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1.
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
2.
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
3.
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
4.
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
5.
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
6.
Salmonella causes the majority of infections in humans and homeothermic animals. This article describes a specific polymerase chain
reaction (PCR) method developed for a rapid identification of Salmonella. A gyrB-targeted species-specific primer pair, S-P-for (5′-GGT GGT TTC CGT AAA AGT A-3′) and S-P-rev (5′-GAA TCG CCT GGT TCT TGC-3′),
was successfully designed. PCR with all the Salmonella strains produced a 366- bp DNA fragment that was absent from all the non-Salmonella strains tested. The detection limit of the PCR was 0.01 ng with genomic DNA or 3.2 cells per assay. Good specificity was
also demonstrated by fecal samples, from which only the gyrB gene of Salmonella was amplified. Using the culture-PCR method, 27 isolates on Salmonella-Shigella (SS) medium were rapidly identified as Salmonella, which was confirmed by the sequencing of the gyrB gene. 相似文献
7.
Yoke-Kqueen Cheah Noorzaleha Awang Salleh Learn-Han Lee Son Radu Sabrina Sukardi Jiun-Horng Sim 《World journal of microbiology & biotechnology》2008,24(3):327-335
Salmonella enterica subsp. enterica (S.) serovar Weltevreden has emerged as a public health problem in many countries. Genomic DNA of S. Weltevreden from indigenous vegetables namely ‘selom’ (Oenanthe stolonifera), ‘pegaga’ (Centella asiatica), ‘kesum’ (Polygonum minus) and ‘kangkong’ (Ipomoea aquatica) were characterized by duplex-polymerase chain reaction (duplex-PCR), multiplex-polymerase chain reaction (multiplex-PCR),
random amplified polymorphic DNA (RAPD), enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR)
and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results demonstrated that a total of
four clusters and three single isolates were generated from ERIC-PCR with primers ERIC-1 and ERIC-2 whereas RAPD with arbitrary
primers OPAR2, OPAR17 and OPAR19 discriminated the S. Weltevreden into nine clusters and eight single isolates at a common 65% similarity level with discriminatory index (D) of 0.7443 and 0.9394 respectively. Composite analysis of banding profiles generated from RAPD-PCR and ERIC-PCR showed eight
clusters and six single isolates at 65% similarity level with the highest D value that is 0.9508. On the other hand, PCR-RFLP and duplex PCR data exhibited a consistent profile for S. Weltevreden. Multiplex-PCR targeting three different antibiotic resistance genes and a common Salmonella specific gene segment produced two distinguishing profiles among the S. Weltevreden examined. These results demonstrated that the combined analysis of RAPD-PCR and ERIC-PCR is a better tool for
characterizing S. Weltevreden than individual methods. 相似文献
8.
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
9.
Kenneth P. Smith Jeffy George Kathleen M. Cadle Sanath Kumar Steven J. Aragon Ricardo L. Hernandez Suzanna E. Jones Jody L. Floyd Manuel F. Varela 《World journal of microbiology & biotechnology》2010,26(6):1025-1031
In this study, we investigated the antimicrobial susceptibility profiles and the distribution of some well known genetic determinants
of virulence in clinical isolates of Salmonella enterica from New Mexico. The minimum inhibitory concentrations for various antimicrobials were determined by using the E-test strip
method according to CLSI guidelines. Virulence genotyping was performed by polymerase chain reaction (PCR) using primers specific
for known virulence genes of S. enterica. Of 15 isolates belonging to 11 different serovars analyzed, one isolate of Salmonella Typhimurium was resistant to multiple drugs namely ampicillin, amoxicillin/clavulanic acid, chloramphenicol and tetracycline,
that also harbored class 1 intergron, bla
TEM encoding genes for β-lactamase, chloramphenicol acetyl transferase (cat1), plus floR, tet(C) and tet(G). This strain was phage typed as DT104. PCR analysis revealed the presence of invA, hilA, stn, agfA and spvR virulence genes in all the isolates tested. The plasmid-borne pefA gene was absent in 11 isolates, while 5 isolates lacked sopE. One isolate belonging to serogroup E4 (Salmonella Sombre) was devoid of multiple virulence genes pefA, iroB, shdA and sopE. These results demonstrate that clinical Salmonella serotypes from New Mexico used here are predominantly sensitive to multiple antimicrobial agents, but vary in their virulence
genotypes. Information on antimicrobial sensitivity and virulence genotypes will help in understanding the evolution and spread
of epidemic strains of S. enterica in the region of study. 相似文献
10.
Porteen Kannan Mahesh Dharne Allen Smith Jeffrey Karns Arvind A. Bhagwat 《Current microbiology》2009,59(6):641-645
11.
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
12.
Huang LJ Cui J Piao HH Hong Y Choy HE Ryu PY 《Journal of microbiology (Seoul, Korea)》2010,48(5):663-667
Cytolysin A (ClyA) is a pore-forming hemolytic protein encoded by the clyA gene. It has been identified in Salmonella enterica serovars Typhi and Paratyphi A. To identify and characterize the clyA genes in various Salmonella enterica strains, 21 different serotypes of strains isolated from clinical specimens were presently examined. Full-length clyA genes were found in S. enterica serovar Brandenburg, Indiana, Panama, and Schwarzengrund strains by polymerase chain reaction amplification. The ClyA proteins
from these four strains showed >97% amino acid identity to that of S. enterica serovar Typhi. Although all four serovars expressed detectable levels of ClyA as determined by Western blot analysis, they
did not show a strong hemolytic effect on blood agar, indicating that ClyA may not be efficiently expressed or secreted. Escherichia coli transformed with clyA genes from the four serovars enhanced production of ClyA proteins and hemolytic activities to a level similar to S. enterica serovar Typhi ClyA. The present results suggest that ClyA may play a role in the pathogenesis of S. enterica serovar Brandenburg, Indiana, Panama and Schwarzengrund. 相似文献
13.
Jun Sik Lee In Duk Jung Chang-Min Lee Jin Wook Park Sung Hak Chun Soo Kyung Jeong Tae kwun Ha Yong Kyoo Shin Dae Jin Kim Yeong-Min Park 《BMC microbiology》2010,10(1):263
Background
Typhoid, which is caused by Salmonella enterica serovar Typhimurium, remains a major health concern worldwide. Multidrug-resistant strains of Salmonella have emerged which exhibit increased survivability and virulence, thus leading to increased morbidity. However, little is known about the protective immune response against this microorganism. The outer membrane protein (Omp)A of bacteria plays an important role in pathogenesis. 相似文献14.
Background
Salmonella enterica and Campylobacter jejuni are amongst the more prevalent bacterial pathogens that cause foodborne diseases. These microorganisms are common contaminants of poultry and poultry products. This study was aimed to evaluate the antibacterial activity of metallic copper surfaces on these important enteropathogens, and to determine the potential acquisition of copper by food exposed to this metal. 相似文献15.
Mohammad Jahangir Alam David Renter Ethel Taylor Diana Mina Rodney Moxley David Smith 《Current microbiology》2009,58(4):354-359
Salmonella enterica in cattle production systems may be associated with important human and animal disease issues. However, tremendous diversity
exists among Salmonella recovered, and more information is needed about strains of greatest potential health concern, particularly those that are
multidrug resistant (MDR). By characterizing Salmonella isolates from commercial feedlot pens, this study aimed to evaluate the strain diversity and prevalence of MDR Salmonella from different types of composite pen samples. Antimicrobial susceptibility profiles, serotype, and presence or absence of
the integron-encoded intI1 gene were determined for 530 Salmonella isolates recovered using composite rope (n = 335), feces (n = 59), and water (n = 136) samples from 21 pens in 3 feedlots. The study investigated only pens with available isolates from multiple sample
types. Most isolates (83.0%) of the 19 Salmonella serotypes identified were susceptible or intermediately susceptible to all the antimicrobials evaluated. Resistance to sulfisoxazole
(14.9%), streptomycin (3.8%), and tetracycline (3.6%) were the most common. None of the isolates tested positive for a class
1 integron, and only 2.5% were resistant to multiple antimicrobials. All the MDR isolates, namely, serotypes Uganda (n = 9), Typhimurium (n = 2), and Give (n = 2), were resistant to at least five antimicrobials. Most MDR isolates (n = 11) were from two pens during 1 week within one feedlot. Overall, many Salmonella isolates collected within a pen were similar in terms of serotype and antimicrobial susceptibility regardless of sample type.
