Dataset Information

Salmonella enterica serotype Typhi infections in a Canadian pediatric hospital: a retrospective case series.

ABSTRACT:

Background

In developed countries, typhoid fever generally occurs in travellers or recent immigrants from endemic areas. Our aim was to describe the epidemiology of Salmonella enterica serotype Typhi infections among children presenting to a pediatric teaching hospital in Montréal, Quebec.

Methods

We included all patients less than 18 years of age who presented to the Montreal Children's Hospital between 1991 and 2011 with a laboratory-confirmed diagnosis of typhoid fever (Salmonella enterica ser. Typhi isolated from blood or stool) in a retrospective case series.

Results

During the study period, we identified 39 cases of typhoid fever (mean age of patient 7.5 yr). Four (10.3%) of these cases occurred in newly arrived immigrants shortly after their arrival in Canada (median 15.5 d). Most cases (76.9%) occurred in children who had visited friends and relatives in their home country. None of the travellers had received a vaccination against typhoid fever before their departure. All cases presented with high fever (mean temperature 40.4°C) that lasted for a mean of 15.8 days. Common accompanying symptoms included anorexia, abdominal pain, vomiting and diarrhea. All 39 isolates of S. enterica ser. Typhi were susceptible to third-generation cephalosporins, and 7 were resistant to ciprofloxacin. Ampicillin resistance occurred in 10 (25.6%) of the isolates. No deaths occurred among the study participants.

Interpretation

Most cases of typhoid fever occurred in children who had travelled to endemic areas to visit friends and relatives. Thus, there is a role for increased awareness on the part of family physicians and pediatricians caring for these children to discuss travel-related infections during regularly scheduled appointments, because parents might not consult travel clinics or discuss their travel plans before travelling back to their home country.

SUBMITTER: Comeau JL

PROVIDER: S-EPMC4006666 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Salmonella enterica serotype Typhi infections in a Canadian pediatric hospital: a retrospective case series.

Comeau Jeannette L JL Tran Thai Hoa TH Moore Dorothy L DL Phi Chi-Minh CM Quach Caroline C

CMAJ open 20130101 1

<h4>Background</h4>In developed countries, typhoid fever generally occurs in travellers or recent immigrants from endemic areas. Our aim was to describe the epidemiology of Salmonella enterica serotype Typhi infections among children presenting to a pediatric teaching hospital in Montréal, Quebec.<h4>Methods</h4>We included all patients less than 18 years of age who presented to the Montreal Children's Hospital between 1991 and 2011 with a laboratory-confirmed diagnosis of typhoid fever (Salmone ...[more]

PMID: 25077103

Similar Datasets

Project description:BackgroundTyphoid fever remains a major public health problem in Zimbabwe with recurrent outbreaks reported since 2009. To provide guidance on appropriate treatment choice in order to minimise the morbidity and mortality of typhoid fever and prevent large scale outbreaks, we investigated the antimicrobial susceptibility patterns, prevalence of Salmonella enterica serotype Typhi (S. Typhi) H58 haplotype and molecular subtypes of S. Typhi from outbreak strains isolated from 2009 to 2017 in Zimbabwe and compared these to isolates from neighbouring African countries.MethodsAntimicrobial susceptibility testing was performed on all isolates using the disk diffusion, and E-Test, and results were interpreted using Clinical and Laboratory Standards Institute (CLSI) guidelines (2017). S. Typhi H58 haplotype screening was performed on 161 (58.3%) isolates. Pulsed-field gel electrophoresis (PFGE) was performed on 91 selected isolates across timelines using antibiotic susceptibility results and geographical distribution (2009 to 2016).ResultsBetween 2009 and 2017, 16,398 suspected cases and 550 confirmed cases of typhoid fever were notified in Zimbabwe. A total of 276 (44.6%) of the culture-confirmed S. Typhi isolates were analysed and 243 isolates (88.0%) were resistant to two or more first line drugs (ciprofloxacin, ampicillin and chloramphenicol) for typhoid. The most common resistance was to ampicillin-chloramphenicol (172 isolates; 62.3%). Increasing ciprofloxacin resistance was observed from 2012 to 2017 (4.2 to 22.0%). Out of 161 screened isolates, 150 (93.2%) were haplotype H58. Twelve PFGE patterns were observed among the 91 isolates analysed, suggesting some diversity exists among strains circulating in Zimbabwe. PFGE analysis of 2013, 2014 and 2016 isolates revealed a common strain with an indistinguishable PFGE pattern (100% similarity) and indistinguishable from PFGE patterns previously identified in strains isolated from South Africa, Zambia and Tanzania.ConclusionsResistance to first line antimicrobials used for typhoid fever is emerging in Zimbabwe and the multidrug resistant S. Typhi H58 haplotype is widespread. A predominant PFGE clone circulating in Zimbabwe, South Africa, Zambia and Tanzania, argues for cross-border cooperation in the control of this disease.

