A real-time multiplexed PCR assay for rapid detection and differentiation of Campylobacter jejuni and Campylobacter coli

Simulated gastrointestinal risk from recreational exposure to Southern California stormwater and relationship to human-associated Bacteroidales marker HF183

Stormwater may contain pathogens that pose a health risk to recreators. In this study, we use quantitative microbial risk assessment (QMRA) to simulate the human health risk associated with recreational exposure to stormwater using a regional dataset of pathogen concentrations measured over two wet seasons during wet weather events in Southern California, USA, a location where stormwater and sewage systems are separate. We model risk using a Monte Carlo simulation using Salmonella, Campylobacter, adenovirus, and norovirus concentrations in stormwater, the volume of water ingested during a recreational swimming event, and pathogen-specific dose-response functions. We estimated the median probability of illness from recreational exposure to stormwater to be approximately 190 illnesses per 1000 swimmers (19%). However, stormwater sampling sites are not always designated for recreational use, so we simulated exposures to diluted stormwater, which may be encountered in downstream receiving waters designated for swimming. We determined that if stormwater is diluted 18% into receiving, pathogen-free, ambient waters, the median health risk meets the US EPA's threshold of 32 illnesses per 1000 swimmers. At this dilution, the concentration of HF183, a human-associated fecal marker, is expected to be 100 copies per 100 milliliters. This study provides a risk-based threshold for HF183 concentrations in stormwater-impacted ambient waters from pathogen and indicator concentrations measured in stormwater. Implementing this risk-based threshold will require many policy considerations.

Symptomatic Entamoeba dispar Infections Among Men Who Have Sex With Men, New York City, 2018

Entamoeba histolytica is considered the primary species causing the parasitic gastrointestinal infection amebiasis. A cluster of amebiasis infections was identified in 2018 among men who have sex with men in New York City and was likely caused by Entamoeba dispar, traditionally considered to be nonpathogenic.

Airborne dust and bioaerosols in Canadian conventional and alternative houses for laying hens

Awareness about laying hen welfare has led to the phase-out of conventional battery cages in favor of the adoption of alternative housing systems for egg production in many countries. However, the greater freedom of movement for animals and the presence of manure and litter (sawdust, straw, feathers, etc.) on the floor in some alternative housing systems may be suitable conditions for dusts, bacteria, and fungi to be aerosolized, raising concerns about indoor air quality and respiratory health of workers. The present project aimed at assessing and comparing indoor air quality and bioaerosols in conventional and alternative houses for laying hens. Six were conventional houses (with battery cages), six were enriched colonies, and six were aviary (multi-level cage-free houses) visited in Eastern Canada from 2020-2022. Higher airborne concentrations of particulate matter (PM) from all size fractions (PM1, PM2.5, PM4, PM10, and total dust), culturable bacteria, total endotoxins, and Clostridium perfringens were found in aviaries compared to houses for laying hens in conventional and enriched colonies. Total endotoxin and Clostridium perfringens concentrations were higher in enriched colonies than in conventional laying-hen housing systems. Campylobacter coli, Campylobacter jejuni, and Salmonella sp. were detected in few hen houses. This study highlights possible markers for indoor air quality evaluation inside laying hen houses. These airborne contaminants could be targeted by mitigation strategies to improve indoor air quality in alternative housing systems for laying hens.

Validation and application of high-throughput quantitative PCR for the simultaneous detection of microbial source tracking markers in environmental water

No single microbial source tracking (MST) marker can be applied to determine the sources of fecal pollution in all water types. This study aimed to validate a high-throughput quantitative polymerase chain reaction (HT-qPCR) method for the simultaneous detection of multiple MST markers. A total of 26 fecal-source samples that had been previously collected from human sewage (n = 6) and ruminant (n = 3), dog (n = 6), pig (n = 6), chicken (n = 3), and duck (n = 2) feces in the Kathmandu Valley, Nepal, were used to validate 10 host-specific MST markers, i.e., Bacteroidales (BacHum, gyrB, BacR, and Pig2Bac), mitochondrial DNA (mtDNA) (swine, bovine, and Dog-mtDNA), and viral (human adenovirus, porcine adenovirus, and chicken/turkey parvovirus) markers, via HT-qPCR. Only Dog-mtDNA showed 100 % accuracy. All the tested bacterial markers showed a sensitivity of 100 %. Nine of the 10 markers were further used to identify fecal contamination in groundwater sources (n = 54), tanker filling stations (n = 14), drinking water treatment plants (n = 5), and river water samples (n = 6). The human-specific Bacteroidales marker BacHum and ruminant-specific Bacteroidales marker BacR was detected at a high ratio in river water samples (83 % and 100 %, respectively). The results of HT-qPCR were in agreement with the standard qPCR. The comparable performances of HT-qPCR and standard qPCR as well as the successful detection of MST markers in the fecal-source and water samples demonstrated the potential applicability of these markers for detecting fecal contamination sources via HT-qPCR.

Quantitative microbial risk assessment (QMRA) of the work of manual pit emptiers, commonly known as bayakous

In Haiti, manual pit emptiers, known as bayakous, face significant health risks. They work by descending naked into latrine pits, exposing themselves to pathogens and contributing to environmental contamination. This study employs the quantitative microbial risk assessment (QMRA) method to evaluate the microbial risks associated with this practice, considering nine prevalent pathogens in Haiti. Three ingestion scenarios were developed: hand-to-mouth contact, ingestion while immersed in excreta, and a combination of both. A sensitivity analysis assessed the impact of input data on study outcomes. The results indicate a high probability of infection and illness during pit emptying operations annually for all scenarios and pathogens. Recommendations include adopting personal protective equipment (PPE) and using a manual Gulper waste pump to eliminate the need to descend directly into the pits, thereby reducing the risk of injury from sharp objects. The study proposes the establishment of intermediate disposal points approximately 5 km from collection sites to deter illegal dumping. National regulations and professionalization of the bayakou profession are suggested, along with awareness campaigns to promote PPE and Gulper pump usage. Addressing these issues is crucial for safeguarding the health of bayakou and public health in Haiti.

Exploration of genes associated with induction of the viable but non-culturable state of Campylobacter jejuni

Campylobacter jejuni is known to enter a viable but non-culturable (VBNC) state when exposed to environmental stresses. Microarray and quantitative real-time polymerase chain reaction (qPCR) analyses were performed to elucidate the genes related to the induction of the VBNC state. The C. jejuni NCTC11168 strain was cultured under low-temperature or high-osmotic stress conditions to induce the VBNC state. mRNA expression in the VBNC state was investigated using microarray analysis, and the gene encoding peptidoglycan-associated lipoprotein, Pal, was selected as the internal control gene using qPCR analysis and software. The three genes showing particularly large increases in mRNA expression, cj1500, cj1254, and cj1040, were involved in respiration, DNA repair, and transporters, respectively. However, formate dehydrogenase encoded by cj1500 showed decreased activity in the VBNC state. Taken together, C. jejuni actively changed its mRNA expression during induction of the VBNC state, and protein activities did not always match the mRNA expression levels.

