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Background Klebsiella is a common pathogen that is dangerous to humans and other animals, including invertebrates, and is widely present in the digestive system. It also appears that the genus Klebsiella is ubiquitous, as it is endemic to surface water, soil, and sewage. Methods In this study, 70 samples were obtained from soil-dwelling invertebrates from September 2021 to March 2022 from Taif and Shafa in different altitudinal regions. Fifteen of these samples contained Klebsiella spp. The Klebsiella isolates were genetically identified as Klebsiella pneumoniae using rDNA sequencing. The antimicrobial susceptibility of the Klebsiella isolates was determined. Amplification of virulence genes was performed using PCR. Results In this study, 16S rDNA sequencing showed similarity from 98–100% with related K. pneumonia from the NCBI database, and the sequences were deposited in NCBI GenBank under accession numbers ON077036 to ON077050. We then screened the growth inhibition properties of ethanolic and methanolic extracts of the medicinal plant Rhazya stricta leaves against some K. pneumoniae strains using minimum inhibitory concentration (MIC) methods and disc diffusion. In addition, the biofilm inhibitory potential of these extracts was investigated using crystal violet. HPLC analysis identified 19 components divided into six flavonoids, 11 phenolic acids, stilbene (resveratrol), and quinol, and revealed variations in the number of components and their quantities between extracts. Both extracts demonstrated interesting antibacterial properties against the K. pneumoniae isolates. The two extracts also showed strong biofilm inhibitory activities, with percentages of inhibition extending from 81.5–98.7% and from 35.1–85.8% for the ethanolic and methanolic extracts, respectively. Conclusion Rhazya stricta leaves extract revealed powerful antibacterial and antibiofilm activities against K. pneumoniae isolates and could be good candidates for the treatment or prevention of K. pneumonia-related infections. |
