An eNose is able to sniff out bacteria that cause soft tissue infections


A recent study conducted at the University of Tampere, Tampere University of Technology, Pirkanmaa Hospital District and Fimlab in Finland has concluded that an electronic nose (eNose) can be used to identify the most common bacteria causing soft tissue infections.

The eNose can be used to detect the bacteria without the prior preparation of samples, and the system was capable of differentiating methicillin-resistant Staphylococcus aureus (MRSA) from methicillin-sensitive Staphylococcus aureus (MSSA).

An electronic nose is a device that produces “an olfactory profile” for each molecular compound in the air. The results are analysed by a computer and the system is programmed to differentiate between different compounds.

“The e-nose can be used to detect the bacteria causing the infection as quickly as possible, which makes it easier to start the right antibiotic treatment,” says Niku Oksala, assistant professor of vascular surgery at the University of Tampere.

“Another significant benefit is that the e-nose is quickly able to diagnose if the infection is caused by a multi-resistant bacterium, in other words a bacterium that cannot usually be cured by regular antibiotics. In those cases, the patient can immediately be placed in isolation in order to stop the bacterium from spreading and to prevent a multi-resistant bacterial epidemic,” Oksala explains.

Making the diagnosis with a bacterial culture

At present, the diagnosis of skin and soft tissue infections is usually based on bacterial cultures, but in uncomplicated cases the diagnosis may be made directly based on the clinical presentation of the disease.

“In the case of severe infections and if the patient has other risk factors, such as diabetes, the doctor may prescribe a broad-spectrum antibiotic because the infection may be caused be several bacteria,” Oksala says.

Especially in severe infections and with patients who have multiple conditions, the doctor refers the patient to a bacterial culture before starting the antibiotics.

“The results from a bacterial culture usually take three days. It can then be determined which bacterium caused the infection and which antibiotic will cure it. It is only then that the treatment will be precise,” Oksala says.

Side effects for the patients

Starting treatment without a specific diagnosis may result in the prescribed antibiotic not being effective with the bacterium causing the infection. Instead, the antibiotic may destroy benign bacteria in the affected area, which might have played a role in curbing the infection.

“The antibiotic can also destroy beneficial bacteria elsewhere in the body, for example in the gastrointestinal tract, which causes diarrhea. Malnutrition associated with diarrhea may further prevent healing the wound,” Oksala says.

“Moreover, even if the prescribed antibiotic could cure the infection to some extent, it can also result in new resistant bacteria that can spread to the environment and expose others,” Oksala says.

E-nose speeds up treatment

By using the e-nose, soft tissue infections could be diagnosed more quickly, enabling earlier referral of the patients to the right treatment.

“If we had such a method, treatment could be started in a timely manner and targeted to the relevant pathogen directly. This would reduce the need for empirical treatments and shorten diagnostic delays,” says doctoral researcher Taavi Saviauk from the Faculty of Medicine and Life Sciences.

“The portable eNose device we used does not require laboratory conditions or special training, so it is well suited for outpatient use. The results of this study are a significant step towards our goal,” Saviauk continues.

Medical and technology experts working together

Medical experts from the University of Tampere and technology experts from Tampere University of Technology (TUT) cooperated in the study.

“Together with researchers at TUT, we built the devices and methods that serve the needs of researchers in medicine,” Oksala says.

“TUT’s expertise in constructing equipment and mathematical processing of the results has been a key factor in the study, especially because we used a device that was not originally intended for detecting bacteria,” Oksala says.

Fimlab Laboratories Oy, from which the bacterial cultures were obtained, was also a key partner in the research.

Saviauk T. - Kiiski J.P. - Nieminen M.K. - Tamminen N.N. - Roine A.N. - Kumpulainen P.S. - Hokkinen L.J. - Karjalainen M.T. - Vuento R.E. - Aittoniemi J.J. - Lehtimäki T.J. - Oksala N.K: Electronic Nose in the Detection of Wound Infection Bacteria from Bacterial Cultures: A Proof-of-Principle Study. European Surgical Research 2018;59:1–11

Text: Ida Vahtera
Photo: Mika Kanerva