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2.
Background
Salmonella enterica serovar Typhi and Typhimurium are closely related serovars as indicated by >96% DNA sequence identity between shared genes. Nevertheless, S. Typhi is a strictly human-specific pathogen causing a systemic disease, typhoid fever. In contrast, S. Typhimurium is a broad host range pathogen causing only a self-limited gastroenteritis in immunocompetent humans. We hypothesize that these differences have arisen because some genes are unique to each serovar either gained by horizontal gene transfer or by the loss of gene activity due to mutation, such as pseudogenes. S. Typhi has 5% of genes as pseudogenes, much more than S. Typhimurium which contains 1%. As a consequence, S. Typhi lacks several protein effectors implicated in invasion, proliferation and/or translocation by the type III secretion system that are fully functional proteins in S. Typhimurium. SseJ, one of these effectors, corresponds to an acyltransferase/lipase that participates in SCV biogenesis in human epithelial cell lines and is needed for full virulence of S. Typhimurium. In S. Typhi, sseJ is a pseudogene. Therefore, we suggest that sseJ inactivation in S. Typhi has an important role in the development of the systemic infection. 相似文献3.
Our aim was to investigate the capability of each of three genes, 16S rRNA, gyrB and aroE, to discriminate, first, among Bacillus thuringiensis H serotypes; second, among B. thuringiensis serovars from the same H serotype; and third, among B. thuringiensis strains from the same serovar. The 16S rRNA, gyrB and aroE genes were amplified from 21 B. thuringiensis H serotypes and their nucleotide sequences determined. Additional strains from four B. cereus sensu lato species were included for comparison purposes. These sequences were pair-wise compared and phylogenetic relationships
were revealed. Each of the three genes under study could discriminate among B. thuringiensis H serotypes. The gyrB and aroE genes showed a discriminatory power among B. thuringiensis H serotypes up to nine fold greater than that of the 16S rRNA gene. The gyrB gene was retained for subsequent analyses to discriminate B. thuringiensis serovars from the same H serotype and to discriminate strains from same serovar. A total of 42 B. thuringiensis strains, which encompassed 25 serovars from 12 H serotypes, were analyzed. The gyrB gene nucleotide sequences were different enough as to be sufficient to discriminate among B. thuringiensis serovars from the same H serotype and among B. thuringiensis strains from the same serovar.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Natural variation in the presence or the absence of STM0517-0529 genes allowing allantoin utilisation has been described in
field isolates of the multidrug resistant Salmonella enterica serovar Typhimurium belonging to the phage type DT104. Interestingly, S. enterica subspecies enterica serovar Typhimurium DT104 is quite frequent in pigs and cattle, but rarely present in egg-laying hens. Taking into account
the different mode of allantoin metabolism in birds and mammals, we were interested in whether the absence of STM0517-0529
genes may disable this clone in poultry colonisation. We have therefore constructed the allB (also designated as STM0523) mutants in S. enterica subspecies enterica serovar Typhimurium and S. enterica subspecies enterica serovar Enteritidis, and with these, we infected mice, newly hatched chickens and adult egg-laying hens to show that the
defect in allantoin utilisation does not influence S. enterica virulence for mice or adult hens, but slightly decreases virulence of S. enterica for chickens. The decrease in virulence of the allB mutant was relatively minor as it could be observed only after a mixed infection model, consistent with a lower prevalence,
but not a total absence of such clones in poultry flocks. 相似文献
5.
Alicia Alonso-Hernando Rosa Capita Miguel Prieto Carlos Alonso-Calleja 《Journal of microbiology (Seoul, Korea)》2009,47(2):142-146
Information on the potential for acquired reduced susceptibility of bacteria to poultry decontaminants occurring is lacking.
Minimal Inhibitory Concentrations (MICs) were established for assessing the initial susceptibility and the adaptative and
cross-adaptative responses of four bacterial strains (Listeria monocytogenes serovar l/2a, L. monocytogenes serovar 4b, Salmonella enterica serotype Typhimurium, and S. enterica serotype Enteritidis) to four poultry decontaminants (trisodium phosphate, acidified sodium chlorite -ASC-, citric acid,
and peroxyacetic acid). The initial susceptibility was observed to differ among species (all decontaminants) and between Salmonella strains (ASC). These inter- and intra-specific variations highlight (1) the need for strict monitoring of decontaminant concentrations
to inactivate all target pathogens of concern, and (2) the importance of selecting adequate test strains in decontamination
studies. MICs of ASC (0.17±0.02 to 0.21±0.02 mg/ml) were higher than the U.S. authorized concentration when applied as a pre-chiller
or chiller solution (0.05 to 0.15 mg/ml). Progressively increasing decontaminant concentrations resulted in reduced susceptibility
of strains. The highest increase in MIC was 1.88 to 2.71-fold (ASC). All decontaminants were shown to cause cross-adaptation
of strains between both related and unrelated compounds, the highest increase in MIC being 1.82-fold (ASC). Our results suggest
that the in-use concentrations of ASC could, in certain conditions, be ineffective against Listeria and Salmonella strains. The adaptative and cross-adaptative responses of strains tested to poultry decontaminants are of minor concern.
