Article

Mechanism of infection of a human isolate Salmonella (3, 10:r:-) in chicken ileum: Ultrastructural study

Biophysics & Electron Microscopy Section, Indian Veterinary Research Institute, Izatnagar India.
The Indian Journal of Medical Research (Impact Factor: 1.4). 01/2008; 126(6):558-66.
Source: PubMed

ABSTRACT

Originally isolated from severe human food-poisoning cases, Salmonella (3,10:r:-), a monophasic variety of otherwise diphasic serotypes such as S. weltevreden and S. simi, causes serious infections in man, animals and poultry. Mechanism of infection of this versatile and deadly organism is important to understand for its control. The objective of this study was to enhance our understanding of infection of Salmonella (3,10:r:-) in vivo at cellular level.
Aliquots of 10(9) cfu of Salmonella (3,10:r:-) organisms were injected intra-ileally in 24 h pre-fasted 3 month old broiler chickens by standard ligated ileal loop method. After 18 h, the fluid accumulated in the ileum was drained and small tissue pieces were fixed in 2.5 per cent buffered (pH 7) glutaraldehyde and subsequently in 1 per cent aqueous osmium tetraoxide. Ultra-thin sections of araldite-embedded tissue pieces were examined under transmission electron microscope operated at 100 KV after staining with uranyl acetate and lead citrate.
Over 70 per cent of salmonellae interacting within 300 nm with ileal epithelial cells developed numerous surface blebs of periplasmic extensions designated "periplasmic organelles" (POs). Large sized POs were apparently pinched off as outer membrane vesicles (OMVs), 50-90 nm in diameter. Type III secretion needle complex-like "rivet complexes" (RCs) were viewed to rivet the bacterial outer and inner membranes together, allowing only pockets of periplasm to expand/inflate in order to liberate OMVs. Many OMVs were found visibly docked on the plasma membrane of host epithelial cells. The invading organisms appeared to leave the epithelial cells so as to find entry into the lymphatic vessels, where, they again appeared to be closely interacting with ileal macrophages, by forming numerous POs and concomitantly liberating OMVs. Inside the cytoplasm of macrophages, numerous tight phagosomes were seen, each containing two organisms. The final stage appeared to contain replicated salmonellae, four in each loose phagosome and, at the same time, macrophages also showed signs of apoptotic disintegration, culminating in the release of replicated salmonellae.
Outer membrane vesicles released from a fiercely virulent human isolate, Salmonella 3,10:r:- pathogens have been implicated in translocating biochemical signals from the host-interactive organisms to the eukaryotic cells at both stages of invasion leading to epithelial cell and macrophage infection in vivo, in the chicken ileal model. A comprehensive cellular mechanism at ultrastructural level is outlined for typhoid-like Salmonella infections caused by this humans-infecting organism.

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    • "The primary source of infection for this pig was possibly the consumption of bacterium-containing alfalfa and this serovar was likely spread by vectors or park personnel to the aquatic birds and other animals. The serovar (3,10, H:r:-) is responsible for severe food-poisoning infections in humans and animals (Rakesh, 2007). Birds are among the animal species affected by this serovar, and this fact supports our isolation of this serovar from three aquatic birdcages and a great hornbill. "
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    ABSTRACT: The aim of the present study was to determine the bacteriological prevalence of subclinical non-typhi Salmonella infections in zoo animals and to determine the most frequently isolated serovars of the bacteria. A total of 267 samples were analyzed, including fecal samples from zoo animals and rodents, insects (Musca domestica and Periplaneta americana) and samples of the zoo animal's food. Salmonella was detected in 11.6% of the samples analyzed. Characterization of the isolates was performed with serotyping and pulsed-field gel electrophoresis. The following serovars were isolated: S. San Diego, S. Oranienburg, S. Weltevreden, S. Braenderup, S. Derby, S. 6,7, H:en x:- and S. 3,10, H:r:-. The isolates showed seven pulsed-field gel electrophoresis patterns with a Jaccard coefficient ⩾0.75 indicating a possible common origin. The prevalence of asymptomatic infections caused by Salmonella spp. in zoo animals was high. These findings demonstrate the diversity of Salmonella serovars in several captive wild animal species.
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    • "Microscopes (SEM and TEM) have been used widely in the study of intestinal colonization by Salmonellae (Soliman et al., 2009; Ohl and Miller, 2001). The ultrastructural study had been done previously (YashRoy, 2007), by other researchers they explained the invasion mechanisms of a human isolate Salmonella in the chicken ileum, in addition they showed that over 70% of Salmonellae interacting with ileal epithelial cells developed numerous surface blebs of periplasmic extensions designated periplasmic organelles. The invading organisms enter the lymphatic vessels, where they again appeared to be closely interacting with ileal macrophages. "
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    ABSTRACT: Problem statement: Recently, Salmonella hadar has been isolated and identified from goat in Iraq. The purpose of the present study was to investigate the ultrastructural changes in the ileum epithelial cells of mice experimentally infected with Salmonella hadar . Approach: The white BALB/c mice inoculated orally with Salmonella enterica serovar hadar strain and their ileums were examined by transmission electron microscopy at 24, 48, 72, 96 and 120 h after inoculation. Results: The challenge organism appeared adhered to the mucosal microvilli of the ileum from 24 h post-inoculation. The early ultrastructural changes characterized by local derangement with slight swelling of the proximal ends of the microvilli. In addition, there was ruffling of the apical cell surfaces of the microvilli with cytoplasmic vacuolization of enterocytes due to invading by the organisms. The Challenge organism was usually intact and enclosed by a membrane. The damage of the epithelial cells started as a minor lesion at 24 h and became severe after 48, 72 and 96 h post infection. The more severe ultrastructural changes in the ileum occurred at 120 h post infection, which revealed hypertrophy of goblet cell, dilatation of endoplasmic reticulum, severe cytoplasmic vacuolization, thickening of the nuclear membrane and several Salmonella Containing Vacuoles (SCV). Conclusion: Our results revealed that the cellular invasion by Salmonella hadar may occurred early than 24 h because of the obvious alterations seen in the cells of the ileum at this time of infection. In addition, the continuation of cellular pathological changes for 120 h post infection may refers that S. hadar has some mechanisms which aid it to survive and replicate within intestinal cells. We recommend further studies with early observation periods in order to determine the invasion time.
    Full-text · Article · Mar 2010
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    • "Microscopes (SEM and TEM) have been used widely in the study of intestinal colonization by Salmonellae (Soliman et al., 2009; Ohl and Miller, 2001). The ultrastructural study had been done previously (YashRoy, 2007), by other researchers they explained the invasion mechanisms of a human isolate Salmonella in the chicken ileum, in addition they showed that over 70% of Salmonellae interacting with ileal epithelial cells developed numerous surface blebs of periplasmic extensions designated periplasmic organelles. The invading organisms enter the lymphatic vessels, where they again appeared to be closely interacting with ileal macrophages. "

