Lacticaseibacillus rhamnosus

Gut intestinal domination by Lacticaseibacillus rhamnosus (71.6% relative abundance by shotgun metagenomics) was temporally associated with bloodstream infection in a post-allogeneic HSCT patient with B-cell ALL; genomic comparison between the gut-dominant strain and the blood culture isolate revealed only 18 SNP differences, supporting direct gut-to-bloodstream translocation as the mechanism of bacteremia.

PMID: 40544256

Lacticaseibacillus rhamnosus was isolated from multiple concurrent blood culture sites (PICC, CVC, peripheral vein) in a severely immunocompromised post-HSCT patient during the final week of life, with markedly elevated sepsis markers (procalcitonin 2.4 ± 1.87 ng/L; D-dimer 7518 ± 2801.7 ng/mL), contributing to a fatal multi-organ toxicity outcome.

PMID: 40544256

Lacticaseibacillus rhamnosus demonstrates intrinsic resistance to glycopeptides (teicoplanin and vancomycin) with no established EUCAST breakpoints, complicating antimicrobial management of Lactobacillus bloodstream infections in immunocompromised patients.

PMID: 40544256

Lactobacillus rhamnosus GG (LGG)–based probiotic administration to germ-free mice colonized with an ICB complete responder's microbiota significantly impaired antitumor response to anti-PD-L1 therapy, resulting in significantly larger tumors compared to sterile water control (P=0.01 by likelihood ratio test in linear mixed model; n=4–5 per group), with concomitant reduction in gut microbiome alpha diversity (inverse Simpson index, P=0.38 vs. control — non-significant trend).

PMID: 34941392

D000082082 Immune Checkpoint Inhibitors D008546 Melanoma, Experimental D019936 Probiotics H00038 Melanoma

LGG-based probiotic administration significantly reduced the frequency of IFN-γ–positive CD8+ cytotoxic T cells in the tumor microenvironment of anti-PD-L1–treated melanoma-bearing germ-free mice (P=0.03 by supervised flow cytometry analysis; n=6 per group), indicating suppression of intratumoral cytotoxic T cell responses as a mechanism of impaired ICB efficacy.

PMID: 34941392

D008546 Melanoma, Experimental D019936 Probiotics D013601 T-Lymphocytes H00038 Melanoma