University of Tabriz Journal of Zoonotic Diseases 2476-535X 2025 12 05 In vitro evaluation of antimicrobial activity of Poulk (Stachys schtschegleevii) hydroethanolic extract against Nocardia isolates 20895 10.22034/jzd.2025.20895 EN Hamed Jafarzadeh Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran Boukaga Farmani Department of Food Science and Technology, Ahar Faculty of Agriculture and Natural Resources, University of Tabriz, Tabriz, Iran Samad Bodbodak Department of Food Science and Technology, Ahar Faculty of Agriculture and Natural Resources, University of Tabriz, Tabriz, Iran Journal Article 2025 08 20 Biofilms represent a fundamental mode of microbial existence, enabling bacteria to adhere to surfaces and persist in challenging environments. Nocardia species cause opportunistic infections in humans and animals. This study sought to determine the antimicrobial performance of Stachys schtschegleevii hydroethanolic extract in inhibiting biofilm-forming Nocardia isolates obtained from the water supply systems of industrial layer pullet farms. Data were organized and classified in Excel, then analyzed using SPSS software (SPSS Inc., Version 23, Chicago, USA). Mean comparisons were carried out, and statistical significance was evaluated via one-way ANOVA with Duncan’s post hoc test. Biofilm development was measured using the Tissue Culture Plate assay. To determine the extract’s antimicrobial properties, serial dilutions were prepared, with the highest concentration tested at 200 mg mL⁻¹. Phytochemical analysis revealed substantial bioactive constituents, including a total phenolic content of 83 mg GAE mL⁻¹, total flavonoid content of 24 mg QE mL⁻¹, and an antioxidant capacity of 65%. The MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) values for the Nocardia isolates were quantified. For the S1-2 isolate, there was no MIC and MBC up to 200 mg mL⁻¹. While the isolate S1-6B required 100 mg mL⁻¹ as MIC and MBC. Also, for the S1-8 isolate, MIC and MBC were 50 mg mL⁻¹. Additionally, the efficacy of sodium hypochlorite (3 mg L⁻¹) was tested via the agar well diffusion assay. Results demonstrated that the S1-8 strain exhibited resistance to sodium hypochlorite, whereas the S1-2 and S1-6B isolates remained susceptible. These results demonstrate the promising potential of S. schtschegleevii extract as a novel natural antimicrobial compound against biofilm-forming Nocardia isolates, particularly in settings where disinfection resistance poses a challenge.

https://jzd.tabrizu.ac.ir/article_20895_9c0da7d7cd403e69d9635c8ffa3bf104.pdf