Evidence that Certain Clones of Campylobacter jejuni Persist during Successive Broiler Flock Rotations

Through the national surveillance program for Campylobacter spp., nine broiler chicken farms that were infected with Campylobacter jejuni in at least five rotations in 1998 were identified. One additional farm, located at the island of Bornholm where divided slaughter is used extensively, was also selected. Twelve broiler houses located on 10 farms were included in the study. The C. jejuni isolates collected from the selected houses during the surveillance were typed using fla typing and macrorestriction profiling (MRP), and a subset of the isolates, representing each of the identified clones, was serotyped according to the Penner scheme. Pulsed-field gel electrophoresis typing using SmaI and KpnI revealed that the majority of houses (11 of 12) carried identical isolates in two or more broiler flocks. Such persistent clones were found in 63% of all flocks (47 of 75). The majority of persistent clones (7 of 13) had fla type 1/1, but MRPs distinguished between isolates from different houses, and fla type 1/1 clones belonged to different serotypes. Seven houses carried persistent clones that covered an interval of at least four broiler flock rotations, or at least one half year. The dominant fla type (1/1) was represented by 44% of isolates, or by at least one isolate from 31 of 62 broiler flocks. This significantly exceeded the prevalence of fla type 1/1 C. jejuni isolates that we have estimated from other studies and suggests that isolates carrying this fla type are overrepresented in flocks with recurrent Campylobacter problems. The MRPs of clones belonging to fla type 1/1 serotype O:2 isolated from persistently infected flocks shared a high percentage of bands compared to the remaining isolates, indicating that some clones that have the ability to cause persistent infections in broiler farms are highly related to each other.     

Resistance to quinolones in Campylobacter jejuni and Campylobacter coli from Danish broilers at farm level

AIMS: To investigate the prevalence of quinolone resistance among Campylobacter jejuni and Camp. coli isolates from Danish poultry at the farm level, as well as for the whole country. METHODS AND RESULTS: Data and isolates were collected from a national surveillance of Campylobacter in poultry. Quinolone resistance was investigated by determination of minimum inhibitory concentration (MIC) to nalidixic acid and enrofloxacin. Among Camp. jejuni and Camp. coli combined, 7.5% were resistant to nalidixic acid. Quinolone resistance varied considerably from farm to farm, with 0% on some farms and almost 100% on others, but the resistance was evenly distributed geographically. With respect to isolates from farms where resistance was detected, quinolone resistance was higher among Camp. coli (28.7%) than among Camp. jejuni (11.3%). PFGE typing of quinolone-resistant and quinolone-susceptible isolates from four farms indicated that certain resistant isolates belonged to specific clones that were able to persist on the farms during several rotations, even in the absence of selective pressure. Some clones were present and repeatedly isolated in both a quinolone-susceptible and quinolone-resistant variant. CONCLUSIONS: Overall, quinolone resistance among Campylobacter isolates from Danish broilers was 7.5% in 1998 and 1999; it was higher among Camp. coli than Camp. jejuni. Genetic diversity among resistant isolates was lower than among susceptible isolates, and certain clones existed in both a resistant and a susceptible variant. Some resistant clones appeared to persist on the farms and were repeatedly isolated from poultry flocks. SIGNIFICANCE AND IMPACT OF THE STUDY: The study is important for the understanding of persistence and dynamics of Campylobacter in broiler houses. It also highlights the extent, farm-to-farm variation and persistence of quinolone-resistant Campylobacter in broiler houses.     

Molecular epidemiology of Campylobacter isolates from poultry production units in southern Ireland

This study aimed to identify the sources and routes of transmission of Campylobacter in intensively reared poultry farms in the Republic of Ireland. Breeder flocks and their corresponding broilers housed in three growing facilities were screened for the presence of Campylobacter species from November 2006 through September 2007. All breeder flocks tested positive for Campylobacter species (with C. jejuni and C. coli being identified). Similarly, all broiler flocks also tested positive for Campylobacter by the end of the rearing period. Faecal and environmental samples were analyzed at regular intervals throughout the rearing period of each broiler flock. Campylobacter was not detected in the disinfected house, or in one-day old broiler chicks. Campylobacter jejuni was isolated from environmental samples including air, water puddles, adjacent broiler flocks and soil. A representative subset of isolates from each farm was selected for further characterization using flaA-SVR sub-typing and multi-locus sequence typing (MLST) to determine if same-species isolates from different sources were indistinguishable or not. Results obtained suggest that no evidence of vertical transmission existed and that adequate cleaning/disinfection of broiler houses contributed to the prevention of carryover and cross-contamination. Nonetheless, the environment appears to be a potential source of Campylobacter. The population structure of Campylobacter isolates from broiler farms in Southern Ireland was diverse and weakly clonal.     

Efficacy of flagellin gene typing for epidemiological studies of Campylobacter jejuni in poultry estimated by comparison with macrorestriction profiling

Thirty isolates of Campylobacter jejuni isolated from 29 different Danish broiler flocks were chosen for the evaluation of PCR-Fla typing as a genotyping tool. Except for two isolates that originated from the same broiler flock, the isolates were clearly distinguishable on basis of their macrorestriction profiles using the restriction endonucleases SmaI and KpnI. PCR-Fla typing of the 30 isolates yielded 16 distinct genotypes, whereas one isolate was untypeable by this method. The dominant PCR-Fla type (1/1) was shared by eight isolates, and five additional Fla groups containing two or three isolates were obtained. The PCR-Fla type of one isolate changed spontaneously after five subcultures, illustrating the relative plasticity of the gene locus. Comparison of MRPs within and between Fla-types support the view that some PCR-Fla types may be conserved within clonal lines. It is concluded that PCR-Fla typing is useful as a genotyping tool in large-scale epidemiological studies but that additional analyses with other methods are required to properly define interstrain relationships.     

Comparison of genotypes and serotypes of Campylobacter jejuni isolated from Danish wild mammals and birds and from broiler flocks and humans.

The incidence of human infection with Campylobacter jejuni is increasing in most developed countries and the reason for this is largely unknown. Although poultry meat is considered to be a major source, it is evident that other reservoirs exist, possibly common to humans and poultry. Environmental sources are believed to be important reservoirs of Campylobacter infection in broiler chicken flocks. We investigated the potential importance of wildlife as a source of infection in commercial poultry flocks and in humans by comparing the serotype distributions, fla types, and macrorestriction profiles (MRPs) of C. jejuni isolates from different sources. The serotype distribution in wildlife was significantly different from the known distributions in broilers and humans. Considerable sero- and genotype diversity was found within the wildlife collection, although two major groups of isolates within serotype O:12 and the O:4 complex were found. Common clonal lines among wildlife, chicken, and/or human isolates were identified within serotype O:2 and the O:4 complex. However, MRPs of O:12 and O:38 strains isolated from wildlife and other sources indicated that some clonal lines propagated in a wide selection of animal species but were not detected in humans or broilers in this study. The applied typing methods successfully identified different clonal groups within a strain collection showing large genomic diversity. However, the relatively low number of wildlife strains with an inferred clonal relationship to human and chicken strains suggests that the importance of wildlife as a reservoir of infection is limited.     

Longitudinal study of Campylobacter jejuni bacteriophages and their hosts from broiler chickens

