Escherichia coli is an important foodborne pathogen and also plays key roles in dissemination of antimicrobial resistance genes (ARGs). However, current data on the prevalence of antimicrobial-resistant E. coli at different nodes of the pork supplying chain are still limited. Herein, we investigated drug-resistant phenotypes and molecular characteristics of E. coli strains isolated from different pig farms, slaughterhouses, and terminal markets in the Henan Province of China. A total of 191 (70.74%), 140 (35.09%), and 77 (30.20%) E. coli strains were isolated from 270, 399, and 255 samples collected from pig farms, slaughterhouses, and retailing markets, respectively. Antimicrobial susceptibility testing revealed that these 408 strains showed severe antimicrobial resistance profiles. Approximately 93.19% (178/191), 66.43% (93/140), and 67.53% (52/77) of the isolates from farms, slaughterhouses, and terminal markets were resistant to three of the nine antibiotic classes tested, respectively. Multilocus sequence typing showed that sequence types (STs) 10 and ST101 were commonly identified among the isolates from farms, slaughterhouses, and terminal markets. Isolates belonging to these two STs carried multiple ARGs, conferring resistance to the antibiotics tested. Two important ARGs with great public health concerns (mcr-1 and blaNDM-1) were found from these two STs. Isolates belonging to these two STs also carried several virulence factor-encoding genes, including astA, tsh, and traT, which might contribute to the pathogenesis of these isolates. The wide prevalence and distribution of these two STs in different nodes of pork supplying chain might represent a big public health threat and should receive more attention.
Meningitis induced by Pasteurella multocida has been substantially described in clinical practice in both human and veterinary medicine, but the underlying mechanisms have not been previously reported. In this study, we investigated the influence of P. multocida infection on the permeability of the blood-brain barrier (BBB) using different models. Our in vivo tests in a mouse model and in vitro tests using human brain microvascular endothelial cell (hBMEC) model showed that P. multocida infection increased murine BBB permeability in mice and hBMEC monolayer permeability. Furthermore, we observed that P. multocida infection resulted in decreased expression of tight junctions (ZO1, claudin-5, occludin) and adherens junctions (E-cadherin) between neighboring hBMECs. Subsequent experiments revealed that P. multocida infection promoted the activation of hypoxia inducible factor-1α (HIF-1α)/vascular endothelial growth factor A (VEGFA) signaling and NF-κB signaling, and suppressed the HIF-1α/VEGFA significantly remitted the decrease in ZO1/E-cadherin induced by P. multocida infection (P < 0.001). NF-κB signaling was found to contribute to the production of chemokines such as TNF-1α, IL-β, and IL-6. Additionally, transmission electron microscopy revealed that paracellular migration might be the strategy employed by P. multocida to cross the BBB. This study provides the first evidence of the migration strategy used by P. multocida to traverse the mammalian BBB. The data presented herein will contribute to a better understanding of the pathogenesis of the zoonotic pathogen P. multocida.
The FlgM-FliA regulatory circuit plays a central role in coordinating bacterial flagellar assembly. In this study, we identified multiple novel binding partners of FlgM using bacterial two-hybrid screening. Among these binding partners, FliS, the secretion chaperone of the filament protein FliC, was identified to compete with FliA for the binding of FlgM. We further showed that by binding to FlgM, FliS protects it from secretion and degradation, thus maintaining an intracellular pool of FlgM reserved as the FliS-FlgM complex. Consequently, we found that the flagellar late-class promoter activities are significantly increased in the fliS deletion mutant. The fliS mutant is weakly motile and shows significantly increased biofilm formation on biotic surface. Based on the results obtained, we established for the first time the regulatory role of the flagellin chaperone FliS to fine-tune late flagellar assembly by modulating FlgM activity.
