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1.
Fey PD Iwen PC Zentz EB Briska AM Henkhaus JK Bryant KA Larson MA Noel RK Hinrichs SH 《Journal of clinical microbiology》2012,50(9):3063-3065
We investigated the use of whole-genome mapping and pulsed-field gel electrophoresis (PFGE) with isolates from an outbreak of Salmonella enterica serotype Saintpaul. PFGE and whole-genome mapping were concordant with 22 of 23 isolates. Whole-genome mapping is a viable alternative tool for the epidemiological analysis of Salmonella food-borne disease investigations. 相似文献
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Tatavarthy A Sanderson R Peak K Scilabro G Davenhill P Cannons A Amuso P 《Journal of clinical microbiology》2012,50(8):2631-2638
Salmonella enterica serotype Typhi is a human pathogen causing 12 to 30% mortality and requiring antibiotic therapy to control the severity of the infection. Typhoid fever in United States is often associated with foreign travel to areas of endemicity. Increasing resistance to multiple drugs, including quinolones, is associated with decreased susceptibility to ciprofloxacin (DCS). We investigated 31 clinical strains isolated in Florida from 2007 to 2010, associated with travel to six countries, to examine the clonal distribution of the organism and apparent nalidixic acid (NAL) resistance. The strains were isolated from blood or stool of patients aged 2 to 68 years. The isolates were subtyped by ribotyping and pulsed-field gel electrophoresis. Susceptibilities to 15 antimicrobials were determined, and the isolates were screened for integrons and gyrase A gene mutations. Both typing techniques effectively segregated the strains. Identical clones were associated with different countries, while diverse types coexisted in the same geographic location. Fifty-one percent of the strains were resistant to at least one antimicrobial, and five were resistant to three or more drugs (multidrug resistant [MDR]). All 12 isolates from the Indian subcontinent were resistant to at least one drug, and 83% of those were resistant to NAL. Three of the MDR strains harbored a 750-bp integron containing the dfr7 gene. Ninety-three percent of the resistant strains showed a DCS profile. All the NAL-resistant strains contained point mutations in the quinolone resistance-determining region of gyrA. This study affirms the global clonal distribution, concomitant genetic heterogeneity, and increased NAL resistance of S. enterica serovar Typhi. 相似文献
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Molecular Typing of Multiple-Antibiotic-Resistant Salmonella enterica Serovar Typhi from Vietnam: Application to Acute and Relapse Cases of Typhoid Fever 下载免费PDF全文
John Wain Tran T. Hien Phillippa Connerton Tahir Ali Christopher M. Parry Nguyen T. T. Chinh Ha Vinh Cao X. T. Phuong Vo A. Ho To S. Diep Jeremy J. Farrar Nicholas J. White Gordon Dougan 《Journal of clinical microbiology》1999,37(8):2466-2472
The rate of multiple-antibiotic resistance is increasing among Salmonella enterica serovar Typhi strains in Southeast Asia. Pulsed-field gel electrophoresis (PFGE) and other typing methods were used to analyze drug-resistant and -susceptible organisms isolated from patients with typhoid fever in several districts in southern Vietnam. Multiple PFGE and phage typing patterns were detected, although individual patients were infected with strains of a single type. The PFGE patterns were stable when the S. enterica serovar Typhi strains were passaged many times in vitro on laboratory medium. Paired S. enterica serovar Typhi isolates recovered from the blood and bone marrow of individual patients exhibited similar PFGE patterns. Typing of S. enterica serovar Typhi isolates from patients with relapses of typhoid indicated that the majority of relapses were caused by the same S. enterica serovar Typhi strain that was isolated during the initial infection. However, some individuals were infected with distinct and presumably newly acquired S. enterica serovar Typhi isolates. 相似文献
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The survival of bacteria in various environments depends on a number of protective responses including acid tolerance response (ATR). In this study, ATR phenomenon was compared in Salmonella enterica serovar Typhi 6 and Salmonella enterica serovar Typhimurium 98 under different culture conditions. Survival of the adapted culture (pre-acid shocked to pH 5.5) was significantly better (p < 0.05) as compared to control, unadapted culture after acid shock at pH 3.3. However, the ATR varied with the serovar, incubation temperature and the growth medium used (all p-values < 0.05). S. Typhi 6 failed to grow in pH 3.3 at 45 degrees C. The addition of tetracycline or chloramphenicol (1.0 microg ml(-1)) to adapted cultures during or after acid shock (pH 3.3) had no effect on ATR expression. In S. Typhimurium 98, growth was increased by 10% or greater in adapted culture (when grown at pH 3.3) as compared to growth observed with an unadapted culture (when grown at pH 7.3) on transfer to fresh growth medium at pH 7.3. A poor ATR observed in non-growing S. Typhimurium 98 suspensions clearly showed that ATR is an energy-consuming process. Storage of S. Typhimurium 98 cultures in pH 4.5 nutrient broth at 4 degrees C demonstrated that prolonged exposure to acidic conditions is more detrimental in comparison to the cultures stored at pH 7.3 at this temperature. 相似文献
