Effect of bacteriophage application on Campylobacter jejuni loads in commercial broiler flocks

FlhF(T368A) modulates motility in the bacteriophage carrier state of Campylobacter jejuni

The carrier state is an alternative bacteriophage life cycle by which virulent bacteriophage can persist in association with host bacteria. Campylobacter jejuni carrier state strains exhibit growth phase dependent motility due to a truncated flagella phenotype. Genome sequencing identified a T368A substitution in the G3 domain of the SRP-like GTPase FlhF from C. jejuni PT14CP30A carrier state strains, which we hypothesized to be the cause of the complex motility phenotype. We have analyzed the role of this mutation in C. jejuni PT14 and demonstrated that flhF(T368A) leads to a large proportion of cells unable to synthesize flagella, while the remaining cells form a single flagellum at one pole leading to significantly reduced motility. The flhF(T368A) mutation causes a reduction in the phage adsorption constant, which leads to a decrease in infection efficiency. Down-regulation of σ28 and σ54 dependent flagellar genes were observed as responses to the flhF(T368A) mutation. FlhF(T368A) protein is impaired in GTPase activity and exhibits reduced stability. C. jejuni carrying flhF(T368A) are less sensitive to bacteriophage infection and formation of the carrier state. The acquisition of flhF(T368A) in carrier state strains acts to prevent super-infection and maintain association with the bacteriophage that provoked the interaction.

The gastrointestinal microbiome and its association with the control of pathogens in broiler chicken production: A review

The microbiome of the broiler chicken gastrointestinal tract (GIT) has been extensively studied, and it has been amply demonstrated that it plays an important role in the health of the host, as it has a positive impact on the immune system, the physiology of the GIT, and productivity. Also, the microbiota is involved in reducing and preventing colonization by enteric pathogens through the process of competitive exclusion and the production of bacteriostatic and bactericidal substances. The taxonomic composition of the microbiota is affected by different factors, such as the organ, the age of the animal, diet and the use of antimicrobials.

Different kinds of additives that regulate the microbial community in feed include probiotics (live microorganisms that when administered in adequate amounts confer a health benefit on the host), prebiotics (ingredients that stimulate increased beneficial microbial activity in the digestive system in order to improve the health of the host) and phytobiotics (primary or secondary components of plants that contain bioactive compounds that exert a positive effect on the growth and health of animals). Phages may potentially provide an integrated solution to modulate the intestinal microbiome of chicken intestines, as they reduce specific pathogenic microbial populations, permitting the proliferation of beneficial microbiota. Studies have shown that the use of cocktails of phages, especially in high concentrations and with short lapses of time between exposure to the bacteria and treatment with phages, optimize the reduction of Salmonella in chickens. Each of these technologies has demonstrable positive effects on the health of the host and the reduction of the pathogen load in controlled assays.

This paper presents a comprehensive summary of the role of the microbiota in the broiler chicken gastrointestinal tract, and discusses the usefulness of different strategies for its modulation to control pathogens, with a particular emphasis on bacteriophages.

Molecular Basis of Bacterial Host Interactions by Gram-Positive Targeting Bacteriophages

The inherent ability of bacteriophages (phages) to infect specific bacterial hosts makes them ideal candidates to develop into antimicrobial agents for pathogen-specific remediation in food processing, biotechnology, and medicine (e.g., phage therapy). Conversely, phage contaminations of fermentation processes are a major concern to dairy and bioprocessing industries. The first stage of any successful phage infection is adsorption to a bacterial host cell, mediated by receptor-binding proteins (RBPs). As the first point of contact, the binding specificity of phage RBPs is the primary determinant of bacterial host range, and thus defines the remediative potential of a phage for a given bacterium. Co-evolution of RBPs and their bacterial receptors has forced endless adaptation cycles of phage-host interactions, which in turn has created a diverse array of phage adsorption mechanisms utilizing an assortment of RBPs. Over the last decade, these intricate mechanisms have been studied intensely using electron microscopy and X-ray crystallography, providing atomic-level details of this fundamental stage in the phage infection cycle. This review summarizes current knowledge surrounding the molecular basis of host interaction for various socioeconomically important Gram-positive targeting phage RBPs to their protein- and saccharide-based receptors. Special attention is paid to the abundant and best-characterized Siphoviridae family of tailed phages. Unravelling these complex phage-host dynamics is essential to harness the full potential of phage-based technologies, or for generating novel strategies to combat industrial phage contaminations.

