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International Microbiology : the... Jun 2015In this work, IS200 and multi-locus sequence typing (MLST) were used to analyze 19 strains previously serotyped as Salmonella enterica serovar Typhi and isolated in... (Comparative Study)
Comparative Study
In this work, IS200 and multi-locus sequence typing (MLST) were used to analyze 19 strains previously serotyped as Salmonella enterica serovar Typhi and isolated in Indonesia (16 strains), Mexico (2 strains), and Switzerland (1 strain). Most of the strains showed the most common Typhi sequence types, ST1 and ST2, and a new Typhi genotype (ST1856) was described. However, one isolate from Mexico and another from Indonesia were of the ST365 and ST426 sequence types, indicating that they belonged to serovars Weltevreden and Aberdeen, respectively. These results were supported by the amplification of IS200 fragments, which rapidly distinguish Typhi from other serovars. Our results demonstrate the utility of IS200 and MLST in the classification of Salmonella strains into serovars. These methods provide information on the clonal relatedness of strains isolated worldwide.
Topics: Base Sequence; Humans; Indonesia; Molecular Sequence Data; Multilocus Sequence Typing; Phylogeny; Polymerase Chain Reaction; Salmonella Infections; Salmonella typhi
PubMed: 26496617
DOI: 10.2436/20.1501.01.239 -
BMC Genomics Oct 2017Typhoid fever is an acute systemic infection of humans caused by Salmonella enterica subspecies enterica serovar Typhi (S. Typhi). In chronic carriers, the bacteria...
BACKGROUND
Typhoid fever is an acute systemic infection of humans caused by Salmonella enterica subspecies enterica serovar Typhi (S. Typhi). In chronic carriers, the bacteria survive the harsh environment of the gallbladder by producing biofilm. The phenotype of S. Typhi biofilm cells is significantly different from the free-swimming planktonic cells, and studies have shown that they are associated with antibiotic resistance, immune system evasion, and bacterial persistence. However, the mechanism of this transition and the events leading to biofilm formation are unknown. High throughput sequencing was performed to identify the genes involved in biofilm formation and to postulate the mechanism of action.
RESULTS
Planktonic S. Typhi cells were cultured using standard nutrient broth whereas biofilm cells were cultured in a stressful environment using high shearing-force and bile to mimic the gallbladder. Sequencing libraries were prepared from S. Typhi planktonic cells and mature biofilm cells using the Illumina HiSeq 2500 platform, and the transcriptome data obtained were processed using Cufflinks bioinformatics suite of programs to investigate differential gene expression between the two phenotypes. A total of 35 up-regulated and 29 down-regulated genes were identified. The identities of the differentially expressed genes were confirmed using NCBI BLAST and their functions were analyzed. The results showed that the genes associated with metabolic processes and biofilm regulations were down-regulated while those associated with the membrane matrix and antibiotic resistance were highly up-regulated.
CONCLUSIONS
It is proposed that the biofilm phenotype of S. Typhi allows the bacteria to increase production of the membrane matrix in order to serve as a physical shield and to adhere to surfaces, and enter an energy conservation state in response to the stressful environment. Conversely, the planktonic phenotype allows the bacteria to produce flagella and increase metabolic activity to enable the bacteria to migrate and form new colonies of infection. This data provide a basis for further studies to uncover the mechanism of biofilm formation in S. Typhi and to discover novel genes or pathways associated with the development of the typhoid carrier state.
Topics: Biofilms; Gene Expression Profiling; Gene Expression Regulation, Bacterial; High-Throughput Nucleotide Sequencing; Humans; Salmonella typhi; Transcriptome
PubMed: 29089020
DOI: 10.1186/s12864-017-4212-6 -
International Journal of... Dec 2015Salmonellosis-induced diarrhea, is one of the commonest cause of childhood mortality in developing countries. Using of probiotics is viewed as a promising means for...