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Molecular basis of resistance displayed by highly ciprofloxacin-resistant Salmonella enterica serovar Typhi in Bangladesh 下载免费PDF全文
Saha SK Darmstadt GL Baqui AH Crook DW Islam MN Islam M Hossain M El Arifeen S Santosham M Black RE 《Journal of clinical microbiology》2006,44(10):3811-3813
Highly ciprofloxacin-resistant (MIC, 512 microg/ml) strains of Salmonella enterica serovar Typhi were isolated from the blood of typhoid patients in Dhaka, Bangladesh. The strains were indistinguishable by their antibiograms, biotypes, and variable-number tandem repeat types and had matching point mutations at positions 83 and 87 of the gyrA gene. The isolation of these strains in an area of high endemicity indicates the need for continuous surveillance of antibiotic resistance of S. enterica serovar Typhi and for the rationalized use of ciprofloxacin. 相似文献
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Rhabdomyolysis has been reported infrequently with salmonella infection. Since 1964, there have been at least 22 reports associated with gastroenteritis or bacteraemia. Twenty cases have been associated with non-typhoidal strains of Salmonella, with single reports of Salmonella enterica serovars Paratyphi and Typhi. A second case of typhoid fever associated with rhabdomyolysis was recently diagnosed in Ann Arbor, USA in a traveller returning from an endemic area. Prompt diagnosis and treatment resulted in a good outcome. Salmonella infection should be considered by clinicians as a possibility in the differential diagnosis of rhabdomyolysis. 相似文献
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Multilocus variable-number tandem repeats (VNTRs) are widely used as molecular markers to differentiate isolates of homogenous pathogenic clones. We explored the genomes of Salmonella enterica serovar Typhi strains CT18 and Ty2 for potential VNTRs. Among the 43 potential VNTRs screened, 2 were found to be polymorphic. Together with seven polymorphic VNTRs from previous studies, they were used to type 73 global serovar Typhi isolates. A total of 70 multilocus VNTR analysis (MLVA) profiles were found, distinguishing all except three pairs of isolates into individual profiles. The discriminatory power was 0.999. Phylogenetic analysis showed that the MLVA profiles can be divided into seven clusters. However, except for the closely related isolates, the relationships derived were in conflict with those inferred from single nucleotide polymorphism (SNP) typing using 38 SNPs done previously. We concluded that MLVA can resolve the relationships only among closely related isolates. A combination of SNP typing and MLVA typing offers the best approach for local and global epidemiology and the evolutionary analysis of serovar Typhi. We suggest that seven of the nine most polymorphic VNTRs be used as a standardized typing scheme for epidemiological typing.Typhoid fever remains a devastating disease in developing countries and is prevalent in areas with inadequate sanitation and poor hygiene. It is a serious systemic disease, spread via the fecal-oral route. Annually, there are more than 16 million cases of typhoid fever with 600,000 deaths reported worldwide (www.who.int). The etiological agent of typhoid fever is Salmonella enterica serovar Typhi, which is highly homogenous (13, 33). The genetic homogeneity of serovar Typhi has significantly impeded the development of suitable typing methods to differentiate serovar Typhi isolates for both phylogenetic and epidemiological purposes.Single nucleotide polymorphisms (SNPs) have recently been shown to be useful markers for typing serovar Typhi isolates (23, 29). SNP typing can resolve the relationships among global serovar Typhi isolates and be more discriminating than widely accepted population genetic methods, including multilocus enzyme electrophoresis (28) and multilocus sequence typing (13). However, some haplotypes or SNP profiles contained many isolates which could not be further differentiated (23, 29). In the study of Roumagnac et al. (29), 88 SNPs differentiated 481 global serovar Typhi