Seoul National University Hospital meticulously finds out the pathogens of diabetic foot infections

- Developed a new method to identify pathogenic bacteria, utilizing nanopore sequencing technology

- Reported superior performance and shorter test time than a conventional culture test

From left, Professor Jangseop Moon, Dongyeon Lee, and Geon Joo

The patients with diabetes have the high level of glucose, which causes blood to be thicker and prevents smooth blood circulation. In particular, feet are exposed to more risks because they are far from the heart and endure heavy loads on the body. 

Diabetic feet is an ulcer and peripheral neuropathy that occurs on the feet. It is infectious and, in severe cases, it requires amputation of the foot.

On the 7th, Seoul National University Hospital announced that the team of Professor Jangseop Moon, Dongyeon Lee, and Geon Joo accurately identified the pathogenic bacteria of diabetic foot infection through a new nanopore sequencing technology.

It is found that, when performed with patient tissue samples, this method has provided faster and better analytical result than conventional culture tests

 

The research team compared the performance of the new technology with the existing culture test using 54 necrotic tissue samples taken during surgery from the patients who suffer from diabetic foot infections. The new sequencing technique found more complex bacterial infections.

While 81% (44/54) of the samples were diagnosed as a complex bacterial infection with the new technology, only 51% (32/54) with existing culture tests, which also incorrectly identified twelve complex bacterial infections as mono bacterial infections (10), or failed identifying bacteria itself (2). 

Figure 1. Comparison of diagnostic results of newly developed 16S sequencing (left) and conventional culture test (right)

* ■ Complex bacterial infections  ■ Mono bacterial infections ■ Not Cultured

Furthermore, it was able to identify which bacteria were most abundant among the multi-bacterial infections and to quantify each bacteria relatively. According to the analysis, it happened frequently that the most abundant bacteria at the nano sequencing were not identified in conventional culture tests. A nano sequencing revealed that it was also common for the bacteria identified by culture tests to be present very little in the lesion.

While conventional culture tests could not detect some anaerobes including prevotella and bacteroidetes, the new sequencing test could with excellent sensitivity proved.

In other words, this study verified that the conventional procedure to search for a disease causative agent of diabetic foot infection, which relied on culture tests, did not sufficiently reflect the actual composition of bacteria.

The speed of analysis was also much faster than that of a conventional culture test. While culture test usually takes 2-3 days or 1 week to culture and identify bacteria, the new analysis through sequencing usually confirmed a disease causative bacteria within 1 day.

Through this study, we could get one step closer to the accurate diagnosis and treatment of causative bacteria of diabetic foot infections.

Professor Jangseop Moon of the Department of Clinical Genomics said, “This study is expected to contribute to improving the prognosis, accurately diagnosing the causative bacteria of diabetic foot infection, with the latest technology of molecular genetics applied. It is a research that can reveal and change the existing treatment paradigm.”

This study was published in the latest issue of the international scientific journal ‘Diabetes’.