Abstract

In vitro activities of 80% ethanol extracts from 26 plants native to South-Eastern Yunnan, China, were evaluated against clinical multi-drug resistant (MDR) pathogens. The extracts were initially screened by the agar hole diffusion test. Then the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) or minimum fungicidal concentration (MFCs) were determined through serial dilution with a standard broth micro-dilution method. Of the 26 extracts, 9 showed different potencies againstStaphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The most active plants against both S. aureus and methicillin-resistant S. aureus (MRSA) were Rhodoleia parvipetala Tong, Diplopanax stachyanthus Hand.-Mazz andSarcosperma kachinense Exell var. simondii Lam.et Royen, and their MIC/MBCs were 512, 512, 256-512 mg/L, respectively. Sladenia celastrifolia Kurz extract showed strong activity against P. aeruginosa and C. albicans, and their MICs were 512-2048 and 2048 mg/L, together with no activities of MBC or MFC up to the concentrations of 2048 mg/L. All these plants showed weak inhibition against E. coli.

Key words: Plants extracts, antimicrobial activity, MRSA, MIC.

Abbreviation

ATCC, American Type Culture Collection; CFU, colony forming unit; CLSI,Clinical Laboratory Standards Institute; DMSO, dimethyl sulfoxide; IPRA, imipenem-resistant pseudomonas aeruginosa; IZD, inhibition zone diameters; KIB, Kunming Institute of Botany; MBC, minimum bactericidal concentration; MFC, minimum fungicidal concentration; MH-A, Standard Mueller–Hinton agar; MH-B, Standard Mueller–Hinton broth;MIC, minimum inhibitory concentration; MDR, multidrug-resistant; MRSA, Methicillin-resistant Staphylococcus aureus; MSSA, Methicillin-sensitive Staphylococcus aureus;NCCLS, National Committee for Clinical Laboratory Standards; S-A, Sabouraud agar; S-B,Sabouraud broth.