Abstract
Several studies have tested antimicrobial activity of combinations of honey and various substances. In this study, we tested a combination of two stingless bee honeys against various bacterial strains. In particular: the antibacterial activity of honeys produced by Scaptotrigona bipunctata (SB) and Scaptotrigona postica (SP) was evaluated against Gram-positive and Gram-negative bacterial strains by agar well diffusion assays, minimum inhibitory concentration (MIC) assessment, construction of growth and viability curves and scanning electron microscopy (SEM). The interaction of the two honeys was also evaluated by the checkerboard assay. Inhibition zones ranged from 8 to 22 mm. The MIC values of the individual honeys ranged from 0.62 to 10% (v v−1) and decreased to 1/4 to 1/32 when the honeys were combined. SEM images showed division inhibition and cell wall disruption for the SB and SP honeys, respectively, and these alterations were observed in same field when the SB and SP honeys were combined. This study demonstrated that the natural honeys possess in vitro antimicrobial activity against Gram-positive and Gram-negative bacteria, including multidrug-resistant strains. Combination of the SB and SP honeys could lead to the development of new broad-spectrum antimicrobials that have the potential to prevent the emergence of resistant bacterial strains.
Highlights
The emergence of multidrug-resistant bacteria and their rapid global spread are growing threats to public health[1]
As an initial screen to evaluate the antimicrobial activity of honey samples against bacterial strains, the Agar well diffusion (AWD) assay was applied, and inhibition zones were measured (Table 1)
Based on an AWD assay performed to evaluate the antibacterial activity of stingless bee honeys, Chan-Rodríguez et al.[20] and Temaru et al.[21] showed that Gram-positive bacteria may be more sensitive to these honeys compared with
Summary
The emergence of multidrug-resistant bacteria and their rapid global spread are growing threats to public health[1]. Despite the use of honey as an antibacterial in folk medicine, this practice has been replaced by synthetic and semisynthetic antimicrobials[5,6]. The indiscriminate use of antibiotics exerts a selective pressure on microorganisms, progressively selecting the most resistant[7]. Given this problem, the search for new antimicrobial compounds derived from different natural products, such as honey, to replace conventional antibiotic therapy is of high importance[8,9,10]. We tested a combination of two stingless bee honeys against various bacterial strains. Bacterial strain Enterococcus faecalis ATCC29212 E. faecium ATCC6569 Escherichia coli ATCC25922 E. coli ATCC8739 Klebsiella pneumoniae ATCC700603 Pseudomonas aeruginosa ATCC27853 P. aeruginosa ATCC9027 Salmonella enterica Enteritidis ATCC13076 S. enterica Typhimurium UK1 Staphylococcus aureus ATCC25923 S. aureus ATCC29213 S. aureus methicillin-resistant BEC9393 S. aureus methicillin-resistant N315 S. epidermidis ATCC12228 Streptococcus mutans UA159 S. pyogenes ATCC19615
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