Table 2.

Minimum inhibitory concentration (MIC), minimum microbicidal concentration (MMC), mean values of inhibition halos (M∅_h mm) and selectivity index (SI) obtained from in vitro antimicrobial susceptibility testing and cytotoxicity assays of the lyophilized extracts of S. praealtum

Microorganism	Lyophilized extract of S. praealtum A.DC.												Controls
	Leaf				Stem				Root				Chlorhexidine	Rifamycin
	MIC/MMC	M∅h	IC50	SI	MIC/MMC	M∅h	IC50	SI	MIC/MMC	M∅h	IC50	SI	M∅h	M∅h
Gram-negative bacteria
E. coli	25/−	0A	4.22	0.17	25/−	0A	5.96	0.24	−/−	0A	–	–	12.3D	na
E. aerogenes	50/−	0A	4.22	0.08	−/−	0A	–	–	−/−	0A	–	–	9.7C	na
S. marcescens	25/50	0A	4.22	0.17	−/−	0A	–	–	−/−	0A	–	–	11.3D	na
P. aeruginosa	25/−	0A	4.22	0.17	−/−	0A	–	–	−/−	0A	–	–	11.3D	na
P. mirabilis	25/−	0A	4.22	0.17	−/−	0A	–	–	50/50	0A	–	> 1*	9.3C	na
S. typhimurium	25/−	0A	4.22	0.17	−/−	0A	–	–	−/−	0A	–	–	10.3C	na
Gram-positive bacteria
B. subtilis	50/−	0A	4.22	0.08	50/−	0A	5.96	0.12	25/25	7.7C	–	> 1*	13.7D	na
B. cereus	25/−	7C	4.22	0.17	25/−	6.3C	5.96	0.24	12.5/−	8.7C	–	> 1*	13D	na
M. luteus	12.5/50	7.3C	4.22	0.34	25/50	4B	5.96	0.24	12.5/50	10.3C	–	> 1*	16E	na
E. faecalis	25/−	0A	4.22	0.17	25/−	0A	5.96	0.24	12.5/−	0A	–	> 1*	14.3D	na
S. aureus	25/50	0A	4.22	0.17	25/−	6.3C	5.96	0.24	12.5/50	8.7C	–	> 1*	13.3D	na
Yeasts
C. albicans	–	0A	–	–	–	0A	–	–	25/−	0A	–	> 1*	13.3D	na
S. cerevisiae	6.25/50	0A	4.22	0.68	12.5/50	6.7C	5.96	0.90	6.25/50	8.7C	–	> 1*	12.7D	na
Mycobacteria
M. tuberculosis	na	0a	na	na	na	0a	na	na	na	0A	na	na	na	11D
M. bovis	na	0a	na	na	na	0a	na	na	na	0A	na	na	na	11D