Instituto de Ingeniería, Universidad Nacional Autónoma de México, Apartado Postal 70-472, Ciudad Universitaria, CP 04510, México, D.F E-mail:
Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Av. Vasco de Quiroga 15 Col, Sección XVI Tlalpan, CP 14000, México, D.F.
Water Sci Technol. 2013;68(11):2468-72. doi: 10.2166/wst.2013.512.
Helicobacter pylori is a Gram-negative spiral-shaped bacterium that colonizes the gastric mucosa and is associated with gastric diseases. It may present a morphological adaptation when it is out of its natural environment, such as in water. The morphological adaptation is a coccoid form, which is a viable but non-culturable state (VNC) in which the DNA remains active and therefore infective. Due to the impossibility of culture by traditional methods in the VNC state, we developed a methodology that includes a molecular technique, quantitative polymerase chain reaction (qPCR), which is capable of measuring the bacteria in both forms (helical and coccoidal) and therefore is able to measure a disinfection process and to estimate the resistance of the bacteria to ozone. The methodology developed measures the efficiency of the ozone disinfection when bacteria are in a VNC state only. Bacterial culture at 9 × 10(8)CFU/mL diluted in 40 mL reaction volumes were exposed to a wide range of CT values (0.11-15 mg min/L). The results show a 3.92-log reduction when treated with 15 mg min/L. Our results demonstrate the feasibility of using qPCR for the quantification and detection of H. pylori, in coccoid form, in water systems treated with an ozone disinfection process.
幽门螺杆菌是一种革兰氏阴性螺旋形细菌，定植于胃黏膜，与胃部疾病有关。当它处于自然环境之外，例如在水中时，可能会呈现形态适应性。这种形态适应性表现为球菌形态，这是一种存活但不可培养的状态（VNC），其中 DNA 仍然保持活跃，因此具有感染性。由于在 VNC 状态下传统方法无法进行培养，我们开发了一种包括分子技术（定量聚合酶链反应，qPCR）的方法，该方法能够测量两种形态（螺旋形和球菌形）的细菌，因此能够测量消毒过程并估计细菌对臭氧的抗性。所开发的方法仅在 VNC 状态下测量当细菌处于不可培养状态时的臭氧消毒效率。将在 40 mL 反应体积中稀释至 9×10(8)CFU/mL 的细菌暴露于广泛的 CT 值（0.11-15 mg min/L）下。结果显示，当用 15 mg min/L 处理时，减少了 3.92 个对数。我们的结果表明，qPCR 可用于定量和检测在臭氧消毒处理的水系统中的球菌形式的幽门螺杆菌。
