The study, published in the journal International Microbiology, examined Shen-Ling-Bai-Zhu-San, or SLBZS, a traditional Chinese medicine formula first recorded in the Song Dynasty text “Tai Ping Hui Min He Ji Ju Fang.” The prescription, traditionally described as strengthening the spleen, eliminating dampness and stopping diarrhea, combines ten botanical ingredients including Codonopsis pilosula, Atractylodes macrocephala, Poria cocos, Dioscorea opposita, lotus seed, white hyacinth bean, coix seed, Amomum villosum, platycodon root and licorice. Clinical reviews have previously suggested that SLBZS can reduce diarrhea frequency and shorten treatment duration in patients with antibiotic-associated diarrhea, but the biological mechanism has remained elusive.

To probe that mechanism, the researchers turned to a controlled animal model. Twenty-two three-week-old female Sprague-Dawley rats were randomly divided into three groups: a normal control group receiving saline, a model group given an antibiotic cocktail to induce diarrhea, and a treatment group given the same antibiotics followed by a week of SLBZS decoction. The cocktail, delivered by oral gavage for seven consecutive days, contained clindamycin, ampicillin and streptomycin dissolved in saline at precisely defined concentrations. After the modeling phase, treated animals received 5.5 grams per kilogram of body weight per day of the herbal decoction for another seven days.

The clinical results were striking. By day eight, immediately after the antibiotic course ended, diarrhea incidence had reached 100 percent in both the model and treatment groups, with fecal consistency scores significantly elevated compared to controls. One week later, the picture had diverged dramatically. Diarrhea persisted in 83.33 percent of untreated model animals, but in the SLBZS-treated group no diarrhea was observed at all, a statistically significant difference. Body weight, notably, did not differ among the groups, suggesting the herbal treatment specifically targeted the diarrheal symptoms rather than overall growth.

With symptom relief confirmed, the team deployed two complementary omics technologies to dissect what had changed inside the gut. The first, 16S rDNA gene sequencing, profiles bacterial communities by amplifying a variable region of the ribosomal RNA gene common to all bacteria. DNA extracted from fecal samples was amplified with barcoded primers targeting the V4 region, sequenced on an Illumina NovaSeq6000 platform, and clustered into amplicon sequence variants for diversity and abundance analysis. The second technique, widely targeted metabolomics, used ultra-performance liquid chromatography coupled to tandem mass spectrometry to quantify thousands of small molecules in the same fecal samples, providing a chemical readout of microbial and host metabolism.

The sequencing data confirmed that antibiotics had devastated the gut microbiome. More than 2,300 amplicon sequence variants were detected across the study, but the model animals retained only 257 unique variants compared with 1,559 in healthy controls. Alpha diversity indices measuring species richness and evenness collapsed after antibiotic exposure, and beta diversity analysis based on weighted UniFrac distances showed that the community structure of diarrheal rats was profoundly altered. At the phylum level, Firmicutes bacteria, which include many lactase-producing species, dropped from roughly 40 percent of the community in healthy rats to under 16 percent, while Bacteroidota surged from about 44 percent to nearly 79 percent, driving the Firmicutes-to-Bacteroidota ratio sharply downward, a pattern consistent with intestinal inflammation.

Seven days of SLBZS treatment nudged these disturbed communities back toward health. Four microbial taxa showed particularly favorable regulation: Muribaculaceae, beneficial bacteria involved in energy metabolism, rebounded after being depleted by antibiotics, while Tannerellaceae, Parabacteroides and its species P. distasonis, all associated with intestinal inflammation, declined toward normal levels. The restoration of the phylum-level balance did not reach statistical significance, but the directional corrections across multiple taxa suggested the formula was actively reshaping the microbial landscape rather than merely masking symptoms.

The metabolomics analysis added a chemical dimension to the story. Of nearly 4,000 metabolites detected, the researchers identified thirty that shifted with antibiotics and shifted back with treatment, twenty-nine of them in a direction favoring recovery. Several carried clear inflammatory signatures. Pro-inflammatory compounds such as desoxycortone, Ser-Ala dipeptide, N-acetyl-L-histidine and 5-aminovaleric acid rose in diarrheal rats and fell after treatment, while the anti-inflammatory molecule 1-methylnicotinamide chloride moved in the opposite direction. Markers of oxidative damage, including ureidosuccinic acid and protocatechuic acid, were elevated in the model group and suppressed by the herbal formula, whereas antioxidant metabolites like equol were restored. Together, the pattern implied that SLBZS was rebalancing the inflammatory and oxidative chemistry of the gut.

The most compelling finding emerged when the researchers mapped these metabolites onto metabolic pathways in the Kyoto Encyclopedia of Genes and Genomes. Among all the pathways disturbed by antibiotics, one stood out after treatment: the ABC transporter pathway, enriched with a statistical significance value approaching zero. ABC transporters are ATP-powered molecular pumps found across living systems, and in the intestine they are critical gatekeepers of epithelial permeability, shuttling nutrients, lipids, toxins and drugs across the gut wall. Eleven of the thirty common differential metabolites, mostly dipeptides, clustered in this pathway, and their elevation in diarrheal animals suggested that antibiotics had increased intestinal mucosal permeability, allowing beneficial substances to leak from the gut while inflammatory mediators accumulated.

Correlation analysis then tied the microbial and chemical threads together. Seven metabolites were significantly associated with P. distasonis, and five of those seven belonged to the ABC transporter pathway. P. distasonis is a paradoxical organism, a core component of the healthy human gut flora that can also behave as a conditionally pathogenic bacterium, influencing immune responses, promoting inflammation and disrupting the intestinal barrier under certain conditions. Its expansion in diarrheal rats, alongside deranged ABC transporter chemistry, and its correction following herbal treatment, position it as a plausible microbial driver of the disease process and a potential therapeutic target for SLBZS.

The authors are careful about the limits of their work. The study establishes associations rather than causal mechanisms, lacks a positive-control group against existing therapies, involves modest and unbalanced sample sizes, and was conducted in rats rather than children with clinical diarrhea. The statistical power of the multi-omics comparisons is necessarily limited by the small cohorts. Nonetheless, the convergence of evidence from symptom scores, microbial sequencing, metabolomic profiling and pathway enrichment paints an internally consistent picture: a thousand-year-old prescription may work, at least in part, by restraining an inflammatory gut bacterium and restoring the transport machinery that maintains the intestinal barrier.

For a condition whose incidence keeps rising with global antibiotic use, and for which treatment options remain limited largely to probiotics, the identification of a specific bacterium-pathway axis offers a concrete molecular hypothesis that can now be tested directly. If future mechanistic studies validate the P. distasonis–ABC transporter link in human patients, an ancient Song Dynasty formula could find a rigorously evidenced place in modern pediatric gastroenterology.