Salmonellosis-induced diarrhea, is one of the commonest cause of childhood mortality in developing countries. Using of probiotics is viewed as a promising means for reducing the pathogenic loads of bacterial infection. The current study aimed to evaluate the potential antimicrobial and immunomodulatory efficacy of isolated lactobacillus strains against the enteropathogenic effect of S. Typhi. Different Lactobacillus strains were isolated from 13 dairy products. Their antimicrobial activities were tested against different bacterial strains. Six groups of CD1 mice were treated for 8 days as follows: group (1) untreated control; group (2) was challenged with single inoculation S. typhi, and groups (3) and (4) were treated with Lactobacillus plantarum (LA5) or Lactobacillus paracsi (LA7) for 7 days, respectively. Groups (5) and (6) were challenged with S. typhi, and then treated with either LA5 or LA 7 for 7 days, respectively. Isolated Lactobacillus showed antimicrobial activity against wide range of bacterial strains. Salmonellosis showed high widal titer, induced significant disturbance of TNF and IL-1β, while sever changes of the histological patterns of the intestinal villi and hepatocytes have been illustrated. LA5 or LA7 succeeded to eradicate typhoid infection, restore the values of inflammatory cytokines to typical levels of control group, and improve histological pictures of intestinal and hepatic tissues. It can be concluded that lactobacilli are promising candidate in protection and eradication against bacterial infection induced by S. Typhi due to its antimicrobial, anti-inflammatory, and immunomodulatory activities.
Topics: Animals; Anti-Infective Agents; Immunologic Factors; Lactobacillus; Male; Mice; Salmonella typhi; Typhoid Fever
PubMed: 26303120
DOI: 10.1177/0394632015592099 -
Journal of Clinical Microbiology Apr 2021
Review
Topics: Anti-Bacterial Agents; Humans; Refugees; Salmonella typhi; Typhoid Fever; United States
PubMed: 33879561
DOI: 10.1128/JCM.01359-20 -
Virulence 2011The ability of bacterial pathogens to sense their immediate environment plays a significant role on their capacity to survive and cause disease. Salmonella enterica... (Review)
Review
The ability of bacterial pathogens to sense their immediate environment plays a significant role on their capacity to survive and cause disease. Salmonella enterica serovar typhi (S. typhi) is an exclusively human pathogen that causes typhoid fever. In a recent study, we have shown that S. typhi senses and responds to host neuroendocrine stress hormones to release the toxin hemolysin E. Hormone-mediated hemolysis by S. typhi was inhibited by the β-blocker propranolol and was dependent on the presence of the CpxAR signal transduction system. Furthermore, we demonstrate that normal expression of the small RNA micA is necessary for the arbitration of the response to host neuroendocrine hormones. This leads to a significant decrease in the levels of the outer membrane protein OmpA and increased formation of membrane vesicles containing HlyE. The exploration of host pathogen interactions is of paramount importance in deciphering pathogen virulence and the discovery of novel treatments.
Topics: Animals; Bacterial Proteins; Hemolysin Proteins; Hormones; Host-Pathogen Interactions; Humans; Neurosecretory Systems; Salmonella typhi; Typhoid Fever; Virulence
PubMed: 21758008
DOI: 10.4161/viru.2.4.16810 -
Brazilian Journal of Microbiology :... 2014An in-house loop-mediated isothermal amplification (LAMP) reaction was established and evaluated for sensitivity and specificity in detecting the presence of Salmonella...
An in-house loop-mediated isothermal amplification (LAMP) reaction was established and evaluated for sensitivity and specificity in detecting the presence of Salmonella Typhi (S. Typhi) isolates from Kelantan, Malaysia. Three sets of primers consisting of two outer and 4 inner were designed based on locus STBHUCCB_38510 of chaperone PapD of S. Typhi genes. The reaction was optimised using genomic DNA of S. Typhi ATCC7251 as the template. The products were visualised directly by colour changes of the reaction. Positive results were indicated by green fluorescence and negative by orange colour. The test was further evaluated for specificity, sensitivity and application on field samples. The results were compared with those obtained by gold standard culture method and Polymerase Chain Reaction (PCR). This method was highly specific and -10 times more sensitive in detecting S. Typhi compared to the optimised conventional polymerase chain reaction (PCR) method.
Topics: Bacteriological Techniques; DNA Primers; Malaysia; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Salmonella typhi; Sensitivity and Specificity; Time Factors; Typhoid Fever
PubMed: 25763045
DOI: 10.1590/s1517-83822014000400032 -
The Brazilian Journal of Infectious... 2012Plasmid pR ST98 is a hybrid resistance-virulence plasmid isolated from Salmonella enterica serovar Typhi (S. typhi). Previous studies demonstrated that pR ST98 could...
