Question

1. The following table is a list of mean kill zone diameters (mm) derived from antibiotic-soaked discs placed in bacterial lawns of different strains grown on isolated, airtight agar plates (n = 20 lawns per strain/antibiotic combination). Based on what you know --- or may research --- about these strains and the targets of these pharmaceutical compounds, are any of the data trends below puzzling or counterintuitive. Why or why not.

	Ampicillin	Bacitracin	Clindamycin	Colistin	Chloramphenicol	Enoxacin
E. coli	0	3	16	46	12	21
C. freundii	2	3	14	22	12	7
P. stutzeri	0	0	15	45	11	18
B. thuringiensis	12	50	17	0	13	30
S. epidermidis	18	8	10	0	10	15
M. luteus	10	39	12	0	10	9

Answer 1

In case of E.coli the results found in case of colistin is counterintuitive. It is because colistin is an antibiotic which works on the gram negative bacteria. So it kills them and to there should be negligible amount of the bacteria. But the amount of stains are most in this antibiotic.

Similar is in case of C.freundii and P.stutzeri.

While in case of last three stains it is the case of Bacitracin.

Comment for further assistance.

Please upvote. Thanks.