LYON, France, November 13, 2018
LYON, France, November 13, 2018 /PRNewswire/ --
Two new highly drug-resistant forms of Salmonella Typhi have been discovered in Bangladesh. The bacteria are responsible for typhoid fever, a life-threatening disease that is highly endemic in parts of Asia and Africa. A new lineage of S. Typhi that is highly resistant to first-line antibiotics in the fluoroquinolone family has been described for the first time, along with a new strain that is highly resistant to ceftriaxone, the most commonly prescribed treatment for typhoid fever.
This discovery has just been published in mBio (Tanmoy et al.) following a study led by the Mérieux Foundation and the Child Health Research Foundation (CHRF) in Bangladesh, with data analytics support from Applied Maths in Belgium.
Both of these new variants of Salmonella Typhi are distinct from the strain discovered in the outbreak of extensively drug-resistant (XDR) typhoid reported in Pakistan earlier this year (Klemm et al.). The authors expected to find evidence that the Pakistan strain was spreading across the region to other endemic countries. The data presented by Tanmoy et al. is instead proof that there are multiple and unrelated genetic mutations causing resistance in strains from diverse geographic origins. A multisource epidemic is a much more serious threat because it greatly enhances rapid, global dissemination, making it more difficult to contain than a single source outbreak.
"The emergence of these highly resistant strains in Pakistan and now Bangladesh could herald the beginning of a global pandemic of XDR strains", said Prof. Hubert Endtz, Director of Applied Research at the Mérieux Foundation and professor of Tropical Bacteriology at Erasmus University Medical Center. "With therapeutic options disappearing, it is urgent to accelerate vaccination programs for populations at high risk", he added.
Typhoid fever is caused by Salmonella enterica serovar Typhi and responsible for an estimated 17-26 million cases of typhoid fever each year worldwide. In the pre-antibiotic era, the mortality rate was 15% vs. 1% today. If typhoid fever were to become untreatable due to a lack of effective antibiotics, a return to pre-antibiotic levels could result in up to 3.9 million deaths a year.
If typhoid is detected and treated quickly, transmission can be stopped. Without effective antibiotics, there are only two options left: improving water sanitation, which is costly and slow to implement in endemic countries, and conducting vaccination campaigns in high-risk populations. WHO has prequalified the first conjugate vaccine to prevent typhoid fever and recommended its introduction into routine immunization programs.
The study was conducted at the Mérieux Foundation's Emerging Pathogens Laboratory in Lyon, dedicated to applied research in the fields of global health and infectious diseases, and part of the International Center for Infectiology Research (CIRI) - Inserm U1111. Data from whole genome sequencing of 536 S. Typhi strains was analyzed by Mérieux Foundation scientists and bioinformaticians, in collaboration with teams at Applied Maths in Belgium and bioMérieux's Data Analytics Unit in France. The strains were collected from the Child Health Research Foundation at the Department of Microbiology, Dhaka Shishu (Children) Hospital, in Dhaka, Bangladesh.
The lead author, Arif M. Tanmoy, from the Child Health Research Foundation in Bangladesh, received an ARTS PhD scholarship from the Mérieux Foundation and the French Institut de Recherche pour le Développement (IRD). The study received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 643476, as part of the COMPARE project for the rapid identification, containment and mitigation of emerging infectious diseases and foodborne outbreaks.
More about the Mérieux Foundation at: http://www.fondation-merieux.org and @MerieuxFdn
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