Typhoid tips off new epidemic approach

A typhoid outbreak in Kathmandu has provided new insights into bacterial epidemics and antibiotic resistance, thanks to a Melbourne scientist’s genomic research.

Kathryn Holt. Credit: L’Oréal Australia/sdpmedia.com.au

Kathryn Holt, of the University of Melbourne’s Bio21 Institute, used genome sequencing to discover that an epidemic of deadly typhoid bacteria in Nepal’s capital city was driven by climate, and not by the outbreak of novel genetic strains.

Her research, published in the Royal Society journal Open Biology, changes our understanding of how typhoid spreads and how we can better respond to other bacterial epidemics.

Kat says the discovery could only have happened through her sequencing of the bacterium’s whole genome. “It’s a very recently emerged pathogen, so there’s little genetic variation to track. To get anywhere with it, you have to sequence everything,” she says.

During her research, Kat was surprised to find that members of the same Kathmandu family each had different strains of the bacterium; it wasn’t a single strain that spread between them. Instead, she found climate mainly drove infection increases.

“In the wet season, you get flooding and the drinking water becomes contaminated, so you get transmission and a lot of infections across the city. That means, in the one season you have infections caused by a whole variety of genetically different typhoid bacteria,” Kat says.

Her achievements won her a 2013 L’Oréal Australia and New Zealand For Women in Science Fellowship, which she will use to study the origin, evolution and spread of antibiotic resistance in Klebsiella—a bacterium that is rapidly becoming a problem in hospitals worldwide because of its capacity for survival in a broad range of environments and its ability to pick up novel genes.

Photo: Kathryn Holt
Credit: L’Oréal Australia/sdpmedia.com.au

Bio21 Institute, The University of Melbourne, Kathryn Holt, Tel: +61 3 9035 3155, kholt@unimelb.edu.au, www.biochemistry.unimelb.edu.au/research/res_holt.html