Native Brazilian Plants Against Nosocomial Infections: A Critical Review on their Potential and the Antimicrobial Methodology

Abstract

The growing incidences of drug-resistant pathogens have increased the attention on several medicinal plants and their metabolites for antimicrobial properties. These pathogens are the main cause of nosocomial infections which led to an increasing mortality among hospitalized patients. Taking into consideration those factors, this paper reviews the state-of-the-art of the research on antibacterial agents from native Brazilian plant species related to nosocomial infections as well as the current methods used in the investigations of the antimicrobial activity and points out the differences in techniques employed by the authors. The antimicrobial assays most frequently used were broth microdilution, agar diffusion, agar dilution and bioautography. The broth microdilution method should be the method of choice for testing new antimicrobial agents from plant extracts or isolated compounds due to its advantages. At the moment, only a small part of the rich Brazilian flora has been investigated for antimicrobial activity, mostly with unfractionated extracts presenting a weak or moderate antibacterial activity. The combination of crude extract with conventional antibiotics represents a largely unexploited new form of chemotherapy with novel and multiple mechanisms of action that can overcome microbial resistance that needs to be further investigated. The antibacterial activity of essential oil vapours might also be an interesting alternative treatment of hospital environment due to their ability in preventing biofilm formation. However, in both alternatives more studies should be done on their mode of action and toxicological effects in order to optimize their use.

Medicinal Properties of Bamboos

“…The growing microbial resistance to existing drugs has generated the need for the pharmaceutical industry to search for new molecules that can be used as preservatives, antibiotics, and disinfectants [38]. This factor associated with the toxicity of certain additives [39] and the consumer appeals for the reduction in synthetic substances [40], encourage the search for alternative solutions. The complexity and molecular diversity of natural products make them an interesting source of new molecules [41].…”

“…The lower the MIC values, the more potent the substance is. To be considered as promising antimicrobial agents, natural products must have MICs below 100 μg/mL [39]. Therefore, the essential oils of Phyllostachys kwangsiensis, P. heterocycla cv.…”

ZnO:SBA-15 Nanocomposites for Potential Use in Sunscreen: Preparation, Properties, Human Skin Penetration and Toxicity

“…Antimicrobial activity of the nanocomposites was assessed using the broth microdilution method [22]. Four typical pathogens were chosen for this assay: Escherichia coli (ATCC 8739), a fermentative Gram-negative bacteria; Pseudomonas aeruginosa (ATCC 9027), a non-fermentative Gram-negative bacteria; Staphylococcus aureus (ATCC 6538), a Gram-positive bacteria; and Candida albicans (ATCC 10231), a yeast.…”

Antifungal Activity of Brazilian Medicinal Plants against Candida Species

“…According to the size of the halo, the microorganisms can be classified as: sensitive, when the diameter of the zone of inhibition is greater or no more than 3 mm less than the positive control; moderately sensitive, halo greater than 2 mm, but smaller than the positive control of more than 3 mm; and resistant, diameter equal to or less than 2 mm. As a positive control, a standard antimicrobial is used, and as a negative control, the solvent is used for the dissolution of the extracts [28][29][30][31][32]. The recommended incubation conditions are 35-37°C for bacteria for 24 to 48 hours and for fungi from 25 to 27°C for 48 to 72 hours [33][34][35][36][37][38][39].…”