OBJECTIVES
Plasmid pR ST98 is a hybrid resistance-virulence plasmid isolated from Salmonella enterica serovar Typhi (S. typhi). Previous studies demonstrated that pR ST98 could enhance the virulence of its host bacteria. However, the mechanism of pR ST98-increased bacterial virulence is still not fully elucidated. This study was designed to gain further insight into the roles of pR ST98 in host responses.
METHODS
Human-derived macrophage-like cell line THP-1 was infected with wild-type (ST8), pR ST98-deletion (ST8-ΔpR ST98), and complemented (ST8-c-pR ST98) S. typhi strains. Macrophage autophagy was performed by extracting the membrane-unbound LC3-I protein from cells, followed by flow cytometric detection of the membrane-associated fraction of LC3-II. Intracellular bacterial growth was determined by colony-forming units (cfu) assay. Macrophage cell death was measured by flow cytometry after propidium iodide (PI) staining. Autophagy activator rapamycin (RAPA) was added to the medium 2 h before infection to investigate the effect of autophagy on intracellular bacterial growth and macrophage cell death after S. typhi infection.
RESULTS
Plasmid pR ST98 suppressed autophagy in infected macrophages and enhanced intracellular bacterial growth and S. typhi-induced macrophage cell death. Pretreatment with RAPA effectively restricted intracellular bacterial growth of ST8 and ST8-c-pR ST98, and alleviated ST8 and ST8-c-pR ST98-induced macrophage cell death, but had no significant effect on ST8-ΔpR ST98.
CONCLUSIONS
Plasmid pR ST98 enhances intracellular bacterial growth and S. typhi-induced macrophage cell death by suppressing autophagy.
Topics: Apoptosis; Autophagy; Bacterial Proteins; Cells, Cultured; Flow Cytometry; Humans; Macrophages; Plasmids; Salmonella typhi
PubMed: 22729194
DOI: No ID Found -
Journal of Applied Microbiology Sep 2017Recently, the cefixime-ofloxacin combination is approved by Drug Controller General of India to treat typhoid fever. We sought to evaluate the antimicrobial activity of...
AIMS
Recently, the cefixime-ofloxacin combination is approved by Drug Controller General of India to treat typhoid fever. We sought to evaluate the antimicrobial activity of cefixime-ofloxacin combination against Salmonella Typhi.
METHODS AND RESULTS
A total of 283 nonduplicate S. Typhi isolates collected during 2012-2014 were included in this study. Minimum inhibitory concentration (MIC) of cefixime and ofloxacin was determined by using broth microdilution method. Combinational testing was performed by using checkerboard assay. In checkerboard assay, synergistic activity was seen in 11% of isolates, while the majority of the isolate showed indifference and none of them showed antagonism. An in silico strategy, an alternative to the animal model, was carried out to understand drug interaction and toxicity. Molecular docking results elucidated that cefixime and ofloxacin are capable of inhibiting the cell wall synthesis and DNA replication, respectively. Computational ADMET analysis showed no toxicity and no drug-drug interaction between cefixime and ofloxacin.
CONCLUSION
Cefixime-ofloxacin combination could be effective against moderately susceptible fluoroquinolone S. Typhi but not fluoroquinolone-resistant isolates.
SIGNIFICANCE AND IMPACT OF THE STUDY
Cefixime-ofloxacin combination with no drug-drug interaction and nontoxic predicted through computational analysis did not show antagonism against S. Typhi in in vitro. Although this study showed no adverse effects with the cefixime-ofloxacin combination, further studies on pharmacokinetic and pharmacodynamic (PK-PD) parameters of cefixime and ofloxacin combination are warranted.
Topics: Anti-Bacterial Agents; Bacteremia; Cefixime; Humans; India; Microbial Sensitivity Tests; Ofloxacin; Salmonella typhi; Typhoid Fever
PubMed: 28650129
DOI: 10.1111/jam.13522 -
BMC Microbiology Jan 2010Typhoid and paratyphoid fever are endemic in China. The objective of this investigation was to determine the molecular features of nalidixic acid-resistant Salmonella...
BACKGROUND
Typhoid and paratyphoid fever are endemic in China. The objective of this investigation was to determine the molecular features of nalidixic acid-resistant Salmonella enteric serovar Typhi (S. typhi) and Paratyphi (S. paratyphi) from blood isolates in Shenzhen, China.
