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Travel Medicine and Infectious Disease 2021Typhoid fever is a bacterial infection caused by the Gram-negative bacterium Salmonella enterica subspecies enterica serovar Typhi (S. Typhi), prevalent in many low- and... (Review)
Review
Typhoid fever is a bacterial infection caused by the Gram-negative bacterium Salmonella enterica subspecies enterica serovar Typhi (S. Typhi), prevalent in many low- and middle-income countries. In high-income territories, typhoid fever is predominantly travel-related, consequent to travel in typhoid-endemic regions; however, data show that the level of typhoid vaccination in travellers is low. Successful management of typhoid fever using antibiotics is becoming increasingly difficult due to drug resistance; emerging resistance has spread geographically due to factors such as increasing travel connectivity, affecting those in endemic regions and travellers alike. This review provides an overview of: the epidemiology and diagnosis of typhoid fever; the emergence of drug-resistant typhoid strains in the endemic setting; drug resistance observed in travellers; vaccines currently available to prevent typhoid fever; vaccine recommendations for people living in typhoid-endemic regions; strategies for the introduction of typhoid vaccines and stakeholders in vaccination programmes; and travel recommendations for a selection of destinations with a medium or high incidence of typhoid fever.
Topics: Anti-Bacterial Agents; Drug Resistance, Microbial; Humans; Salmonella typhi; Travel; Travel-Related Illness; Typhoid Fever; Vaccination
PubMed: 33301931
DOI: 10.1016/j.tmaid.2020.101946 -
Frontiers in Cellular and Infection... 2020Within the species of , there is significant diversity represented among the numerous subspecies and serovars. Collectively, these account for microbes with variable... (Review)
Review
Within the species of , there is significant diversity represented among the numerous subspecies and serovars. Collectively, these account for microbes with variable host ranges, from common plant and animal colonizers to extremely pathogenic and human-specific serovars. Despite these differences, many species find commonality in the ability to form biofilms and the ability to cause acute, latent, or chronic disease. The exact outcome of infection depends on many factors such as the growth state of , the environmental conditions encountered at the time of infection, as well as the infected host and immune response elicited. Here, we review the numerous biofilm lifestyles of (on biotic and abiotic surfaces) and how the production of extracellular polymeric substances not only enhances long-term persistence outside the host but also is an essential function in chronic human infections. Furthermore, careful consideration is made for the events during initial infection that allow for gut transcytosis which, in conjunction with host immune functions, often determine the progression of disease. Both typhoidal and non-typhoidal salmonellae can cause chronic and/or secondary infections, thus the adaptive immune responses to both types of bacteria are discussed with particular attention to the differences between Typhi, Typhimurium, and invasive non-typhoidal that can result in differential immune responses. Finally, while strides have been made in our understanding of immunity to in the lymphoid organs, fewer definitive studies exist for intestinal and hepatobiliary immunity. By examining our current knowledge and what remains to be determined, we provide insight into new directions in the field of immunity, particularly as it relates to chronic infection.
Topics: Animals; Biofilms; Humans; Intestines; Salmonella enterica; Salmonella typhi; Salmonella typhimurium
PubMed: 33604308
DOI: 10.3389/fcimb.2020.624622 -
ELife Sep 2023The Global Typhoid Genomics Consortium was established to bring together the typhoid research community to aggregate and analyse serovar Typhi (Typhi) genomic data to... (Meta-Analysis)
Meta-Analysis
BACKGROUND
The Global Typhoid Genomics Consortium was established to bring together the typhoid research community to aggregate and analyse serovar Typhi (Typhi) genomic data to inform public health action. This analysis, which marks 22 years since the publication of the first Typhi genome, represents the largest Typhi genome sequence collection to date (n=13,000).
METHODS
This is a meta-analysis of global genotype and antimicrobial resistance (AMR) determinants extracted from previously sequenced genome data and analysed using consistent methods implemented in open analysis platforms GenoTyphi and Pathogenwatch.
RESULTS
Compared with previous global snapshots, the data highlight that genotype 4.3.1 (H58) has not spread beyond Asia and Eastern/Southern Africa; in other regions, distinct genotypes dominate and have independently evolved AMR. Data gaps remain in many parts of the world, and we show the potential of travel-associated sequences to provide informal 'sentinel' surveillance for such locations. The data indicate that ciprofloxacin non-susceptibility (>1 resistance determinant) is widespread across geographies and genotypes, with high-level ciprofloxacin resistance (≥3 determinants) reaching 20% prevalence in South Asia. Extensively drug-resistant (XDR) typhoid has become dominant in Pakistan (70% in 2020) but has not yet become established elsewhere. Ceftriaxone resistance has emerged in eight non-XDR genotypes, including a ciprofloxacin-resistant lineage (4.3.1.2.1) in India. Azithromycin resistance mutations were detected at low prevalence in South Asia, including in two common ciprofloxacin-resistant genotypes.
CONCLUSIONS
The consortium's aim is to encourage continued data sharing and collaboration to monitor the emergence and global spread of AMR Typhi, and to inform decision-making around the introduction of typhoid conjugate vaccines (TCVs) and other prevention and control strategies.