isolates into 85 haplotypes. The majority of the isolates belonged to H58 (35%), H50 (12%), and H52 (11%). In the study by Octavia and Lan (23), 38 SNPs distinguished 73 global serovar Typhi isolates into 23 SNP profiles, and the majority of these isolates had SNP profile 10 (32%) and SNP profile 2 (16%). Clearly, SNP typing still has limited discriminatory power.Variable-number tandem repeats (VNTRs) have the potential to be more discriminating than SNPs and also to be used to establish the evolutionary relationships of the isolates. VNTRs are short sequence repeats, which are unique DNA elements repeated in tandem. The polymorphisms in VNTRs are believed to be a result of slippage strand misalignment (17). Therefore, isolates may contain different copy numbers for a repeat locus, allowing differentiation between isolates. Multilocus VNTR analysis (MLVA) involves determination of the number of repeats at multiple VNTR loci, and the number of loci required varies depending on the diversity of the organism studied. MLVA has been particularly effective in typing homogenous clones including Yersinia pestis (1, 14, 21, 25), Bacillus anthracis (8, 11, 12, 34), and Mycobacterium tuberculosis (7, 16, 32, 35, 36). In S. enterica, a few serovars, including serovars Enteritidis, Typhimurium, and Typhi have been studied by MLVA (3, 4, 18-20, 27).Two MLVA studies of serovar Typhi showed different levels of variation of VNTR loci analyzed (20, 27). Liu et al. (20) found five potential VNTR loci designated TR1 to TR5, with the first three showing variation among 59 serovar Typhi isolates from several Asian countries studied. Ramisse et al. (27) found five new polymorphic VNTRs (SAL02, SAL06, SAL10, SAL15, and SAL20). Together with two markers from previous serovar Typhi and Typhimurium studies, TR1 (20) and STTR5/Sal16 (18), a total of seven VNTRs distinguished 27 serovar Typhi isolates from France into 25 MLVA profiles (27). In these two studies, VNTR PCR products were resolved on standard agarose gels. However, the resolution of agarose gels is known to be low, which makes it especially difficult to resolve short repeat units, such as SAL10 with a 2-bp repeat unit. In this study we used seven published VNTRs, including SAL02, SAL06, SAL10, SAL16, SAL20, TR1, and TR2, and two new VNTRs uncovered in this study as markers to explore their potential in studying the molecular evolution of global serovar Typhi isolates. Our MLVA assay employed universal M13 tail primer tagged with a different fluorescent dye to resolve the tandem repeats by capillary electrophoresis. We combined the more rapidly evolving VNTR markers with the slower evolving SNPs to achieve an optimal resolution for typing global serovar Typhi isolates. 相似文献
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Suneel Kumar Ahirwar Chandra Bhan Pratap Saurabh Kumar Patel Vijay K. Shukla Indarjeet Gambhir Singh Om Prakash Mishra Kailash Kumar Tej Bali Singh Gopal Nath 《Journal of clinical microbiology》2014,52(12):4330-4333
Salmonella enterica serovar Typhi faces several environmental stresses while going through the stomach (acidic pH) to the small intestine (basic pH) and intracellularly in macrophages (acidic pH) in humans. The acidic pH followed by alkaline pH in the small intestine might be responsible for expression of certain stress-induced genes, resulting in not only better survival but also induction of multiplication and invasion of the bacterium in the small intestine. Based on this hypothesis, we developed a process wherein we exposed the blood, urine, and stool specimens from 90 acute typhoid fever patients and 36 chronic typhoid carriers to acidic pH to see the effect on isolation rate of S. Typhi. About 5 g of freshly passed unpreserved stool, a centrifuged deposit of 15 ml of urine, and 5 ml of blood clot were subjected to 5 ml of Luria-Bertani (LB) broth (pH 3.5) for 20 min, followed by enrichment in bile broth-selenite F broth. When the combined isolation from all 3 specimens, i.e., blood, urine, and stool, after acid exposure was considered, a total of 77.7% of the acute typhoid patients were observed to be positive for the isolation of the S. Typhi serotype, compared to 8.8% by the conventional method. Similarly, 42% (15/36) of chronic carriers yielded positive for S. Typhi growth after acid exposure, compared to 5.5% (2/36) by the conventional method. It therefore can be concluded that acid shock triggers the multiplication of the bacteria, resulting in better isolation rates from blood clot, stool, and urine specimens. 相似文献