Transcriptomic Analysis of the Campylobacter jejuni Response to T4-Like Phage NCTC 12673 Infection

Campylobacter jejuni is a frequent foodborne pathogen of humans. As C. jejuni infections commonly arise from contaminated poultry, phage treatments have been proposed to reduce the C. jejuni load on farms to prevent human infections. While a prior report documented the transcriptome of C. jejuni phages during the carrier state life cycle, transcriptomic analysis of a lytic C. jejuni phage infection has not been reported. We used RNA-sequencing to profile the infection of C. jejuni NCTC 11168 by the lytic T4-like myovirus NCTC 12673. Interestingly, we found that the most highly upregulated host genes upon infection make up an uncharacterized operon (cj0423⁻cj0425), which includes genes with similarity to T4 superinfection exclusion and antitoxin genes. Other significantly upregulated genes include those involved in oxidative stress defense and the Campylobactermultidrug efflux pump (CmeABC). We found that phage infectivity is altered by mutagenesis of the oxidative stress defense genes catalase (katA), alkyl-hydroxyperoxidase (ahpC), and superoxide dismutase (sodB), and by mutagenesis of the efflux pump genes cmeA and cmeB. This suggests a role for these gene products in phage infection. Together, our results shed light on the phage-host dynamics of an important foodborne pathogen during lytic infection by a T4-like phage.

Complete Genome Sequences of Three Campylobacter jejuni Phage-Propagating Strains

Bacteriophage therapy can potentially reduce Campylobacter jejuni numbers in livestock, but it requires a detailed understanding of phage-host interactions. C. jejuni strains readily infected by certain phages are designated as phage-propagating strains. Here, we report the complete genome sequences of three such strains, NCTC 12660, NCTC 12661, and NCTC 12664.

Framing the Future with Bacteriophages in Agriculture

The ability of agriculture to continually provide food to a growing world population is of crucial importance. Bacterial diseases of plants and animals have continually reduced production since the advent of crop cultivation and animal husbandry practices. Antibiotics have been used extensively to mitigate these losses. The rise of antimicrobial resistant (AMR) bacteria, however, together with consumers’ calls for antibiotic-free products, presents problems that threaten sustainable agriculture. Bacteriophages (phages) are proposed as bacterial population control alternatives to antibiotics. Their unique properties make them highly promising but challenging antimicrobials. The use of phages in agriculture also presents a number of unique challenges. This mini-review summarizes recent development and perspectives of phages used as antimicrobial agents in plant and animal agriculture at the farm level. The main pathogens and their adjoining phage therapies are discussed.

Bacteriophage Applications for Food Production and Processing

Foodborne illnesses remain a major cause of hospitalization and death worldwide despite many advances in food sanitation techniques and pathogen surveillance. Traditional antimicrobial methods, such as pasteurization, high pressure processing, irradiation, and chemical disinfectants are capable of reducing microbial populations in foods to varying degrees, but they also have considerable drawbacks, such as a large initial investment, potential damage to processing equipment due to their corrosive nature, and a deleterious impact on organoleptic qualities (and possibly the nutritional value) of foods. Perhaps most importantly, these decontamination strategies kill indiscriminately, including many—often beneficial—bacteria that are naturally present in foods. One promising technique that addresses several of these shortcomings is bacteriophage biocontrol, a green and natural method that uses lytic bacteriophages isolated from the environment to specifically target pathogenic bacteria and eliminate them from (or significantly reduce their levels in) foods. Since the initial conception of using bacteriophages on foods, a substantial number of research reports have described the use of bacteriophage biocontrol to target a variety of bacterial pathogens in various foods, ranging from ready-to-eat deli meats to fresh fruits and vegetables, and the number of commercially available products containing bacteriophages approved for use in food safety applications has also been steadily increasing. Though some challenges remain, bacteriophage biocontrol is increasingly recognized as an attractive modality in our arsenal of tools for safely and naturally eliminating pathogenic bacteria from foods.

