Drug resistance in Salmonella Typhi: implications for South Asia and travel

Curr Opin Infect Dis. 2020 Oct;33(5):347-354. doi: 10.1097/QCO.0000000000000672.

Abstract

Purpose of review: Recent attempts at mapping Typhoid epidemiology have revealed an enormous burden of disease in developing countries. Countries hitherto believed to have a low incidence, such as the African subcontinent, on accurate mapping were found to have a significant burden of disease. Drug resistance, because of rampant overuse of antibiotics, has driven selection pressure to extensively drug-resistant typhoid becoming a reality in the Indian subcontinent. With widespread travel, importation of this variety of typhoid to nonendemic countries is likely to lead to outbreaks in a nonimmune population.

Recent findings: A strain of extensively drug-resistant Salmonella Typhi isolated in Pakistan in 2016 has been responsible for multiple outbreaks in Pakistan and multiple travel-related cases all over the world in United States, UK, and Australia. This novel strain belongs to H58 lineage harbouring a plasmid encoding additional resistance elements like blaCTX-M-15 and a qnrS fluoroquinolone resistance gene. This resistance pattern has rendered many therapeutic options like Ceftriaxone and Fluoroquinolones clinically inactive impacting care in endemic and traveller populations alike.

Summary: Changing epidemiology and drug resistance in typhoid indicates that it may be prudent to vaccinate nonimmune travellers travelling to typhoid endemic areas, especially the Indian subcontinent.

Publication types

  • Review

MeSH terms

  • Anti-Bacterial Agents / therapeutic use
  • Asia / epidemiology
  • Azithromycin / therapeutic use
  • Ceftriaxone / therapeutic use
  • Communicable Diseases, Imported / epidemiology
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Fluoroquinolones / therapeutic use
  • Genes, Bacterial
  • Humans
  • Pakistan / epidemiology
  • Public Health
  • Salmonella typhi / drug effects
  • Salmonella typhi / genetics*
  • Travel
  • Typhoid Fever / drug therapy
  • Typhoid Fever / epidemiology*

Substances

  • Anti-Bacterial Agents
  • Fluoroquinolones
  • Ceftriaxone
  • Azithromycin