Reduced infectivity of waterborne viable but nonculturable Helicobacter pylori strain SS1 in mice

Wake Up! Resuscitation of Viable but Nonculturable Bacteria: Mechanism and Potential Application

The viable but nonculturable (VBNC) state is a survival strategy for bacteria when encountered with unfavorable conditions. Under favorable environments such as nutrient supplementation, external stress elimination, or supplementation with resuscitation-promoting substances, bacteria will recover from the VBNC state, which is termed "resuscitation". The resuscitation phenomenon is necessary for proof of VBNC existence, which has been confirmed in different ways to exclude the possibility of culturable-cell regrowth. The resuscitation of VBNC cells has been widely studied for the purpose of risk control of recovered pathogenic or spoilage bacteria. From another aspect, the resuscitation of functional bacteria can also be considered a promising field to explore. To support this point, the resuscitation mechanisms were comprehensively reviewed, which could provide the theoretical foundations for the application of resuscitated VBNC cells. In addition, the proposed applications, as well as the prospects for further applications of resuscitated VBNC bacteria in the food industry are discussed in this review.

Essential oils and their active components applied as: free, encapsulated and in hurdle technology to fight microbial contaminations. A review

Microbial contaminations are responsible for many chronic, healthcare, persistent microbial infections and illnesses in the food sector, therefore their control is an important public health challenge. Over the past few years, essential oils (EOs) have emerged as interesting alternatives to synthetic antimicrobials as they are biodegradable, extracted from natural sources and potent antimicrobials. Through their multiple mechanisms of actions and target sites, no microbial resistance has been developed against them till present. Although extensive documentation has been reported on the antimicrobial activity of EOs, comparisons between the use of whole EOs or their active components alone for an antimicrobial treatment are less abundant. It is also essential to have a good knowledge about EOs to be used as alternatives to the conventional antimicrobial products such as chemical disinfectants. Moreover, it is important to focus not only on planktonic vegetative microorganisms, but to study also the effect on more resistant forms like spores and biofilms. The present article reviews the current knowledge on the mechanisms of antimicrobial activities of EOs and their active components on microorganisms in different forms. Additionally, in this review, the ultimate advantages of encapsulating EOs or combining them with other hurdles for enhanced antimicrobial treatments are discussed.

Helicobacter pylori in the Oral Cavity: Current Evidence and Potential Survival Strategies

Helicobacter pylori (H. pylori) is transmitted primarily through the oral–oral route and fecal–oral route. The oral cavity had therefore been hypothesized as an extragastric reservoir of H. pylori, owing to the presence of H. pylori DNA and particular antigens in distinct niches of the oral cavity. This bacterium in the oral cavity may contribute to the progression of periodontitis and is associated with a variety of oral diseases, gastric eradication failure, and reinfection. However, the conditions in the oral cavity do not appear to be ideal for H. pylori survival, and little is known about its biological function in the oral cavity. It is critical to clarify the survival strategies of H. pylori to better comprehend the role and function of this bacterium in the oral cavity. In this review, we attempt to analyze the evidence indicating the existence of living oral H. pylori, as well as potential survival strategies, including the formation of a favorable microenvironment, the interaction between H. pylori and oral microorganisms, and the transition to a non-growing state. Further research on oral H. pylori is necessary to develop improved therapies for the prevention and treatment of H. pylori infection.

Helicobacter pylori results in lysis and death after exposure to water

BACKGROUND

Helicobacter pylori has a high infection rate, and it is possible that more than half of the world's population is infected. The route of transmission of H. pylori has not been completely elucidated yet. The coccoid form of H. pylori is generally considered to be in a VBNC (viable but nonculturable) state, and this form in the environment is thought to play an important role in infection and transmission, but its stability and survivability are still unknown.

MATERIALS AND METHODS

In order to promote its changing to coccoid form, the spiral form of H. pylori grown in a culture medium was exposed to sterile distilled water, and we investigated the bacterial cell number and the morphological changes by using fluorescence staining methods and electron microscopic observation. We also examined the dynamics of its growth ability by measuring the colony forming unit on an agar-plate medium.

RESULTS

After exposure to sterile distilled water, the H. pylori spiral form rapidly lost its growth ability at 37°C. One day after exposure, approximately 95% of the spiral form disappeared and the proportion of the coccoid form increased. The total number of bacteria also decreased to less than half and continued to decrease over time. Epi-microscopic and electron microscopic observations revealed that deformation of bacterial cells, collapse, and leaking out of cell contents were promoted in exposure to sterile distilled water.

CONCLUSION

Helicobacter pylori quickly begins to transform into the coccoid form after exposure to sterile distilled water, rapidly loses its growth ability, and then lyses and dies. Water-exposure is lethal for H. pylori and it is unlikely to survive in the VBNC state in water.