1st German Phage Symposium-Conference Report

In Germany, phage research and application can be traced back to the beginning of the 20th century. However, with the triumphal march of antibiotics around the world, the significance of bacteriophages faded in most countries, and respective research mainly focused on fundamental questions and niche applications. After a century, we pay tribute to the overuse of antibiotics that led to multidrug resistance and calls for new strategies to combat pathogenic microbes. Against this background, bacteriophages came into the spotlight of researchers and practitioners again resulting in a fast growing “phage community”. In October 2017, part of this community met at the 1st German Phage Symposium to share their knowledge and experiences. The participants discussed open questions and challenges related to phage therapy and the application of phages in general. This report summarizes the presentations given, highlights the main points of the round table discussion and concludes with an outlook for the different aspects of phage application.

Randomized control trial to test the effect of a feed additive on Campylobacter contamination in commercial broiler flocks up to slaughter

A randomized controlled trial (RCT) was carried to evaluate the effect of a feed additive on Campylobacter contamination of broilers reared in commercial conditions. Twenty-four broiler flocks naturally contaminated with Campylobacter were enrolled in the RCT: 12 were assigned to a control group (C) fed with a conventional finishing feed from 4 weeks of age to slaughter (around 35 days), and the other group of 12 flocks (S) was fed with a finishing feed supplemented with 250 ppm of a patented feed additive (an ion-exchanged clay compound) previously proven to reduce Campylobacter contamination in broiler caeca under experimental conditions. Enumeration of Campylobacter colonies in caeca (8 per flock) was carried out following ISO standards before feed distribution and at slaughter. Before treatment, the caecal Campylobacter load tended to be lower in C flocks (7.1 ± 1.9 log CFU/g, CI_95% [6.6-7.5]) than in S flocks (7.7 ± 1.0 log UFC/g, CI_95% [7.5-7.9]) (p = .05). At slaughter, the bacterial load was similar in the S (7.7 ± 1.0 log CFU/g, CI_95% [7.5-7.9]) and C groups (7.5 ± 1.2 log CFU/g, CI_95% [7.2-7.8]) (p = .73). Therefore, the feed additive had no significant effect on the caecal Campylobacter load at slaughter under the tested conditions. The logistical constraints inherent in field trials and the natural variability of Campylobacter contamination in naturally infected broiler flocks make it difficult to reproduce experimental results in in situ farm conditions. RCT testing of an intervention strategy in commercial situation is therefore a key step in evaluating pre-harvest interventions against food-borne pathogens.

Use of encapsulated bacteriophages to enhance farm to fork food safety

Bacteriophages have been successfully applied to control the growth of pathogens in foods and to reduce the colonization and shedding of pathogens by food animals. They are set to play a dominant role in food safety in the future. However, many food-processing operations and the microenvironments in food animals' guts inactivate phages and reduce their infectivity. Encapsulation technologies have been used successfully to protect phages against extreme environments, and have been shown to preserve their activity and enable their release in targeted environments. A number of encapsulation technologies have shown potential for use with bacteriophages. This review discusses the current state of knowledge about the use of encapsulation technologies with bacteriophages to control pathogens in foods and food animals.

A multiplex real-time PCR for the detection and differentiation of Campylobacter phages

Campylobacter jejuni and C. coli are important food-borne pathogens that are widespread in animal husbandry. To combat Campylobacter along the food chain, the application of lytic phages has been shown to be a promising tool. Campylobacter phages are currently classified into three groups, of which group II and group III phages are the most common. Members of each group are closely related, whereas the two groups share only little DNA similarity. Moreover, while group III phages are specific for C. jejuni, group II phages additionally infect C. coli. Phage cocktails intended to be used for applications should be composed of various phages that differ in their host range and growth kinetics. The isolation of phages is generally performed by plaque assays. This approach has the limitation that phages are merely identified by their lytic activity on certain indicator strains and that relatively high numbers of phages must be present in a tested sample. Therefore, a more sensitive molecular detection system would be beneficial, which allows a pre-screening of samples and the quick detection and discrimination of group II and group III phages. New phages can then be isolated by use of indicator strains that may be different from those typically applied. On the basis of available Campylobacter phage genome sequences, we developed a multiplex PCR system for group II and group III phages selecting the tail tube gene and the gene for the base plate wedge, respectively, as target. Phages of both groups could be identified with primers deduced from the putative tail fiber gene. Efficient release of phage DNA from capsids was achieved by an extended heat treatment or digestion of phage particles with proteinase K/SDS yielding a detection limit of 1 pfu/ml. Individual detection of group II phages, group III phages and of both groups was studied with artificially contaminated chicken skin. To recover phages that had strongly adhered to the skin, stomaching was the most efficient technique. The developed PCR protocol was employed to detect Campylobacter phages in food and environmental samples. In 50 out of 110 samples group II and/or group III phages were identified.

