Sniffing-out smell of disease in feces: 'Electronic nose' for rapid detection of Clostridum difficile infection

This image depicts from lef to right Dr Martha Clokie, Professor Andy Ellis and Professor Paul Monks from the University of Leicester with the mass spectrometer. Credit: University of Leicester

A fast-sensitive "electronic-nose" for sniffing the highly infectious bacteria C-diff, that causes diarrhea, temperature and stomach cramps, has been developed by a team at the University of Leicester.

Using a mass spectrometer, the research team has demonstrated that it is possible to identify the unique 'smell' of C-diff which would lead to rapid diagnosis of the condition.

What is more, the Leicester team say it could be possible to identify different strains of the disease simply from their smell -- a chemical fingerprint -- helping medics to target the particular condition.

The research is published on-line in the journal Metabolomics.

Professor Paul Monks, from the Department of Chemistry, said: "The rapid detection and identification of the bug Clostridium difficile (often known as C-diff) is a primary concern in healthcare facilities. Rapid and accurate diagnoses are important to reduce Clostridum difficile infections, as well as to provide the right treatment to infected patients.

"Delayed treatment and inappropriate antibiotics not only cause high morbidity and mortality, but also add costs to the healthcare system through lost bed days. Different strains of C. difficile can cause different symptoms and may need to be treated differently so a test that could determine not only an infection, but what type of infection could lead to new treatment options."

The new published research from the University of Leicester has shown that is possible to 'sniff' the infection for rapid detection of Clostridium difficile. The team have measured the Volatile Organic Compounds (VOCs) given out by different of strains of Clostridium difficile and have shown that many of them have a unique "smell." In particular, different strains show different chemical fingerprints which are detected by a mass spectrometer.

The work was a collaboration between University chemists who developed the "electronic-nose" for sniffing volatiles and a colleague in microbiology who has a large collection of well characterised strains of Clostridium difficile.

The work suggests that the detection of the chemical fingerprint may allow for a rapid means of identifying C. difficile infection, as well as providing markers for the way the different strains grow.

Professor Monks added: "Our approach may lead to a rapid clinical diagnostic test based on the VOCs released from faecal samples of patients infected with C. difficile. We do not underestimate the challenges in sampling and attributing C. difficile VOCs from fecal samples."

Dr Martha Clokie, from the Department of Microbiology and Immunology, added: "Current tests for C. difficile don't generally give strain information -- this test could allow doctors to see what strain was causing the illness and allow doctors to tailor their treatment."

Professor Andy Ellis, from the Department of Chemistry, said: "This work shows great promise. The different strains of C-diff have significantly different chemical fingerprints and with further research we would hope to be able to develop a reliable and almost instantaneous tool for detecting a specific strain, even if present in very small quantities."

Source: University of Leicester

Microbiologists discover how gut bacterial resources are hijacked to promote intestinal, foodborne illnesses

Dr. Vanessa Sperandio. Credit: Image courtesy of UT Southwestern Medical Center

UT Southwestern Medical Center microbiologists have identified key bacteria in the gut whose resources are hijacked to spread harmful foodborne E. coli infections and other intestinal illnesses.

Though many E. coli bacteria are harmless and critical to gut health, some E. coli species are harmful and can be spread through contaminated food and water, causing diarrhea and other intestinal illnesses. Among them is enterohemorrhagic E. coli or EHEC, one of the most common foodborne pathogens linked with outbreaks featured in the news, including the multistate outbreaks tied to raw sprouts and ground beef in 2014.

The UT Southwestern team discovered that EHEC uses a common gut bacterium called Bacteroides thetaiotaomicron to worsen EHEC infection. B. thetaiotaomicron is a predominant species in the gut's microbiota, which consists of tens of trillions of microorganisms used to digest food, produce vitamins, and provide a barrier against harmful microorganisms.

"EHEC has learned to how to steal scarce resources that are made by other species in the microbiota for its own survival in the gut," said lead author Dr. Meredith Curtis, Postdoctoral Researcher at UT Southwestern.

The research team found that B. thetaiotaomicron causes changes in the environment that promote EHEC infection, in part by enhancing EHEC colonization, according to the paper, appearing in the journal Cell Host Microbe.

"We usually think of our microbiota as a resistance barrier for pathogen colonization, but some crafty pathogens have learned how to capitalize on this role," said Dr. Vanessa Sperandio, Professor of Microbiology and Biochemistry at UT Southwestern and senior author.

EHEC senses changes in sugar concentrations brought about by B. thetaiotaomicron and uses this information to turn on virulence genes that help the infection colonize the gut, thwart recognition and killing by the host immune system, and obtain enough nutrients to survive. The group observed a similar pattern when mice were infected with their equivalent of EHEC, the gut bacterium Citrobacter rodentium. Mice whose gut microbiota consisted solely of B. thetaiotaomicron were more susceptible to infection than those that had no gut microbiota. Once again, the research group saw that B. thetaiotaomicron caused changes in the environment that promoted C. rodentium infection.

"This study opens up the door to understand how different microbiota composition among hosts may impact the course and outcome of an infection," said Dr. Sperandio, whose lab studies how bacteria recognize the host and how this recognition might be exploited to interfere with bacterial infections. "We are testing the idea that differential gastrointestinal microbiota compositions play an important role in determining why, in an EHEC outbreak, some people only have mild diarrhea, others have bloody diarrhea and some progress to hemolytic uremic syndrome, even though all are infected with the same strain of the pathogen."

The Centers for Diseases Control and Prevention (CDC) estimates that each year roughly 1 in 6 Americans (or 48 million people) gets food poisoning; 128,000 are hospitalized;, and 3,000 die of their food-borne disease. EHEC, which also caused a widespread outbreak in Europe in 2011, can lead to bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome, which in turn can lead to kidney disease and failure. EHEC is among the top five pathogens contributing to domestically acquired foodborne illnesses resulting in hospitalization, according to the CDC. Outbreaks in 2014 were reported in California, Idaho, Massachusetts, Michigan, Missouri, Ohio, Montana, Utah, and Washington.

Source: UT Southwestern Medical Center