A longitudinal study of bacteriophages and their hosts was carried out at a broiler house that had been identified as having a population of Campylobacter-specific bacteriophages. Cloacal and excreta samples were collected from three successive broiler flocks reared in the same barn. Campylobacter jejuni was isolated from each flock, whereas bacteriophages could be isolated from flocks 1 and 2 but were not isolated from flock 3. The bacteriophages isolated from flocks 1 and 2 were closely related to each other in terms of host range, morphology, genome size, and genetic content. All Campylobacter isolates from flock 1 were genotypically indistinguishable by pulsed-field gel electrophoresis (PFGE). PFGE and multilocus sequence typing indicated that this C. jejuni type was maintained from flock 1 to flock 2 but was largely superseded by three genetically distinct C. jejuni types insensitive to the resident bacteriophages. All isolates from the third batch of birds were insensitive to bacteriophages and genotypically distinct. These results are significant because this is the first study of an environmental population of C. jejuni bacteriophages and their influence on the Campylobacter populations of broiler house chickens. The role of developing bacteriophage resistance was investigated as this is a possible obstacle to the use of bacteriophage therapy to reduce the numbers of campylobacters in chickens. In this broiler house succession was largely due to incursion of new genotypes rather than to de novo development of resistance.     

Study on the epidemiology and control of Campylobacter jejuni in poultry broiler flocks.

Broiler flocks are frequently infected with Campylobacter jejuni. The origin of the infection is still unclear. The question of whether colonization of flocks results from transmission of C. jejuni from breeder flocks to progeny (vertical transmission) or from environmental sources (horizontal transmission) remains to be answered. Therefore, in this study samples were taken from successive broiler flocks in two broiler houses (house A on farm A and house B1 on farm B) as well as from the environment of the houses. All C. jejuni isolates were typed by using the Penner serotyping system, and part of the isolates from farm B were typed by using a randomly amplified polymorphic DNA-typing system. In poultry house A, C. jejuni was isolated from the first flock but not from subsequent flocks. In poultry house B1, C. jejuni strains of the same Penner serotypes and exhibiting identical DNA profiles were isolated from successive flocks. Infection of the flocks from a common source via horizontal pathways is suspected, while a vertical route of infection is not likely to exist. Application of measures to control horizontal transmission of C. jejuni on farm B was successful.     

Study on the epidemiology and control of Campylobacter jejuni in poultry broiler flocks.

Broiler flocks are frequently infected with Campylobacter jejuni. The origin of the infection is still unclear. The question of whether colonization of flocks results from transmission of C. jejuni from breeder flocks to progeny (vertical transmission) or from environmental sources (horizontal transmission) remains to be answered. Therefore, in this study samples were taken from successive broiler flocks in two broiler houses (house A on farm A and house B1 on farm B) as well as from the environment of the houses. All C. jejuni isolates were typed by using the Penner serotyping system, and part of the isolates from farm B were typed by using a randomly amplified polymorphic DNA-typing system. In poultry house A, C. jejuni was isolated from the first flock but not from subsequent flocks. In poultry house B1, C. jejuni strains of the same Penner serotypes and exhibiting identical DNA profiles were isolated from successive flocks. Infection of the flocks from a common source via horizontal pathways is suspected, while a vertical route of infection is not likely to exist. Application of measures to control horizontal transmission of C. jejuni on farm B was successful.     

Genomic diversity of Campylobacter coli and Campylobacter jejuni isolates recovered from free-range broiler farms and comparison with isolates of various origins

In many industrialized countries, the incidence of campylobacteriosis exceeds that of salmonellosis. Campylobacter bacteria are transmitted to humans mainly in food, especially poultry meat products. Total prevention of Campylobacter colonization in broiler flocks is the best way to reduce (or eliminate) the contamination of poultry products. The aim of this study was to establish the sources and routes of contamination of broilers at the farm level. Molecular typing methods (DNA macrorestriction pulsed-field gel electrophoresis and analysis of gene polymorphism by PCR-restriction fragment length polymorphism) were used to characterize isolates collected from seven broiler farms. The relative genomic diversity of Campylobacter coli and Campylobacter jejuni was determined. Analysis of the similarity among 116 defined genotypes was used to determine clusters within the two species. Furthermore, evidence of recombination suggested that there were genomic rearrangements within the Campylobacter populations. Recovery of related clusters from different broiler farms showed that some Campylobacter strains might be specifically adapted to poultry. Analysis of the Campylobacter cluster distribution on three broiler farms showed that soil in the area around the poultry house was a potential source of Campylobacter contamination. The broilers were infected by Campylobacter spp. between days 15 and 36 during rearing, and the type of contamination changed during the rearing period. A study of the effect of sanitary barriers showed that the chickens stayed Campylobacter spp. free until they had access to the open area. They were then rapidly colonized by the Campylobacter strains isolated from the soil.     