The Minor Flagellin of Campylobacter jejuni (FlaB) Confers Defensive Properties against Bacteriophage Infection

A screen of bacteriophages infecting a panel of Campylobacter jejuni PT14 gene knock-out mutants identified a role for the minor flagellin encoded by the flaB gene, in the defense of the host against CP8unalikevirus bacteriophage CP_F1 infection. Inactivation of the flaB gene resulted in an increase in the susceptibility of PT14 cultures to infection by CP_F1 and an increase in bacteriophage yields. Infection of wild type PT14 with CP_F1 produces turbid plaques in bacterial lawns, from which 78% of the resistant isolates recovered exhibit either attenuation or complete loss of motility. CP_F1 produces clear plaques on the flaB mutant with no regrowth in the lysis zones. Complementation of the mutant restored overgrowth and the development of resistance at the expense of motility. Further analyses revealed an increase in bacteriophage adsorption constant of nearly 2-fold and burst-size 3-fold, relative to the wild type. Motility analysis showed no major reduction in swarming motility in the flaB mutant. Thus, we propose a new role for FlaB in the defense of campylobacters against bacteriophage infection.

Campylobacters and their bacteriophages from chicken liver: The prospect for phage biocontrol

Consumption of foods containing chicken liver has been associated with Campylobacter enteritis. Campylobacters can contaminate the surface of livers post-mortem but can also arise through systemic infection of colonising bacteria in live birds. The use of bacteriophage to reduce levels of Campylobacter entering the food chain is a promising intervention approach but most phages have been isolated from chicken excreta. This study examined the incidence and contamination levels of Campylobacter and their bacteriophage in UK retail chicken liver. Using enrichment procedures, 87% of 109 chicken livers were surface contaminated with Campylobacter and 83% contaminated within internal tissues. Direct plating on selective agar allowed enumeration of viable bacteria from 43% of liver samples with counts ranging from 1.8->3.8log10CFU/cm2 for surface samples, and 3.0->3.8log10CFU/g for internal tissue samples. Three C. jejuni isolates recovered from internal liver tissues were assessed for their ability to colonise the intestines and extra-intestinal organs of broiler chickens following oral infection. All isolates efficiently colonised the chicken intestines but were variable in their abilities to colonise extra-intestinal organs. One isolate, CLB104, could be recovered by enrichment from the livers and kidneys of three of seven chickens. Campylobacter isolates remained viable within fresh livers stored at 4°C over 72h and frozen livers stored at -20°C over 7days in atmospheric oxygen, and therefore constitute a risk to human health. Only three Campylobacter-specific bacteriophages were isolated, and these exhibited a limited host range against the Camplylobacter chicken liver isolates. All were identified as group III virulent bacteriophage based on their genome size of 140kb. The application of broad host range group II virulent phages (8log10PFU/g) to liver homogenates containing C. jejuni strains of diverse origin at 4°C resulted in modest but significant reductions in the viable counts ranging from 0.2 to 0.7log10CFU/g.

The efficacy of a commercial competitive exclusion product on Campylobacter colonization in broiler chickens in a 5-week pilot-scale study

The efficacy of the commercial competitive exclusion product Broilact against Campylobacter jejuni was evaluated in broiler chickens in a 5-week pilot-scale study. Newly-hatched broiler chicks were brought from a commercial hatchery. After arrival 50 seeder chicks were challenged orally with approximately 10(3) cfu of C. jejuni, wing marked, and placed back in a delivery box and moved to a separate room. The rest of the chicks (contact chicks) were placed in floor pens, 100 chicks per pen. Birds in two pens were treated orally on the day of hatch with the commercial competitive exclusion (CE) product Broilact, and three pens were left untreated. The following day 10 seeder chicks were introduced into the Broilact treated and untreated control pens. One pen was left both untreated and unchallenged (0-control). Each week the ceca of 10 contact chicks and one seeder chick were examined quantitatively for Campylobacter The treatment prevented or significantly reduced the colonization of the challenge organism in the ceca during the two first weeks; the percentage of colonized birds being 0% after the first week and 30% after the second week in the Broilact treated groups but was 100% in the control groups the entire 5-week rearing period. During the third rearing week the proportion of Campylobacter positive birds started to increase in the treated pens, being 80% after the third week and 95 and 90% after the fourth and fifth rearing weeks, respectively. Similarly the average count of Campylobacter in the cecal contents of the Broilact treated chicks started to increase, the difference between the treated and control chicks being 1.4 logs at the end of the rearing period. Although the protective effect was temporary and occurred only during the first two weeks of the rearing period, the results of this study support the earlier observations that CE flora designed to protect chicks from Salmonella may also reduce Campylobacter colonization of broiler chickens.

