ObjectiveTo analyze the phylogroups of Klebsiella pneumoniae isolates from laboratory rats and mice housed at the Laboratory Animal Center Fudan University, optimize the identification method for Klebsiella pneumoniae, and perform virulence genes detection and antimicrobial susceptibility testing, thereby providing a practical basis for microbial detection strategies and prevention and control measures in laboratory animal facilities. MethodsBetween September 2023 and September 2025, ileocecal contents were collected from laboratory rats and mice purchased from laboratory animal suppliers, from which 11 strains of Klebsiella pneumoniae were isolated and cryopreserved. These strains were tested for β-lactamase genes using multiplex PCR for phylogrouping. Furthermore, representative strains from different phylogroups were selected for biochemical tests, mass spectrometry analysis, 16S rRNA gene and tyrB gene sequencing, as well as virulence genes detection and antimicrobial susceptibility testing. ResultsMultiplex PCR detection of β-lactamase genes revealed that among 11 strains, 4 were identified as Klebsiella pneumoniae (Kp1), 4 as Klebsiella quasipneumoniae (Kp2), and 3 as Klebsiella variicola (Kp3). Kp1-Kp3 could not be differentiated using biochemical tests, mass spectrometry analysis, or 16S rRNA gene sequencing, whereas multiplex PCR of β-lactamase genes and tyrB gene sequencing enabled phylogrouping of all three. There were differences in the detection rates of capsular genes (capsule associated gene G and magnesium transport system ATP-binding protein A) and siderophore genes (Klebsiella pneumoniae iron uptake system genes) among Kp1-Kp3; susceptibility to different antibiotics also varied considerably. ConclusionKlebsiella pneumoniae phylogroups isolated from commercially produced laboratory rats and mice are similar to those in human clinical samples and likewise include multiple phylogroups of the species complex. In this study, the identification methods of Kp1-Kp3 were optimized,furthermore selected virulence genes and antimicrobial resistance in Kp1-Kp3 were preliminarily investigated, which could provide precise reference for the treatment of infections caused by different phylogroups occurring in laboratory animal facilities.

Aim To investigate the role of physiological concentration of glucocorticoids on the inflammation mediator IL-6 expression in response to LPS in rat alveolar epithelial cells(CCL149).Methods The CCL149 were treated with LPS,H2O2 and glucocorticoid respectively.Flammtory mediator IL-6 protein expression was measured with ELISA,and the activity of histone deacetylase(HDAC) was measured using colorimetric HDAC activity assay kit.Results IL-6 protein levels were increased in cells exposed to 10 mg?L-1 LPS.Hydrocortisone decreased IL-6 protein expression induced by LPS.Such effect of hydrocortisone was blunt by HDAC inhibitor trichostatinA treatment(10 ?g?L-1).LPS decreased HDAC activity.Hydrocortisone increased HDAC activity.The expression of IL-6 protein induced by LPS was further enhanced by H2O2 treatment.Pretreatment with H2O2 resulted in the inhibition of antiflammtion effect of glucocorticoids.Conclusion Physiological concentration of glucocorticoids could suppress inflammatory response,and this effects requires recruitment of HDAC.Oxidants such as H2O2 may cause the failure of glucocorticoids to function effectively,and the reason may be related to the reduction of HDAC activity.This mechanism may contribute to the pathogenesis of pulmonary disorder.