Evaluation of a PCR assay for the detection and identification of Campylobacter jejuni and Campylobacter coli in retail poultry products

Combined Loop-Mediated Isothermal Amplification Assays for Rapid Detection and One-Step Differentiation of Campylobacter jejuni and Campylobacter coli in Meat Products

A loop-mediated isothermal amplification (LAMP) assay system was established, allowing rplD gene-based simultaneous detection of Campylobacter jejuni and Campylobacter coli in enriched meat products. Additionally, one-step differentiation of target species on agar plates was enabled by cdtC gene- and gyrA gene-based duplex LAMP. Both the rplD and cdtC–gyrA LAMP assays amplified the target sequences in all 62 C. jejuni and 27 C. coli strains used for determining inclusivity and revealed 100% exclusivity toward 85 tested non-target species. Throughout the entire experiments, C. jejuni and C. coli strains were 100% distinguishable by melting curves of cdtC and gyrA LAMP products. After 24-h enrichment, the rplD LAMP assay reliably detected initial inoculation levels of 10–100 CFU/g in artificially contaminated minced meat. Investigation of naturally contaminated meat samples revealed a diagnostic accuracy of 95% toward real-time PCR and 94.1% toward the standard culture method applying the 24-h incubation period. Diagnostic sensitivity and specificity, and positive and negative predictive values were 89.8, 100, 100, and 91.2%, respectively, when measured against real-time PCR, and 89.6, 98.1, 97.7, and 91.2%, respectively, when measured against the standard culture method. After 48-h enrichment, the detection limit of the rplD LAMP assay improved to initial inoculation levels of 1–10 CFU/g in artificially contaminated minced meat. Applying the 48-h incubation period on naturally contaminated meat samples resulted in 100% concordant results between rplD LAMP, real-time PCR, and the standard culture method. The established LAMP assay system was proved to be suitable for rapid meat sample screening. Furthermore, it constitutes a promising tool for investigating other Campylobacter sources and could therefore make a valuable contribution to protect consumers from foodborne illness.

A ten-year-surveillance program of zoonotic pathogens in feral pigeons in the City of Madrid (2005-2014): The importance of a systematic pest control

Feral pigeons have increased in urban settings worldwide becoming a potential health risk for humans and other animals. Control and surveillance programs are essential to prevent the possible transmission of zoonotic pathogens carried by pigeons. A surveillance program was carried out in Madrid City (Spain) during 2005-2014 to determine the role of urban pigeons as carriers of zoonotic agents comparing these results with studies performed elsewhere in the last fifteen years. A total of 1372 pigeons were randomly captured and tested for detection of Antimicrobial susceptibility and genetic heterogeneity of Campylobacter and Salmonella isolates were determined. During the first phase (August 2005-July 2010), 428 animals were analyzed individually, while in the second period (August 2010-December 2014), 944 pigeons were analyzed in pools (n = 2-3 in 2010 and n = 5-6 in 2013 and 2014). The most prevalent pathogen during the first phase was Campylobacter spp., (6.57%, 95% confidence interval 3.05-12.10%) followed by Salmonella spp. (4.41%, 95% CI: 2.30-7.58%) and C. psittaci (2.56%, 95% CI: 0.70-6.53%)]. The PCR techniques, used during the 2010-2014 phase of the study, confirmed the presence of Campylobacter spp. (prevalence of 0-14.83%) and C. psittaci (0-12,94%) among pigeons of Madrid. Antimicrobial susceptibility testing suggested low levels of resistance. Presence of zoonotic agents in feral pigeons highlights the importance of surveillance programs on this species, although the relative low prevalence found suggests a limited risk to Public and Animal Health in Madrid.