Project description:BACKGROUND & OBJECTIVES: Infection with Salmonella enterica serovar Typhi (hereafter S. Typhi) is an important public health problem in India. There has been an increase in the number of reported clinical failures to ciprofloxacin treatment but the data on possible mechanism of failure are limited. One mechanism that has been widely reported and found associated with ciprofloxacin resistance, is the mutations in target genes in QRDR (quinolone resistance determining region). It is hypothesized that mutations in DNA gyrase or topoisomerase IV result in therapeutic failure under selective pressure of antibiotic while the patient is on treatment. We undertook in vitro sequential selection studies to expose the clinical isolates of S. Typhi to different concentration of ciprofloxacin to study the role of antibiotic selective pressure in the development of mutations in QRDR. METHODS: Total 26 clinical isolates were divided in to two parts: part I included six isolates obtained from three patients with relapse of enteric fever and part II included 20 isolates with different ciprofloxacin MIC levels. For in vitro induction of mutation experiment, five S. Typhi isolates were selected which included three NAS (nalidixic acid sensitive) and 2 NAR (nalidixic acid resistant) S. Typhi. These isolates were grown under increasing concentrations of ciprofloxacin and mutations acquired in QRDR of DNA gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE) were investigated by sequencing. RESULTS: For the isolates included in the part I of the study, it was found that the MIC to ciprofloxacin increased in the isolates obtained during the relapse of enteric fever as compare to the first isolate. All isolates had single mutation in gyrA gene at S83 without additional mutation in the second isolate. In the second part of the study, the nine isolates with varying MICs to ciprofloxacin also had single mutation in gyrA gene at S83 and another six had triple mutations, two mutations in gyrA gene (at S83 and D87) and one mutation in parC gene (at S80). In in vitro induction of mutation experiment, all mutated isolates showed triple mutation (two mutation in gyrA and one in parC gene) while no mutations were found in wild isolates. INTERPRETATION & CONCLUSIONS: Upon exposure to the step-wise increased concentration of ciprofloxacin, isolates become more tolerant to the ciprofloxacin and showed 2-4 fold higher MICs without new mutation after 8 ?g/ml. So the accumulation of mutations under continuous ciprofloxacin pressure and tolerance of the mutant isolates led to the clinical failure. These results also suggested that there could be another mechanism responsible for resistance.

Project description:Salmonella enterica serotype Typhi is a human-restricted intracellular pathogen and the cause of typhoid fever. Cellular immune responses are required to control and clear Salmonella infection. Despite this, there are limited data on cellular immune responses in humans infected with wild type S. Typhi.For this work, we used an automated approach to purify a subset of S. Typhi proteins identified in previous antibody-based immuno-affinity screens and antigens known to be expressed in vivo, including StaF-putative fimbrial protein-STY0202, StbB-fimbrial chaperone-STY0372, CsgF-involved in curli production-STY1177, CsgD- putative regulatory protein-STY1179, OppA-periplasmic oligopeptide binding protein precursor-STY1304, PagC-outer membrane invasion protein-STY1878, and conserved hypothetical protein-STY2195; we also generated and analyzed a crude membrane preparation of S. Typhi (MP). In comparison to samples collected from uninfected Bangladeshi and North American participants, we detected significant interferon-? responses in PBMCs stimulated with MP, StaF, StbB, CsgF, CsgD, OppA, STY2195, and PagC in patients bacteremic with S. Typhi in Bangladesh. The majority of interferon-? expressing T cells were CD4 cells, although CD8 responses also occurred. We also assessed cellular proliferation responses in bacteremic patients, and confirmed increased responses in infected individuals to MP, StaF, STY2195, and PagC in convalescent compared to acute phase samples and compared to controls. StaF is a fimbrial protein homologous to E. coli YadK, and contains a Pfam motif thought to be involved in cellular adhesion. PagC is expressed in vivo under the control of the virulence-associated PhoP-regulon required for intra-macrophage survival of Salmonella. STY2195 is a conserved hypothetical protein of unknown function.This is the first analysis of cellular immune responses to purified S. Typhi antigens in patients with typhoid fever. These results indicate that patients generate significant CD4 and CD8 interferon-? responses to specific S. Typhi antigens during typhoid fever, and that these responses are elevated at the time of clinical presentation. These observations suggest that an interferon-? based detection system could be used to diagnose individuals with typhoid fever during the acute stage of illness.

Project description:BackgroundSalmonella enterica serotype Typhi can colonize and persist in the biliary tract of infected individuals, resulting in a state of asymptomatic chronic carriage. Chronic carriers may act as persistent reservoirs of infection within a community and may introduce infection to susceptible individuals and new communities. Little is known about the interaction between the host and pathogen in the biliary tract of chronic carriers, and there is currently no reliable diagnostic assay to identify asymptomatic S. Typhi carriage.Methodology/principal findingsTo study host-pathogen interactions in the biliary tract during S. Typhi carriage, we applied an immunoscreening technique called in vivo-induced antigen technology (IVIAT), to identify potential biomarkers unique to carriers. IVIAT identifies humorally immunogenic bacterial antigens expressed uniquely in the in vivo environment, and we hypothesized that S. Typhi surviving in the biliary tract of humans may express a distinct antigenic profile. Thirteen S. Typhi antigens that were immunoreactive in carriers, but not in healthy individuals from a typhoid endemic area, were identified. The identified antigens included a number of putative membrane proteins, lipoproteins, and hemolysin-related proteins. YncE (STY1479), an uncharacterized protein with an ATP-binding motif, gave prominent responses in our screen. The response to YncE in patients whose biliary tract contained S. Typhi was compared to responses in patients whose biliary tract did not contain S. Typhi, patients with acute typhoid fever, and healthy controls residing in a typhoid endemic area. Seven of 10 (70%) chronic carriers, 0 of 8 bile culture-negative controls (0%), 0 of 8 healthy Bangladeshis (0%), and 1 of 8 (12.5%) Bangladeshis with acute typhoid fever had detectable anti-YncE IgG in blood. IgA responses were also present.Conclusions/significanceFurther evaluation of YncE and other antigens identified by IVIAT could lead to the development of improved diagnostic assays to identify asymptomatic S. Typhi carriers.

Dataset Information

Salmonella enterica serotype Typhi infections in a Canadian pediatric hospital: a retrospective case series.

Background

Methods

Results

Interpretation

Publications

Salmonella enterica serotype Typhi infections in a Canadian pediatric hospital: a retrospective case series.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets