細菌感染不論在醫院、自然環境中一直都是威脅人類身體健康的議題，然而在臨床上細菌感染的即時診斷是困難的，即使科學家不斷各種抗生素來治療細菌感染，但敗血症仍然是全球主要死因之一。現有細菌檢測主要可分成兩大類:(1)傳統培養基檢測法:細菌經過特殊培養基培養1~2天後觀察菌落顏色變化。(2)免疫分析法:利用抗體或抗原進行相關檢測，可獲得高專一性之檢測結果。目前細菌檢測上尚未具有低成本、簡單操作、不需額外設備協助之快速檢測方法，以即時提供樣品中細菌濃度之資訊。在本研究我們選擇大腸桿菌及金黃色葡萄球菌作為偵測細菌，大腸桿菌為自然環境中常見的指標性細菌，而金黃色葡萄球菌經常是造成細菌感染的原因。本研究利用MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) 及PMS (Phenazine methosulfate)與細菌內酵素產生氧化還原反應，並添加氫氧化鈉增強反應呈色效果。實驗結果顯示，細菌與反應試劑在595 nm波長下隨著細菌濃度越高有較高的吸收度。我們也利用伊紅Y-甲基藍複合染劑(Eosin Y-Methylene blue)及Triton X-100來分辨不同濃度的細菌，在菌液中依序加入添加Triton X-100之伊紅Y溶液、亞甲基藍染劑，根據細菌成分化學性質不同，細菌細胞質透過離子鍵與酸性染料伊紅Y結合呈粉紅色，細菌核酸透過離子鍵與鹼性染料亞甲基藍結合成藍紫色。隨著樣本中細菌量越多被染成藍紫色的核酸越多，因此，菌量越多顏色越深，反之菌量越少則顏色越淡。

Bacterial infections have been a threat to human health in hospitals and the natural environment. However, immediate diagnosis of bacterial infections is difficult. Even if various antibiotics have been administrated to treat bacterial infections, sepsis is still one of the major causes of death worldwide. Nowadays, the bacteria detection methods can be mainly divided into two categories: (1) traditional medium detection method: bacteria are cultured in a special medium for 1 to 2 days to observe the colony color change. (2) Immunoassay: The detection of antibodies or antigens can be used to obtain highly specific test results. At present, there is no rapid detection method for low-cost, simple operation and no additional equipment requirement for bacterial detection. In an addition, current methods are unable to provide instant information about the concentration of bacteria in the sample. In our study, we chose Escherichia coli and Staphylococcus aureus as the materials. We used MTT - PMS reagent to produce redox with enzymes in bacterium, and add Sodium hydroxide to enhance the color of the reaction. The absorbance value in 595 nm increases with the increasing concentration of bacteria. We use Eosin Y - Methylene blue reagent to identify different concentrations of bacteria.

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