A Flagellar Glycan-Specific Protein Encoded by Campylobacter Phages Inhibits Host Cell Growth

We previously characterized a carbohydrate binding protein, Gp047, derived from lytic Campylobacter phage NCTC 12673, as a promising diagnostic tool for the identification of Campylobacter jejuni and Campylobacter coli. We also demonstrated that this protein binds specifically to acetamidino-modified pseudaminic acid residues on host flagella, but the role of this protein in the phage lifecycle remains unknown. Here, we report that Gp047 is capable of inhibiting C. jejuni growth both on solid and liquid media, an activity, which we found to be bacteriostatic. The Gp047 domain responsible for bacterial growth inhibition is localized to the C-terminal quarter of the protein, and this activity is both contact- and dose-dependent. Gp047 gene homologues are present in all Campylobacter phages sequenced to date, and the resulting protein is not part of the phage particle. Therefore, these results suggest that either phages of this pathogen have evolved an effector protein capable of host-specific growth inhibition, or that Campylobacter cells have developed a mechanism of regulating their growth upon sensing an impending phage threat.

Campylobacter group II phage CP21 is the prototype of a new subgroup revealing a distinct modular genome organization and host specificity

BACKGROUND

The application of phages is a promising tool to reduce the number of Campylobacter along the food chain. Besides the efficacy against a broad range of strains, phages have to be safe in terms of their genomes. Thus far, no genes with pathogenic potential (e.g., genes encoding virulence factors) have been detected in Campylobacter phages. However, preliminary studies suggested that the genomes of group II phages may be diverse and prone to genomic rearrangements.

RESULTS

We determined and analysed the genomic sequence (182,761 bp) of group II phage CP21 that is closely related to the already characterized group II phages CP220 and CPt10. The genomes of these phages are comprised of four modules separated by very similar repeat regions, some of which harbouring open reading frames (ORFs). Though, the arrangement of the modules and the location of some ORFs on the genomes are different in CP21 and in CP220/CPt10. In this work, a PCR system was established to study the modular genome organization of other group II phages demonstrating that they belong to different subgroups of the CP220-like virus genus, the prototypes of which are CP21 and CP220. The subgroups revealed different restriction patterns and, interestingly enough, also distinct host specificities, tail fiber proteins and tRNA genes. We additionally analysed the genome of group II phage vB_CcoM-IBB_35 (IBB_35) for which to date only five individual contigs could be determined. We show that the contigs represent modules linked by long repeat regions enclosing some yet not identified ORFs (e.g., for a head completion protein). The data suggest that IBB_35 is a member of the CP220 subgroup.

CONCLUSION

Campylobacter group II phages are diverse regarding their genome organization. Since all hitherto characterized group II phages contain numerous genes for transposases and homing endonucleases as well as similar repeat regions, it cannot be excluded that these phages are genetically unstable. To answer this question, further experiments and sequencing of more group II phages should be performed.

Bacteriophages Isolated from Chicken Meat and the Horizontal Transfer of Antimicrobial Resistance Genes

Antimicrobial resistance in microbes poses a global and increasing threat to public health. The horizontal transfer of antimicrobial resistance genes was thought to be due largely to conjugative plasmids or transposons, with only a minor part being played by transduction through bacteriophages. However, whole-genome sequencing has recently shown that the latter mechanism could be highly important in the exchange of antimicrobial resistance genes between microorganisms and environments. The transfer of antimicrobial resistance genes by phages could underlie the origin of resistant bacteria found in food. We show that chicken meat carries a number of phages capable of transferring antimicrobial resistance. Of 243 phages randomly isolated from chicken meat, about a quarter (24.7%) were able to transduce resistance to one or more of the five antimicrobials tested into Escherichia coli ATCC 13706 (DSM 12242). Resistance to kanamycin was transduced the most often, followed by that to chloramphenicol, with four phages transducing tetracycline resistance and three transducing ampicillin resistance. Phages able to transduce antimicrobial resistance were isolated from 44% of the samples of chicken meat that we tested. The statistically significant (P = 0.01) relationship between the presence of phages transducing kanamycin resistance and E. coli isolates resistant to this antibiotic suggests that transduction may be an important mechanism for transferring kanamycin resistance to E. coli. It appears that the transduction of resistance to certain antimicrobials, e.g., kanamycin, not only is widely distributed in E. coli isolates found on meat but also could represent a major mechanism for resistance transfer. The result is of high importance for animal and human health.