    Full-text · Article · Jan 2010 · American Journal of Animal and Veterinary Sciences
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Questions & Answers about this publication

  • Rakesh Yashroy asked a question in Lysosome:
    What is de-acidification of lysosomes? Can de-acidfied lysosomes fuse with phagosomes?
    Some micobes can signal de-acidification of host cell lysosomes and avert lytic breakdown.
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      [Show abstract] [Hide abstract]
      ABSTRACT: Originally isolated from severe human food-poisoning cases, Salmonella (3,10:r:-), a monophasic variety of otherwise diphasic serotypes such as S. weltevreden and S. simi, causes serious infections in man, animals and poultry. Mechanism of infection of this versatile and deadly organism is important to understand for its control. The objective of this study was to enhance our understanding of infection of Salmonella (3,10:r:-) in vivo at cellular level. Aliquots of 10(9) cfu of Salmonella (3,10:r:-) organisms were injected intra-ileally in 24 h pre-fasted 3 month old broiler chickens by standard ligated ileal loop method. After 18 h, the fluid accumulated in the ileum was drained and small tissue pieces were fixed in 2.5 per cent buffered (pH 7) glutaraldehyde and subsequently in 1 per cent aqueous osmium tetraoxide. Ultra-thin sections of araldite-embedded tissue pieces were examined under transmission electron microscope operated at 100 KV after staining with uranyl acetate and lead citrate. Over 70 per cent of salmonellae interacting within 300 nm with ileal epithelial cells developed numerous surface blebs of periplasmic extensions designated "periplasmic organelles" (POs). Large sized POs were apparently pinched off as outer membrane vesicles (OMVs), 50-90 nm in diameter. Type III secretion needle complex-like "rivet complexes" (RCs) were viewed to rivet the bacterial outer and inner membranes together, allowing only pockets of periplasm to expand/inflate in order to liberate OMVs. Many OMVs were found visibly docked on the plasma membrane of host epithelial cells. The invading organisms appeared to leave the epithelial cells so as to find entry into the lymphatic vessels, where, they again appeared to be closely interacting with ileal macrophages, by forming numerous POs and concomitantly liberating OMVs. Inside the cytoplasm of macrophages, numerous tight phagosomes were seen, each containing two organisms. The final stage appeared to contain replicated salmonellae, four in each loose phagosome and, at the same time, macrophages also showed signs of apoptotic disintegration, culminating in the release of replicated salmonellae. Outer membrane vesicles released from a fiercely virulent human isolate, Salmonella 3,10:r:- pathogens have been implicated in translocating biochemical signals from the host-interactive organisms to the eukaryotic cells at both stages of invasion leading to epithelial cell and macrophage infection in vivo, in the chicken ileal model. A comprehensive cellular mechanism at ultrastructural level is outlined for typhoid-like Salmonella infections caused by this humans-infecting organism.
      Full-text · Article · Jan 2008 · The Indian Journal of Medical Research
  • Rakesh Yashroy asked a question in Molecular Microbiology:
    What factors render bacterial pathogens in phagosomes, resistant to degradation by lysosomes e.g., in given paper here or elsewhere?
    Lysosomes normally fuse with phagosomes to degrade their contents by enzymatic lysis, but this does not happen in some cases of infections.
    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: Originally isolated from severe human food-poisoning cases, Salmonella (3,10:r:-), a monophasic variety of otherwise diphasic serotypes such as S. weltevreden and S. simi, causes serious infections in man, animals and poultry. Mechanism of infection of this versatile and deadly organism is important to understand for its control. The objective of this study was to enhance our understanding of infection of Salmonella (3,10:r:-) in vivo at cellular level. Aliquots of 10(9) cfu of Salmonella (3,10:r:-) organisms were injected intra-ileally in 24 h pre-fasted 3 month old broiler chickens by standard ligated ileal loop method. After 18 h, the fluid accumulated in the ileum was drained and small tissue pieces were fixed in 2.5 per cent buffered (pH 7) glutaraldehyde and subsequently in 1 per cent aqueous osmium tetraoxide. Ultra-thin sections of araldite-embedded tissue pieces were examined under transmission electron microscope operated at 100 KV after staining with uranyl acetate and lead citrate. Over 70 per cent of salmonellae interacting