However, the observations being presented here are based on in vitro studies, and further research into practical applications are needed in order to confirm these findings. 相似文献
6.
Chai-Hoon Khoo Yoke-Kqueen Cheah Learn-Han Lee Jiun-Horng Sim Noorzaleha Awang Salleh Shiran Mohd Sidik Son Radu Sabrina Sukardi 《Antonie van Leeuwenhoek》2009,96(4):441-457
The increased occurrence of Salmonella occurrence in local indigenous vegetables and poultry meat can be a potential health hazards. This study is aimed to detect
the prevalence of twenty different virulence factors among Salmonella enterica strains isolated from poultry and local indigenous vegetables in Malaysia via an optimized, rapid and specific multiplex
PCR assay. The assay encompasses a total of 19 Salmonella pathogenicity islands genes and a quorum sensing gene (sdiA) in three multiplex reaction sets. A total of 114 Salmonella
enterica isolates belonging to 38 different serovars were tested. Each isolate in under this study was found to possess up to 70%
of the virulence genes tested and exhibited variable pathogenicity gene patterns. Reproducibility of the multiplex PCR assay
was found to be 100% and the detection limit of the optimized multiplex PCR was tested with lowest detectable concentration
of DNA 0.8 pg μl−1. This study demonstrated various Salmonella pathogenicity island virulence gene patterns even within the same serovar. This sets of multiplex PCR system provide a fast
and reliable typing approach based on Salmonella pathogenicity islands, thus enabling an effective monitoring of emerging pathogenic Salmonella strains as an additional tool in Salmonella surveillance studies. 相似文献
7.
Ammini Parvathi Jasna Vijayan Greeshma Murali Preethi Chandran 《Current microbiology》2011,62(1):21-26
Salmonella
enterica serotype Newport is an important cause of non-typhoidal salmonellosis, a clinically less severe infection than typhoid fever
caused by S. enterica serotype Typhi. In this investigation, the virulence genotypes of S. enterica Newport isolated from a backwater environment were compared with Salmonella Typhi from clinical cases in the same region where salmonellosis is endemic. Genotyping was done by PCR screening for virulence
markers associated with Salmonella pathogenicity islands (SPIs) and plasmids. The virulence genes associated with SPIs I–VI were detected in 95–100% of all
the isolates, while the viaB locus representing SPI-7 was detectable in 66 and 73% of the environmental and clinical isolates, respectively. A significant
number of Salmonella Newport lacked virulence genes shdA and sopE compared to S. Typhi. All S. Typhi and S. Newport isolates lacked large plasmid-borne virulence genes spvR and pefA. Further investigations into the antimicrobial resistance of S. Newport revealed multiple drug resistance to ampicillin, amoxicillin/clavulanic acid, trimethorprim-sulfamethoxazole, chloramphenicol,
tetracycline, cephalothin, and cephalexin. In comparison, S. Typhi were susceptible to all clinically relevant antimicrobials. The results of this study will help in understanding the
spread of virulence genotypes and antibiotic resistance in S. Newport in the region of study. 相似文献
8.
Salmonella enterica is divided into four subspecies containing a large number of different serovars, several of which are important zoonotic
pathogens and some show a high degree of host specificity or host preference. We compare 45 sequenced S. enterica genomes that are publicly available (22 complete and 23 draft genome sequences). Of these, 35 were found to be of sufficiently
good quality to allow a detailed analysis, along with two Escherichia coli strains (K-12 substr. DH10B and the avian pathogenic E. coli (APEC O1) strain). All genomes were subjected to standardized gene finding, and the core and pan-genome of Salmonella were estimated to be around 2,800 and 10,000 gene families, respectively. The constructed pan-genomic dendrograms suggest
that gene content is often, but not uniformly correlated to serotype. Any given Salmonella strain has a large stable core, whilst there is an abundance of accessory genes, including the Salmonella pathogenicity islands (SPIs), transposable elements, phages, and plasmid DNA. We visualize conservation in the genomes in
relation to chromosomal location and DNA structural features and find that variation in gene content is localized in a selection
of variable genomic regions or islands. These include the SPIs but also encompass phage insertion sites and transposable elements.
The islands were typically well conserved in several, but not all, isolates—a difference which may have implications in, e.g.,
host specificity. 相似文献
9.