Demonstration of persistent strains of Campylobacter jejuni within broiler farms over a 1‐year period in Lithuania

Aims: The aim of the study was to investigate the flock prevalence of Campylobacter jejuni and Campylobacter coli in broiler farms in Lithuania and to identify possible persistent strains of Camp. jejuni using amplified fragment length polymorphism (AFLP) typing method. Methods and Results: During 1 year, 42 broiler flocks from 9 broiler farms were examined to determine the prevalence of Campylobacter‐positive broiler flocks in Lithuania. Among 42 broiler flocks examined, 31 flocks (73·8%) were positive for Camp. jejuni and 17 flocks (40·48%) for Camp. coli. Campylobacter jejuni isolates were genotyped by AFLP method using BspDI and BglII restriction enzymes. Typing of 190 isolates generated 50 AFLP genotypes with the highest diversity of strains found in the summer season. Each farm showed one or more predominant AFLP types, and one AFLP type (A32) was found in five broiler farms over a 1‐year period. Conclusions: Campylobacter jejuni and Camp. coli are highly prevalent in broiler farms in Lithuania. Farm‐specific genotypes were identified in all farms examined. Type A32 was present and persisted in different broiler farms, and a common source of transmission of Camp. jejuni was suspected. Significance and Impact of the Study: For the first time, Camp. jejuni in broiler flocks has been genetically characterized in Lithuania. Persistent strains of Camp. jejuni were detected over one period at the beginning of broiler meat production chain and, therefore, the identification of contamination source of such strains and the mechanism of their particular ability to persist are crucial to establish effective control measures against Camp. jejuni infection in broiler farms.     

Genetic characterization and antibiotic resistance of Campylobacter spp. isolated from poultry and humans in Senegal

AIMS: The main objectives of this study were to investigate the diversity of Campylobacter genotypes circulating in Senegal and to determine the frequency of antibiotic resistance. METHODS AND RESULTS: Strains of Campylobacter jejuni isolated from poultry (n = 99) and from patients (n = 10) and Campylobacter coli isolated from poultry (n = 72) were subtyped by pulsed-field gel electrophoresis (PFGE). The pulsotypes obtained after digestion by SmaI and KpnI revealed a significant genetic diversity in both species, but without any predominant pulsotypes. However, farm-specific clones were identified in the majority of poultry houses (76.5%). Human and poultry isolates of C. jejuni had common PFGE patterns. High quinolone-resistance rates were observed for C. jejuni (43.4%) and C. coli (48.6%) isolates obtained from poultry. CONCLUSIONS: The results showed a genetic diversity of Campylobacter between farms indicating multiple sources of infection; but specific clones had the ability to colonize the broiler farms. The antimicrobial resistance patterns were not related to any specific PFGE pattern suggesting that resistance was due to the selective pressure of antibiotic usage. Campylobacter with similar genotypes were circulating in both human and poultry. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is important for the understanding of the epidemiology of Campylobacter in broiler farms in Senegal. It also emphasizes the need for a more stringent policy in the use of antimicrobial agents in food animals.     

Molecular subtype analyses of Campylobacter spp. from Arkansas and California poultry operations