Quantitative microbial risk assessment associated with the use of container-based toilets in Haiti

A container-based toilet (CBT) is a type of ecological toilet that allows users to compost their feces. During emptying, bucket washing, and composting operations, operators are exposed to microbial risks. This paper aims to evaluate these risks using the Quantitative Microbial Risk Assessment (QMRA) method. Nine pathogens prevalent in Haiti were targeted: Ascaris lumbricoides, Campylobacter spp., Cryptosporidium parvum, Escherichia coli O157:H7, Giardia intestinalis, poliovirus, Salmonella spp., Shigella spp., and Vibrio cholerae. Information regarding pathogens' concentration in feces came from scientific literature data. The exposure scenarios considered were those in which operators accidentally ingested a low dose of feces during the aforementioned operations. A Monte Carlo simulation was conducted to address uncertainties. The results showed that the probability of infection is highly elevated, while the probability of illness is generally moderate or minor, except for poliovirus and Ascaris. Preventive measures can be implemented to reduce these risks during various operations, such as wearing gloves, disposable protective masks, and appropriate clothing. It is up to the political authorities to develop guidelines in this regard and to organize awareness-raising activities with the help of local organizations mandated by the relevant authorities to ensure the safer use of technology by households.

Wastewater surveillance beyond COVID-19: a ranking system for communicable disease testing in the tri-county Detroit area, Michigan, USA

Introduction

Throughout the coronavirus disease 2019 (COVID-19) pandemic, wastewater surveillance has been utilized to monitor the disease in the United States through routine national, statewide, and regional monitoring projects. A significant canon of evidence was produced showing that wastewater surveillance is a credible and effective tool for disease monitoring. Hence, the application of wastewater surveillance can extend beyond monitoring SARS-CoV-2 to encompass a diverse range of emerging diseases. This article proposed a ranking system for prioritizing reportable communicable diseases (CDs) in the Tri-County Detroit Area (TCDA), Michigan, for future wastewater surveillance applications at the Great Lakes Water Authority's Water Reclamation Plant (GLWA's WRP).

Methods

The comprehensive CD wastewater surveillance ranking system (CDWSRank) was developed based on 6 binary and 6 quantitative parameters. The final ranking scores of CDs were computed by summing the multiplication products of weighting factors for each parameter, and then were sorted based on decreasing priority. Disease incidence data from 2014 to 2021 were collected for the TCDA. Disease incidence trends in the TCDA were endowed with higher weights, prioritizing the TCDA over the state of Michigan.

Results

Disparities in incidences of CDs were identified between the TCDA and state of Michigan, indicating epidemiological differences. Among 96 ranked CDs, some top ranked CDs did not present relatively high incidences but were prioritized, suggesting that such CDs require significant attention by wastewater surveillance practitioners, despite their relatively low incidences in the geographic area of interest. Appropriate wastewater sample concentration methods are summarized for the application of wastewater surveillance as per viral, bacterial, parasitic, and fungal pathogens.

Discussion

The CDWSRank system is one of the first of its kind to provide an empirical approach to prioritize CDs for wastewater surveillance, specifically in geographies served by centralized wastewater collection in the area of interest. The CDWSRank system provides a methodological tool and critical information that can help public health officials and policymakers allocate resources. It can be used to prioritize disease surveillance efforts and ensure that public health interventions are targeted at the most potentially urgent threats. The CDWSRank system can be easily adopted to geographical locations beyond the TCDA.

Digital Droplet-PCR for Quantification of Viable Campylobacter jejuni and Campylobacter coli in Chicken Meat Rinses

The EU commission established Regulation (2017/1495) in 2017 to reduce Campylobacter on chicken skin and to decrease the number of human cases of campylobacteriosis attributable to the consumption of poultry meat. A Process Hygiene Criterion based on colony-forming unit data was set to a maximum of 1000 CFU Campylobacter spp. per gram chicken neck skin at slaughterhouses. Confronted with stressors, including cold, oxidative stress or antibiotic treatment, live cells may enter into a viable but non-cultivable state (VBNC) and lose the ability to grow, in reference to the plate count ISO 10272-2:2017 method, but still possess the potential to recover and cause infections under favorable conditions. In this study, a droplet digital PCR combined with the intercalating dye propidium monoazide (PMA) was established for quantification of C. coli and C. jejuni in chicken meat rinses. The PMA was used to inactivate DNA from dead cells in this technique. This method was successfully validated against the reference method according to ISO 16140-2:2016 for accuracy and relative trueness. Additionally, it presented a 100% selectivity for Campylobacter jejuni and C. coli. Moreover, the technical measurement uncertainty was determined according to ISO 19036:2019, and the applicability of ddPCR for quantifying C. coli and C. jejuni in chicken meat rinses was investigated on naturally contaminated samples from slaughterhouses and supermarkets. Results obtained from this study demonstrated a strong correlation to qPCR as well as the classical microbiological reference method.

A carvacrol‐based product reduces Campylobacter jejuni load and alters microbiota composition in the caeca of chickens

Aim

This study was conducted to test the ability of a carvacrol‐based formulation (Phodé, France) to decrease the C. jejuni caecal load in inoculated broiler chickens and to study the impact of the C. jejuni inoculation alone or combined with the product, on the caecal microbiota.

Methods and Results

On day 1, chickens were either fed a control feed or the same diet supplemented with a carvacrol‐based product. On day 21, the carvacrol‐supplemented chickens and half of the non‐supplemented chickens were inoculated with C. jejuni (10⁸ CFU). Quantitative PCR was used to quantify C. jejuni in chicken caecal samples and 16S rRNA gene sequencing was carried out at 25, 31 and 35 days of age. A significant decrease of 1.4 log of the C. jejuni caecal load was observed in 35‐day‐old chickens supplemented with the product, compared to the inoculated and unsupplemented group (p < 0.05). The inoculation with C. jejuni significantly increased the population richness, Shannon and Simpson diversity and altered beta‐diversity. Compared to the control group, the C. jejuni inoculation causes significant changes in the microbiota. The carvacrol‐based product associated with C. jejuni inoculation increased the diversity and strongly modified the structure of the microbial community. Functional analysis by 16S rRNA gene‐based predictions further revealed that the product up‐regulated the pathways involved in the antimicrobial synthesis, which could explain its shaping effect on the caecal microbiota.

Conclusions

Our study confirmed the impairment of the caecal bacterial community after inoculation and demonstrated the ability of the product to reduce the C. jejuni load in chickens. Further investigations are needed to better understand the mode of action of this product to promote the installation of a beneficial microbiota to its host.

Significance and Impact of the Study

Results suggested that this product could be promising to control C. jejuni contamination of broilers.

Molecular Methods for Pathogenic Bacteria Detection and Recent Advances in Wastewater Analysis

With increasing concerns about public health and the development of molecular techniques, new detection tools and the combination of existing approaches have increased the abilities of pathogenic bacteria monitoring by exploring new biomarkers, increasing the sensitivity and accuracy of detection, quantification, and analyzing various genes such as functional genes and antimicrobial resistance genes (ARG). Molecular methods are gradually emerging as the most popular detection approach for pathogens, in addition to the conventional culture-based plate enumeration methods. The analysis of pathogens in wastewater and the back-estimation of infections in the community, also known as wastewater-based epidemiology (WBE), is an emerging methodology and has a great potential to supplement current surveillance systems for the monitoring of infectious diseases and the early warning of outbreaks. However, as a complex matrix, wastewater largely challenges the analytical performance of molecular methods. This review synthesized the literature of typical pathogenic bacteria in wastewater, types of biomarkers, molecular methods for bacterial analysis, and their recent advances in wastewater analysis. The advantages and limitation of these molecular methods were evaluated, and their prospects in WBE were discussed to provide insight for future development.

