Antimicrobial Activity of Croton macrostachyus Stem Bark Extracts against Several Human Pathogenic Bacteria

Table 1

Zone of inhibition of the different C. macrostachyus extracts against selected human pathogens.

Pathogen	Zone of inhibition
	Extract			Antibiotic
	^1MeOH	^2EtOAc	^3BuOH	A	B
Escherichia coli	9.0 ± 1.1	12.2 ± 1.6	13.7 ± 1.4	20.1 ± 0.9	16.2 ± 0.8
Salmonella typhi	2.3 ± 1.87	16.0 ± 1.2	8.3 ± 1.5	22.1 ± 0.9	20.8 ± 0.8
Klebsiella pneumoniae	14.9 ± 1.3	10.7 ± 1.0	11.1 ± 1.9	19.7 ± 0.5	17.3 ± 0.9
Enterobacter aerogenes	10.8 ± 1.1	10.1 ± 0.6	10.8 ± 1.2	21.3 ± 0.5	18.6 ± 0.5
Listeria monocytogenes	0.0 ± 0.0	11.7 ± 1.3	0.0 ± 0.0	21.0 ± 0.8	18.3 ± 0.5
Candida albicans	12.0 ± 1.4	5.6 ± 1.0	0.0 ± 0.0	21.5 ± 0.7	13.4 ± 0.7

MeOH, methanol extract.
² EtOAc, ethyl acetate extract.
³BuOH, isobutanol extract.
Zone of inhibition (diameter in mm) including diameter of the well (6 mm). The experiments were carried out using triplicate samples. The results are from three independent analyses and are the mean of 9 values ().
In negative control DMSO no inhibition was found.
For E. coli, S. typhi, K. pneumoniae, and E. aerogenes antibiotic A was amoxicillin and antibiotic B was ciprofloxacin.
For L. monocytogenes antibiotic control A was ampicillin and antibiotic control B was benzylpenicillin.
For C. albicans antibiotic control A was clotrimazole and antibiotic control B was cefotaxime.