scholarly journals Azithromycin Inhibits the Formation of Flagellar Filaments without Suppressing Flagellin Synthesis in Salmonella enterica Serovar Typhimurium

2005 ◽  
Vol 49 (8) ◽  
pp. 3396-3403 ◽  
Author(s):  
Hidenori Matsui ◽  
Masahiro Eguchi ◽  
Katsufumi Ohsumi ◽  
Akio Nakamura ◽  
Yasunori Isshiki ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Culture Medium ◽  
Macrolide Antibiotic ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Bacterial Cells ◽  
Immunoblotting Analysis ◽  
Serovar Typhimurium ◽  
Methylase Gene ◽  
The One

ABSTRACT The present study shows that a sub-MIC of the macrolide antibiotic azithromycin (AZM) diminishes the virulence function of Salmonella enterica serovar Typhimurium. We first constructed an AZM-resistant strain (MS248) by introducing ermBC, an erythromycin ribosome methylase gene, into serovar Typhimurium. The MIC of AZM for MS248 exceeded 100 μg/ml. Second, we managed to determine the efficacy with which a sub-MIC of AZM reduced the virulence of MS248 in vitro. On the one hand, AZM (10 μg/ml) in the culture medium was unable to inhibit the total protein synthesis, growth rate, or survival within macrophages of MS248. On the other hand, AZM (10 μg/ml) reduced MS248's swarming and swimming motilities in addition to its invasive activity in Henle-407 cells. Electron micrographs revealed no flagellar filaments on the surface of MS248 after overnight growth in L broth supplemented with AZM (10 μg/ml). However, immunoblotting analysis showed that flagellin (FliC) was fully synthesized within the bacterial cells in the presence of AZM (10 μg/ml). In contrast, the same concentration of AZM reduced the export of FliC to the culture medium. These results indicate that a sub-MIC of AZM was able to affect the formation of flagellar filaments, specifically by reducing the amount of flagellin exported from bacterial cells, but it was not involved in suppressing the synthesis of flagellin. Unfortunately, AZM treatment was ineffective against murine salmonellosis caused by MS248.

scholarly journals Attenuation of Salmonella enterica Serovar Typhimurium by Altering Biological Functions of Murein Lipoprotein and Lipopolysaccharide

2005 ◽  
Vol 73 (12) ◽  
pp. 8433-8436 ◽  
Author(s):  
A. A. Fadl ◽  
J. Sha ◽  
G. R. Klimpel ◽  
J. P. Olano ◽  
C. L. Galindo ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Biological Functions ◽  
Double Knockout ◽  
In Vivo Models ◽  
Background Strain ◽  
Knockout Mutants ◽  
Serovar Typhimurium

ABSTRACT We constructed Salmonella enterica serovar Typhimurium double-knockout mutants in which either the lipoprotein A (lppA) or the lipoprotein B (lppB) gene was deleted from an msbB-negative background strain by marker exchange mutagenesis. These mutants were highly attenuated when tested with in vitro and in vivo models of Salmonella pathogenesis.

scholarly journals Persistent Salmonella enterica Serovar Typhimurium Infection Induces Protease Expression During Intestinal Fibrosis

2019 ◽  
Vol 25 (10) ◽  
pp. 1629-1643 ◽  
Author(s):  
Katrin Ehrhardt ◽  
Natalie Steck ◽  
Reinhild Kappelhoff ◽  
Stephanie Stein ◽  
Florian Rieder ◽  
...  
Keyword(s):  
Protease Inhibitors ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Salmonella Infection ◽  
Intestinal Fibrosis ◽  
Fibrotic Tissue ◽  
Serovar Typhimurium ◽  
Inflammatory Bowel ◽  
Protease Expression

