have been many antibiotics that have been developed.,These have been found to be effective in controlling various,infectious bacteria in humans and thus used extensively,in disease control(treatment of bacterial infections),While there are many different kinds of antibiotics and still,many more kinds of bacteria,not all antibiotics are,effective in inhibiting all bacteria.,Hence,it is essential to determine whether an organism is,sensitive,to the inhibitory action of the antibiotic or not.,Many procedures have been developed to determine,antibiotic sensitivity,.,The most common method is the,Disc diffusion,method:,Filter paper discs are saturated with specific amounts of,certain antibiotics and placed on a growth of the particular,bacterial culture to be tested.,If,growth is inhibited,then,sensitivity,is seen,If,growth is seen,then the culture is,resistant,to the,antibiotic action and is,not inhibited,(which will mean that it cannot be used to treat an infection,by the bacterium),It has also been discovered that antibiotics inhibit bacteria,by,stopping their growth(bacteriostatic,)or,by,killing them(bactericidal,).,Antibiotics have been found to have different,modes of action,to inhibit bacteria:destruction of cell wall,destruction of cell membrane,inhibition of protein synthesis,inhibition of DNA synthesis,inhibition of intermediary metabolism,Also,most antibiotics are effective only against bacteria,(which have a prokaryotic cell structure and processes different,from eukaryotic cells resulting in antibiotics being effective,primarily against prokaryotic cells i.e.other bacteria),