RESULTS
Twenty-five S. typhi and 66 S. paratyphi were isolated from 91 bacteremic patients between 2002 and 2007 at a hospital in Shenzhen, Southern China. Fifty-two percent (13/25) of S. typhi and 95.3% (61/64) of S. paratyphi A were resistant to nalidixic acid. Sixty-seven isolates of nalidixic acid-resistant Salmonella (NARS) showed decreased susceptibility to ciprofloxacin (MICs of 0.125-1 microg/mL). All 75 NARS isolates had a single substitution in the quinolone resistance-determining region (QRDR) of GyrA (Ser83-->Phe/Pro/Tyr, or Asp87-->Gly/Asn), and 90.7% of these isolates carried the substitution Ser83Phe in GyrA. No mutation was found in the QRDR of gyrB, parC, or parE. Plasmid mediated quinolone resistance genes including qnr and aac(6')-Ib-cr were not detected in any isolate. Twenty-two distinct pulsed field gel electrophoresis (PFGE) patterns were observed among S. typhi. Sixty-four isolates of S. paratyphi A belonged to one clone. Eighty-seven investigated inpatients were infected in the community. Six patients infected by S. paratyphi A had a travel history before infection.
CONCLUSIONS
Nalidixic acid-resistant S. typhi and S. paratyphi A blood isolates were highly prevalent in Shenzhen, China. PFGE showed the variable genetic diversity of nalidixic acid-resistant S. typhi and limited genetic diversity of nalidixic acid -resistant S. paratyphi A.
Topics: Adolescent; Adult; Aged; Child; Child, Preschool; China; DNA, Bacterial; Drug Resistance, Bacterial; Electrophoresis, Gel, Pulsed-Field; Female; Genetic Variation; Humans; Infant; Infant, Newborn; Male; Microbial Sensitivity Tests; Middle Aged; Nalidixic Acid; Paratyphoid Fever; Prevalence; Salmonella paratyphi A; Salmonella typhi; Sequence Analysis, DNA; Typhoid Fever; Young Adult
PubMed: 20113512
DOI: 10.1186/1471-2180-10-32 -
The Journal of Antimicrobial... Feb 2020The molecular structure of circulating enteric fever pathogens was studied using hospital-based genomic surveillance in a tertiary care referral centre in South India as...
BACKGROUND
The molecular structure of circulating enteric fever pathogens was studied using hospital-based genomic surveillance in a tertiary care referral centre in South India as a first genomic surveillance study, to our knowledge, of blood culture-confirmed enteric fever in the region.
METHODS
Blood culture surveillance was conducted at St John's Medical College Hospital, Bengaluru, between July 2016 and June 2017. The bacterial isolates collected were linked to demographic variables of patients and subjected to WGS. The resulting pathogen genomic data were also globally contextualized to gauge possible phylogeographical patterns.
RESULTS
Hospital-based genomic surveillance for enteric fever in Bengaluru, India, identified 101 Salmonella enterica Typhi and 14 S. Paratyphi A in a 1 year period. Ninety-six percent of isolates displayed non-susceptibility to fluoroquinolones. WGS showed the dominant pathogen was S. Typhi genotype 4.3.1.2 (H58 lineage II). A fluoroquinolone-resistant triple-mutant clone of S. Typhi 4.3.1.2 previously associated with gatifloxacin treatment failure in Nepal was implicated in 18% of enteric fever cases, indicating ongoing inter-regional circulation.
CONCLUSIONS
Enteric fever in South India continues to be a major public health issue and is strongly associated with antimicrobial resistance. Robust microbiological surveillance is necessary to direct appropriate treatment and preventive strategies. Of particular concern is the emergence and expansion of the highly fluoroquinolone-resistant triple-mutant S. Typhi clone and its ongoing inter- and intra-country transmission in South Asia, which highlights the need for regional coordination of intervention strategies, including vaccination and longer-term strategies such as improvements to support hygiene and sanitation.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Fluoroquinolones; Humans; India; Microbial Sensitivity Tests; Salmonella typhi; Typhoid Fever; Whole Genome Sequencing
PubMed: 31665304
DOI: 10.1093/jac/dkz435