Global Epidemiology of Campylobacter Infection

Campylobacter jejuni infection is one of the most widespread infectious diseases of the last century. The incidence and prevalence of campylobacteriosis have increased in both developed and developing countries over the last 10 years. The dramatic increase in North America, Europe, and Australia is alarming, and data from parts of Africa, Asia, and the Middle East indicate that campylobacteriosis is endemic in these areas, especially in children. In addition to C. jejuni, there is increasing recognition of the clinical importance of emerging Campylobacter species, including Campylobacter concisus and Campylobacter ureolyticus. Poultry is a major reservoir and source of transmission of campylobacteriosis to humans. Other risk factors include consumption of animal products and water, contact with animals, and international travel. Strategic implementation of multifaceted biocontrol measures to reduce the transmission of this group of pathogens is paramount for public health. Overall, campylobacteriosis is still one of the most important infectious diseases that is likely to challenge global health in the years to come. This review provides a comprehensive overview of the global epidemiology, transmission, and clinical relevance of Campylobacter infection.

Bacteriophages Isolated from Chicken Meat and the Horizontal Transfer of Antimicrobial Resistance Genes

Antimicrobial resistance in microbes poses a global and increasing threat to public health. The horizontal transfer of antimicrobial resistance genes was thought to be due largely to conjugative plasmids or transposons, with only a minor part being played by transduction through bacteriophages. However, whole-genome sequencing has recently shown that the latter mechanism could be highly important in the exchange of antimicrobial resistance genes between microorganisms and environments. The transfer of antimicrobial resistance genes by phages could underlie the origin of resistant bacteria found in food. We show that chicken meat carries a number of phages capable of transferring antimicrobial resistance. Of 243 phages randomly isolated from chicken meat, about a quarter (24.7%) were able to transduce resistance to one or more of the five antimicrobials tested into Escherichia coli ATCC 13706 (DSM 12242). Resistance to kanamycin was transduced the most often, followed by that to chloramphenicol, with four phages transducing tetracycline resistance and three transducing ampicillin resistance. Phages able to transduce antimicrobial resistance were isolated from 44% of the samples of chicken meat that we tested. The statistically significant (P = 0.01) relationship between the presence of phages transducing kanamycin resistance and E. coli isolates resistant to this antibiotic suggests that transduction may be an important mechanism for transferring kanamycin resistance to E. coli. It appears that the transduction of resistance to certain antimicrobials, e.g., kanamycin, not only is widely distributed in E. coli isolates found on meat but also could represent a major mechanism for resistance transfer. The result is of high importance for animal and human health.

Effects of fibrinopurulent polyserositis in broilers on post-harvest microbiological parameters relevant to public health of broiler meat

Fibrinopurulent polyserositis is of utmost importance in commercial broiler production worldwide. This multifactorial endemic disease is marked by severe clinical alterations post-mortem, yet its effects on food safety and processing hygiene criteria remain unclear. Current considerations presume that bacteraemia lead to meat being unfit for consumption. In the present study, we evaluated some microbiological criteria of affected broiler carcasses in comparison to unaffected control broiler carcasses. The results thereof indicated that the lesions did not result in higher bacterial counts or in an increased percentage of contaminated meat. The carry-over of associated zoonotic pathogens into the food chain seems to be not more prevalent in birds affected with non-systemic affections of polyserositis.

Reduction of Campylobacter jejuni in broiler chicken by successive application of group II and group III phages

BACKGROUND

Bacteriophage treatment is a promising tool to reduce Campylobacter in chickens. Several studies have been published where group II or group III phages were successfully applied. However, these two groups of phages are different regarding their host ranges and host cell receptors. Therefore, a concerted activity of group II and group III phages might enhance the efficacy of a treatment and decrease the number of resistant bacteria.

