title: Quantification of Helicobacter pylori in the viable but nonculturable state by quantitative PCR in water disinfected with ozone.
abstract: 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.
authors: Instituto de Ingeniería, Universidad Nacional Autónoma de México, Apartado Postal 70-472, Ciudad Universitaria, CP 04510, México, D.F E-mail: BCasasolaR@iingen.unam.mx.
authors: B
authors: B
authors: Casasola-Rodríguez
authors: Instituto de Ingeniería, Universidad Nacional Autónoma de México, Apartado Postal 70-472, Ciudad Universitaria, CP 04510, México, D.F E-mail: BCasasolaR@iingen.unam.mx.
authors: M T
authors: MT
authors: Orta de Velásquez
authors: Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Av. Vasco de Quiroga 15 Col, Sección XVI Tlalpan, CP 14000, México, D.F.
authors: V G
authors: VG
authors: Luqueño-Martínez
authors: Instituto de Ingeniería, Universidad Nacional Autónoma de México, Apartado Postal 70-472, Ciudad Universitaria, CP 04510, México, D.F E-mail: BCasasolaR@iingen.unam.mx.
authors: I
authors: I
authors: Monje-Ramírez
mesh_terms: D004203:Disinfection; D016480:Helicobacter pylori / Q000302:isolation & purification*; D010126:Ozone; D060888:Real-Time Polymerase Chain Reaction; D014871:Water Microbiology
chemical_list: D010126:Ozone