Ceftazidime Combined with Bifico Improves Therapeutic Efficacy and Intestinal Safety in a Mouse Model of Pseudomonas aeruginosa Pneumonia

DNA extraction, library preparation, and sequencing were performed by Majorbio Bio-Pharm Technology Co., Ltd. (Shanghai, China). The V3-V4 region of the bacterial 16S rRNA gene was amplified using barcoded primers. PCR products from the same sample were pooled, recovered from a 2% agarose gel, purified, and sequenced on the Illumina PE300 platform. Read-stitching was performed using FLASH software. Denoising and chimera removal were conducted using the DADA2 algorithm to obtain high-quality amplicon sequence variants (ASVs) . ASV clustering, chimera removal, and taxonomic annotation were conducted using UPARSE software. Chimeric sequences were identified and removed de novo during this process. Taxonomic assignment of ASVs was performed against the SILVA database (release SILVA SSU 138.2) with a confidence threshold of 70%. Downstream analyses, including alpha- and beta-diversity metrics, were conducted in QIIME2, and graphical visualization was performed using the Majorbio Cloud Platform.