Background: Acute upper gastrointestinal bleeding (AUGIB) represents a major risk factor for mortality in patients with hepatocellular carcinoma (HCC) and liver cirrhosis. This retrospective observational study aimed to evaluate the prognostic performance of neutrophil to lymphocyte ratio (NLR) and albumin-bilirubin (ALBI) score for the assessment of in-hospital outcomes of cirrhotic patients with HCC and AUGIB. Methods: All consecutive HCC patients with AUGIB were included in our study. The areas under the receiving operator characteristics curves (AUCs) of NLR, platelet to lymphocyte ratio (PLR), ALBI score, Child-Pugh score, and model of end-stage liver disease (MELD) score for predicting the in-hospital mortality were calculated. Results: Overall, 191 HCC patients with AUGIB were included. In the overall analysis, the AUCs of NLR, PLR, ALBI score, Child-Pugh score, and MELD score were 0.74 (P=0.0007), 0.486 (P=0.8681), 0.78 (P<0.0001), 0.804 (P<0.0001), and 0.81 (P<0.0001), respectively. In the subgroup analysis of 112 patients with only hepatitis B virus-related HCC, the AUCs of NLR, PLR, ALBI score, Child-Pugh score, and MELD score were 0.723 (P=0.0169), 0.528 (P=0.8009), 0.772 (P<0.0001), 0.848 (P<0.0001), and 0.86 (P<0.0001), respectively. In the subgroup analysis of 58 HCC patients treated with endoscopic therapy for AUGIB, the AUCs of NLR, PLR, ALBI score, Child-Pugh score, and MELD score were 0.959 (P<0.0001), 0.536 (P=0.8544), 0.644 (P=0.4882), 0.717 (P=0.0349), and 0.917 (P<0.0001), respectively. In the subgroup analysis of 81 patients with infection, the AUCs of NLR, PLR, ALBI score, Child-Pugh score, and MELD score were 0.771 (P=0.0005), 0.53 (P=0.7702), 0.729 (P<0.0028), 0.772 (P<0.0001), and 0.759 (P=0.0037), respectively. Conclusions: Patients with HCC and AUGIB have a high risk of in-hospital mortality, and NLR and ALBI score appear as promising predictors of adverse outcome. Future studies should prospectively evaluate these scores, potentially in conjunction with other bio-markers, to improve prognostication in clinical practice.
Oral antibiotics such as metronidazole, vancomycin and fidaxomicin are therapies of choice for Clostridium difficile infection. Several important mechanisms for C. difficile antibiotic resistance have been described, including the acquisition of antibiotic resistance genes via the transfer of mobile genetic elements, selective pressure in vivo resulting in gene mutations, altered expression of redox-active proteins, iron metabolism, and DNA repair, as well as via biofilm formation. This update summarizes new information published since 2010 on phenotypic and genotypic resistance mechanisms in C. difficile and addresses susceptibility test methods and other strategies to counter antibiotic resistance of C. difficile.
Multidrug resistance (MDR) in Enterobacteriaceae including resistance to quinolones is rising worldwide. The plasmid-mediated quinolone resistance (PMQR) gene qnrS is prevalent in Enterobacteriaceae. However, the qnrS gene is rarely found in Enterobacter hormaechei (E. hormaechei). Here, we reported one multidrug resistant E. hormaechei strain M1 carrying the qnrS1 and blaTEM-1 genes. This study was to analyze the characteristics of MDR E. hormaechei strain M1. The E. hormaechei strain M1 was identified as Enterobacter cloacae complex by biochemical assay and 16S rRNA sequencing. The whole genome was sequenced by the Oxford Nanopore method. Taxonomy of the E. hormaechei was based on multilocus sequence typing (MLST). The qnrS with the other antibiotic resistance genes were coexisted on IncF plasmid (pM1). Besides, the virulence factors associated with pathogenicity were also located on pM1. The qnrS1 gene was located between insertion element IS2A (upstream) and transposition element ISKra4 (downstream). The comparison result of IncF plasmids revealed that they had a common plasmid backbone. Susceptibility experiment revealed that the E. hormaechei M1 showed extensive resistance to the clinical antimicrobials. The conjugation transfer was performed by filter membrane incubation method. The competition and plasmid stability assays suggested the host bacteria carrying qnrS had an energy burden. As far as we know, this is the first report that E. hormaechei carrying qnrS was isolated from chicken feed. The chicken feed and poultry products could serve as a vehicle for these MDR bacteria, which could transfer between animals and humans through the food chain. We need to pay close attention to the epidemiology of E. hormaechei and prevent their further dissemination. IMPORTANCE Enterobacter hormaechei is an opportunistic pathogen. It can cause infections in humans and animals. Plasmid-mediated quinolone resistance (PMQR) gene qnrS can be transferred intergenus, which is leading to increase the quinolone resistance levels in Enterobacteriaceae. Chicken feed could serve as a vehicle for the MDR E. hormaechei. Therefore, antibiotic-resistance genes (ARGs) might be transferred to the intestinal flora after entering the gastrointestinal tract with the feed. Furthermore, antibiotic-resistant bacteria (ARB) were also excreted into environment with feces, posing a huge threat to public health. This requires us to monitor the ARB and antibiotic-resistant plasmids in the feed. Here, we demonstrated the characteristics of one MDR E. hormaechei isolate from chicken feed. The plasmid carrying the qnrS gene is a conjugative plasmid with transferability. The presence of plasmid carrying antibiotic-resistance genes requires the maintenance of antibiotic pressure. In addition, the E. hormaechei M1 belonged to new sequence type (ST). These data show the MDR E. hormaechei M1 is a novel strain that requires our further research.