Absolute Quantification of Viable but Nonculturable Vibrio cholerae Using Droplet Digital PCR with Oil-Enveloped Bacterial Cells

When exposed to adverse conditions, many bacterial pathogens, including Vibrio cholerae, can adapt to the environment by entering the viable but nonculturable (VBNC) state. Cells in this state cannot grow on conventional media but still survive. The VBNC state is a significant threat to aquatic safety and public health due to the enhanced ability of the bacteria to remain in the environment and escape from monitoring. Detecting and quantifying VBNC cells and distinguishing them from nonviable cells is necessary for microbiological studies and pathogen monitoring. Cell staining and microscopy are used for the observation of VBNC cells, but it is difficult to quantify VBNC cells accurately. In this study, we developed droplet digital PCR (ddPCR) with a chromosomal single-copy gene as an internal reference combined with Propidium monoazide (PMA) treatment to enumerate VBNC cells of V. cholerae. In this method, bacterial cells, but not extracted chromosomal DNA, were used directly to form oil-enveloped droplets in the ddPCR procedure. One bacterial cell possesses one copy of the chromosome. Thus, enumeration of a single-copy gene on the chromosome can be used to count VBNC cells. ddPCR showed greater accuracy and sensitivity than qPCR. This study showed that the oil-enveloped bacterial method can reduce the number of steps needed and improve the accuracy of VBNC cells quantification and has the potential to be extended to quantify bacterial VBNC cells and assess pathogen survival in the environment.

IMPORTANCE The viable but nonculturable (VBNC) state of bacteria represents an important life state for their survival in adverse environments. The VBNC cells of the pathogenic bacteria in the environment and food will be a potential threat to public health because these pathogens cannot be found by the detection of culture. We developed a sensitive molecular method to detect and enumerate the VBNC cells of V. cholerae, which can distinguish the VBNC and dead cells, and count the VBNC cells in the sample without the step of DNA extraction from cells. It can be used to improve the sensitivity of pathogen detection in the surveillance, risk assessment of environment and food contamination, and outbreak warning. The accurate identification and numeration of VBNC cells will also facilitate the microbiological and genetic studies on the development, adaptation, resuscitation, and elimination of the VBNC state.

Research progress in the Helicobacter pylori with viable non-culturable state

Helicobacter pylori (H. pylori) is one of the most common pathogens in human beings and it is responsible for diseases such as chronic gastritis, peptic ulcer, and even gastric cancer. Studies in recent years have found that H. Pylori could transform from the normal spiral-shaped bacillary form into the coccoid form and enter a viable but non-culturable (VBNC) state, which may pose a potential threat to public health. In this state,the morphological structure and physiological characteristics of H. Pylori have changed. It can maintain the metabolic activity but protein expression is decreased. And the H. Pylori in this state cannot grow in the culture medium. Conditions such as environmental factors, antibiotics, and inhibitors can induce H. Pylori to enter the VBNC state, but it is still not known whether H. pylori in the VBNC state can reactivate or not. Based on the cell membrane integrity and metabolic activity of H. pylori in the VBNC state, it can be detected by classical methods including direct microscopy of live bacteria and molecular biological methods such as reverse transcription-polymerase chain reaction. H. pylori in the VBNC state has been detected in water source and biological media. It has been also found that H. pylori can enter the VBNC state in artificially contaminated food, which poses challenges to public health and food safety. Therefore, it is of great significance to study the change pattern and detection methods of H. pylori in the VBNC state for the prevention and control of H. pylori in the VBNC state. It is valuable to further study the underlying mechanisms of H. pylori in the VBNC state.

Epidemiology, Diagnosis and Risk Factors of Helicobacter pylori Infection

Helicobacter pylori is a human-specific pathogen, which leads to gastric pathologies including gastric cancer. It is a highly unique bacterium considered as a carcinogenic agent. H. pylori remains a major human health problem, responsible for ~90% of the gastric cancer cases. Approximately four billion individuals have been detected for H. pylori infection worldwide in 2015. At the turn of the twenty-first century, the prevalence of H. pylori has been declining in highly industrialized countries of the Western world, whereas prevalence has plateaued at a high level in developing and newly industrialized countries. However, the infection status remains high in immigrants coming from countries with high prevalence of H. pylori infection. H. pylori can be diagnosed both by invasive and non-invasive methods. Urea breath test and stool antigens detection are among the most commonly used non-invasive ones. Although the way H. pylori is transmitted remains still not fully clear, the level of contamination is strongly dependent on the familial and environmental context, with a drastic impact of living conditions with poor hygiene and sanitation. However, familial socioeconomic status is the main risk factor for H. pylori infection among children. In addition, food and water source have a high impact on the prevalence of H. pylori infection worldwide. This chapter highlights the latest knowledge in the epidemiology of H. pylori infection, its diagnosis and critical risk factors responsible for its high prevalence in some populations and geographic areas.