AbstractBackgroundIntestinal fibrosis is a common and serious complication of Crohn’s disease characterized by the accumulation of fibroblasts, deposition of extracellular matrix, and formation of scar tissue. Although many factors including cytokines and proteases contribute to the development of intestinal fibrosis, the initiating mechanisms and the complex interplay between these factors remain unclear.MethodsChronic infection of mice with Salmonella enterica serovar Typhimurium was used to induce intestinal fibrosis. A murine protease-specific CLIP-CHIP microarray analysis was employed to assess regulation of proteases and protease inhibitors. To confirm up- or downregulation during fibrosis, we performed quantitative real-time polymerase chain reaction (PCR) and immunohistochemical stainings in mouse tissue and tissue from patients with inflammatory bowel disease. In vitro infections were used to demonstrate a direct effect of bacterial infection in the regulation of proteases.ResultsMice develop severe and persistent intestinal fibrosis upon chronic infection with Salmonella enterica serovar Typhimurium, mimicking the pathology of human disease. Microarray analyses revealed 56 up- and 40 downregulated proteases and protease inhibitors in fibrotic cecal tissue. Various matrix metalloproteases, serine proteases, cysteine proteases, and protease inhibitors were regulated in the fibrotic tissue, 22 of which were confirmed by quantitative real-time PCR. Proteases demonstrated site-specific staining patterns in intestinal fibrotic tissue from mice and in tissue from human inflammatory bowel disease patients. Finally, we show in vitro that Salmonella infection directly induces protease expression in macrophages and epithelial cells but not in fibroblasts.ConclusionsIn summary, we show that chronic Salmonella infection regulates proteases and protease inhibitors during tissue fibrosis in vivo and in vitro, and therefore this model is well suited to investigating the role of proteases in intestinal fibrosis.

In Vitro Effects of Thymol-β-d-Glucopyranoside on Salmonella enterica Serovar Typhimurium and Escherichia coli K88†

2016 ◽  
Vol 79 (2) ◽  
pp. 299-303 ◽  
Author(s):  
G. LEVENT ◽  
R. B. HARVEY ◽  
G. CIFTCIOGLU ◽  
R. C. BEIER ◽  
K. J. GENOVESE ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gastrointestinal Tract ◽  
Pure Culture ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Lower Gastrointestinal Tract ◽  
Serovar Typhimurium ◽  
In Vitro Effects ◽  
Porcine Feces

ABSTRACT Although thymol is bactericidal against many pathogens in vitro, its in vivo effectiveness against pathogens in the lower gastrointestinal tract is limited because of its rapid absorption in the proximal gut. Thymol-β-d-glucopyranoside (β-thymol), a conjugated form of thymol, can deliver thymol to the lower gastrointestinal tract and has shown antibacterial effects. In the present study, we examined the in vitro effects of β-thymol on Salmonella enterica serovar Typhimurium (ST) and Escherichia coli K88 (K88). We inoculated one-half strength Mueller-Hinton broth with 5.8 ± 0.09 log CFU/ml novobiocin- and naladixic acid–resistant (NN) ST (NVSL 95-1776) and 5.1 ± 0.09 log CFU ml−1 NN-resistant K88, with or without porcine feces (0.1% [wt/vol]) (fecal incubations). The resultant bacterial suspensions were distributed under N2 to triplicate sets of tubes to achieve initial concentrations of 0, 3, 6, and 12 mM for ST treatments and 0, 3, 12, and 30 mM for K88 treatments. Samples were incubated at 39°C and then plated onto NN-containing brilliant green agar and NN-containing MacConkey agar; ST and K88 CFU concentrations were determined via 10-fold dilutions, and viable cell counts were performed at 0, 6, and 24 h. No differences in ST CFU counts were observed in β-thymol–treated tubes without the added porcine feces (i.e., pure culture) at 6 or 24 h. However, in tubes that contained fecal incubations, ST CFU counts were reduced (P < 0.05) from controls at 6 h in tubes treated with 6 and 12 mM β-thymol, whereas in tubes treated with 3, 6, and 12 mM β-thymol the CFU counts were reduced (P < 0.05) at 24 h. No differences were observed in K88 CFU counts in pure culture or in fecal incubations at 6 h, but K88 CFU counts were reduced (P < 0.05) in both pure and fecal incubations at 24 h. The results from this study demonstrate that β-thymol, in the presence of fecal suspensions, has anti-Salmonella and anti–E. coli effects, suggesting a role of β-glycoside–hydrolyzing microbes for the release of bactericidal thymol from β-thymol.

scholarly journals The enzyme phosphoglucomutase (Pgm) is required by Salmonella enterica serovar Typhimurium for O-antigen production, resistance to antimicrobial peptides and in vivo fitness

Microbiology ◽  
2009 ◽  
Vol 155 (10) ◽  
pp. 3403-3410 ◽  
Author(s):  
G. K. Paterson ◽  
D. B. Cone ◽  
S. E. Peters ◽  
D. J. Maskell
Keyword(s):  
Antimicrobial Peptides ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Live Attenuated Vaccine ◽  
Antigen Production ◽  
O Antigen ◽  
Serovar Typhimurium

