Scientists who unlocked the genetic code of bacteria grown from a soldier who died of dysentery in World War I say it revealed a superbug already resistant to penicillin and other antibiotics decades before they were in common use.

The discovery sheds light on the history of antibiotic resistance – now a global health threat – and offers fresh clues on how to tackle dysentery, a disease that kills hundreds of thousands of children every year in developing countries.

“Even before the description and widespread use of penicillin, this bacterium was resistant to it,” said Kate Baker of Britain’s Wellcome Trust Sanger Institute, who worked on the research with colleagues at Public Health England (PHE).

World War I soldiers in trenches: researchers say superbugs already resistant to penicillin and other antibiotics decades before they were in common use were rife.

Dysentery is a life-threatening disease that is becoming increasingly hard to treat due to its growing ability to evade antibiotic treatment. It was rife in the trenches during World War I, and still spreads now in unsanitary conditions in poor countries and in conflict zones.

The genetic data from this sample of bacteria – known as Shigella flexneri –which infected a soldier on the Western Front, show how the pathogen has changed in the past century.

Baker’s research is to be published in The Lancet medical journal today.

She said in a telephone interview that analysis of genetic differences between this 1915 sample of Shigella flexneri and three others isolated in 1954, 1984 and 2002 showed that, while the bacterium has changed relatively little, the mutations it has acquired have made it more dangerous and persistent.

It also went through what is known as a “serotype conversion”, she said, which made it able to re-infect and cause illness in people who had already been infected before and would previously have been immune to further attacks.

The three other samples were one known as 2457T from a Japanese patient in 1954, a strain called 301 taken from Beijing in 1984, and a further epidemic strain from China from 2002.

“Only two per cent of its [Shigella’s] genome differed over that time,” Baker said.

“But the changes is has acquired were crucial to helping it evade the antimicrobials [antibiotics] we use to fight it. It’s quite remarkable.”

She said she hoped the findings may ultimately help her team and other scientists in the search for an effective vaccine for Shigella, since there are now few existing antibiotics to which the bug has not developed some level of resistance.

Finding Ernest and learning his story was a chance to commemorate those who fought in World War I, and to highlight the burden of infectious disease during this time

Intrigued by the 99-year-old stool sample, the first in Britain’s National Collection of Type Cultures, Alison Mather, another scientist on the team, set out to find the soldier with the sample’s name, Cable, her only starting clue.

Using PHE and National Archives records, she tracked down the hospital where the sample was taken – a converted hotel in the French coastal town of Wimereux – and trawled through papers there until she found an entry for a Private Ernest Cable of the Second Battalion of the East Surrey Regiment.

It was the record of his death from dysentery on March 13, 1915.

“So many of the samples we work with in bacterial genomics have stories that we’ll never know,” Mather said in a statement about the research.

“Finding Ernest and learning his story was a chance to commemorate those who fought in World War I, and to highlight the burden of infectious disease during this time.”

What is dysentery?

Dysentery is an intestinal inflammation, especially in the colon, that can lead to severe diarrhoea.

Patients typically experience mild to severe abdominal pain or stomach cramps.

In some cases, untreated dysentery can be life-threatening, especially if the infected person cannot replace lost fluids fast enough.

When people in industrialised nations have dysentery, signs and symptoms tend to be mild. Many won’t even see their doctor, and the problem resolves in a few days. Even so, if a doctor in Western Europe, North America and many other countries comes across a case of dysentery, local authorities need to be told – it is a notifiable disease.

The World Health Organisation (WHO) says there are two main types of dysentery:

• Bacillary dysentery, caused by shigella, a bacterium. In Western Europe and the US it is the most common type of dysentery among people who have not recently been to the tropics.

• Amoebic dysentery (amoebiasis) which is caused by Entamoeba histolytica, a type of amoeba, and is more common in the tropics. An amoeba is a protozoan (single-celled) organism that constantly changes shape.

The WHO estimates that shigellosis accounts for about 120 million cases of severe dysentery.

The vast majority of cases occur in developing nations among children aged less than five years. Approximately 1.1 million people are thought to die from shigella infection globally each year.

Sixty per cent of these deaths are among very young children.