However, MDR Salmonella and rare serotypes were not recovered frequently enough to suggest a general strategy for appropriate composite sampling
of feedlot cattle populations for Salmonella detection and monitoring. 相似文献
16.
Ferreira LQ Avelar KE Vieira JM de Paula GR Colombo AP Domingues RM Ferreira MC 《Current microbiology》2007,54(5):348-353
The Bacteroides genus, the most prevalent anaerobic bacteria of the intestinal tract, carries a plethora of the mobile elements, such as
plasmids and conjugative and mobilizable transposons, which are probably responsible for the spreading of resistance genes.
Production of β-lactamases is the most important resistance mechanism including cephalosporin resistance to β-lactam agents
in species of the Bacteroides fragilis group. In our previous study, the cfxA gene was detected in B. distasonis species, which encodes a clinically significant broad-spectrum β-lactamase responsible for widespread resistance to cefoxitin
and other β-lactams. Such gene has been associated with the mobilizable transposon Tn4555. Therefore, the aim of this study was to detect the association between the cfxA gene and the presence of transposon Tn4555 in 53 Bacteroides strains isolated in Rio de Janeiro, Brazil, by PCR assay. The cfxA gene was detected in 11 strains and the Tn4555 in 15. The transposon sequence revealed similarities of approximately 96% with the B. vulgatus sequence which has been deposited in GenBank. Hybridization assay was performed in attempt to detect the cfxA gene in the transposon. It was possible to associate the cfxA gene in 11 of 15 strains that harbored Tn4555. Among such strains, 9 presented the cfxA gene as well as Tn4555, but in 2 strains the cfxA gene was not detected by PCR assay. Our results confirm the involvement of Tn4555 in spreading the cfxA gene in Bacteroides species. 相似文献
17.
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
18.
Päivikki Perko-Mäkelä Pauliina Isohanni Marianne Katzav Marianne Lund Marja-Liisa Hänninen Ulrike Lyhs 《Acta veterinaria Scandinavica》2009,51(1):18
Background
Campylobacter is the most common cause of bacterial enteritis worldwide. Handling and eating of contaminated poultry meat has considered as one of the risk factors for human campylobacteriosis. Campylobacter contamination can occur at all stages of a poultry production cycle. The objective of this study was to determine the occurrence of Campylobacter during a complete turkey production cycle which lasts for 1,5 years of time. For detection of Campylobacter, a conventional culture method was compared with a PCR method. Campylobacter isolates from different types of samples have been identified to the species level by a multiplex PCR assay. 相似文献19.
Background
The type III secretion system (TTSS) is an important virulence determinant of Gram-negative bacterial pathogens. It enables the injection of effector proteins into the cytosol of eukaryotic cells. These effectors ultimately manipulate the cellular functions of the infected organism. Salmonella enterica serovar Typhimurium encodes two virulence associated TTSSs encoded by the Salmonella Pathogenicity Islands (SPI) 1 and 2 that are required for the intestinal and systemic phases of the infection, respectively. However, recent studies suggest that the roles of these TTSSs are not restricted to these compartments. The regulation of TTSSs in Salmonella is very complex with several regulators operating to activate or to repress expression depending on the environmental conditions. 相似文献20.
Salmonella is a major public health concern due to the consumption of contaminated food. Salmonella enterica serovar Enteritidis (SE) infection in humans is often associated with the consumption of contaminated poultry products. Binding of the bacterium to the intestinal mucosa is a major pathogenic mechanism of Salmonella in poultry. In this study, transposon mutagenesis identified SEN3800 as a potential binding mutant of SE. Therefore, we hypothesize that SEN3800 plays a role in the colonization ability of SE in the gastrointestinal tract of poultry. To test our hypothesis, we created a mutant of SE in which SEN3800 was deleted. We then tested the in-vitro and in-vivo binding ability of ?SEN3800 when compared to the wild-type and complemented SE strains. Our data showed a significant decrease in the binding ability of ?SEN3800 to T84 intestinal epithelial cells, as well as in the small intestine and cecum of poultry. Furthermore, this binding defect correlated to a defect in invasion, as evidenced by a cell culture model using T84 intestinal epithelial cells and bacterial recovery from the livers and spleens of chickens. Overall, these studies indicate that SEN3800 contributes to the colonization ability of Salmonella in the gastrointestinal tract of poultry. 相似文献