Isolation and Identification of Campylobacter spp. from Poultry and Poultry By-Products in Tunisia by Conventional Culture Method and Multiplex Real-Time PCR

Thermophilic Campylobacter spp. are one of the primary causes of bacterial human diarrhea. The consumption of poultry meats, by-products, or both is suspected to be a major cause of human campylobacteriosis. The aims of this study were to determine the prevalence of thermophilic Campylobacter spp. in fresh poultry meat and poultry by-products by conventional culture methods and to confirm Campylobacter jejuni and Campylobacter coli isolates by using the multiplex PCR assay. Two hundred fifty fresh poultry samples were collected from a variety of supermarkets and slaughterhouses located in Sfax, Tunisia, including chicken (n =149) and turkey (n =101). The samples were analyzed using conventional microbiological examinations according to the 2006 International Organization for Standardization method (ISO 10272-1) for Campylobacter spp. Concurrently, a real-time PCR was used for identification of C. jejuni and C. coli . Of the 250 samples of poultry meat and poultry by-products, 25.6% (n = 64) were contaminated with Campylobacter spp. The highest prevalence of Campylobacter spp. was found in chicken meat (26.8%) followed by turkey meat (23.7%). Among the different products, poultry breasts showed the highest contamination (36.6%) followed by poultry by-products (30%), poultry wings (28%) and poultry legs (26%) showed the lowest contamination, and no contamination was found on neck skin. Of the 64 thermophilic Campylobacter isolates, C. jejuni (59.7%) was the most frequently isolated species and 10.9% of the isolates were identified as C. coli . All of the 64 Campylobacter isolates identified by the conventional culture methods were further confirmed by PCR. The seasonal peak of Campylobacter spp. contamination was in the warm seasons (spring and summer). The study concluded that high proportions of poultry meat and poultry by-products marketed in Tunisia are contaminated by Campylobacter spp. Furthermore, to ensure food safety, poultry meats must be properly cooked before consuming.

Higher resistance of Campylobacter coli compared to Campylobacter jejuni at chicken slaughterhouse

In order to compare the prevalence of Campylobacter coli and Campylobacter jejuni during the processing of broilers at slaughterhouse a total of 848 samples were analyzed during 2012 in southern Spain. Four hundred and seventy six samples were collected from cloaca, carcass surfaces and quartered carcasses. Moreover, 372 environmental swabs from equipment and scalding water were collected. Minimum inhibitory concentration (MIC) to ciprofloxacin, erythromycin, streptomycin, tetracycline and gentamicin was determined for isolates from chicken meat. The general prevalence of Campylobacter was 68.8% (40.2% of C. coli and 28.5% of C. jejuni). The relative prevalence of C. coli increased from loading dock area (41.5%) to packing area (64.6%). In contrast, the relative prevalence of C. jejuni decreased from 58.5% to 35.4%. These differences between species from initial to final area were significant (p=0.02). The highest antimicrobial resistance for C. jejuni and C. coli was detected to tetracycline (100%) and ciprofloxacin (100%), respectively. Campylobacter coli showed an antimicrobial resistance significantly higher than C. jejuni to streptomycin (p=0.002) and erythromycin (p<0.0001).

Rapid detection and differentiation of important Campylobacter spp. in poultry samples by dot blot and PCR

The detection of Campylobacter, the most commonly reported cause of foodborne gastroenteritis in the European Union, is very important for human health. The most commonly recognised risk factor for infection is the handling and/or consumption of undercooked poultry meat. The methods typically applied to evaluate the presence/absence of Campylobacter in food samples are direct plating and/or enrichment culture based on the Horizontal Method for Detection and Enumeration of Campylobacter spp. (ISO 10272-1B: 2006) and PCR. Molecular methods also allow for the detection of cells that are viable but cannot be cultivated on agar media and that decrease the time required for species identification. The current study proposes the use of two molecular methods for species identification: dot blot and PCR. The dot blot method had a sensitivity of 25 ng for detection of DNA extracted from a pure culture using a digoxigenin-labelled probe for hybridisation; the target DNA was extracted from the enrichment broth at 24 h. PCR was performed using a pair of sensitive and specific primers for the detection of Campylobacter jejuni and Campylobacter coli after 24 h of enrichment in Preston broth. The initial samples were contaminated by 5 × 10 C. jejuni cells/g and 1.5 × 10(2)C. coli cells/g, thus the number of cells present in the enrichment broth at 0 h was 1 or 3 cell/g, respectively.