Rapid determination of viable but non-culturable Campylobacter jejuni in food products by loop-mediated isothermal amplification coupling propidium monoazide treatment

Campylobacter is the leading cause of foodborne human diarrhea worldwide. This microbe in the viable but non-culturable (VBNC) state can evade detection by routinely used culture-based methods and remain viable for extended periods of time. Bacteria in this dormancy state can resume their metabolic activity and virulence by resuscitation under favorable conditions, and subsequently cause infections. In this study, an assay combining loop-mediated isothermal amplification (LAMP) and propidium monoazide (PMA) treatment was developed for the detection and quantification of VBNC C. jejuni in agri-foods. PMA-qLAMP targeting the hipO gene demonstrated 100% high specificity to C. jejuni. A linear detection of C. jejuni was achieved between 8.77 × 102 and 8.77 × 07 CFU/mL with a coefficient of determination (R2) of 0.9956, indicating a good quantitative capacity. C. jejuni was effectively induced into the VBNC state by osmotic stress (i.e., 7% NaCl, w/v) over 48 h. VBNC C. jejuni cells were spiked into three representative food products and determined by PMA-qLAMP coupled with plating assay. The detection limits of PMA-qLAMP were 1.58 × 102 CFU/mL in milk, 3.78 × 102 CFU/g in chicken breast meat, and 4.33 × 102 CFU/g in romaine lettuce. PMA-qLAMP demonstrated rapid (25-40 min), specific (100% inclusivity and 100% exclusivity) and sensitive (~102 CFU/mL) determination of VBNC C. jejuni. This method can be applied in the agri-food industry to decrease the risks related to the consumption of contaminated agri-foods with pathogenic bacteria in the VBNC state and reduce the burden of C. jejuni infections to public health.

Water and microbial monitoring technologies towards the near future space exploration

Space exploration is demanding longer lasting human missions and water resupply from Earth will become increasingly unrealistic. In a near future, the spacecraft water monitoring systems will require technological advances to promptly identify and counteract contingent events of waterborne microbial contamination, posing health risks to astronauts with lowered immune responsiveness. The search for bio-analytical approaches, alternative to those applied on Earth by cultivation-dependent methods, is pushed by the compelling need to limit waste disposal and avoid microbial regrowth from analytical carryovers. Prospective technologies will be selected only if first validated in a flight-like environment, by following basic principles, advantages, and limitations beyond their current applications on Earth. Starting from the water monitoring activities applied on the International Space Station, we provide a critical overview of the nucleic acid amplification-based approaches (i.e., loop-mediated isothermal amplification, quantitative PCR, and high-throughput sequencing) and early-warning methods for total microbial load assessments (i.e., ATP-metry, flow cytometry), already used at a high readiness level aboard crewed space vehicles. Our findings suggest that the forthcoming space applications of mature technologies will be necessarily bounded by a compromise between analytical performances (e.g., speed to results, identification depth, reproducibility, multiparametricity) and detrimental technical requirements (e.g., reagent usage, waste production, operator skills, crew time). As space exploration progresses toward extended missions to Moon and Mars, miniaturized systems that also minimize crew involvement in their end-to-end operation are likely applicable on the long-term and suitable for the in-flight water and microbiological research.

Whole genome sequencing reveals extended natural transformation in Campylobacter impacting diagnostics and the pathogens adaptive potential

Campylobacter is the major bacterial agent of human gastroenteritis worldwide and represents a crucial global public health burden. Species differentiation of C. jejuni and C. coli and phylogenetic analysis is challenged by inter-species horizontal gene transfer. Routine real-time PCR on more than 4000 C. jejuni and C. coli field strains identified isolates with ambiguous PCR results for species differentiation, in particular, from the isolation source eggs. K-mer analysis of whole genome sequencing data indicated the presence of C. coli hybrid strains with huge amounts of C. jejuni introgression. Recombination events were distributed over the whole chromosome. MLST typing was impaired, since C. jejuni sequences were also found in six of the seven housekeeping genes. cgMLST suggested that the strains were phylogenetically unrelated. Intriguingly, the strains shared a stress response set of C. jejuni variant genes, with proposed roles in oxidative, osmotic and general stress defence, chromosome maintenance and repair, membrane transport, cell wall and capsular biosynthesis and chemotaxis. The results have practical impact on routine typing and on the understanding of the functional adaption to harsh environments, enabling successful spreading and persistence of Campylobacter.

Viability Quantitative PCR Utilizing Propidium Monoazide, Spheroplast Formation, and Campylobacter coli as a Bacterial Model

A viability quantitative PCR (qPCR) utilizing propidium monoazide (PMA) is presented for rapid quantification of viable cells using the foodborne pathogen Campylobacter coli as a bacterial model. It includes optimized spheroplast formation via lysozyme and EDTA, induction of a mild osmotic shock for enhancing the selective penetration of PMA into dead cells, and exploitation of an internal sample process control (ISPC) involving cell inactivation to assess residual false-positive signals within each sample. Spheroplasting of bacteria in exponential phase did not permit PMA entrance into viable cells since a strong linear relationship was detected between simple qPCR and PMA-qPCR quantification, and no differences were observed regardless of whether spheroplasting was utilized. The PMA-qPCR signal suppression of dead cells was elevated using spheroplast formation. With regard to the ISPC, cell inactivation by hydrogen peroxide resulted in higher signal suppression during qPCR than heat inactivation did. Viability quantification of C. coli cells by optimized spheroplasting-PMA-qPCR with ISPC was successfully applied in an aging pure culture under aerobic conditions and artificially inoculated meat. The same method exhibited a high linear range of quantification (1.5 to 8.5 log10 viable cells ml-1), and results were highly correlated with culture-based enumeration. PMA-qPCR quantification of viable cells can be affected by their rigidity, age, culture media, and niches, but spheroplast formation along with osmotic shock and the use of a proper ISPC can address such variations. The developed methodology could detect cells in a viable-but-nonculturable state and might be utilized for the quantification of other Gram-negative bacteria.IMPORTANCE There is need for rapid and accurate methods to detect viable bacterial cells of foodborne pathogens. Conventional culture-based methods are time-consuming and unable to detect bacteria in a viable-but-nonculturable state. The high sensitivity and specificity of the quantitative PCR (qPCR) are negated by its inability to differentiate the DNAs from viable and dead cells. The combination of propidium monoazide (PMA), a DNA-intercalating dye, with qPCR assays is promising for detection of viable cells. Despite encouraging results, these assays still encounter various challenges, such as false-positive signals by dead cells and the lack of an internal control identifying these signals per sample. The significance of our research lies in enhancing the selective entrance of PMA into dead Campylobacter coli cells via spheroplasting and in developing an internal sample process control, thus delivering reliable results in pure cultures and meat samples, approaches that can be applicable to other Gram-negative pathogens.

Evaluation of Two Multiplex PCR-High-Resolution Melt Curve Analysis Methods for Differentiation of Campylobacter jejuni and Campylobacter coli Intraspecies

Campylobacter infection is a common cause of bacterial gastroenteritis in humans and remains a significant global public health issue. The capability of two multiplex PCR (mPCR)-high-resolution melt (HRM) curve analysis methods (i.e., mPCR1-HRM and mPCR2-HRM) to detect and differentiate 24 poultry isolates and three reference strains of Campylobacter jejuni and Campylobacter coli was investigated. Campylobacter jejuni and C. coli were successfully differentiated in both assays, but the differentiation power of mPCR2-HRM targeting the cadF gene was found superior to that of mPCR1-HRM targeting the gpsA gene or a hypothetical protein gene. However, higher intraspecies variation within C. coli and C. jejuni isolates was detected in mPCR1-HRM when compared with mPCR2-HRM. Both assays were rapid and required minimum interpretation skills for discrimination between and within Campylobacter species when using HRM curve analysis software.

