Date of Award

Spring 1960

Document Type



Life & Environmental Sciences

First Advisor

Donald Waldhalm


The value of the work performed In the clinical laboratory can be seen more readily in the field of bacteriologic control of antibiotic therapy. The treatment of infectious disease was greatly altered with the discovery of penicillin. Since that time (1929) the number of available chemotherapeutic agents for combating disease has increased in unbelievable proportions. Aside from the role of isolation and identification of the etiological agent, the clinical laboratory has been faced with the problem of performing sensitivity tests on a routine basis in order to tell the physician the most effective antibiotic.

A number of techniques have been developed to aid the clinician in his work. The method which has become the standard procedure in the greater percentage of laboratories Is the use of Impregnated dies.

"Estimates of the extent of this use of paper discs of all types indicate that currently there are approximately 2,500,000 bacteriological specimens examined yearly by this test / and that this represents they utilization of approximately 1 7 ,000,000 disc determinations" (1)

The utilization of discs ha« brought forth a number of problems in evaluating the results obtained. Among these problems is the concentration of antibiotic which will give the more beneficial results. The present study is limited to a very small phase of the above problem. The basic attempt is to test the value of the 2 unit and 10 unit discs of penicillin against a test organism, Staphylococcus. For routine work It is necessary to know which disc will give sufficient and reliable evidence as to sensitivity and resistance. The question arises, is the use of a lower concentration as good as a higher concentration; or is it necessary to use both concentrations?