Evaluation of virulence of Klebsiella pneumoniae using zebrafish behavior as a biological indicator.

INTRODUCTION: Klebsiella pneumoniae is one of the common pathogenic bacteria that can cause infections in hospitals and communities and can cause respiratory, urinary, and other multi-system infections. In recent years, the emergence of highly virulent and drug-resistant Klebsiella pneumoniae has greatly increased the difficulty of treatment for infection. Clinically, it is very important to accurately judge the virulence of isolated Klebsiella pneumoniae for treatment, but there is no better method to evaluate its virulence. METHODS: In this study, zebrafish were used as a model organism, and the swimming distance was used as a detection index to identify clinically isolated Klebsiella pneumoniae. In this study, we selected two different strains of Klebsiella pneumoniae, i.e., NTUH-K2044 and ATCC BAA-1705, with known high and low virulence, respectively, to infect zebrafish juveniles and evaluated their behavioral ability according to different bacterial concentrations and different developmental times. RESULTS: It was found that highly virulent Klebsiella pneumoniae caused a significant decrease in the behavioral ability of zebrafish larvae, while low-virulence Klebsiella pneumoniae had relatively little effect. CONCLUSIONS: These results indicate that it is entirely feasible to assess the virulence of Klebsiella pneumoniae based on behavioral ability.

MiR-181a-5p Delivered by Adipose-Derived Mesenchymal Stem Cell Exosomes Alleviates Klebsiella pneumonia Infection-Induced Lung Injury by Targeting STAT3 Signaling.

Background: Klebsiella pneumoniae (K. pneu) is a leading cause of gram-negative pneumonia, which requires effective treatment. Adipose-derived mesenchymal stem cell- (ADSC-) derived exosomal microRNAs (miRNAs) have presented the inhibitory effect of multiple diseases. However, the function of ADSC-derived exosomal miRNAs in K. pneu remains unclear. Aim: In this study, we aimed to explore the effect of ADSC-derived exosomal miR-181-5p on K. pneu infection-induced lung injury. Methods: C57BL/6 mouse model was established by infection of K. pneu. ADSCs and exosomes were extracted and characterized in vitro. The translocation of ADSC-derived exosomes to bone marrow-derived macrophages (BMDMs) was detected. The level of miR-181a-5p was detected by real-time PCR. The secretion of inflammatory factors was determined by ELISA. The interaction between miR-181a-5p with STAT3 was identified. Results: We successfully isolated the ADSCs that express positive markers CD90 and CD105 rather than CD31 and CD45. The exosomal miR-181a-5p secreted by ADSCs were internalized by BMDM and K. pneu infection stimulated the miR-181a-5p level in bronchoalveolar lavage fluid (BALF) and BMDM. ADSC-derived exosomal miR-181a-5p repressed pulmonary outgrowth and dissemination of K. pneu infection in mice, repressed cellular infiltration in lung tissue, and attenuated the inflammasome activity and the levels of IL-1ß and IL-18 in the lung. Mechanically, miR-181a-5p was able to inhibit STAT3 expression at posttranscriptional levels and repressed Nlrp3 and Asc expression in BMDM. Conclusion: Consequently, we concluded that ADSC-derived exosomal miR-181a-5p alleviated Klebsiella pneumonia infection-induced lung injury by targeting STAT3 signaling. ADSC-derived exosomal miR-181a-5p may serve as a potential candidate for the treatment of Klebsiella pneumonia infection-induced lung injury.

Biological characterization and literature review of Robinsoniella peoriensis from bloodstream infection / 中国热带医学

@#Abstract: Objective　To analyze the phenotype and drug resistance of Robinsoniella peoriensis strains isolated from the blood of patients with prostate cancer and to learn the epidemiological characteristics of the strains. Methods　Culture medium growth characteristics analysis, Gram staining, VITEK MS mass spectrometry identification, in vitro drug susceptibility test, 16S rRNA gene sequencing were performed on the strains, and case summary analysis, historical drug sensitivity results comparison and phylogenetic tree construction were carried out. Results　Four of the repeatability tests of mass spectrometry identification were R. peoriensis, and the identification accuracy was 99.9%, which was the first time that mass spectrometry analysis in China accurately detected this strain. The 16S rRNA gene sequencing confirmed that the strain was R. peoriensis, and GenBank accession number is OL826796. There are currently 18 cases of R. peoriensis related to human infection in the world, mainly including bloodstream infection, prosthetic joint infection, and postoperative wound infection. The homology of OL826796 in this case with HGUE-09/943 (GU322806.1) isolated in Spanish was 99.58%; in vitro drug susceptibility showed that OL826796 was resistant to penicillin and clindamycin, and sensitive to vancomycin, imipenem, tetracycline and metronidazole. Statistical analysis of drug susceptibility of 18 cases found that R. peoriensis could be tested for drug susceptibility by E-test method: penicillin 100% (7/7), clindamycin 70% (7/10), ampenem 0% (0/4), metronidazole 0% (0/9), meropenem 0% (0/4), vancomycin 0% (0/3). Conclusion　R. peoriensis is a rare anaerobic-positive bacillus. When sterile site infection occurs, attention should be paid to timely communication with clinical reports, and penicillin and clindamycin should be used cautiously to fight infection, so as to improve the cure rate of postoperative immunocompromised patients.