Chemical and microbial characteristics of municipal drinking water supply systems in the Canadian Arctic

Drinking water in the vast Arctic Canadian territory of Nunavut is sourced from surface water lakes or rivers and transferred to man-made or natural reservoirs. The raw water is at a minimum treated by chlorination and distributed to customers either by trucks delivering to a water storage tank inside buildings or through a piped distribution system. The objective of this study was to characterize the chemical and microbial drinking water quality from source to tap in three hamlets (Coral Harbour, Pond Inlet and Pangnirtung-each has a population of <2000) on trucked service, and in Iqaluit (population ~6700), which uses a combination of trucked and piped water conveyance. Generally, the source and drinking water was of satisfactory microbial quality, containing Escherichia coli levels of <1 MPN/100 mL with a few exceptions, and selected pathogenic bacteria and parasites were below detection limits using quantitative polymerase chain reaction (qPCR) methods. Tap water in households receiving trucked water contained less than the recommended 0.2 mg/L of free chlorine, while piped drinking water in Iqaluit complied with Health Canada guidelines for residual chlorine (i.e. >0.2 mg/L free chlorine). Some buildings in the four communities contained manganese (Mn), copper (Cu), iron (Fe) and/or lead (Pb) concentrations above Health Canada guideline values for the aesthetic (Mn, Cu and Fe) and health (Pb) objectives. Corrosion of components of the drinking water distribution system (household storage tanks, premise plumbing) could be contributing to Pb, Cu and Fe levels, as the source water in three of the four communities had low alkalinity. The results point to the need for robust disinfection, which may include secondary disinfection or point-of-use disinfection, to prevent microbial risks in drinking water tanks in buildings and ultimately at the tap.

Pharmacokinetic and antimicrobial activity of a new carvacrol-based product against a human pathogen, Campylobacter jejuni

AIM

In vitro and in vivo studies were conducted to test a new carvacrol-based product designed to delay the carvacrol release so that it could reach the caeca of broiler chickens in order to control Campylobacter jejuni.

METHODS AND RESULTS

Antimicrobial activity of carvacrol, a constituent of oregano and thyme essential oil, has been demonstrated against C. jejuni in vitro, and this compound was found beneficial for broiler growth. Here, we tested a new liquid formulation that did not change the antibacterial efficacy of carvacrol against C. jejuni in vitro, as assessed by broth microdilution. The mode of action of carvacrol also remained unchanged as illustrated by electronic microscopy. A pharmacokinetic assay monitored carvacrol of the solid galenic formulation in the avian digestive tract and this showed that this compound was mainly found in the last part (caeca, large intestine) and in the droppings. Extremely low concentrations of free carvacrol were present in blood plasma, with larger amounts of carvacrol metabolites: carvacrol glucuronide and sulphate. A qPCR analysis showed that the solid galenic form of carvacrol added at 5 kg per tonne of food (i.e. 9·5 mg of carvacrol per kg of bodyweight per day) significantly decreased the C. jejuni caecal load by 1·5 log.

CONCLUSIONS

The new liquid formulation was as effective as unformulated carvacrol in vitro. In vivo the solid galenic form seems to delay the carvacrol release into the caeca and presented interesting results on C. jejuni load after 35 days.

SIGNIFICANCE AND IMPACT OF THE STUDY

Results suggested that this product could be promising to control Campylobacter contamination of broilers.

Zoonotic Fecal Pathogens and Antimicrobial Resistance in Canadian Petting Zoos

This study aimed to better understand the potential public health risk associated with zoonotic pathogens in agricultural fairs and petting zoos in Canada. Prevalence of Salmonella, Shiga toxin-producing Escherichia coli (STEC) O157:H7, and top six non-O157 STEC serogroups in feces (n = 88), hide/feather (n = 36), and hand rail samples (n = 46) was assessed, as well as distributions of antimicrobial resistant (AMR) broad and extended-spectrum β-lactamase (ESBL)-producing E. coli. Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in pig nasal swabs (n = 4), and Campylobacter, Cryptosporidium, and Giardia in feces was also assessed. Neither Salmonella nor MRSA were detected. Campylobacter spp. were isolated from 32% of fecal samples. Cryptosporidium and Giardia were detected in 2% and 15% of fecal samples, respectively. Only one fecal sample was positive for STEC O157, whereas 22% were positive for non-O157 STEC. Multi-drug resistance (MDR) to antibiotics classified as critically and highly important in human medicine was proportionally greatest in E. coli from cattle feces. The β-lactamase-producing E. coli from pig, horse/donkey feces, and hand rail samples, as well as the STEC E. coli from handrail swabs were MDR. The diversity and prevalence of zoonotic pathogens and AMR bacteria detected within agricultural fairs and petting zoos emphasize the importance of hygienic practices and sanitization with respect to reducing associated zoonotic risks.

Quantification of pathogens and markers of fecal contamination during storm events along popular surfing beaches in San Diego, California

Along southern California beaches, the concentrations of fecal indicator bacteria (FIB) used to quantify the potential presence of fecal contamination in coastal recreational waters have been previously documented to be higher during wet weather conditions (typically winter or spring) than those observed during summer dry weather conditions. FIB are used for management of recreational waters because measurement of the bacterial and viral pathogens that are the potential causes of illness in beachgoers exposed to stormwater can be expensive, time-consuming, and technically difficult. Here, we use droplet digital Polymerase Chain Reaction (digital PCR) and digital reverse transcriptase PCR (digital RT-PCR) assays for direct quantification of pathogenic viruses, pathogenic bacteria, and source-specific markers of fecal contamination in the stormwater discharges. We applied these assays across multiple storm events from two different watersheds that discharge to popular surfing beaches in San Diego, CA. Stormwater discharges had higher FIB concentrations as compared to proximal beaches, often by ten-fold or more during wet weather. Multiple lines of evidence indicated that the stormwater discharges contained human fecal contamination, despite the presence of separate storm sewer and sanitary sewer systems in both watersheds. Human fecal source markers (up to 100% of samples, 20-12440 HF183 copies per 100 ml) and human norovirus (up to 96% of samples, 25-495 NoV copies per 100 ml) were routinely detected in stormwater discharge samples. Potential bacterial pathogens were also detected and quantified: Campylobacter spp. (up to 100% of samples, 16-504 gene copies per 100 ml) and Salmonella (up to 25% of samples, 6-86 gene copies per 100 ml). Other viral human pathogens were also measured, but occurred at generally lower concentrations: adenovirus (detected in up to 22% of samples, 14-41 AdV copies per 100 ml); no enterovirus was detected in any stormwater discharge sample. Higher concentrations of avian source markers were noted in the stormwater discharge located immediately downstream of a large bird sanctuary along with increased Campylobacter concentrations and notably different Campylobacter species composition than the watershed that had no bird sanctuary. This study is one of the few to directly measure an array of important bacterial and viral pathogens in stormwater discharges to recreational beaches, and provides context for stormwater-based management of beaches during high risk wet-weather periods. Furthermore, the combination of culture-based and digital PCR-derived data is demonstrated to be valuable for assessing hydrographic relationships, considering delivery mechanisms, and providing foundational exposure information for risk assessment.