Abstract Salmonella enterica serovar Weltevreden is a recently emerged pathogen, and as such we lack a comprehensive knowledge of its microbiology, genomics, epidemiology and biogeography. In this study, we analyzed 174 novel S . Weltevreden isolates including 111 isolates recovered from diarrheal patients in China between 2006 and 2017. Our results demonstrate that the ST365 clone was the predominant causative agent of the diarrhea-outbreak during this period, as vast majority of the isolates recovered from diarrheal patients belonged to this sequence type (97.37%, 74/76). We also determined the ST365 clone as the predominant sequence type of S . Weltevreden from diarrheal patients globally from previously published sequences (97.51%, 196/201). In order to determine the possible antimicrobial genes and virulence factors associated with S . Weltevreden, we performed whole genome sequencing on our novel isolates. We were able to identify a range of key virulence factors associated with S . Weltevreden that are likely to be beneficial to their fitness and pathogenesis. Furthermore, we were able to isolate a novel 100.03-kb IncFII(S) type virulence plasmid that used the same replicon as pSPCV virulence plasmid. Importantly, we demonstrated through plasmid elimination a functional role for this plasmid in bacterial virulence. These findings are critical to further our knowledge of this high consequence pathogen. Importance Salmonella Weltevreden is a newly emerged foodborne pathogen and has caused several outbreaks of diarrheal diseases in some regions in the world. However, comprehensive knowledge of microbiology, genomics, epidemiology and biogeography of this newly emerged pathogen is still lack. In this study, we made an unexpected discovery that S . Weltevreden sequence type (ST) 365 is the causative agent in the diarrhea-outbreak in China and many other regions of the world. We also shown that this sequence type was widely recovered from animal, food, and environmental samples collected in different regions in the world. Importantly, we discovered a novel IncFII(S) type virulence plasmid commonly carried by S . Weltevreden strains of both human, animal, and food origins. These data facilitate future studies investigating the emergence of S . Weltevreden involved in diarrheal outbreaks and the global spread of S . Weltevreden strains.
Abstract Pasteurella multocida is a zoonotic pathogen that can cause fatal infections in both animals and humans. A significant number of putative adhesive factors have been predicted to contribute to the pathogenesis of P. multocida , but their interactive proteins on host cells remain unclear. In this study, we experimentally verified the roles of three previously proposed proteins (PlpE, PtfA, Hsf-2) in the adherence of P. multocida . Through turboID-based proximity labeling screening, we identified ATP-binding cassette sub-family F member 2 (ABCF2) as a host interactive protein for PlpE/PtfA/Hsf-2. Crucial amino acid residues in PlpE, PtfA, and/or Hsf-2 that are essential for interacting with ABCF2 included Asp-123 (PlpE), Lys-88 (PtfA), Asp-136 (PtfA), Ala-464 (Hsf-2), Glu-473 (Hsf-2), and Arg-489 (Hsf-2). Knocking down or knocking out ABCF2 significantly reduced the adherence and invasion of P . multocida to host cells, while overexpression of ABCF2 markedly increased these effects. However, ABCF2 did not contribute to the adherence of other bacterial species such as Klebsiella pneumoniae and Bordetella bronchiseptica . Additionally, we demonstrated that P. multocida infection upregulated the expression of host ABCF2 by activating the p38 MAPK and NF-κB signaling pathways. Furthermore, we showed that ABCF2 was involved in the P. multocida -induced p53-dependent apoptotic signaling pathway. To the best of our knowledge, this is the first identification of ABCF2 as a host factor contributing to the adherence of P. multocida and only the second report of ABCF2’s involvement in bacterial pathogenesis. Importance P. multocida can cause fatal infections in both animals and humans, yet the mechanisms related to its pathogenesis remain to be fully explored. In this study, we identified ABCF2 as a crucial host interactive protein for three adhesive proteins encoded by P. multocida and experimentally verified its role in the adherence and invasion of P. multocida . Furthermore, we elucidated how P. multocida modulates ABCF2 during its infection and revealed p53-dependent apoptosis as a downstream effect of ABCF2 during P. multocida infection. Given the absence of reports on ABCF2 contributing to the pathogenesis of P. multocida and only one previous report on the involvement of ABCF2 in bacterial pathogenesis prior to this study, this research could be valuable for comprehending the interactions between bacteria and hosts during bacterial infections.
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