Campylobacter isolates from diverse samples within broiler production and processing environments were typed by using flaA short variable region DNA sequence analysis. Sixteen flocks from four different farms representing two broiler producers in Arkansas and California were analyzed. Fourteen of the flocks (87.5%) were Campylobacter-positive; two remained negative throughout the 6-week rearing period. In general, multiple clones were present within a flock. Additionally, clones found within a flock were also present on the final product, although the diversity of Campylobacter spp. on the final product appeared to be reduced relative to that observed within the flock. Comparison of clones between flocks on the same farm revealed that some clones of Campylobacter persisted in multiple flocks. Furthermore, some clones were identified across the two farms that were under the same management. In two sampling periods, environmental isolates were positive for Campylobacter prior to flock shedding. Environmental samples associated with five additional flocks were positive for Campylobacter concomitantly with recovery of Campylobacter from the birds. Analysis of the environmental isolates that were positive prior to flock shedding demonstrated that in some instances the environmental isolates possessed genotypes identical to those of isolates originating from the flock, while in other cases the environmental isolates possessed genotypes that were distantly related to isolates obtained from the flock. Analyses of environmental isolates that tested positive concurrently with the positive isolates from the flocks demonstrated varied results; in some instances the environmental isolates possessed genotypes identical to those of isolates originating from the flock, while in other cases the environmental isolates possessed genotypes that were distantly related to isolates obtained from the flock. These data suggest that the external environment may contribute to Campylobacter contamination during poultry production and processing. However, environmental contamination with Campylobacter does not appear to be the sole contributing factor.     

Microbial ecology of Campylobacter jejuni in a United Kingdom chicken supply chain: intermittent common source, vertical transmission, and amplification by flock propagation.

A study of Campylobacter jejuni on a broiler chicken farm between 1989 and 1994 gave an estimated isolation rate of 27% (3,304 of 12,233) from a 0.9% sample of 1.44 million broiler chickens from six to eight sheds over 32 consecutive rearing flocks comprising 251 broiler shed flocks. During the study, C. jejuni was found in 35.5% of the 251 shed flocks but only 9.2% (23 of 251) had Campylobacter isolates in successive flocks, with 9 of those 23 sheds having the same serotype between consecutive flocks, indicating a low level of transmission between flocks. Analysis of a systematic sample of 484 of 3,304 (14.6%) C. jejuni isolates showed that 85% were of 10 serotype complexes but 58% were of 3 serotype complexes, indicating a high degree of strain similarity throughout the entire study. The three commonest types were detected in 8 of 32 flocks during the 5-year study period, suggesting an intermittent common external Campylobacter source. This hypothesis was tested by a retrospective cohort analysis of C. jejuni rates and types by reference to hatchery supplier of the 1-day-old chicks. Isolation rates of C. jejuni and frequency distribution of types were determined in 6-week-old broiler chickens identified by the hatchery supplying the original chicks. The isolation rate of C. jejuni in broilers, supplied by hatchery A, was 17.6%, compared to 42.9% (P < 0.0001) for broilers reared from chicks supplied by hatchery B. In two instances, when both hatcheries were used to stock the same farm flock, Campylobacter isolates were found only in those sheds with chicks supplied by hatchery B. Thus, the frequency distribution of Campylobacter types for chickens supplied by the two hatcheries over the 5-year period showed marked dissimilarity. These findings suggest that the isolation rate and type of Campylobacter isolates in broiler chickens was associated with the hatchery supplying chicks. The lack of diversity of types and the intermittent high positivity of sheds is evidence for a common source of C. jejuni introduced by vertical transmission rather than contamination at the hatchery or during transportation.     

Sources of Campylobacter spp. colonizing housed broiler flocks during rearing

The study aimed to identify sources of campylobacter in 10 housed broiler flocks from three United Kingdom poultry companies. Samples from (i) the breeder flocks, which supplied the broilers, (ii) cleaned and disinfected houses prior to chick placement, (iii) the chickens, and (iv) the environments inside and outside the broiler houses during rearing were examined. Samples were collected at frequent intervals and examined for Campylobacter spp. Characterization of the isolates using multilocus sequence typing (MLST), serotyping, phage typing, and flaA restriction fragment length polymorphism typing was performed. Seven flocks became colonized during the growing period. Campylobacter spp. were detected in the environment surrounding the broiler house, prior to as well as during flock colonization, for six of these flocks. On two occasions, isolates detected in a puddle just prior to the birds being placed were indistinguishable from those colonizing the birds. Once flocks were colonized, indistinguishable strains of campylobacter were found in the feed and water and in the air of the broiler house. Campylobacter spp. were also detected in the air up to 30 m downstream of the broiler house, which raises the issue of the role of airborne transmission in the spread of campylobacter. At any time during rearing, broiler flocks were colonized by only one or two types determined by MLST but these changed, with some strains superseding others. In conclusion, the study provided strong evidence for the environment as a source of campylobacters colonizing housed broiler flocks. It also demonstrated colonization by successive campylobacter types determined by MLST during the life of a flock.     

