Stingless bee honey: Nutritional, physicochemical, phytochemical and antibacterial validation properties against wound bacterial isolates

Abstract

With the rise of AMR the management of wound infections are becoming a big challenge. This has been attributed to the fact that most wound bacterial isolates have been found to possess various virulence factors like enzymes, toxins & biofilms production. Therefore, need for discovery of new lead compounds is paramount as such factors make these microbes to be resistant to already existing arsenal of antibiotics or even the immune system. This study aimed at documenting the nutritional, physicochemical, phytochemical and antibacterial properties of stingless bee honey. Isolation and characterization of bacterial isolates from 34 samples obtained from wounds of outpatients and surgical wards of Nakuru County Referral Hospital, Kenya was done. Various bacterial isolates (43) were isolated Staphylococcus aureus (34.8%) being predominant, followed by Pseudomonas aeruginosa (27.9%), Klebsiella pneumoniae (23.3%) and Escherichia coli (14.0%). A total of 36 out of the total isolates were genotypically characterized using molecular techniques detecting the prevalence of the following virulence genes; 16 srRNA (756 bp), hla (229 bp), cnf1 (426 bp), cnf2 (543 bp), hlyA (1011 bp), rmpA (461 bp), lasL (600 bp), gyrB (411 bp), khe (77 bp) and magA (128 bp). An assessment of the in vitro antibacterial activity of 26 stingless bee honey samples collected from their cerumen egg-shaped pots in Marigat sub-County, Baringo County, Kenya was done. Antibacterial properties of the stingless bee honey was done with varying susceptibility patterns being observed at different concentrations of honey impregnated discs (10x104, 20x104, 50x104 and 75x104 ml μg/ ml) giving mean inhibition diameters of 18.23 ± 0.4 mm (Staphylococcus aureus), 17.49 ± 0.3 mm (Pseudomonas aeruginosa), 16.05 ± 0.6 mm (Klebsiella pneumoniae) and 10.19 ± 0.5 mm (Escherichia coli) with a mean range of 14.54 ± 2.0 mm to 17.58 ± 3 mm. Higher susceptibility to honey was recorded across all the bacterial isolates compared to conventional antibiotics while the mean MIC and MBC of the honey were recorded at 62.5 ml μg/ ml and 250 ml μg/ ml respectively. Control bacterial isolates Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 27736 and Pseudomonas aeruginosa ATCC 27858 were used in the analysis. The stingless bee honey was found to be rich in various nutritive components like sugar (89.85 ± 5.07 g/100 g) and moisture (81.75 ± 10.35 mg/g) with a significant difference of P <0.05 as the main antibacterial components. Additionally, the stingless honey did possess water soluble vitamins, proteins and minerals of which potassium was the most dominant one. In regard to phytochemicals, on our preliminary analysis phenolic, flavonoid and carotenoid compounds were found to be present with phenolic compounds being the most dominant one. Stingless bee honey from Marigat, has antimicrobial properties which could be attributed to the rich phytochemicals it possesses and its physicochemical properties in addition to its high nutritive value.