The enzyme phosphoglucomutase (Pgm) catalyses the interconversion of glucose 1-phosphate and glucose 6-phosphate and contributes to glycolysis and the generation of sugar nucleotides for biosynthesis. To assess the role of this enzyme in the biology of the pathogen Salmonella enterica serovar Typhimurium we have characterized a pgm deletion mutant in strain SL1344. Compared to SL1344, SL1344 pgm had impaired growth in vitro, was deficient in the ability to utilize galactose as a carbon source and displayed reduced O-antigen polymer length. The mutant was also more susceptible to antimicrobial peptides and showed decreased fitness in the mouse typhoid model. The in vivo phenotype of SL1344 pgm indicated a role for pgm in the early stages of infection, most likely through deficient O-antigen production. Although pgm mutants in other pathogens have potential as live attenuated vaccine strains, SL1344 pgm was not sufficiently attenuated for such use.

scholarly journals In vitro synergistic potentials of novel antibacterial combination therapies against Salmonella enterica serovar Typhimurium

2020 ◽  
Author(s):  
Md. Akil Hossain ◽  
Hae-Chul Park ◽  
Kwang-jick Lee ◽  
Sung-Won Park ◽  
Seung-Chun Park ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Clinical Importance ◽  
Farm Animals ◽  
Health Concern ◽  
Epicatechin Gallate ◽  
Serovar Typhimurium

Abstract Background: The antibiotics generally used in farm animals are rapidly losing their effectiveness all over the world as bacteria develop antibiotic resistance. Like some other pathogenic bacteria multidrug-resistant strains of Salmonella enterica serovar Typhimurium (S. Typhimurium) are also frequently found in animals and humans which poses a major public health concern. New strategies are needed to block the development of resistance and to prolong the life of traditional antibiotics. Thus, this study aimed to increase the efficacy of existing antibiotics against S. Typhimurium by combining them with opportunistic phenolic compounds gallic acid (GA), epicatechin, epicatechin gallate, epigallocatechin and hamamelitannin. Fractional inhibitory concentration indexes (FICI) of phenolic compound-antibiotic combinations against S. Typhimurium were determined. Based on the FICI and clinical importance, 1 combination (GA and ceftiofur) was selected for evaluating its effects on the virulence factors of this bacterium. Viability of Rattus norvegicus (IEC-6) cell in presence of this antibacterial combination was evaluated.Results: Minimum inhibitory concentrations (MICs) of GA, epigallocatechin and hamamelitannin found against different strains of S. Typhimurium were 256, (512–1024), and (512–1024) μg/mL, respectively. Synergistic antibacterial effect was obtained from the combination of erythromycin-epicatechin gallate (FICI: 0.50) against S. Typhimurium. Moreover, additive effects (FICI: 0.502–0.750) were obtained from 16 combinations against this bacterium. The time-kill assay and ultrastructural morphology showed that GA-ceftiofur combination more efficiently inhibited the growth of S. Typhimurium compared to individual antimicrobials. Biofilm viability, and swimming and swarming motilities of S. Typhimurium in presence of GA-ceftiofur combination were more competently inhibited than individual antimicrobials. Viabilities of IEC-6 cells were more significantly enhanced by GA-ceftiofur combinations than these antibacterials alone.Conclusions: This study suggests that GA-ceftiofur combination can be potential medication to treat S. Typhimurium-associated diarrhea and prevent S. Typhimurium-associated blood-stream infections (e.g.: fever) in farm animals, and ultimately its transmission from animal to human. Further in vivo study to confirm these effects and safety profiles in farm animal should be undertaken for establishing these combinations as medications.

scholarly journals In vitro synergistic potentials of novel antibacterial combination therapies against Salmonella enterica serovar Typhimurium

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Md. Akil Hossain ◽  
Hae-Chul Park ◽  
Kwang-Jick Lee ◽  
Sung-Won Park ◽  
Seung-Chun Park ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Combination Therapies ◽  
Serovar Typhimurium

scholarly journals Effect of Inactivation of degS on Salmonella enterica Serovar Typhimurium In Vitro and In Vivo

2005 ◽  
Vol 73 (1) ◽  
pp. 459-463 ◽  
Author(s):  
Gary Rowley ◽  
Andrew Stevenson ◽  
Jan Kormanec ◽  
Mark Roberts
Keyword(s):  
Sigma Factor ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Wild Type ◽  
Alternative Pathways ◽  
E Coli ◽  
Mammalian Tissues ◽  
Serovar Typhimurium