RESULTS

In this study we have compared the lytic properties of some group II and group III phages and analysed the suitability of various phages for a reduction of C. jejuni in broiler chickens. We show that group II and group III phages exhibit different kinetics of infection. Two group III and one group II phage were selected for animal experiments and administered in different combinations to three groups of chickens, each containing ten birds. While group III phage CP14 alone reduced Campylobacter counts by more than 1 log10 unit, the concomitant administration of a second group III phage (CP81) did not yield any reduction, probably due to the development of resistance induced by this phage. One group of chickens received phage CP14 and, 24 hours later, group II phage CP68. In this group of animals, Campylobacter counts were reduced by more than 3 log10 units.

CONCLUSION

The experiments illustrated that Campylobacter phage cocktails have to be carefully composed to achieve the best results.

Prevention of bacterial foodborne disease using nanobiotechnology

Foodborne disease is an important source of expense, morbidity, and mortality for society. Detection and control constitute significant components of the overall management of foodborne bacterial pathogens, and this review focuses on the use of nanosized biological entities and molecules to achieve these goals. There is an emphasis on the use of organisms called bacteriophages (phages: viruses that infect bacteria), which are increasingly being used in pathogen detection and biocontrol applications. Detection of pathogens in foods by conventional techniques is time-consuming and expensive, although it can also be sensitive and accurate. Nanobiotechnology is being used to decrease detection times and cost through the development of biosensors, exploiting specific cell-recognition properties of antibodies and phage proteins. Although sensitivity per test can be excellent (eg, the detection of one cell), the very small volumes tested mean that sensitivity per sample is less compelling. An ideal detection method needs to be inexpensive, sensitive, and accurate, but no approach yet achieves all three. For nanobiotechnology to displace existing methods (culture-based, antibody-based rapid methods, or those that detect amplified nucleic acid) it will need to focus on improving sensitivity. Although manufactured nonbiological nanoparticles have been used to kill bacterial cells, nanosized organisms called phages are increasingly finding favor in food safety applications. Phages are amenable to protein and nucleic acid labeling, and can be very specific, and the typical large "burst size" resulting from phage amplification can be harnessed to produce a rapid increase in signal to facilitate detection. There are now several commercially available phages for pathogen control, and many reports in the literature demonstrate efficacy against a number of foodborne pathogens on diverse foods. As a method for control of pathogens, nanobiotechnology is therefore flourishing.

Natural solution to antibiotic resistance: bacteriophages 'The Living Drugs'

Antibiotics have been a panacea in animal husbandry as well as in human therapy for decades. The huge amount of antibiotics used to induce the growth and protect the health of farm animals has lead to the evolution of bacteria that are resistant to the drug's effects. Today, many researchers are working with bacteriophages (phages) as an alternative to antibiotics in the control of pathogens for human therapy as well as prevention, biocontrol, and therapy in animal agriculture. Phage therapy and biocontrol have yet to fulfill their promise or potential, largely due to several key obstacles to their performance. Several suggestions are shared in order to point a direction for overcoming common obstacles in applied phage technology. The key to successful use of phages in modern scientific, farm, food processing and clinical applications is to understand the common obstacles as well as best practices and to develop answers that work in harmony with nature.

Colonisation of a phage susceptible Campylobacter jejuni population in two phage positive broiler flocks

The pathogens Campylobacter jejuni and Campylobacter coli are commensals in the poultry intestine and campylobacteriosis is one of the most frequent foodborne diseases in developed and developing countries. Phages were identified to be effective in reducing intestinal Campylobacter load and this was evaluated, in the first field trials which were recently carried out. The aim of this study was to further investigate Campylobacter population dynamics during phage application on a commercial broiler farm. This study determines the superiority in colonisation of a Campylobacter type found in a field trial that was susceptible to phages in in vitro tests. The colonisation factors, i.e. motility and gamma glutamyl transferase activity, were increased in this type. The clustering in phylogenetic comparisons of MALDI-TOF spectra did not match the ST, biochemical phenotype and phage susceptibility. Occurrence of Campylobacter jejuni strains and phage susceptibility types with different colonisation potential seem to play a very important role in the success of phage therapy in commercial broiler houses. Thus, mechanisms of both, phage susceptibility and Campylobacter colonisation should be further investigated and considered when composing phage cocktails.