Animal derived milk which is an important part of human diet due to its high nutritional value not only supports humans but also presents a growth environment for pathogenic bacteria. Milk may become contaminated with bacteria through udder infections or through contact within the dairy farm environment. Infections are treated with antibiotics, with β-lactams most commonly used in veterinary medicine. However, their frequent use leads to the emergence of β-lactam resistant bacterial strains, which causes difficulties in the treatment of infections in both humans and animals. Detection of pathogens as well as their antibiotic sensitivity is a pre-requisite for successful treatment and this is generally achieved with laboratory-based techniques such as growth inhibition assays, enzyme-linked immunosorbent assays (ELISA) or polymerase chain reactions (PCRs), which are unavailable in resource-limited settings. Here, we investigated paper-based analytical devices (μPADs) for the presumptive detection of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and their antibiotic resistant bacterial strains in milk samples. The μPADs were fabricated on filter paper using wax printing, and then impregnated with chromogenic substrates, which reacted with bacterial enzymes to form coloured products. Limits of detection of S. aureus and E. coli and their antibiotic resistant strains in milk samples were found to be 10⁶ cfu mL⁻¹. Enrichment of milk samples in a selective medium for 12 h enabled detection as low as 10 cfu mL⁻¹. The paper devices tested on a set of 640 milk samples collected from dairy animals in Pakistan demonstrated more than 90% sensitivity and 100% selectivity compared to PCR, showing promise to provide inexpensive and portable diagnostic solutions for the detection of pathogenic bacteria in resource-limited settings.

中文翻译：

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用于牛奶中金黄色葡萄球菌和大肠杆菌及其抗药性菌株比色检测的纸质分析设备。

动物源性牛奶由于其高营养价值而成为人类饮食的重要组成部分，不仅支持人类，而且还为病原菌提供了生长环境。牛奶可能因乳房感染或奶牛场环境中的接触而被细菌污染。用抗生素治疗感染，最常用的是兽医用β-内酰胺。然而，它们的频繁使用导致出现对β-内酰胺抗性的细菌菌株，这在治疗人和动物的感染方面造成困难。检测病原体及其对抗生素的敏感性是成功治疗的先决条件，通常可通过基于实验室的技术（例如生长抑制测定，酶联免疫吸附测定（ELISA）或聚合酶链反应（PCR），在资源有限的环境中不可用。在这里，我们研究了基于纸质的分析设备（μPADs）的假定检测牛奶样品中的金黄色葡萄球菌（S. aureus）和大肠杆菌（E. coli）及其耐药菌菌株。μPAD使用蜡印法在滤纸上制成，然后浸渍有生色底物，该底物与细菌酶反应形成有色产物。牛奶样品中金黄色葡萄球菌和大肠杆菌及其耐药菌株的检出限为10 ⁶ cfu mL ^-1。在选择性培养基中富集牛奶样品12小时，可检测低至10 cfu mL ^-1。与从PCR相比，在从巴基斯坦的奶牛身上收集的640个牛奶样本中测试的纸质设备显示出90％以上的灵敏度和100％的选择性，表明有望为资源有限的病原菌检测提供廉价，便携式的诊断解决方案设置。