Microfluidic quantification of multiple enteric and opportunistic bacterial pathogens in roof-harvested rainwater tank samples

Potable and non-potable uses of roof-harvested rainwater (RHRW) are increasing due to water shortages. To protect human health risks, it is important to identify and quantify disease-causing pathogens in RHRW so that appropriate treatment options can be implemented. We used a microfluidic quantitative PCR (MFQPCR) system for the quantitative detection of a wide array of fecal indicator bacteria (FIB) and pathogens in RHRW tank samples along with culturable FIB and conventional qPCR analysis of selected pathogens. Among the nine pathogenic bacteria and their associated genes tested with the MFQPCR, 4.86 and 2.77% samples were positive for Legionella pneumophila and Shigella spp., respectively. The remaining seven pathogens were absent. MFQPCR and conventional qPCR results showed good agreement. Therefore, direct pathogen quantification by MFQPCR systems may be advantageous for circumstances where a thorough microbial analysis is required to assess the public health risks from multiple pathogens that occur simultaneously in the target water source.

Prevalence of most common human pathogenic Campylobacter spp. in dogs and cats in Styria, Austria

The aim of this study was to determine the frequency of occurrence of most common human pathogenic Campylobacter species, Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli), in dogs and cats in Styria, Austria. In the period from April 2010 to April 2012, 842 faecal samples from dogs and cats from Styria, Austria were examined for Campylobacter (C.) species (spp.). All samples were subjected to qualitative microbiological culture testing, and additionally, some of them have been studied using qualitative real‐time PCR. In microbiological culture, 5.9% of all samples investigated were C. spp. positive. With 3.1% out of positive samples, C. jejuni was the most common type. Campylobacter upsaliensis (C. upsaliensis) was detected only in 0.5% of the samples. The remaining positive samples (2.4%) were classified as C. species (sp.). C. coli could not be found in any of the samples. A higher prevalence of C. jejuni was found in kittens with 14.3% and in diarrhoeic dogs (7.4%) and cats (23.8%). The real‐time PCR revealed for dogs and cats together, 27% of C. jejuni‐positive faecal and 8% positive faecal swap samples. The obtained C. jejuni strains underwent antibiotic resistance testing using three different tests (agar diffusion, MIC testing and E‐test) with different numbers of antibiotics. From the antibiotics used in this study, several showed high test‐dependent resistance rates (cephalexin, cefovecin, kanamycin, sulfamethoxazole/trimethoprim, penicillin G, ciprofloxacin, enrofloxacin, marbofloxacin, nalidixic acid). Overall, the prevalence of C. spp. in this study was very low compared to others, with the exception of C. jejuni in kittens and diarrhoeic animals. The results of the real‐time PCR suggest that the rate of colonization of C. jejuni was actually higher than the results of the culture showed. As the resistance rates of C. jejuni isolates partly were very high, possible transmission of (multi‐) resistant C. jejuni strains to humans especially from kittens and diarrhoeic animals must be expected.

Incidence of gastrointestinal illness following wet weather recreational exposures: Harmonization of quantitative microbial risk assessment with an epidemiologic investigation of surfers

We modeled the risk of gastrointestinal (GI) illness associated with recreational exposures to marine water following storm events in San Diego County, California. We estimated GI illness risks via quantitative microbial risk assessment (QMRA) techniques by consolidating site specific pathogen monitoring data of stormwater, site specific dilution estimates, literature-based water ingestion data, and literature based pathogen dose-response and morbidity information. Our water quality results indicated that human sources of contamination contribute viral and bacterial pathogens to streams draining an urban watershed during wet weather that then enter the ocean and affect nearshore water quality. We evaluated a series of approaches to account for uncertainty in the norovirus dose-response model selection and compared our model results to those from a concurrently conducted epidemiological study that provided empirical estimates for illness risk following ocean exposure. The preferred norovirus dose-response approach yielded median risk estimates for water recreation-associated illness (15 GI illnesses per 1000 recreation events) that closely matched the reported epidemiological results (12 excess GI illnesses per 1000 wet weather recreation events). The results are consistent with norovirus, or other pathogens associated with norovirus, as an important cause of gastrointestinal illness among surfers in this setting. This study demonstrates the applicability of QMRA for recreational water risk estimation, even under wet weather conditions and describes a process that might be useful in developing site-specific water quality criteria in this and other locations.

β-Resorcylic Acid, a Phytophenolic Compound, Reduces Campylobacter jejuni in Postharvest Poultry

Human Campylobacter infections, a leading foodborne illness globally, has been linked with the high prevalence of this bacterium on raw retail chicken products. Reduction of Campylobacter counts on poultry products would greatly reduce the risk of subsequent infections in humans. To this end, this study investigated the potential of the phytophenolic compound β-resorcylic acid (BR) to reduce Campylobacter counts on postharvest poultry (chicken skin or meat). Four trials in total, two each on thigh skin or breast meat, were conducted in which chicken skin or meat samples (2 ± 0.1 g; 10 samples per treatment) were inoculated with 50 μL (∼10⁶ CFU per sample) of a cocktail of four wild strains of C. jejuni. After 30 min of attachment, inoculated samples were dipped in a 0, 0.5, 1, or 2% BR solution for 30 s immediately followed by vigorously vortexing the samples in Butterfield's phosphate diluent and plating the supernatant for Campylobacter enumeration. In addition, the effect of BR on the color of skin and meat samples was studied. Moreover, the change in the expression of survival and virulence genes of C. jejuni exposed to BR was evaluated. Data were analyzed by the PROC MIXED procedure of SAS (P < 0.05; SAS Institute Inc., Cary, NC). All BR treatments significantly reduced Campylobacter populations on both chicken or meat samples by 1 to 3 log CFU/g compared with non-BR-treated washed controls. No significant difference in the lightness, redness, and yellowness of skin and meat samples was observed on exposure to BR wash (P > 0.05). Real-time PCR results revealed that BR treatment down-regulated expression of select genes coding for motility (motA, motB) and attachment (cadF, ciaB) in the majority of C. jejuni strains. Stress response genes (sodB, katA) were upregulated in C. jejuni S-8 (P < 0.05). Overall, our results suggest that BR could be effectively used as antimicrobial dip treatment during poultry processing for reducing Campylobacter on chicken carcasses.

Simultaneous Identification of Campylobacter jejuni, Campylobacter coli, and Campylobacter lari with SmartCycler-Based Multiplex Quantitative Polymerase Chain Reaction

BACKGROUND

Consumption of Campylobacter contaminated food or water is a leading cause of human acute gastroenteritis. Campylobacter jejuni, Campylobacter coli, and Campylobacter lari account for over 95% of total Campylobacter infections. A multiplex quantitative polymerase chain reaction (qPCR) for simultaneous identification of C. jejuni, C. coli, and C. lari was developed for use with the SmartCycler II system.

MATERIALS AND METHODS

We evaluated and combined previously described primers and probes for Campylobacter detection, designed a new internal amplification control, and optimized the multiplex qPCR for the detection of C. jejuni, C. coli, and C. lari.

