Diagnosing bacterial growth

Antibiotics are used regularly for treating bacterial infections, but there is currently no quick and simple test to determine the most effective type or dose of antibiotic for a specific patient infection. As a result, it’s estimated that around 30% of all antibiotic prescriptions are not the optimum choice. This can lead to the formation of drug-resistant bacteria, delayed recovery, and in some cases death from an infection.

Tests for the most appropriate antibiotic choice are performed for life-threatening patient infections. However, microbes have to be grown on agar plates from a very small patient sample which delays results for a few days. Hiroaki Suzuki et al have designed a microfluidic device that is able to determine the most effective antibiotic treatment in just 12 hours.

The device consists of eight separate culture chambers, which can test a range of concentrations simultaneously. Once bacteria are added the growth rate is recorded using a reflection-microscopy technique. The images obtained allow the volume of bacteria present to be calculated, which in turn allows estimation of the minimum concentration of antibiotic required to effectively treat a patient.

Shuqi Wang, an expert in microfluidic diagnostic devices, at Harvard Medical School, USA, comments ‘This method has broad potential applications to help clinicians choose the right antibiotics at the right concentration against given bacteria, and thus to avoid empirical antibiotic treatment. In particular, the multi-chamber microfluidic design allows simultaneous evaluation of multiple antibiotics at various concentrations in one testing.’