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09 Jun 2023

Alarming rise in paratyphoid fever cases in Cambodia linked to antibiotic resistance

Scientists have discovered a concerning increase in a type of bacteria that causes paratyphoid fever to become resistant to antibiotics in Cambodia. 

In a study published in Microbial Genomics, co-funded by the Peter Doherty Institute for Infection and Immunity (Doherty Institute), scientists from the Institut Pasteur du Cambodge found that the bacterium responsible for causing life-threatening paratyphoid fever, called Salmonella enterica Serovar Paratyphi A, is becoming increasingly resistant to fluoroquinolones - an antibiotic class commonly used to treat bacterial infections. 

Studying bacteria samples collected in Cambodia’s capital, Phnom Penh, the scientists looked at the genetic makeup of the bacteria and found that it had mutated to survive and grow even when the antibiotic was used to fight it.  

Lead author of the study and group leader of the Bacterial Phylogenomics group at the Institut Pasteur du Cambodge, Dr Koen Vandelannoote said the research demonstrates the power of genomics and how it informs our understanding of the spread of superbugs. 

“Antibiotic resistance is a huge problem because it limits the treatment options for people who get sick with paratyphoid fever,” Dr Vandelannoote said. 

“Antibiotics are powerful medicines that can kill bacteria and help us fight infections. However, when they are overused or used inappropriately, bacteria can develop resistance and become stronger.” 

Co-author of the study University of Melbourne’s Professor Tim Stinear, added that the research calls for increased genomic surveillance of antimicrobial resistance in low- and middle-income countries, like Cambodia, to better understand and combat the spread of resistant strains.  

“This highlights the need for ongoing surveillance of antibiotic resistance globally, and the development of new strategies to combat the problem. By working together and taking responsible actions, we can help prevent the spread of antibiotic-resistant bacteria and protect public health,” Professor Stinear said. 

“Although there are challenges in terms of initial investment, infrastructure, expertise, and training, the decreasing cost of whole-genome sequencing presents an opportunity to strengthen public health efforts and address the rising threat of antibiotic resistance.” 

Salmonella Paratyphi, the bacterium responsible for Paratyphoid fever, can be found in contaminated water and food. While less severe than typhoid, paratyphoid can cause severe fever, headache, loss of appetite and abdominal pain. 

Peer review: Microbial Genomics (DOI:

Funding: The research was funded by a collaborative research fund supported by the University of Melbourne (Doherty Institute), Institut Pasteur (Paris) and Institut Pasteur du Cambodge. The authors were in part supported by a PHA4GE/2021-01 subgrant (AMR-SG-01).