abstract
This study aimed to assess antibacterial activity of Knema retusa wood extract (KRe) against antibiotic resistant staphylococci which are causative agents of bovine mastitis. From 75 cases of intramammary infections in dairy cows, 66 staphylococcal isolates were collected, including 11 Staphylococcus aureus isolates (17%) and 55 coagulase-negative staphylococci (83%). Sixty isolates (91%) formed strong biofilms. KRe had minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) against the isolates ranging 32-256 ug/mL and 64-512 ug/mL, respectively. Two-hour KRe exposures at 4xMIC, viabilities of S. aureus and S. haemolyticus decreased by 3 log(10) compared to the control. Scanning EM (SEM) showed that KRe disrupted the bacterial cells of both species. KRe at 1/16xMIC significantly inhibited biofilm formation (P < 0.05) in both S. aureus and S. haemolyticus. At 1/2xMIC, S. aureus and S. haemolyticus biofilm inhibition ranged from 75 to 99%. Cells within established biofilms were disrupted 66-83% by KRe at 32xMIC. Moreover, 1/2xMIC KRe reduced bacterial adhesion to glass surfaces observed by SEM. According to GC-MS analysis, the major compound in KRe was endo-2-hydroxy-9,9-(ethylenedioxy)-1-carbethoxy bicyclo [3.3.1] nonane (E2N). Molecular docking analysis of E2N has a high affinity for staphylococcal accessory regulator A (SarA), binding free-energy - 6.40kcal/mol. The results suggested that KRe may have medicinal benefits by inhibiting the growth, biofilm, and adhesion of antibiotic resistant staphylococci isolated from bovine mastitis.
keywords
TOMENTOSA AITON HASSK.; BIOFILM FORMATION; SARA; RHODOMYRTONE; EXTRACT
subject category
Veterinary Sciences
authors
Chuprom, J; Kidsin, K; Sangkanu, S; Nissapatorn, V; Wiart, C; Pereira, MD; Wongtawan, T; Daus, M; Sotthibandhu, DS; Tipmanee, V; Paul, AK; Scholfield, CN; Zulkipli, MB; Abdullah, NH; Mitsuwan, W
our authors
Maria de Lourdes Gomes Pereira
Associate Professor with Aggregationacknowledgements
This work was funded by Walailak University's Individual Research Grant, Walailak University (Grant number; WUIRG-64-023), Thailand Science Research and Innovation Fund (Contract No. FRB650082/0227), and Center of Excellence in Innovation of Essential Oil (Grant no. WU-COE-65-05). The funders had no role in conceiving, design the study design, or manuscript.