Laboratory Report

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To determine antiseptics evaluation by the filter paper disc method

An antiseptic is a substance which inhibits the growth and development of microorganisms. Antiseptics are a diverse class of drugs which are applied to skin surfaces or mucous membranes for their anti-infective effects. This may be either bacteriocidal or bacteriostatic. Their uses include cleansing of skin and wound surfaces after injury, preparation of skin surfaces prior to injections or surgical procedures, and routine disinfection of the oral cavity. In this experiment, filter paper disc method or known as zone of inhibition method is be used. It is satisfactory method employed to evaluate the effectiveness of antiseptic agents against selected test organism. In this method, sterile filter paper disk is impregnated with an antiseotic and placed on fresh heavily inoculated agar plate of a test organism. Following incubation, the agar plate is looked for a zone of inhibition. The presence of a clear zone of inhibition surrounding the disk is indicative of inhibitory (antimicrobial) activity against the organism. This experiment deal with the evaluation of antimicrobial activity of two antiseptics which are 5 % iodine and 5% formaldehyde, against two organism Pseudomonas fluorescens (gram-negative) and Serratia marcescens (gram-negative).

Chemical agent to be tested (5 % iodine and 5 % formaldehyde) Cultures of Pseudomonas fluorescens and Serratia marcescens. Sterile petri dishes
Liquid nutrient agar
Sterile filter paper disc

i. The bottom of a petri dish has been labeled with the name of the organism, the chemical agent and name and date of experimenter and experiment respectively.

ii. One or two loopfuls of the organism has been taken from the cultures provided and a tube of liquid nutrient agar has been aseptically inoculated at 50oC. The mixture has been poured into a sterile petri dish.

iii. When the...
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