Matiasovicova J Adams P Barrow PA Hradecka H Malcova M Karpiskova R Budinska E Pilousova L Rychlik I 《Archives of microbiology》2007,187(5):415-424
The origin of multidrug-resistant Salmonella enterica serovar typhimurium (S. typhimurium) harboring the Salmonella Genomic Island 1 (SGI1), which was detected for the first time in the mid-1980s is unknown. In this study, we performed microarray
genomotyping of four multidrug-resistant SGI1 positive strains and found that unlike the S. typhimurium LT2 strain, the multidrug-resistant strains lacked genes STM0517-0529 allowing the utilization of allantoin as a sole nitrogen
source. We extended this observation by PCR screening of additional 120 S. typhimurium field strains and found that this locus was absent in all SGI1 positive and also in 24% of SGI1 negative strains, which were
proposed to be the original recipients of SGI1. To prove this hypothesis, we compared the STM0517-0529 negative strains (with
or without the SGI1) by PFGE and PCR prophage typing and found that 8 out of 11 of the SGI1 negative strains and 17 out of
22 SGI1 positive strains were of identical PFGE pattern and PCR prophage pattern, while this specific pattern was never observed
among STM0517-0529 positive strains. We therefore propose that a lineage of the S. typhimurium DT104 sensitive strain first lost the ability to metabolize allantoin and then acquired SGI1. 相似文献
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11.
Ulrich Methner Martin Heller Herbert Bocklisch 《European Journal of Wildlife Research》2010,56(4):493-502
Salmonella (S.) enterica subspecies enterica serovar Choleraesuis, the swine-adapted serovar is found rarely in Western European countries including Germany. However,
the regional laboratory of the federal state Thuringia in Germany examined diseased wild boars routinely also for the occurrence
of Salmonella organisms. Between 2006 and 2008, only the serovar S. Choleraesuis was islolated from 24 animals, three strains isolated from domestic pigs were included. In order to detect a
possible epidemiological context, the strains of S. Choleraesuis were characterised by macrorestriction and plasmid analysis, repetitive sequence PCR, antimicrobial testing
and determining the biochemical profile. A combination of all methods enabled the identification of five epidemiological groups.
Two groups were detected in the same territory but three other discriminative groups were predominant in different regions.
S. Choleraesuis strains of the different epidemiological groups circulate in wild boar populations in the corresponding regions.
However, it could be concluded that both natural barriers like mountains and artificial barriers like arterial roads may cause
the separation of wild boar populations and as a result also the respective S. Choleraesuis organisms. The occurrence of the identical epidemiological groups in wild boars and domestic pigs indicates
the possible mutual exposure of the pathogen. To avoid risks for human and domestic pig health regular inspection of meat
from wildlife by official veterinarians and advice of hunters and persons who prepare and consume wild boar meat should be
enhanced. 相似文献
12.
Decreased expression (twofold) of a putative yehUTS operon of which yehUT encodes a putative YehU/YehT two-component system in the ompR mutant from Salmonella enterica serovar Typhi (S. Typhi) GIFU10007 under hypotonic growth condition was observed by qRT-PCR. Purified recombinant protein OmpRHis6 of GIFU10007 was shown to bind the upstream region of the yehU gene by the gel-shift assay. In addition, the yehT deletion mutant (ΔyehT) displayed differential expression (twofold or higher) of 26 genes under the condition by the DNA microarray analysis. Altogether,
OmpR might regulate the YehUT system in S. Typhi under hypotonic growth condition. 相似文献
13.
In seawater, enteric bacteria evolve toward a stressed state that is difficult to identify because of major alterations of
their phenotype. In this study, we incubated four reference strains of S. enterica serovar Typhimurium in seawater microcosms for 10 months and studied the modifications of their main phenotypic characters.
All of the strains lost some key characters used for traditional identification of the Salmonella genus. They became able to produce acetoin, and tryptophane deaminase activity became positive, but they lost the capacity
to use rhamnose. We were able to show some modifications of the level of enzymatic profile as well as in their antibiotic
susceptibility. The atypical cells of S. enterica serovar Typhimurium were identified by polymerase chain reaction (PCR) methods using the internal transcribed spacer region,
and they were confirmed by multiplex PCR after the simultaneous amplification of the phoP, Hin, and H-li genes. 相似文献
14.
Porteen Kannan Mahesh Dharne Allen Smith Jeffrey Karns Arvind A. Bhagwat 《Current microbiology》2009,59(6):641-645
15.
