Analysis of the Survival of H. pylori Within a Laboratory-based Aquatic Model System Using Molecular and Classical Techniques

Abstract

Despite the significance of Helicobacter pylori infection for man, its transmission is not clearly known. The human stomach is considered the reservoir of this pathogen, and one of the accepted routes is fecal-oral, in which water acts as a vector. However, although H. pylori epidemiology associates its transmission with water, only molecular and not cultural analysis detects the bacteria in water. This study was carried out to understand these data through studying the survival of H. pylori in a laboratory water model using cultural, morphological, and molecular methods. A mineral water system spiked with H. pylori and stored at 7 +/- 1 degrees C in the dark was analyzed by different methods over a period of 3 weeks. The total number of cells observed by DAPI staining and their DNA content remained constant over this study period. In contrast, cells could no longer be cultured after 5 days. Cell viability, which was determined via the LIVE/DEAD BacLight kit, decreased up to day 14, and at day 21 all cell membranes were damaged. In addition, a gradual conversion from spiral to coccal morphology occurred from day 3 onward. However, polymerase chain reaction (PCR) technique detected H. pylori DNA at day 21 and 3 months later. A study of the cell morphology of a young colony demonstrated the coexistence of bacilli and cocci. The results of this study show that H. pylori survives in water but loses its culturability and bacillar morphology rapidly, although it remains viable for longer periods and its DNA is still detectable much later. Thus, interpreting H. pylori's behavior in water differs according to the type of analysis. Consequently, we suggest that the presence of H. pylori infective cells is overestimated by PCR, whereas, in contrast, culture techniques underestimate it. Nevertheless, H. pylori should be considered a waterborne pathogen during its viable period, independently of its shape and culturability, as its presence in water may be risky for human health.

Failure To Detect Helicobacter pylori DNA in Drinking and Environmental Water in Dhaka, Bangladesh, Using Highly Sensitive Real-Time PCR Assays

“…Finally, the viability and putative infectious capability of H. pylori under environmental conditions are controversial. Suggestions that H. pylori persists in the environment in a viable but nonculturable coccoid form (27,42,45) have been challenged (28), and there is only scattered evidence for reversion to the actively dividing form (9,11,47). Furthermore, our results show that coccoids, regardless of viability, are readily detected at low numbers by our real-time PCR assays.…”

Survival of spinach-associated Helicobacter pylori in the viable but nonculturable state

“…Despite its relatively recent discovery, H. pylori is considered to be the most prevalent human pathogen world-wide, having an infection rate as high as 80% in developing countries and 40% in developed countries (Cover & Blaser, 1995;Nayak & Rose, 2007). It is believed that H. pylori is transmitted via the fecal/oral and oral/oral routes, based on the isolation of H. pylori cells from human stool (Gramley, Asghar, Frierson, & Powell, 1999;Nayak & Rose, 2007;Queralt & Araujo, 2007;Thomas, Gibson, Darboe, Dale, & Weaver, 1992) and saliva samples (Ferguson et al, 1993), however the exact method of transmission from person-to-person continues to elude investigators. This is primarily due to the inability to recover culturable H. pylori cells from the environment.…”

Quantitative PCR Monitoring of Antibiotic Resistance Genes and Bacterial Pathogens in Three European Artificial Groundwater Recharge Systems

“…paratuberculosis. For all of these pathogens, surviving long-term in aquatic systems and causing waterborne diseases are well documented (6,8,23,29,30,33,43,45). Additionally, the ability of Y. enterocolitica (39), H. pylori (1,29,32), and M. avium (5,34,46) to persist for a long time in a dormant or viable but nonculturable state in aquatic environments has been reported.…”