Abstract:Recently, drug resistance due to the extensive abuse and over-use of antibiotics has become an increasingly serious problem, making the development of alternative antibiotics a very urgent issue. In this study, the Chinese herbal medicine, Polygonum cuspidatum, was extracted with 95% ethanol and the crude extracts were further purified by partition based on solvent polarity. The antimicrobial activities of the extracts and fractions were determined by the disk diffusion and minimum inhibitory concentration (MIC) methods. The results showed that the ethyl ether fraction (EE) of the ethanol extracts possesses a broader antimicrobial spectrum and greater antimicrobial activity against all of the tested clinical drug-resistant isolates, with a range of MIC values between 0.1-3.5 mg/mL. The active extract showed complete inhibition of pathogen growth and did not induce resistance to the active components. In addition, according to scanning electron microscope observations, EE resulted in greater cell morphological changes by degrading and disrupting the cell wall and cytoplasmic membrane, whereby ultimately this cell membrane integrity damage led to cell death. In conclusion, the EE extracts from Polygonum cuspidatum may provide a promising antimicrobial agent for therapeutic applications against nosocomial drug-resistant bacteria.

Rapid and accurate identification of the drug susceptibility profile of clinical strains is very important for controlling bacterial infections and determining the antibiotic therapy. The objective of this study was to investigate the spectrum of the correlation between phenotypic and genetic characters of the drug-resistant clinical isolates. A total of 133 clinical isolates, including 76 Acinetobacter baumannii and 57 Pseudomonas aeruginosa, were examined for their antibiotic susceptibility by the method of disc diffusion. Among them, most of the isolates were multiresistant, and 80% of the strains showed phenotypic resistance to beta-lactam antibiotics. Using PCR analysis, among the several types of beta-lactamases, TEM was the most prevalent, and OXA was the second most prevalent. The integron harbored was identified by conserved segment PCR, and 50% of the test isolates carried integrons with various gene cassette sizes inserted. The results obtained from this study reveal that the majority of these isolates displayed multiple drug resistance phenotypes that were associated with their mutational gene profiles.

Purpose: To analyze the drug susceptibility phenotypes and the patterns of plasmid-mediated β-lactamase genes among nosocomial Staphylococcus aureus drug resistance isolates in Taiwan