RESULTS

This method was 100% specific when tested against a panel of 32 target Campylobacter strains and 31 non-Campylobacter reference strains. Furthermore, there was no cross-reactivity with seven strains from four nontarget Campylobacter species. The amplification efficiency of each target in this multiplex qPCR was over 90%, and each coefficient of linearity was greater than 0.99. With artificially mixed genomic DNA, this method detected as few as two, three, and two genome copies of C. jejuni, C. coli, and C. lari, respectively. This method was also able to detect these three Campylobacter species in artificially contaminated milk with a sensitivity of five spiked cells of each target per reaction.

CONCLUSION

The three Campylobacter targets were simultaneously identified using artificially mixed genomic DNA and spiked raw milk. This SmartCycler-based multiplex qPCR is a rapid, specific, and sensitive method to identify C. jejuni, C. coli, and C. lari.

Isolation, identification and differentiation of Campylobacter spp. using multiplex PCR assay from goats in Khartoum State, Sudan

The aim of this study was to identify and characterize thermophilic Campylobacter species in faecal samples from goats in Khartoum State, Sudan, by application of multiplex polymerase chain reaction. Campylobacteriosis is a zoonotic disease of global concern, and the organisms can be transmitted to human via food, water and through contact with farm animals and pets. There are five clinically related Campylobacter species: Campylobacter jejuni (C. jejuni). Campylobacter coli, Campylobacter lari, Campylobacter upsaliensis and Campylobacter fetus. Conventional cultural methods to diagnose campylobacteriosis are tedious and time consuming. Wide ranges of genes have been reported to be used for PCR-based identification of Campylobacter spp. We used a multiplex PCR assay to simultaneously detect genes from the major five clinically significant Campylobacter spp. The genes selected were hipO (hippuricase) and 23S rRNA from glyA (serine hydroxymethyl transferase) from each of C. jejuni. C. coli, C. lari, and C. upsaliensis; and sapB2 (surface layer protein) from C. fetus subsp. fetus. The assay was used to identify Campylobacter isolates recovered from 336 cultured faecal samples from goats in three localities in Khartoum State. C. coli was the most predominant isolate (234; 69.6%), followed by C. jejuni (19; 5.7%), C. upsaliensis (13; 3.9%), C. fetus subsp. fetus (7; 2.1%) and C. lari (6; 1.8%). Twenty-nine goats showed mixed infection with Campylobacter spp., 21 of which harbored two Campylobacter spp., while eight animals were infected with three species. Ten out of twelve goats that displayed diarrhea harbored C. coli only. C. coli, C. jejuni and C. upsaliensis showed significant variation with localities. The prevalence of C. coli was significantly higher (87; 25.9%) in goats from Omdurman, whereas C. jejuni and C. upsaliensis were significantly higher (11; 3.3%, 9; 2.7%) in goats from Khartoum. The multiplex PCR assay was found to be rapid and easy to perform and had a high sensitivity and specificity for characterizing the isolates, even in mixed cultures. The study demonstrated the significance of goats as reservoirs in the dissemination of Campylobacter spp. which could be considered as potential agent of caprine enteritis and abortion as well as contamination of the wider environment posing serious public health concern in Khartoum State.

Antibiotic Resistance of Campylobacter Recovered from Faeces and Carcasses of Healthy Livestock

Campylobacter is of major significance in food safety and human and veterinary medicine. This study highlighted resistance situation in the area of veterinary public health in Ghana. Using selective mCCDA agar, isolates were confirmed phenotypically on API CAMPY and genotypically by multiplex PCR of IpxA gene. The susceptibility profile of species to common and relevant antibiotics was determined by the Kirby-Bauer disk diffusion method. Cattle, sheep, goat, and pig faecal samples analysed, respectively, yielded 13.2% (16/121), 18.6% (22/102), 18.5% (25/135), and 28.7% (29/101) Campylobacter species while 34.5% (38/110), 35.9% (42/117), 23.9% (32/134), and 36.3% (37/102) were, respectively, recovered from the carcasses. Species identified in faeces were C. jejuni 35.8% (33/92), C. jejuni subsp. doylei 4.3% (4/92), C. coli 47.8% (44/92), and C. lari 12.0% (11/92). Species discovered in carcasses were C. jejuni 83.9% (125/149), C. jejuni subsp. doylei 2.0% (3/149), C. coli 6.0% (9/149), and C. lari 8.1% (12/149). Resistance ranged from 92 to 97% to the β-lactams, 7 to 69% to the quinolones, 0 to 44% to the aminoglycosides, 97 to 100% to erythromycin, 48 to 94% to tetracycline, 45 to 88% to chloramphenicol, and 42 to 86% to trimethoprim/sulfamethoxazole as 0% resistance was observed against imipenem.

Evaluation of Luminex xTAG Gastrointestinal Pathogen Panel Assay for Detection of Multiple Diarrheal Pathogens in Fecal Samples in Vietnam

Diarrheal disease is a complex syndrome that remains a leading cause of global childhood morbidity and mortality. The diagnosis of enteric pathogens in a timely and precise manner is important for making treatment decisions and informing public health policy, but accurate diagnosis is a major challenge in industrializing countries. Multiplex molecular diagnostic techniques may represent a significant improvement over classical approaches. We evaluated the Luminex xTAG gastrointestinal pathogen panel (GPP) assay for the detection of common enteric bacterial and viral pathogens in Vietnam. Microbiological culture and real-time PCR were used as gold standards. The tests were performed on 479 stool samples collected from people admitted to the hospital for diarrheal disease throughout Vietnam. Sensitivity and specificity were calculated for the xTAG GPP for the seven principal diarrheal etiologies. The sensitivity and specificity for the xTAG GPP were >88% for Shigellaspp.,Campylobacterspp., rotavirus, norovirus genotype 1/2 (GI/GII), and adenovirus compared to those of microbiological culture and/or real-time PCR. However, the specificity was low (∼60%) for Salmonella species. Additionally, a number of important pathogens that are not identified in routine hospital procedures in this setting, such as Cryptosporidiumspp. and Clostridium difficile, were detected with the GPP. The use of the Luminex xTAG GPP for the detection of enteric pathogens in settings, like Vietnam, would dramatically improve the diagnostic accuracy and capacity of hospital laboratories, allowing for timely and appropriate therapy decisions and a wider understanding of the epidemiology of pathogens associated with severe diarrheal disease in low-resource settings.

ERIC-PCR Genotyping of Some Campylobacter jejuni Isolates of Chicken and Human Origin in Egypt

The public health importance of the genus Campylobacter is attributed to several species causing diarrhea in consumers. Poultry and their meat are considered the most important sources of human campylobacteriosis. In this study, 287 samples from chicken (131 cloacal swabs, 39 chicken skin, 78 chicken meat, and 39 cecal parts) obtained from retail outlets as well as 246 stool swabs from gastroenteritis patients were examined. A representative number of the biochemically identified Campylobacter jejuni isolates were identified by real-time PCR, confirming the identification of the isolates as C. jejuni. Genotyping of the examined isolates (n = 31) by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) revealed a high discriminatory index of ERIC-PCR (D = 0.948), dividing C. jejuni isolates of chicken and human origins into 18 profiles and four clusters. The 18 profiles obtained indicated the heterogeneity of C. jejuni. Dendrogram analysis showed that four clusters were generated; all human isolates fell into clusters I and III. These observations further support the existence of a genetic relationship between human and poultry isolates examined in the present study. In conclusion, the results obtained support the speculation that poultry and poultry meat have an important role as sources of infection in the acquisition of Campylobacter infection in humans.

