Gut colonisation with multidrug-resistant Klebsiella pneumoniae worsens Pseudomonas aeruginosa lung infection.

Carbapenemase-producing Enterobacterales (CPE) are spreading rapidly in hospital settings. Asymptomatic CPE gut colonisation may be associated with dysbiosis and gut-lung axis alterations, which could impact lung infection outcomes. In this study, in male C57BL/6JRj mice colonised by CPE, we characterise the resulting gut dysbiosis, and analyse the lung immune responses and outcomes of subsequent Pseudomonas aeruginosa lung infection. Asymptomatic gut colonisation by CPE leads to a specific gut dysbiosis and increases the severity of P. aeruginosa lung infection through lower numbers of alveolar macrophages and conventional dendritic cells. CPE-associated dysbiosis is characterised by a near disappearance of the Muribaculaceae family and lower levels of short-chain fatty acids. Faecal microbiota transplantation restores immune responses and outcomes of lung infection outcomes, demonstrating the involvement of CPE colonisation-induced gut dysbiosis in altering the immune gut-lung axis, possibly mediated by microbial metabolites such as short-chain fatty acids.

Classification and Regression Trees for Bacterial Vaginosis Diagnosis in Pregnant Women Based on High-Throughput Quantitative PCR.

Bacterial vaginosis (BV) diagnosis in pregnancy is based on the Nugent score, which consists of semiquantitation of bacterial morphotypes. Limited data exist concerning molecular-based diagnosis in asymptomatic pregnant women. Using high-throughput quantitative PCR, 34 microorganisms were screened in asymptomatic pregnant women and compared with the Nugent score. Three-hundred and four vaginal samples had a Nugent score <7 (69.9%) and 131, a Nugent score ≥7 (30.1%), consistent with BV. More pregnant women with BV share Atopobiumvaginae, bacterial vaginosis associated bacteria-2, Gardnerella spp., Mobiluncus curtisii, Mo. mulieris, Mycoplasma hominis, Ureaplasma urealyticum, Prevotella bivia, Megasphaera 1, and Megasphaera 2 in their vaginal sample. Fewer pregnant women with BV share Lactobacillus crispatus, L. gasseri, L. jensenii, and Enterococcus faecalis in their vaginal sample (P < 0.001). Classification and regression tree analysis was performed to determine which combinations of detected bacteria optimally diagnose BV in this population. A set of only four bacteria of 34 microorganisms (A. vaginae, Gardnerella spp., L. crispatus, and P. bivia) was the best combination to identify BV in a cohort of asymptomatic pregnant women, with a sensitivity of 77.1%, and specificity of 97.0% compared with the Nugent score. The quantitative PCR in the present study responds to the limits of the Nugent score by implementing an easily reproducible quantitative assay to assess the absence of BV in pregnancy.

Antibiotic-related gut dysbiosis induces lung immunodepression and worsens lung infection in mice.

BACKGROUND: Gut dysbiosis due to the adverse effects of antibiotics affects outcomes of lung infection. Previous murine models relied on significant depletion of both gut and lung microbiota, rendering the analysis of immune gut-lung cross-talk difficult. Here, we study the effects of antibiotic-induced gut dysbiosis without lung dysbiosis on lung immunity and the consequences on acute P. aeruginosa lung infection. METHODS: C57BL6 mice received 7 days oral vancomycin-colistin, followed by normal regimen or fecal microbial transplant or Fms-related tyrosine kinase 3 ligand (Flt3-Ligand) over 2 days, and then intra-nasal P. aeruginosa strain PAO1. Gut and lung microbiota were studied by next-generation sequencing, and lung infection outcomes were studied at 24 h. Effects of vancomycin-colistin on underlying immunity and bone marrow progenitors were studied in uninfected mice by flow cytometry in the lung, spleen, and bone marrow. RESULTS: Vancomycin-colistin administration induces widespread cellular immunosuppression in both the lung and spleen, decreases circulating hematopoietic cytokine Flt3-Ligand, and depresses dendritic cell bone marrow progenitors leading to worsening of P. aeruginosa lung infection outcomes (bacterial loads, lung injury, and survival). Reversal of these effects by fecal microbial transplant shows that these alterations are related to gut dysbiosis. Recombinant Flt3-Ligand reverses the effects of antibiotics on subsequent lung infection. CONCLUSIONS: These results show that gut dysbiosis strongly impairs monocyte/dendritic progenitors and lung immunity, worsening outcomes of P. aeruginosa lung infection. Treatment with a fecal microbial transplant or immune stimulation by Flt3-Ligand both restore lung cellular responses to and outcomes of P. aeruginosa following antibiotic-induced gut dysbiosis.

Impact of the Timing of Antibiotic Administration on Digestive Colonization with Carbapenemase-Producing Enterobacteriaceae in a Murine Model.

While antibiotic use is a risk factor of carbapenemase-producing Enterobacteriaceae (CPE) acquisition, the importance of timing of antibiotic administration relative to CPE exposure remains unclear. In a murine model of gut colonization by New Delhi metallo-beta-lactamase-1 (NDM-1)-producing Klebsiella pneumoniae, a single injection of clindamycin within at most 1 week before or after CPE exposure induced colonization persisting up to 100 days. The timing of antibiotic administration relative to CPE exposure may be relevant to infection control and antimicrobial stewardship approaches.

Draft Genome Sequences of Two Carbapenemase-Producing Klebsiella pneumoniae Strains Isolated from Blood Cultures.

Carbapenemase-producing Klebsiella pneumoniae represents an emerging public health issue. Here, we present the draft whole-genome sequences of K. pneumoniae clinical strains KPL0.1 (OXA-48 carbapenemase) and KPL0.2 (NDM-1 carbapenemase). These genome sequences should help in investigating pathophysiological mechanisms of digestive colonization or infection with these highly resistant bacteria.

Tetraphenylethylene-based glycoclusters with aggregation-induced emission (AIE) properties as high-affinity ligands of bacterial lectins.

Tetraphenylethylene (TPE) is fluorescent through aggregation induced emission (AIE) in water. Herein, TPE was used as the core of glycoclusters that target the bacterial lectins LecA and LecB of Pseudomonas aeruginosa. Synthesis of these TPE-based glycoclusters was accomplished by using azide-alkyne "click" chemistry. The AIE properties of the resulting glycoclusters could be readily verified, but imaging could not be pursued due to the overlap of the fluorescence signals from cells and bacteria. Nonetheless, the glycoclusters displayed nanomolar affinities toward LecA and LecB. Further evaluation in a cell-based anti-adhesive assay highlighted a limited decrease in adhesion (20%) for the fucosylated glycocluster. This confirmed that these TPE-based glycoclusters are indeed LecA and LecB high-affinity ligands. Nevertheless, the hypotheses involving their application in imaging or anti-adhesive therapy could not be verified.