Objective:To compare the effects of sodium butyrate(Sob)on aged and young asthmatic mice.Methods:Male C57BL/6 mice aged 24 months(n=18)and 4 months(n=18)were divided using randomly generated numbers into 3 groups: a control group, a model group(treated with ovalbumin, OVA), and a treatment group(OVA+ Sob), with 6 mice in each group.The control group was given normal saline as the blank control.Two days before the OVA challenge, the treatment group was given 1 mg/g Sob by intraperitoneal injections and the OVA+ Sob group and the control group were given normal saline intervention.Endpoint evaluation was performed 1 day after the last challenge.Differences in airway hyperresponsiveness(AHR), pathological manifestations of lung tissue sections stained with hematoxylin eosin(HE), and inflammatory factors in lung tissues were compared between aged and young mice and the effects of Sob on asthmatic mice of different ages were evaluated.Results:Under the stimulation of methacholine(Mch), AHR of the O-OVA group was significantly higher than that of the Y-OVA group(6.250 g/L: 276.28±113.62 vs.103.02±19.55, t=3.368, P=0.026; 12.500 g/L: 457.5±157.29 vs.114.76±20.28, t=4.338, P=0.022; 25.000 g/L: 1113.16±256.98 vs.567.87±187.34, t=3.538, P=0.009). HE staining revealed that, compared with the Y-control group, the O-control group exhibited a reduced area of alveolar cavity, partial lung consolidation, proliferation of interstitial fibrous connective tissues, alveolar epithelial cells and capillary endothelial cells.Compared with its control group, the O-OVA group had significantly elevated levels of eotaxin( P=0.035), IL-17A( P=0.004)and IL-1β( P=0.001), among the inflammatory factors, whereas the Y-OVA group had elevated levels of eotaxin( P=0.001), IL-17A( P=0.001), IL-4( P=0.004), KC( P=0.012)and IL-1β( P<0.001). Compared with the O-OVA group, the Y-OVA group had increased levels of IL-4( Z=2.882, P=0.004)but decreased levels of IL-1β( t=2.728, P=0.020). As for the effects of Sob on asthmatic mice of different ages, AHR of the O-OVA+ Sob group was significantly alleviated with stimulation of 12.500 g/L Mch( P=0.015)and 25 g/L Mch( P=0.014), compared with the O-OVA group.With stimulation of 3.125 g/L Mch, AHR of the Y-OVA+ Sob group was significantly decreased( P=0.021)and levels of IL-4( P=0.004)and IL-1β( P=0.014)were significantly reduced in the Y-OVA+ Sob group, compared with the Y-OVA group. Conclusions:The severity of asthma in aged mice is greater than in young mice, perhaps as a result of different immunophenotypes; The alleviating effects of Sob on inflammatory factors in young asthmatic mice may be related to mild AHR in young asthmatic mice, compared with aged asthmatic mice.

Objective:To investigate the drug resistance status and genomic characterization of Proteus mirabilis (PM) isolated from outpatient cases with diarrhea in Tai′an City and Laizhou City, Shandong Province. Methods:A total of 510 fecal samples were collected from 510 patients with acute diarrhea admitted to 43 sentinel hospitals in Tai′an City and Laizhou City, Shandong Province, between January 2021 and December 2022. The samples were cultured and isolated to identify Proteus spp. by direct inoculation, the drug susceptibility testing was performed by microbroth dilution method, and resistance genes and virulence genes were obtained by whole genome sequencing and bioinformatic analysis, thereby revealing the genetic environment surrounding the blaOXA-1 and blaCTX-M-65 genes. Single nucleotide polymorphism (SNP) analysis and core genome multilocus sequence typing (cgMLST) were conducted on the current strains and 100 PM isolates downloaded from the National Center for Biotechnology Information (NCBI) database via customizable methods utilizing RidomSeqSphere+ software, with the objective of exploring the phylogenetic relationships among the strains. Results:A total of 35 strains of Proteus were isolated from 510 fecal samples, including 31 strains of PM with a detection rate of 6.08% (31/510) and four strains of Proteus vulgaris.The multidrug resistance rate of PM was 100.00% (31/31).The 35 isolates carried a total of 43 resistance genotypes.Thirteen strains of PM carried blaOXA-1, six strains carried both blaOXA-1 and blaCTX-M-65, and 15 PM strains carried at least 15 antibiotic resistance genes (ARGs). The virulence genes included ureA, mrpA, ZapA, hpmA and so on. blaOXA-1 and blaCTX-M-65 genes were surrounded by mobile elements such as Tn3, ISL3 and IS6. cgMLST showed consistency with the SNP clustering results. Isolate 2022LZ41 from Laizhou City clustered with isolates 2022TA018, 2022TA017 and 2022TA019 from Tai′an City, with the number of allelic differences ranging from zero to two, and the Laizhou City isolate 2022LZ40 was highly genetically related to strain CRK0056 (human, USA, 2015). Conclusions:PM isolated from patients with diarrhea is multidrug-resistant, carrying many resistance and virulence genes.The presence of mobile genetic elements can lead to horizontal transfer of resistance genes.

Objective:To investigate the drug-resistant gene characteristics and core genome characteristics of carbapenem-resistant Enterobacter cloacae (CR-ECL) in rural residents of Weifang City, Shandong Province. Methods:Fecal samples were collected from rural community residents in Weifang City, Shandong Province in 2017. Drug-resistant strains were screened using a carbapenem-resistant enterobacter chromogenic medium. CR-ECL positive strains were acquired via Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry(MALDI-TOFMS) analysis. The antibiotic resistance phenotype of CR-ECL was determined using a microbroth dilution assay. Whole genome sequencing (WGS) and analysis were conducted, along with an examination of the immediate vicinity of the blaNDM gene and phylogenetic analysis of the strains. Results:A total of 628 fecal samples were collected and tested, of which 6 were CR-ECL positive (detection rate 0.96%), all exhibiting multiple drug resistance (MDR) phenotypes. Six CR-ECL strains had four MLST genotypes (ST), all of which carried multiple drug resistance genes ( blaNDM-1, blaNDM-5, etc.) and virulence genes ( acrA, acrB, entB, fepC, etc.). There were mobile genetic elements ISAba125, TN3-IS3000, TN3 and IS5 in the genetic environment surrounding the blaNDM gene. The phylogenetic tree showed that the multi-locus sequence typing of the core genome (cgMLST) was consistent with the single nucleotide polymorphism (SNPs) results. The cgMLST results showed that the allele differences between strains 2BC0101B and 2BC0251B, 2BG0561B and 2BI0221B were 2 and 1, respectively. The SNPs results showed that the above two pairs of bacteria also clustered together. It was found that the strains of chicken fecal samples in the National Center for Biotechnology Information (NCBI) database were located in the center of the evolutionary tree, and the local sequences could be traced back to American human sequences. Conclusion:Multidrug-resistant CR-ECL is detected in rural community residents in Weifang City, Shandong Province.