Helicobacter pylori recrudescence and its influencing factors

Helicobacter pylori (H pylori) is known as one of the most common infectious pathogens, with high infection and recurrence rates worldwide. The prevalence of H pylori is up to 90% in developing countries, while the annual recurrence rate is much higher than that in developed countries. Recurrence can occur either by recrudescence or reinfection. Compared with reinfection, the time window for recrudescence is generally shorter, followed by the recurrence of H pylori–associated diseases in the short‐term. Many factors are involved in the H pylori reinfection, such as the prevalence of H pylori infection, living conditions and economic development, health conditions and so forth. Previous studies focused less on H pylori recrudescence. Therefore, the influencing factors for H pylori recrudescence needed further exploration. This study reviewed the recrudescence of H pylori infection and its influencing factors.

Phenotypic variations in persistence and infectivity between and within environmentally transmitted pathogen populations impact population-level epidemic dynamics

BACKGROUND

Human pathogens transmitted through environmental pathways are subject to stress and pressures outside of the host. These pressures may cause pathogen pathovars to diverge in their environmental persistence and their infectivity on an evolutionary time-scale. On a shorter time-scale, a single-genotype pathogen population may display wide variation in persistence times and exhibit biphasic decay.

METHODS

We use a transmission modeling framework to develop an infectious disease model with biphasic pathogen decay. We take a differential algebra approach to assessing model identifiability, calculate basic reproduction numbers by the next generation method, and use simulation to explore model dynamics.

RESULTS

For both long and short time-scales, we demonstrate that epidemic-potential-preserving trade-offs have implications for epidemic dynamics: less infectious, more persistent pathogens cause epidemics to progress more slowly than more infectious, less persistent (labile) pathogens, even when the overall risk is the same. Using identifiability analysis, we show that the usual disease surveillance data does not sufficiently inform these underlying pathogen population dynamics, even when combined with basic environmental monitoring data. However, risk could be indirectly ascertained by developing methods to separately monitor labile and persistent subpopulations. Alternatively, determining the relative infectivity of persistent pathogen subpopulations and the rates of phenotypic conversion will help ascertain how much disease risk is associated with the long tails of biphasic decay.

CONCLUSION

A better understanding of persistence-infectivity trade-offs and associated dynamics can improve our ecological understanding of environmentally transmitted pathogens, as well as our risk assessment and disease control strategies.

An assessment of drinking water contamination with Helicobacter pylori in Lima, Peru

BACKGROUND

Helicobacter pylori is a gut bacterium that is the primary cause of gastric cancer. H. pylori infection has been consistently associated with lack of access to sanitation and clean drinking water. In this study, we conducted time-series sampling of drinking water in Lima, Peru, to examine trends of H. pylori contamination and other water characteristics.

MATERIALS AND METHODS

Drinking water samples were collected from a single faucet in Lima's Lince district 5 days per week from June 2015 to May 2016, and pH, temperature, free available chlorine, and conductivity were measured. Quantities of H. pylori in all water samples were measured using quantitative polymerase chain reaction. Relationships between the presence/absence and quantity of H. pylori and water characteristics in the 2015-2016 period were examined using regression methods accounting for the time-series design.

RESULTS

Forty-nine of 241 (20.3%) of drinking water samples were contaminated with H. pylori. Statistical analyses identified no associations between sampling date and the likelihood of contamination with H. pylori. Statistically significant relationships were found between lower temperatures and a lower likelihood of the presence of H. pylori (P < .05), as well as between higher pH and higher quantities of H. pylori (P < .05).

CONCLUSIONS

This study has provided evidence of the presence of H. pylori DNA in the drinking water of a single drinking water faucet in the Lince district of Lima. However, no seasonal trends were observed. Further studies are needed to determine the presence of H. pylori in other drinking water sources in other districts in Lima, as well as to determine the viability of H. pylori in these water sources. Such studies would potentially allow for better understanding and estimates of the risk of infection due to exposure to H. pylori in drinking water.

Diversity of virulence genes in Brucella melitensis and Brucella abortus detected from patients with rheumatoid arthritis

The presence of Brucella melitensis and Brucella abortus genomes were investigated in the synovial fluid (SF) samples from 90 patients with rheumatoid arthritis (RA). DNA extraction and PCR assay were performed for simultaneous identification and discrimination of B. melitensis and B. abortus from the SF using three specific primers. After gel electrophoresis, the PCR products were confirmed by DNA sequencing. The cbg, omp31, manA, virB, and znuA virulence genes typing were performed by multiplex-PCR. Of the 90 samples, 14 were positive for B. melitensis (n = 9; 10%) and B. abortus (n = 5; 5.5%). The virulotyping of positive samples revealed the presence of all five virulence genes in B. melitensis. The virB, cbg, and om31 were detected in all five samples of B. abortus. In addition, zhuA and manA were detected in three (60%) and four (80%) samples, respectively, of the B. abortus-positive samples. Moreover, a total of 94.2% and 89.2% of the 14 positive samples were also found positive for manA and znuA, respectively. Our findings revealed that the Brucella spp. genomes can be detected in the SF of RA patients by the PCR-based method. We thus suggest that physicians should consider the Brucella spp. as indicators of potential RA for the timely diagnosis and treatment of RA.