Use of multilocus sequence typing to investigate the association between the presence of Campylobacter spp. in broiler drinking water and Campylobacter colonization in broilers

The presence of campylobacters in broiler chickens and throughout the broiler water delivery systems of 12 farms in northeastern Scotland was investigated by sensitive enrichment methods and large-volume filtration. Campylobacter presence was independent of the water source and whether the water was treated. The genotypes of Campylobacter jejuni isolates recovered from chickens and various locations within the water delivery systems were compared by multilocus sequence typing. Matching strains in shed header tanks and birds were found at 1 of the 12 farms investigated. However, the sequence of contamination or whether the source was within or outside the shed was not determined. Nevertheless, these data provide evidence that drinking water could be associated with broiler infection by campylobacters.     

Prevalence and antimicrobial susceptibility of thermophilic Campylobacter in organic and conventional broiler flocks

AIMS: To determine the flock prevalence and to estimate the within flock prevalence of Campylobacter in broiler flocks from different rearing systems, and to determine the antimicrobial susceptibility of Campylobacter isolates to selected antimicrobial substances. METHODS AND RESULTS: One hundred and sixty broiler flocks originating from organic, conventional and extensive indoor production farms were investigated for the presence of Campylobacter at the time of slaughter. Campylobacter isolates from a subsample of positive flocks were subjected to susceptibility testing. Campylobacter spp. were isolated from 100% of organic broiler flocks, from 36.7% of conventional broiler flocks and from 49.2% of extensive indoor broiler flocks. Six of 62 Campylobacter isolates were resistant to one or more of the antimicrobials tested. CONCLUSION: These results indicate that the special characteristics of organic broiler production provide a high prevalence of Campylobacter-positive flocks. Antimicrobial resistance was scarce among Campylobacter isolates from all rearing systems. SIGNIFICANCE AND IMPACT OF THE STUDY: Organic broiler flocks constitute a strong potential for introduction of Campylobacter to the processing line upon arrival at slaughter.     

Changes in the carriage of Campylobacter strains by poultry carcasses during processing in abattoirs

The recent development of simple, rapid genotyping techniques for Campylobacter species has enabled investigation of the determinative epidemiology of these organisms in a variety of situations. In this study we have used the technique of fla typing (PCR-restriction fragment length polymorphism analysis of the flaA and flaB genes) to identify the sources of strains contaminating the carcasses of five campylobacter-positive and two campylobacter-negative broiler flocks during abattoir processing. The results confirmed that, in the United Kingdom, individual broiler flocks are colonized by a limited number of subtypes of Campylobacter jejuni or C. coli. In some but not all cases, the same subtypes, isolated from the ceca, contaminated the end product as observed in carcass washes. However, the culture methodology, i.e, use of direct plating or enrichment, affected this subtype distribution. Moreover, the number of isolates analyzed per sample was limited. fla typing also indicated that some campylobacter subtypes survive poultry processing better than others. The extent of resistance to the environmental stresses during processing varied between strains. The more robust subtypes appeared to contaminate the abattoir environment, surviving through carcass chilling, and even carrying over onto subsequent flocks. From these studies it is confirmed that some campylobacter-negative flocks reach the abattoir but the carcasses from such flocks are rapidly contaminated by various campylobacter subtypes during processing. However, only some of these contaminating subtypes appeared to survive processing. The sources of this contamination are not clear, but in both negative flocks, campylobacters of the same subtypes as those recovered from the carcasses were isolated from the crates used to transport the birds. In one case, this crate contamination was shown to be present before the birds were loaded.     