ABSTRACT The alternative sigma factor (RpoE σE) enables Salmonella enterica serovar Typhimurium to adapt to stressful conditions, such as oxidative stress, nutrient deprivation, and growth in mammalian tissues. Infection of mice by Salmonella serovar Typhimurium also requires σE. In Escherichia coli, activation of the σE pathway is dependent on proteolysis of the anti-sigma factor RseA and is initiated by DegS. DegS is also important in order for E. coli to cause extraintestinal infection in mice. We constructed a degS mutant of the serovar Typhimurium strain SL1344 and compared its behavior in vitro and in vivo with those of its wild-type (WT) parent and an isogenic rpoE mutant. Unlike E. coli degS strains, the Salmonella serovar Typhimurium degS strain grew as well as the WT strain at 42°C. The degS mutant survived very poorly in murine macrophages in vitro and was highly attenuated compared with the WT strain for both the oral and parenteral routes of infection in mice. However, the degS mutant was not as attenuated as the serovar Typhimurium rpoE mutant: 100- to 1,000-fold more degS bacteria than rpoE bacteria were present in the livers and spleens of mice 24 h after intraperitoneal challenge. In most assays, the rpoE mutant was more severely affected than the degS mutant and a σE-dependent reporter gene was more active in the degS mutant than the rpoE strain. These findings indicate that degS is important for activation of the σE pathway in serovar Typhimurium but that alternative pathways for σE activation probably exist.

scholarly journals SitABCD Is the Alkaline Mn2+ Transporter of Salmonella enterica Serovar Typhimurium

2002 ◽  
Vol 184 (12) ◽  
pp. 3159-3166 ◽  
Author(s):  
David G. Kehres ◽  
Anuradha Janakiraman ◽  
James M. Slauch ◽  
Michael E. Maguire
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory Element ◽  
Natural Resistance ◽  
Transcriptional Level ◽  
Promoter Sequences ◽  
Potent Inhibition ◽  
Serovar Typhimurium ◽  
Macrophage Protein ◽  
The One

ABSTRACT MntH, a bacterial homolog of the mammalian natural resistance-associated macrophage protein 1 (Nramp1), is a primary Mn2+ transporter of Salmonella enterica serovar Typhimurium and Escherichia coli. S. enterica serovar Typhimurium MntH expression is important for full virulence; however, strains carrying an mntH deletion are only partially attenuated and display no obvious signs of Mn2+ deficiency. We noted that promoter sequences for mntH and for the putative Fe2+ transporter sitABCD appeared to have the same regulatory element responsive to Mn2+ and so hypothesized that sitABCD could transport Mn2+ with high affinity. We have now characterized transport by SitABCD in S. enterica serovar Typhimurium using 54Mn2+ and 55Fe2+ and compared its properties to those of MntH. SitABCD mediates the influx of Mn2+ with an apparent affinity (Ka ) identical to that of MntH, 0.1 μM. It also transports Fe2+ but with a Ka 30 to 100 times lower, 3 to 10 μM. Inhibition of 54Mn2+ transport by Fe2+ and of 55Fe2+ transport by Mn2+ gave inhibition constants comparable to each cation's Ka for influx. Since micromolar concentrations of free Fe2+ are improbable in a biological system, we conclude that SitABCD functions physiologically as a Mn2+ transporter. The cation inhibition profiles of SitABCD and MntH are surprisingly similar for two structurally and energetically unrelated transporters, with a Cd2+ Ki of ≈1 μM and a Co2+ Ki of ≈20 μM and with Ni2+, Cu2+, and Fe3+ inhibiting both transporters only at concentrations of >0.1 mM. The one difference is that Zn2+ exhibits potent inhibition of SitABCD (Ki = 1 to 3 μM) but inhibits MntH weakly (Ki > 50 μM). We have previously shown that MntH transports Mn2+ most effectively under acidic conditions. In sharp contrast, SitABCD has almost no transport capacity at acid pHs and optimally transports Mn2+ at slightly alkaline pHs. Overall, coupled with evidence that each transporter is multiply but distinctly regulated at the transcriptional level, the distinct transport properties of MntH versus SitABCD suggest that each transporter may be specialized for Mn2+ uptake in different physiological environments.

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