Effects of dietary fats rich in lauric and myristic acid on performance, intestinal morphology, gut microbes, and meat quality in broilers

This study investigated the hypothesis that dietary fats rich in lauric (C12) and myristic acid (C14) increase broiler performance and that the underlying mechanism involves antimicrobial effects on gut bacteria and changes in gut morphology. One hundred eighty 1-day-old Cobb-500 broilers were allotted to 3 groups. All groups received a basal diet consisting of maize, wheat, soybean meal, and a fat source (4.5, 7.0, 7.6, and 8.0% of fat product in the diet during d 1 to 9, 10 to 17, 18 to 27, and 28 to 35, respectively) until 35 d of age. The diet of the control group contained a fat with 67% of oleic and linoleic acid and 1.4% of C12 and C14 of total fatty acids, that of the esterified lauric and myristic acid (ELA) group a fat with 33% of esterified C12 and C14 and that of the free lauric and myristic acid (FLA) group a fat with 31% of both esterified and free (1:1) C12 and C14 (6 replicates/treatment, 10 birds/replicate). Gain and feed consumption did not differ between groups, but feed:gain was lower in FLA group as compared to the control group (P < 0.05). Carcass weight, liver weight, triglyceride content of liver and muscle, and muscle cholesterol were similar between groups; however, breast muscle weight was higher in the FLA than in the control group (P < 0.05). The villus height:crypt depth ratio of the duodenal wall did not differ between groups, but in the jejunum, it was lower in the FLA group as compared to the control group (P < 0.05). DNA copy numbers of Lactobacillus, Bifidobacteria, Enterobacteria, Escherichia coli, and Campylobacter jejuni in jejunal digesta were similar among groups. The study shows that dietary fats rich in free C12 and C14 improved feed:gain and breast muscle yield, but the observed effects could not be conclusively explained based on the parameters measured. The decreased jejunal villi:crypt ratio may point to changes in gut protein or cell turnover.

Waterborne pathogens: detection methods and challenges

Waterborne pathogens and related diseases are a major public health concern worldwide, not only by the morbidity and mortality that they cause, but by the high cost that represents their prevention and treatment. These diseases are directly related to environmental deterioration and pollution. Despite the continued efforts to maintain water safety, waterborne outbreaks are still reported globally. Proper assessment of pathogens on water and water quality monitoring are key factors for decision-making regarding water distribution systems’ infrastructure, the choice of best water treatment and prevention waterborne outbreaks. Powerful, sensitive and reproducible diagnostic tools are developed to monitor pathogen contamination in water and be able to detect not only cultivable pathogens but also to detect the occurrence of viable but non-culturable microorganisms as well as the presence of pathogens on biofilms. Quantitative microbial risk assessment (QMRA) is a helpful tool to evaluate the scenarios for pathogen contamination that involve surveillance, detection methods, analysis and decision-making. This review aims to present a research outlook on waterborne outbreaks that have occurred in recent years. This review also focuses in the main molecular techniques for detection of waterborne pathogens and the use of QMRA approach to protect public health.

The epidemiology and aetiology of diarrhoeal disease in infancy in southern Vietnam: a birth cohort study

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The diarrhoeal disease burden in a large, prospective infant cohort in Vietnam is defined.

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Minimum incidence of clinic-based diarrhoea in infants: 271/1000 infant-years.

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Rotavirus was most commonly identified, followed by norovirus and bacterial pathogens.

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Frequent repeat infections with the same pathogen within 1 year.

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Inclusion of rotavirus in the immunization schedule for Vietnam is warranted.

Objectives

Previous studies indicate a high burden of diarrhoeal disease in Vietnamese children, however longitudinal community-based data on burden and aetiology are limited. The findings from a large, prospective cohort study of diarrhoeal disease in infants in southern Vietnam are presented herein.

Methods

Infants were enrolled at birth in urban Ho Chi Minh City and a semi-rural district in southern Vietnam, and followed for 12 months (n = 6706). Diarrhoeal illness episodes were identified through clinic-based passive surveillance, hospital admissions, and self-reports.

Results

The minimum incidence of diarrhoeal illness in the first year of life was 271/1000 infant-years of observation for the whole cohort. Rotavirus was the most commonly detected pathogen (50% of positive samples), followed by norovirus (24%), Campylobacter (20%), Salmonella (18%), and Shigella (16%). Repeat infections were identified in 9% of infants infected with rotavirus, norovirus, Shigella, or Campylobacter, and 13% of those with Salmonella infections.

Conclusions

The minimum incidence of diarrhoeal disease in infants in both urban and semi-rural settings in southern Vietnam was quantified prospectively. A large proportion of laboratory-diagnosed disease was caused by rotavirus and norovirus. These data highlight the unmet need for a rotavirus vaccine in Vietnam and provide evidence of the previously unrecognized burden of norovirus in infants.

Molecular-based approaches to characterize coastal microbial community and their potential relation to the trophic state of Red Sea

Molecular-based approaches were used to characterize the coastal microbiota and to elucidate the trophic state of Red Sea. Nutrient content and enterococci numbers were monitored, and used to correlate with the abundance of microbial markers. Microbial source tracking revealed the presence of >1 human-associated Bacteroides spp. at some of the near-shore sampling sites and at a heavily frequented beach. Water samples collected from the beaches had occasional exceedances in enterococci numbers, higher total organic carbon (TOC, 1.48–2.18 mg/L) and nitrogen (TN, 0.15–0.27 mg/L) than that detected in the near-shore waters. Enterococci abundances obtained from next-generation sequencing did not correlate well with the cultured enterococci numbers. The abundance of certain genera, for example Arcobacter, Pseudomonas and unclassified Campylobacterales, was observed to exhibit slight correlation with TOC and TN. Low abundance of functional genes accounting for up to 41 copies/L of each Pseudomonas aeruginosa and Campylobacter coli were detected. Arcobacter butzleri was also detected in abundance ranging from 111 to 238 copies/L. Operational taxonomic units (OTUs) associated with cyanobacteria, Prochlorococcus,Ostreococcus spp. and Gramella were more prevalent in waters that were likely impacted by urban runoffs and recreational activities. These OTUs could potentially serve as quantifiable markers indicative of the water quality.

Investigating the host specificity of Campylobacter jejuni and Campylobacter coli by sequencing gyrase subunit A

BACKGROUND

Surveillance and field investigations of Campylobacter infections require molecular tools with genetic markers appropriate for tracing purposes, i.e. based on the principle that some Campylobacter lineages acquire a host signature under adaptive selection pressure. We developed a sequence-based method targeting the quinolone resistance determining region within the subunit A of DNA gyrase (gyrA). Host specificity was evaluated by characterizing two collections of Campylobacter jejuni (N = 430) and Campylobacter coli (N = 302) originating from surface waters, domestic mammals and poultry.

RESULTS

Based on nucleotide identity, a total of 80 gyrA alleles were observed. Thirty nine alleles assigned to C. coli encoding two peptides fell into three clades: two associated with surface waters and one associated with domestic mammals and poultry. The variability in GC content generated by synonymous mutations suggested that surface waters isolates originated from two distinct ecological niches. A total of 42 alleles were recorded from C. jejuni strains and encoded 8 peptides including one lying in a distinct lineage associated with wildlife. Seven of the 23 alleles encoding peptide #1 displayed the synonymous mutation G408A not identified in poultry isolates. By contrast, the substitution Ser22Gly observed in 4 different peptide groups was significantly associated with domestic birds (P = 0.001). The change in amino acid sequences Thr86Ile conferring resistance to quinolones was significantly associated with poultry (P < 0.001) in both C. jejuni and C. coli with 38.7% and 67.9% of quinolone-resistant strains, respectively.