Influence of season and geography on Campylobacter jejuni and C. coli subtypes in housed broiler flocks reared in Great Britain

Geographical and seasonal variation in the incidence and prevalence of Campylobacter jejuni and C. coli in housed broiler flocks reared in Great Britain in 2004 to 2006 was investigated in this study. Ceca (30) from 797 flocks, not subject to prior partial depopulation and reared on 211 farms, were examined individually for the presence of Campylobacter spp. The best-fitting climatic factors explained approximately 46% of the prevalence of Campylobacter-colonized flocks at slaughter and consisted of a combination of temperature at slaughter, number of sunshine hours in placement month, and millimeters of rainfall in placement month. Positive flocks were more likely to be slaughtered between June and November than during the rest of the year and to be reared in northern Great Britain than in central or southern Great Britain. C. jejuni was identified in approximately 90% of flocks, and C. coli was present in 10% of flocks. The most common clonal complexes identified in 226 isolates typed by multilocus sequence typing (MLST) were ST-45, ST-21, ST-574, ST-443, and ST-828. Flocks slaughtered at the same time were more likely to have similar complexes, and ST-45 had a seasonal pattern, with the highest prevalence in June, and was also more likely to be present in flocks reared in northern Great Britain.     

Prevalence of Campylobacter spp. in a subset of intensive poultry flocks in Ireland

Aim:  The aim of this study was to investigate the prevalence of Campylobacter species in a subset of intensive poultry flocks by examining samples collected in geographically disparate areas on the island of Ireland.
Methods and Results:  Faecal, water and environmental samples were collected from the interior of poultry houses on nine farms. Three cultural methods were used for Campylobacter isolation: direct plating, enrichment culture and a recovery method for emerging Campylobacter spp. Presumptive Campylobacter isolates were confirmed using biochemical tests and further identified to species level by multiplex PCR. All flocks sampled in this study were found to be contaminated with Campylobacter at the time of sampling. Structural and air samples taken from the interior of broiler houses were also found to be Campylobacter positive. All water samples were found to be Campylobacter negative. The Campycheck method was used for the isolation of emerging Campylobacter spp.
Conclusions:  Campylobacter spp. were recovered (as contaminants) from the poultry house interior, air and environmental samples in all intensive poultry flocks surveyed.
Significance and Impact of the Study:  This study highlights the need for improved biosecurity on selected poultry farms.     

Bacteriophage therapy to reduce Campylobacter jejuni colonization of broiler chickens

Colonization of broiler chickens by the enteric pathogen Campylobacter jejuni is widespread and difficult to prevent. Bacteriophage therapy is one possible means by which this colonization could be controlled, thus limiting the entry of campylobacters into the human food chain. Prior to evaluating the efficacy of phage therapy, experimental models of Campylobacter colonization of broiler chickens were established by using low-passage C. jejuni isolates HPC5 and GIIC8 from United Kingdom broiler flocks. The screening of 53 lytic bacteriophage isolates against a panel of 50 Campylobacter isolates from broiler chickens and 80 strains isolated after human infection identified two phage candidates with broad host lysis. These phages, CP8 and CP34, were orally administered in antacid suspension, at different dosages, to 25-day-old broiler chickens experimentally colonized with the C. jejuni broiler isolates. Phage treatment of C. jejuni-colonized birds resulted in Campylobacter counts falling between 0.5 and 5 log10 CFU/g of cecal contents compared to untreated controls over a 5-day period postadministration. These reductions were dependent on the phage-Campylobacter combination, the dose of phage applied, and the time elapsed after administration. Campylobacters resistant to bacteriophage infection were recovered from phage-treated chickens at a frequency of <4%. These resistant types were compromised in their ability to colonize experimental chickens and rapidly reverted to a phage-sensitive phenotype in vivo. The selection of appropriate phage and their dose optimization are key elements for the success of phage therapy to reduce campylobacters in broiler chickens.