within 300 nm with ileal epithelial cells developed numerous surface blebs of periplasmic extensions designated "periplasmic organelles" (POs). Large sized POs were apparently pinched off as outer membrane vesicles (OMVs), 50-90 nm in diameter. Type III secretion needle complex-like "rivet complexes" (RCs) were viewed to rivet the bacterial outer and inner membranes together, allowing only pockets of periplasm to expand/inflate in order to liberate OMVs. Many OMVs were found visibly docked on the plasma membrane of host epithelial cells. The invading organisms appeared to leave the epithelial cells so as to find entry into the lymphatic vessels, where, they again appeared to be closely interacting with ileal macrophages, by forming numerous POs and concomitantly liberating OMVs. Inside the cytoplasm of macrophages, numerous tight phagosomes were seen, each containing two organisms. The final stage appeared to contain replicated salmonellae, four in each loose phagosome and, at the same time, macrophages also showed signs of apoptotic disintegration, culminating in the release of replicated salmonellae. Outer membrane vesicles released from a fiercely virulent human isolate, Salmonella 3,10:r:- pathogens have been implicated in translocating biochemical signals from the host-interactive organisms to the eukaryotic cells at both stages of invasion leading to epithelial cell and macrophage infection in vivo, in the chicken ileal model. A comprehensive cellular mechanism at ultrastructural level is outlined for typhoid-like Salmonella infections caused by this humans-infecting organism.
      Full-text · Article · Jan 2008 · The Indian Journal of Medical Research
  • Rakesh Yashroy asked a question in Animal Salmonella Infections:
    Do all human Salmonella pathogens multiply in macrophages?
    Salmonella species that multiply in macrophages can lead to systemic typhoid-like infections.
    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: Originally isolated from severe human food-poisoning cases, Salmonella (3,10:r:-), a monophasic variety of otherwise diphasic serotypes such as S. weltevreden and S. simi, causes serious infections in man, animals and poultry. Mechanism of infection of this versatile and deadly organism is important to understand for its control. The objective of this study was to enhance our understanding of infection of Salmonella (3,10:r:-) in vivo at cellular level. Aliquots of 10(9) cfu of Salmonella (3,10:r:-) organisms were injected intra-ileally in 24 h pre-fasted 3 month old broiler chickens by standard ligated ileal loop method. After 18 h, the fluid accumulated in the ileum was drained and small tissue pieces were fixed in 2.5 per cent buffered (pH 7) glutaraldehyde and subsequently in 1 per cent aqueous osmium tetraoxide. Ultra-thin sections of araldite-embedded tissue pieces were examined under transmission electron microscope operated at 100 KV after staining with uranyl acetate and lead citrate. Over 70 per cent of salmonellae interacting within 300 nm with ileal epithelial cells developed numerous surface blebs of periplasmic extensions designated "periplasmic organelles" (POs). Large sized POs were apparently pinched off as outer membrane vesicles (OMVs), 50-90 nm in diameter. Type III secretion needle complex-like "rivet complexes" (RCs) were viewed to rivet the bacterial outer and inner membranes together, allowing only pockets of periplasm to expand/inflate in order to liberate OMVs. Many OMVs were found visibly docked on the plasma membrane of host epithelial cells. The invading organisms appeared to leave the epithelial cells so as to find entry into the lymphatic vessels, where, they again appeared to be closely interacting with ileal macrophages, by forming numerous POs and concomitantly liberating OMVs. Inside the cytoplasm of macrophages, numerous tight phagosomes were seen, each containing two organisms. The final stage appeared to contain replicated salmonellae, four in each loose phagosome and, at the same time, macrophages also showed signs of apoptotic disintegration, culminating in the release of replicated salmonellae. Outer membrane vesicles released from a fiercely virulent human isolate, Salmonella 3,10:r:- pathogens have been implicated in translocating biochemical signals from the host-interactive organisms to the eukaryotic cells at both stages of invasion leading to epithelial cell and macrophage infection in vivo, in the chicken ileal model. A comprehensive cellular mechanism at ultrastructural level is outlined for typhoid-like Salmonella infections caused by this humans-infecting organism.
      Full-text · Article · Jan 2008 · The Indian Journal of Medical Research