FUNDING
No specific funding was awarded for this meta-analysis. Coordinators were supported by fellowships from the European Union (ZAD received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 845681), the Wellcome Trust (SB, Wellcome Trust Senior Fellowship), and the National Health and Medical Research Council (DJI is supported by an NHMRC Investigator Grant [GNT1195210]).
Topics: Humans; Salmonella typhi; Typhoid Fever; Anti-Bacterial Agents; Travel; Drug Resistance, Bacterial; Ciprofloxacin
PubMed: 37697804
DOI: 10.7554/eLife.85867 -
BMJ (Clinical Research Ed.) Feb 2021
Topics: Anti-Bacterial Agents; Azithromycin; Dengue; Diagnosis, Differential; Doxycycline; Drug Resistance, Bacterial; Endemic Diseases; Humans; Malaria; Paratyphoid Fever; Polysaccharides, Bacterial; Salmonella paratyphi A; Salmonella typhi; Travel-Related Illness; Typhoid Fever; Typhoid-Paratyphoid Vaccines
PubMed: 33637488
DOI: 10.1136/bmj.n437 -
Brazilian Journal of Microbiology :... Jun 2022Salmonella enterica serovar Typhi (S. Typhi) is a human enteropathogen that can survive in macrophages and cause systemic infection. Autophagy and inflammation are two...
Salmonella enterica serovar Typhi (S. Typhi) is a human enteropathogen that can survive in macrophages and cause systemic infection. Autophagy and inflammation are two important immune responses of macrophages that contribute to the elimination of pathogens. However, Salmonella has derived many strategies to evade inflammation and autophagy. This study investigated inflammation-related NF-κB signaling pathways and autophagy in S. Typhi-infected macrophages. RNA-seq and quantitative real-time PCR indicated that mRNA levels of NF-κB signaling pathway and autophagy-related genes were dynamically influenced in S. Typhi-infected macrophages. Western blots revealed that S. Typhi activated the NF-κB signaling pathway and induced the expression of inhibitor protein IκBζ. In addition, S. Typhi enhanced autophagy during early stages of infection and may inhibit autophagy during late stages of infection. Thus, we propose that S. Typhi can influence the NF-κB signaling pathway and autophagy in macrophages.
Topics: Autophagy; Humans; Inflammation; Macrophages; NF-kappa B; Salmonella typhi
PubMed: 35274232
DOI: 10.1007/s42770-022-00719-z -
International Journal of Infectious... Jun 2022Salmonella enterica serotype Typhi (S Typhi) causes typhoid fever and is responsible for an estimated 9 million cases and 110,000 deaths globally per annum. Typhoid...
Salmonella enterica serotype Typhi (S Typhi) causes typhoid fever and is responsible for an estimated 9 million cases and 110,000 deaths globally per annum. Typhoid fever is endemic in areas where water, sanitation, and hygiene (WaSH) infrastructure is poor. Serious complications develop in approximately 10%-15% of patients if left untreated, and this is driven by inadequate diagnostic methods and the high burden of antibiotic-resistant strains, complicating clinical management and ultimately prognosis. Asymptomatic chronic carriers, in addition to acutely infected patients, contribute to continued transmission through the shedding of the organism in the feces. The high morbidity and mortality of typhoid fever in low- and middle-income countries reinforce the need for an integrated control approach, which may ultimately lead to elimination of the disease in the 21 century. Here we discuss the challenges faced in pursuit of typhoid fever elimination.
Topics: Anti-Bacterial Agents; Humans; Salmonella; Salmonella typhi; Typhoid Fever
PubMed: 35338009
DOI: 10.1016/j.ijid.2022.03.036 -
Archives of Razi Institute Apr 2022serovar Typhi () and paratyphi () bacteria exclusively found in humans, cause typhoid fever, an acute, and possibly deadly systemic infection. Typhoid fever is caused...
serovar Typhi () and paratyphi () bacteria exclusively found in humans, cause typhoid fever, an acute, and possibly deadly systemic infection. Typhoid fever is caused by a species of rod-shaped, Gram-negative Enterobacteriaceae called . The present study aimed to examine the gene and investigate the possible relation between this gene and multi-drug resistance in . A total of 30 blood samples were obtained from patients who were suspicious of typhoid fever using the direct strategy of inoculation. Each specimen was injected into a culture of a selective medium, such as XLD and SS agar, and then incubated at 37°C for 24 h. The genomic DNA was extracted through a boiling process. Tris-EDTA was used to suspend bacterial colonies cultured on MacConkey agar plates. The suspension of bacterial colonies was centrifuged for 5 min at 8000×g and for 20 min at -20°C which lyses the organisms and extracts the DNA from the buffer. The supernatant is then transferred to a fresh Eppendorf tube. Gel electrophoresis was carried out utilizing a UV transilluminator. The gene for was found using a PCR test. The antibiotic sensitivity testing showed that the isolates were classed as multi-resistant. These results were confirmed using the polymerase chain reaction (PCR) technique using gene where twenty specimens isolated from typhoid patients were positive for .
Topics: Humans; Agar; Anti-Bacterial Agents; Drug Resistance, Bacterial; Edetic Acid; Integrons; Salmonella paratyphi A; Salmonella typhi; Typhoid Fever
PubMed: 36284974
DOI: 10.22092/ARI.2021.356953.1944