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Sheep were immunized with killed Salmonella enterica serotype Urbana cells and their sera were tested in various serological tests for antibody to Brucella sp., Yersinia enterocolitica O:9 and Escherichia coli O:157 H:7. Of the eight sheep, all gave a positive agglutination reaction in the brucellosis buffered antigen plate agglutination test (BPAT), seven gave positive brucellosis standard tube agglutination test (TAT) and complement fixation test (CFT) results and four gave slightly positive reactions in a competitive enzyme immunoassay (CELISA). Seven sera were negative in an indirect enzyme immunoassay (IELISA-SLPS) using B. abortus smooth lipopolysaccharide (SLPS) antigen and all were negative in a fluorescence polarization assay (FPA-OPS) using B. abortus O-polysaccharide antigen. Two sheep gave a slight positive reaction in an IELISA using Brucella rough lipopolysaccharide antigen (IELISA-RLPS) and four sheep were slightly positive in an FPA using Brucella LPS core antigen (FPA-CORE). All sheep had high antibody responses to S. enterica serotype Urbana, Y. and E. coli O:157 and 7 were positive for antibody to Y. enterocolitica O:9 when tested by IELISA. The sheep were negative when tested in the FPA using OPS from Y. enterocolitica O:9 but all were strongly positive in the FPA using OPS from E. coli O:157 while seven sheep had titers to S. enterica serotype Urbana. The impact on diagnostic serology for brucellosis is discussed. 相似文献
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Typing of Salmonella enterica Serotype Paratyphi C Isolates from Various Countries by Plasmid Profiles and Pulsed-Field Gel Electrophoresis 下载免费PDF全文
S. Kariuki J. Cheesbrough A. K. Mavridis C. A. Hart 《Journal of clinical microbiology》1999,37(6):2058-2060
Pulsed-field gel electrophoresis (PFGE) of 61 Salmonella enterica serotype Paratyphi C isolates from six countries gave five distinct clusters. Twenty-four isolates from five countries were susceptible to 10 antimicrobials tested and gave similar restriction endonuclease digest patterns of the 38-MDa plasmid. In contrast, plasmid and PFGE profiles of 37 multidrug-resistant isolates from Zaire were different from those from other countries. 相似文献
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Rene S. Hendriksen Pimlapas Leekitcharoenphon Oksana Lukjancenko Chileshe Lukwesa-Musyani Bushimbwa Tambatamba John Mwaba Annie Kalonda Ruth Nakazwe Geoffrey Kwenda Jacob Dyring Jensen Christina A. Svendsen Karen K. Dittmann Rolf S. Kaas Lina M. Cavaco Frank M. Aarestrup Henrik Hasman James C. L. Mwansa 《Journal of clinical microbiology》2015,53(1):262-272
Retrospectively, we investigated the epidemiology of a massive Salmonella enterica serovar Typhi outbreak in Zambia during 2010 to 2012. Ninety-four isolates were susceptibility tested by MIC determinations. Whole-genome sequence typing (WGST) of 33 isolates and bioinformatic analysis identified the multilocus sequence type (MLST), haplotype, plasmid replicon, antimicrobial resistance genes, and genetic relatedness by single nucleotide polymorphism (SNP) analysis and genomic deletions. The outbreak affected 2,040 patients, with a fatality rate of 0.5%. Most (83.0%) isolates were multidrug resistant (MDR). The isolates belonged to MLST ST1 and a new variant of the haplotype, H58B. Most isolates contained a chromosomally translocated region containing seven antimicrobial resistance genes, catA1, blaTEM-1, dfrA7, sul1, sul2, strA, and strB, and fragments of the incompatibility group Q1 (IncQ1) plasmid replicon, the class 1 integron, and the mer operon. The genomic analysis revealed 415 SNP differences overall and 35 deletions among 33 of the isolates subjected to whole-genome sequencing. In comparison with other genomes of H58, the Zambian isolates separated from genomes from Central Africa and India by 34 and 52 SNPs, respectively. The phylogenetic analysis indicates that 32 of the 33 isolates sequenced belonged to a tight clonal group distinct from other H58 genomes included in the study. The small numbers of SNPs identified within this group are consistent with the short-term transmission that can be expected over a period of 2 years. The phylogenetic analysis and deletions suggest that a single MDR clone was responsible for the outbreak, during which occasional other S. Typhi lineages, including sensitive ones, continued to cocirculate. The common view is that the emerging global S. Typhi haplotype, H58B, containing the MDR IncHI1 plasmid is responsible for the majority of typhoid infections in Asia and sub-Saharan Africa; we found that a new variant of the haplotype harboring a chromosomally translocated region containing the MDR islands of IncHI1 plasmid has emerged in Zambia. This could change the perception of the term “classical MDR typhoid” currently being solely associated with the IncHI1 plasmid. It might be more common than presently thought that S. Typhi haplotype H58B harbors the IncHI1 plasmid or a chromosomally translocated MDR region or both. 相似文献
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Anthony M. Smith Mnikelwa A. Mthanti Carel Haumann Nomalungisa Tyalisi Gerald P. G. Boon Arvinda Sooka Karen H. Keddy 《Journal of clinical microbiology》2014,52(2):627-631
We describe a nosocomial outbreak of diarrheal disease caused by extended-spectrum β-lactamase-producing multidrug-resistant Salmonella enterica serovar Typhimurium, focused on a pediatric ward in South Africa. The outbreak peaked between May 2012 and July 2012. Person-to-person transmission was the most likely mechanism of spread of the infection, expedited due to a breakdown in hand-washing and hygiene, suboptimal infection control practices, overcrowding of hospital wards, and an undesirable nurse-to-patient ratio. 相似文献
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Molecular methods for the epidemiological typing of Salmonella enterica serotype Typhi from Hong Kong and Vietnam 总被引:2,自引:0,他引:2 下载免费PDF全文
Ling JM Lo NW Ho YM Kam KM Hoa NT Phi LT Cheng AF 《Journal of clinical microbiology》2000,38(1):292-300
A total of 217 and 73 strains of Salmonella enterica serotype Typhi isolated from 1985 to 1997 in Hong Kong and in 2 months of 1989 and 1990 in Vietnam, respectively, were studied. These isolates were typed by plasmid profile analysis, plasmid fingerprinting, ribotyping with PstI, and total DNA fingerprinting with NarI. There appeared to be no major outbreak of typhoid fever in Hong Kong during the study period since there was considerable heterogeneity among the isolates. Isolates from Hong Kong were different from those from Vietnam. Thirty-seven percent of Vietnamese isolates belonged to two predominant clones, with the rest being heterogeneous in nature. Total DNA fingerprinting supplemented with ribotyping could be a reliable and rapid method for epidemiological typing of S. enterica serotype Typhi. 相似文献
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Salmonella enterica serovar Typhi is highly homogeneous. Single nucleotide polymorphisms (SNPs) have been shown to be valuable markers for molecular typing of S. enterica serovar Typhi. Here, we used a hairpin primer real-time PCR assay for SNP typing of S. enterica serovar Typhi isolates. Forty-two SNPs were selected from a comparison of 19 published S. enterica serovar Typhi genomes and sequences from other studies. The SNPs were used to type 71 global S. enterica serovar Typhi isolates and differentiated these S. enterica serovar Typhi isolates and the 19 genome sequenced strains into 25 SNP profiles. Phylogenetic analysis revealed that these SNP profiles were grouped into six major clusters. These clusters can be identified by using five SNPs, while the full differentiation of the 25 SNP profiles requires a minimum of 24 SNPs. This real-time PCR-based SNP typing method will be useful for global epidemiological analysis.Salmonella enterica serovar Typhi is highly homogeneous (10, 17, 18). The lack of genetic diversity is a major challenge to the development of suitable typing methods to differentiate S. enterica serovar Typhi isolates for both phylogenetic and epidemiological purposes. Single nucleotide polymorphisms (SNPs) are considered the most valuable markers, particularly for studying the evolutionary relationships of isolates of homogeneous pathogenic clones, such as Bacillus anthracis (16), Mycobacterium tuberculosis (4), and Yersinia pestis (1).SNPs have been used as markers for molecular typing of S. enterica serovar Typhi in a large study by Roumagnac et al. (17). A total of 88 SNPs, found from analysis of 200 gene fragments from 105 diverse S. enterica serovar Typhi isolates, could differentiate 481 global S. enterica serovar Typhi isolates into 85 haplotypes (SNP profiles) and five major clusters (17). However, despite the large number of SNPs used, each of the five clusters was supported by only a single SNP and there was little resolution of the relationships of the haplotypes within a cluster. Eighty of the SNPs have also been used to differentiate 140 Indonesian S. enterica serovar Typhi isolates into nine haplotypes (2).We have also shown that genome-wide SNPs are useful for molecular typing and determining the relationships of global S. enterica serovar Typhi isolates (14). Thirty-seven SNPs selected from a comparison of the genomes of S. enterica serovar Typhi strains CT18 (15) and Ty2 (3) were typed using restriction enzyme digestion to differentiate 73 global S. enterica serovar Typhi isolates into 23 SNP profiles and four distinct genetic groups. As the SNPs were selected by comparison of only two S. enterica serovar Typhi genomes, this resulted in a phylogenetic bias which revealed the full path of the last common ancestors connecting strains