Novel technique developed to treat middle ear infections

Researchers at the University of Illinois at Urbana-Champaign, US, have designed a miniaturised 3D-printed device to treat middle ear infections (otitis media). The device – a microplasma jet array – zaps infection-causing bacteria, namely Pseudomonas aeruginosa, with tiny jets of charged plasma; the microplasma treatment is much more effective than antibiotics and is also relatively harmless.

Middle ear infections affect more than 80% of children in the US – such infections are usually treated with topically-applied antibiotics. The antibiotics, however, may be unable to penetrate the bacterial biofilm that has formed on the surface of the inner ear tissue, especially in acute infections. The greater amount of antibiotics used may additionally lead to antibiotic resistance, as the bacteria develop a tolerance to them over time.

Read also: 3D-printed eardrum patch to repair damage and aid regeneration

The microplasma jet array, then, generates plasma to disrupt the structure of the biofilm of the bacteria that attach to the surface of the ear. This plasma is composed of charged particles and reactive molecules that have been previously shown to inactivate various pathogens.

In tests on a physical model of an inner ear – using an excised rat’s eardrum – the researchers found that 15 minutes of microplasma treatment was enough to kill off most of the bacteria; if some of the bacteria did remain unharmed, a relatively small amount of antibiotics would be required to kill them.

“We also monitored the tissue to see if we had created any holes or ruptures, but we didn’t find any obvious physical damage,” added graduate student Jungeun Won.

Although the thickness of a rat’s eardrum is 30% lower than that of a human, which is about the width of a hair strand, the results suggest that the microplasma treatment could be adapted to treat middle ear infections in humans.

The researchers are now working on a smaller and less obtrusive earbud-like version of the device that will allow longer exposure times. They are also investigating the effectiveness of the treatment on other infection-causing bacteria including Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis.

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