Experimental Parameters Influence the Observed Antimicrobial Response of Oak Wood (Quercus petraea)

Abstract

The present investigation aimed to utilize a direct wood disc diffusion method to study the influence of plane of cutting, cutting method, sterilization method, and origin of tree on the antimicrobial activity of wood material. Six oak wood trees (Quercus petraea) were collected from 3 different locations in France. They were cut into 4 mm thick slices with either transverse (RT), tangential (LT) or radial (LR) faces. Round discs (diameter 9.95 ± 0.1 mm) were cut from the slices via a laser machine or a manual punch machine, and were sterilized with gamma irradiation (25 kGy) or autoclaving (121 °C). The antimicrobial activity of wood was tested using a direct diffusion method against Staphylococcus aureus and Acinetobacter baumannii isolates. The zone of inhibition around the wooden disc was recorded following the recommendations used for antibiotics tests. The results showed that S. aureus was more susceptible than A. baumannii, to the chemicals that diffused from the wood. The transverse face discs exhibited higher antimicrobial activity. Samples that had been sterilized by autoclaving showed significantly (p < 0.05) lower antimicrobial activity, whereas the cutting method and origin of tree did not influence the antimicrobial activity of wood material. Therefore, the choice of sterilization method and cutting planes must be taken into account while studying and interpreting the antibacterial properties of wood material.

Survival of Bacterial Strains on Wood (Quercus petraea) Compared to Polycarbonate, Aluminum and Stainless Steel

“…However, the antimicrobial properties of wood are a combination of chemical, but also of anatomical parameters which create unsuitable growth conditions for many pathogenic bacteria. This assertion is supported by the fact that in previous studies, A. baumannii and E. faecalis showed mild susceptibility to the diffusion-based antimicrobial properties of solid oak wood [ 9 , 12 ]. However, in the current investigation, the two E. faecalis and A. baumannii isolates survived less than 24 h on transversal and tangential oak.…”

“…This observation can be explained by the antimicrobial activity of wooden material, that can be associated both with the anatomical structure of this material and its chemical composition [ 13 ]. The antimicrobial properties of oak wood species against S. aureus , K. pneumoniae , A. baumannii and E. faecalis have been documented in the literature [ 8 , 9 , 10 , 11 , 12 , 14 , 15 ]. In these studies, only the antimicrobial properties of the extractive content of oak wood have been documented.…”

“…The use of wood material for the indoor construction of healthcare buildings has been shown to have a positive influence on the mental health and wellbeing of patients and medical staff, but also on physiological parameters [ 6 , 7 ]. Recently, some growing evidence attests that some wood species such as oak, have antimicrobial properties [ 8 , 9 , 10 , 11 ]. Indeed, in a preceding study, Quercus petraea has been shown to have antimicrobial activity, using agar diffusion method, against a panel of MRSA and Methicillin-Susceptible Staphylococcus aureus (MSSA) isolates [ 10 ].…”

“…Indeed, in a preceding study, Quercus petraea has been shown to have antimicrobial activity, using agar diffusion method, against a panel of MRSA and Methicillin-Susceptible Staphylococcus aureus (MSSA) isolates [ 10 ]. Another study of Munir et al has pointed out that the antimicrobial activity of Quercus petraea , tested with wood disc diffusion method, was stronger on S. aureus isolates than on A. baumannii ones [ 9 ]. This antimicrobial activity was also greater using discs cut respecting transverse section, than tangential or radial sections, giving rise to the suspicion of a better delivery of the antimicrobial compounds using the transversal cut [ 9 ].…”

“…Another study of Munir et al has pointed out that the antimicrobial activity of Quercus petraea , tested with wood disc diffusion method, was stronger on S. aureus isolates than on A. baumannii ones [ 9 ]. This antimicrobial activity was also greater using discs cut respecting transverse section, than tangential or radial sections, giving rise to the suspicion of a better delivery of the antimicrobial compounds using the transversal cut [ 9 ]. The underlying mechanisms of this antimicrobial activity are not completely understood and are assumed to be a combination of the anatomical parameters of this material and its chemical composition.…”