CT18 and Ty2 but only the node locations for the other SNP profiles (14).Advances in technology, such as high-throughput sequencing, allow SNPs to be discovered to obtain a full resolution of the phylogenetic relationships of isolates. A recent study by Holt et al. (8) utilized 454 and/or Solexa technologies to sequence 19 S. enterica serovar Typhi isolates selected from the five major clusters found by Roumagnac et al. (17). There were more than 1,700 SNPs found, and these gave a fully resolved phylogenetic tree of these isolates. These SNPs are invaluable resources for investigation of the evolutionary history of global S. enterica serovar Typhi isolates. This study aimed to select a better set of SNPs on the basis of the genome tree and the previous SNP studies by Roumagnac et al. (17) to differentiate and establish the phylogenetic relationships of global S. enterica serovar Typhi isolates, using real-time (R-T) PCR assays based on hairpin (HP) primers (6). 相似文献
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The involvement of nitric oxide (NO) in host defense and cytoprotective functions in murine salmonellosis has been reported. Salmonella mutants with the altered sigma factor RpoS (sigmaS) are less virulent and are susceptible to various stresses. This study investigated the role of the rpoS gene of Salmonella enterica serovar Typhi in NO-dependent host defense in vitro and in vivo. Wild-type mice and mice deficient in inducible NO synthase (iNOS) were infected intraperitoneally or orally with serovar Typhi strains. iNOS-deficient mice were more susceptible to infection by both wild-type and rpoS mutant strains of serovar Typhi and showed extensive apoptotic liver damage compared with wild-type mice. Intracellular killing of Salmonella was analyzed with RAW 264 macrophage-like cells and primary peritoneal macrophages from wild-type and iNOS-deficient mice after cells were infected with the serovar Typhi parent or rpoS mutant strain. The rpoS mutant was more susceptible to killing by macrophages than was the wild-type strain. Also, the wild-type strain produced more extensive apoptotic changes in macrophages than did rpoS mutant. These effects were nullified in RAW 264 cells treated with an NOS inhibitor and in iNOS-deficient primary macrophages. Peroxynitrite susceptibility assays of these strains were also performed. The rpoS mutant Typhi strain was more sensitive to in vitro peroxynitrite treatment than was the parent strain. Together these data show that NO has a significant host defense function during serovar Typhi infection, and that Salmonella RpoS, because it reacts to the presence of NO or its reactive derivatives, is thought to have a role in the pathogenicity of serovar Typhi. 相似文献
19.
Vi antigen expression in Salmonella enterica serovar Typhi clinical isolates from Pakistan 总被引:2,自引:0,他引:2
Wain J House D Zafar A Baker S Nair S Kidgell C Bhutta Z Dougan G Hasan R 《Journal of clinical microbiology》2005,43(3):1158-1165
The accurate identification of Salmonella enterica subsp. enterica serovar Typhi variants that fail to express the capsular polysaccharide, Vi, is an important and much discussed issue for medical microbiology. We have tested a multiplex PCR method which shows the presence or absence of the genetic locus required for Vi expression. Of 2,222 Salmonella serovar Typhi clinical isolates collected from patients' blood over a 4-year period in a region of Pakistan where typhoid is endemic, 12 tested negative for Vi expression by serological agglutination. However, only 1 of these 12 was Vi negative by the multiplex PCR method. This result was confirmed by immunofluorescence, the most sensitive method for Vi characterization in Salmonella serovar Typhi. The multiplex PCR described therefore represents a simple and accurate method for surveillance for Vi-negative variants of Salmonella serovar Typhi in Pakistan. Testing of clinical isolates of Salmonella serovar Typhi, before subculture, from other regions where Vi-negative Salmonella serovar Typhi has been described should be carried out so that the impact of vaccination with purified Vi antigen on the levels of Vi-negative Salmonella serovar Typhi in bacterial populations can be assessed. 相似文献
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Al Naiemi N Zwart B Rijnsburger MC Roosendaal R Debets-Ossenkopp YJ Mulder JA Fijen CA Maten W Vandenbroucke-Grauls CM Savelkoul PH 《Journal of clinical microbiology》2008,46(8):2794-2795
A Salmonella enterica serotype Typhi strain was cultured from blood and fecal samples from a 54-year-old man with fever and diarrhea. He had returned from travel to the Philippines a few days earlier. Phenotypic and genotypic analysis confirmed the production of the SHV-12 extended-spectrum beta-lactamase. 相似文献