Background
Salmonella spp. have been isolated from a wide range of wild animals. Opportunistic wild carnivores such as red foxes (Vulpes vulpes) and badgers (Meles meles) may act as environmental indicators or as potential sources of salmonellosis in humans. The present study characterizes Salmonella spp. isolated from the intestinal contents of hunted or dead red foxes (n?=?509) and badgers (n?=?17) in northern Italy.Findings
Thirty-one strains of Salmonella belonging to 3 Salmonella enterica subspecies were isolated. Fourteen different serovars of S. enterica subsp. enterica were identified, among which were serovars often associated with human illness.Conclusions
Wild opportunistic predators can influence the probability of infection of both domestic animals and humans through active shedding of the pathogen to the environment. The epidemiological role of wild carnivores in the spread of salmonellosis needs to be further studied.16.
The gene cspH , which encodes one of the cold-shock proteins in Salmonella enterica serovar Typhimurium, has previously been reported to be induced during early exponential phase at 37°C. In the present study, the expression of cspH upon nutrient up-shift at 37°C was investigated and found to be affected by DNA gyrase and DNA-binding protein Fis. When cells at stationary phase were subcultured into a rich medium, the mRNA level of cspH increased dramatically prior to the first cell division. However, when the cells were treated with DNA gyrase inhibitors, cspH mRNA was not induced upon nutrient up-shift. The low level of DNA superhelical density at the cspH promoter in part affected the expression of cspH mRNA in vitro. In addition, a fis-deficient strain had a lower level of cspH mRNA than the wild-type upon nutrient up-shift. Finally, a cspH–lacZ construct, in which the putative binding region for Fis was deleted in the cspH promoter, expressed a low level of LacZ, in contrast to the native cspH–lacZ construct.This revised version was published online in July 2004 with corrections to Fig. 4. 相似文献
17.
Joanna Mokracka Sylwia Krzymińska Danił Ałtunin Dariusz Wasyl Ryszard Koczura Krzysztof Dudek Monika Dudek Zofia Anna Chyleńska Anna Ekner-Grzyb 《Antonie van Leeuwenhoek》2018,111(10):1863-1870
The aim of this study was to estimate virulence potential of Salmonella enterica strains colonizing the gut of free-living sand lizards (Lacerta agilis L.). The strains belonged to three Salmonella serovars: Abony, Schleissheim, and Telhashomer. Adhesion and invasion abilities of the strains were determined in quantitative assays using the gentamicin protection method. Induction of apoptosis was assessed using HeLa cell monolayers. PCR assays were used for detection of 26 virulence genes localised within mobile elements: pathogenicity islands, virulence plasmids, and prophage sequences. In vitro studies revealed that all strains had adhesion and invasion abilities to human epithelial cells. The isolates were cytotoxic and induced apoptosis of the cells. The serovars differed in the number of virulence-associated genes: up to 18 genes were present in Salmonella Schleissheim, 17 in Salmonella Abony, whereas as few as six genes were found in Salmonella Telhashomer. Generally, Salmonella Abony and Salmonella Schleissheim did not differ much in gene content connected with the presence SPI-1 to -5. All of the strains lacked genes localised within bacteriophages and plasmids. The presence of virulence-associated genes and in vitro pathogenicity assays suggest that Salmonella sp. strains originating from autochthonous, free-living lizards can potentially infect and cause disease in humans. 相似文献
18.
Background
Salmonella enterica subspecies I includes several closely related serovars which differ in host ranges and ability to cause disease. The basis for the diversity in host range and pathogenic potential of the serovars is not well understood, and it is not known how host-restricted variants appeared and what factors were lost or acquired during adaptations to a specific environment. Differences apparent from the genomic data do not necessarily correspond to functional proteins and more importantly differential regulation of otherwise identical gene content may play a role in the diverse phenotypes of the serovars of Salmonella. 相似文献19.
Forty-three epidemiologically unrelated emerging Salmonella enterica subsp. enterica serovar 4,[5],12:i:- strains isolated during the period 2009–2010 in Slovakia were characterized by phenotypic and genotypic
methods. Thirty-one isolates (72.1%) expressed resistance to ampicillin, streptomycin, sulfizoxazole, and tetracycline [R-type
ASSuT]. The majority of the strains belonged to both definitive phage types DT193 (30.2%) and U311 (27.9%). Other phage types
identified were U302 (6.9%), DT18 (4.7%), and DT194 (2.3%). Twelve strains (27.9%) were not typeable. Pulsed-field gel electrophoresis
analysis identified three closely related major banding profiles (X1, X1a, and X2), suggesting the similarity and close epidemiological
relationship between S. enterica serovar 4,[5],12:i:- strains. In two isolates with R-type ASSuT, phage type NT and in one isolate with R-type ACROSSuSxTTTMPNA,
phage type DT193 class 1 integrons were found encoding blaPSE-1 and dfrA, aadA1, respectively. 相似文献
20.
Xiu Sheng Xinxiang Huang Jun Li Xin Xie Shun Xu Hai Zhang Hua Xu 《Current microbiology》2009,59(6):628-635