Antimicrobial Lab Report

Introduction: Chemical methods of control: Antimicrobial drugs, involves the use of chemicals to prevent and treat infectious diseases. Pasteur and others observed that infecting an animal with Pseudomonas aeruginosa protected the animal against Bacillus anthracis. Later, the word “antibiosis” (against life) for this inhibition and called the inhibiting substance “Antibiotic”. As researchers found out more and more about these chemicals they were able to discover that antibiotics are chemicals or natural substances such as bacteria, fungi, as well as synthetic drugs; that inhibit or kill microbes in small amounts. Chemotherapeutic agents are antimicrobial chemicals (natural or synthetic) that can be used internally or may be absorbed. The purpose of antimicrobial drugs is either to inhibit virus replication, without harming host tissues or to interrupt the cell processes or structures of bacteria, fungi, and protozoa. This lab has brought great interest to me because this is the way physicians’ control/treat infectious disease within our bodies. In this lab, chemotherapeutic agents were evaluated by the disk-diffusion method. Chemotherapeutic agents are placed on the surface of a Petri plate containing Mueller-Hinton agar, which allows the agents to diffuse freely, and a growth medium is incubated over its’ surface. During incubation, the chemotherapeutic agents move from levels of high concentration, to low levels of concentration. To be effective, the agent must inhibit bacteria growth and measurements that were made by the zones of inhibition around the Petri disk. Zone size is affected by diffusion rate of the antibiotic and growth rate of the organism. The Minimum Inhibitory Concentration (MIC) is represented by the concentration of chemotherapeutic that stands at the edge of the zone of inhibition. The MIC is determined by comparing the zone of inhibition with the *Table 1 MIC values. The cultures assigned were Staphylococcus aureus (gram positive

References: Non-profit Organization. "Tetracycline Antibiotics." Wikipedia, the Free Encyclopedia. Wikimedia Foundation, Inc., 13 Oct. 2011. Web. 18 Oct. 2011. . From Chapter 25 of Laboratory Experiments in Microbiology, Ninth Edition. Ted R. Johnson, Christine L. Chase, Copyright@2009 by Pearson Education, Inc. Published by Pearson Benjamin Cummings.