CONCLUSIONS

The gyrA typing method presented here is an informative tool as sequences appear to be predictive of particular ecological niches. Combined with multi-locus sequence typing, it could increase the resolution of source attribution, and combined with porA/flaA typing it could be suitable for detecting temporal clusters of human cases. All gyrA alleles identified were deposited in the freely accessible online database http://pubmlst.org/campylobacter.

DNA extraction from protozoan oocysts/cysts in feces for diagnostic PCR

PCR detection of intestinal protozoa is often restrained by a poor DNA recovery or by inhibitors present in feces. The need for an extraction protocol that can overcome these obstacles is therefore clear. QIAamp® DNA Stool Mini Kit (Qiagen) was evaluated for its ability to recover DNA from oocysts/cysts directly from feces. Twenty-five Giardia-positive, 15 Cryptosporidium-positive, 15 Entamoeba histolytica-positive, and 45 protozoa-free samples were processed as control by microscopy and immunoassay tests. DNA extracts were amplified using 3 sets of published primers. Following the manufacturer's protocol, the kit showed sensitivity and specificity of 100% towards Giardia and Entamoeba. However, for Cryptosporidium, the sensitivity and specificity were 60% (9/15) and 100%, respectively. A series of optimization experiments involving various steps of the kit's protocol were conducted using Cryptosporidium-positive samples. The best DNA recoveries were gained by raising the lysis temperature to the boiling point for 10 min and the incubation time of the InhibitEX tablet to 5 min. Also, using a pre-cooled ethanol for nucleic acid precipitation and small elution volume (50-100 µl) were valuable. The sensitivity of the amended protocol to Cryptosporidium was raised to 100%. Cryptosporidium DNA was successfully amplified by either the first or the second primer set. When applied on parasite-free feces spiked with variable oocysts/cysts counts, ≈ 2 oocysts/cysts were theoretically enough for detection by PCR. To conclude, the Qiagen kit with the amended protocol was proved to be suitable for protozoan DNA extraction directly from feces and support PCR diagnosis.

Detection, identification and quantification of Campylobacter jejuni, coli and lari in food matrices all at once using multiplex qPCR

BACKGROUND

Thermotolerant Campylobacter jejuni, coli and lari are recognized as leading food-borne pathogens causing an acute bacterial enteritis worldwide. Due to narrow spectrum of their biochemical activity, it is very complicated to distinguish between individual species. For reliable risk assessment, proper incidence evaluation or swift sample analysis regarding individual species, a demand for simple and rapid method for their distinguishing is reasonable. In this study, we evaluated a reliable and simple approach for their simultaneous detection, species identification and quantification using multiplex qPCR.

RESULTS

Species specific primers and hydrolysis probes are directed to hippuricase gene of C. jejuni, serine hydroxymethyltransferase gene of C. coli and peptidase T gene of C. lari. Efficiencies of reactions were 90.85% for C. jejuni, 96.97% for C. coli and 92.89% for C. lari. At 95.00% confidence level and when cut off is set to 38 cycles, limits of detection are in all cases under 10 genome copies per reaction which is very appreciated since it is known that infectious doses are very low.

CONCLUSIONS

Proposed assay was positively validated on different food matrices (chicken wing rinses, chicken juice and homogenized fried chicken strips). No inhibition of PCR reaction occurred. Assay was evaluated in accordance with MIQE handbook.

Simultaneous quantification of multiple food- and waterborne pathogens by use of microfluidic quantitative PCR

The direct quantification of multiple pathogens has been desired for diagnostic and public health purposes for a long time. In this study, we applied microfluidic quantitative PCR (qPCR) technology to the simultaneous detection and quantification of multiple food- and waterborne pathogens. In this system, multiple singleplex qPCR assays were run under identical detection conditions in nanoliter-volume chambers that are present in high densities on a chip. First, we developed 18 TaqMan qPCR assays that could be run in the same PCR conditions by using prevalidated TaqMan probes. Specific and sensitive quantification was achieved by using these qPCR assays. With the addition of two previously validated TaqMan qPCR assays, we used 20 qPCR assays targeting 10 enteric pathogens, a fecal indicator bacterium (general Escherichia coli), and a process control strain in the microfluidic qPCR system. We preamplified the template DNA to increase the sensitivity of the qPCR assays. Our results suggested that preamplification was effective for quantifying small amounts of the template DNA without any major impact on the sensitivity, efficiency, and quantitative performance of qPCR. This microfluidic qPCR system allowed us to detect and quantify multiple pathogens from fecal samples and environmental water samples spiked with pathogens at levels as low as 100 cells/liter. These results suggest that the routine monitoring of multiple pathogens in food and water samples is now technically feasible. This method may provide more reliable information for risk assessment than the current fecal contamination indicator approach.

Application of quantitative PCR for the detection of microorganisms in water

The occurrence of microorganisms in water due to contamination is a health risk and control thereof is a necessity. Conventional detection methods may be misleading and do not provide rapid results allowing for immediate action. The quantitative polymerase chain reaction (qPCR) method has proven to be an effective tool to detect and quantify microorganisms in water within a few hours. Quantitative PCR assays have recently been developed for the detection of specific adeno- and polyomaviruses, bacteria and protozoa in different water sources. The technique is highly sensitive and able to detect low numbers of microorganisms. Quantitative PCR can be applied for microbial source tracking in water sources, to determine the efficiency of water and wastewater treatment plants and act as a tool for risk assessment. Different qPCR assays exist depending on whether an internal control is used or whether measurements are taken at the end of the PCR reaction (end-point qPCR) or in the exponential phase (real-time qPCR). Fluorescent probes are used in the PCR reaction to hybridise within the target sequence to generate a signal and, together with specialised systems, quantify the amount of PCR product. Quantitative reverse transcription polymerase chain reaction (q-RT-PCR) is a more sensitive technique that detects low copy number RNA and can be applied to detect, e.g. enteric viruses and viable microorganisms in water, and measure specific gene expression. There is, however, a need to standardise qPCR protocols if this technique is to be used as an analytical diagnostic tool for routine monitoring. This review focuses on the application of qPCR in the detection of microorganisms in water.

Antimicrobial susceptibility, pulsed-field gel electrophoresis, and multi-locus sequence typing of Campylobacter coli in swine before, during, and after the slaughter process

The objective of this study was to determine persistence of clonal strains from farm to retail by assessing the clonal relatedness of Campylobacter coli isolated on farm, peri-harvest, and at processing from 11 individually identified pigs. Phenotypic (antimicrobial susceptibility) and genotypic (pulsed field gel electrophoresis [PFGE] and multi-locus sequence typing [MLST]) characterization of isolates was conducted. There was high genetic diversity of Campylobacter isolates from on-farm fecal samples. Campylobacter isolates from farm, post-evisceration, hide, and carcass samples showed similar phenotypes and belonged to the same genotypic clusters based on PFGE and sequence types (STs) based on MLST. Five STs that have not been previously reported were identified (ST-4083, ST-4084, ST-4085, ST-4086, ST-4087). Despite high genotypic diversity of C. coli on farm, retail meat products were consistently contaminated with isolates of the same STs, particularly ST854 and ST1056, as isolates collected from previous stages confirming persistence of strains from pre- to post-harvest.