Prevalence of Campylobacter spp. in skinless, boneless retail broiler meat from 2005 through 2011 in Alabama, USA

BACKGROUND

The prevalence of Campylobacter spp. in 755 skinless, boneless retail broiler meat samples (breast, tenderloins and thighs) collected from food stores in Alabama, USA, from 2005 through 2011 was examined. Campylobacter spp. were isolated using enrichment and plate media. Isolates were identified with multiplex PCR assays and typed with pulsed field gel electrophoresis (PFGE). Data were analyzed by nominal variables (brand, plant, product, season, state and store) that may affect the prevalence of these bacteria.

RESULTS

The average prevalence of Campylobacter spp. in retail broiler meat for these years was 41%, with no statistical differences in the prevalence by year (P > 0.05). Seasons did not affect the prevalence of C. jejuni but statistically affected the prevalence of C. coli (P < 0.05). The prevalence by brand, plant, product, state and store were different (P < 0.05). Establishments from two states had the highest prevalence (P < 0.05). C. coli and C. jejuni had an average prevalence of 28% and 66%, respectively. The prevalence of C. coli varied by brand, plant, season, state, store and year, while the prevalence of C. jejuni varied by brand, product, state and store. Tenderloins had a lower prevalence of Campylobacter spp. than breasts and thighs (P < 0.05). Although no statistical differences (P > 0.05) were observed in the prevalence of C. jejuni by season, the lowest prevalence of C. coli was recorded from October through March. A large diversity of PFGE profiles was found for C. jejuni, with some profiles from the same processing plants reappearing throughout the years.

CONCLUSIONS

The prevalence of Campylobacter spp. did not change during the seven years of the study; however, it did change when analyzed by brand, product and state. Seasons did not affect the prevalence of C. jejuni, but they did affect the prevalence of C. coli. Larger PFGE databases are needed to assess the temporal reoccurrence of PFGE profiles to help predict the risk associated with each profile.

Tracing Campylobacter jejuni strains along the poultry meat production chain from farm to retail by pulsed-field gel electrophoresis, and the antimicrobial resistance of isolates

In this study Campylobacter jejuni isolates were recovered from birds, carcasses and carcass portions from two broiler chicken flocks and from equipment used for carcass and meat processing along the production chain from farms to retail stores. Isolates were subjected to pulsed-field gel electrophoresis (PFGE) using SmaI and KpnI restriction enzymes and their antimicrobial susceptibilities were determined. C. jejuni was recovered from product and equipment used with both flocks at each point in the production chain. The prevalence of C. jejuni in poultry products at retail stores was 58.97% (flock 1) and 69.23% (flock 2). SmaI divided 122 C. jejuni strains from flock 1 and 106 from flock 2 into 17 and 13 PFGE types, respectively. PFGE types H and F were present at all steps along the chain, from farms to retail products. Similarly, for both flocks PFGE type D was detected in crates, slaughterhouse and retail stores. Moreover, the PFGE types were highly diverse at the processing and retail steps. Most PFGE types were resistant to ciprofloxacin (95.45%) and tetracycline (81.82%); and multidrug resistant PFGE types were found in the final products. Our study showed that there were several points of cross-contamination of product along the chain, and a high diversity of PFGE types with antimicrobial resistance to ciprofloxacin and tetracycline in the retail products.

Detection and quantification of Campylobacter jejuni and Campylobacter coli using real-time multiplex PCR

AIMS

We describe a real-time quantitative multiplex polymerase chain reaction (qmPCR) assay to identify and discriminate between isolates of Campylobacter jejuni and Campylobacter coli.

METHODS AND RESULTS

Two novel sets of primers and hydrolysis probes were designed to amplify the unique DNA sequences within the hipO, ccoN and cadF genes that are specific to Camp. jejuni and Camp. coli. Using the designed optimized qmPCR assay conditions, the amplification efficiency is in range from 108 to 116%. These qmPCR assays are highly specific for Camp. jejuni and Camp. coli, as seen through testing of 40 Campylobacter strains and 17 non-Campylobacter strains. In chicken juice and tap water models spiked with known quantities of Camp. jejuni, qmPCR detected 10(2) -10(3) CFU ml(-1) within 4 h.

CONCLUSIONS

The qmPCR assays developed in this study provide reliable and simultaneous detection and quantification of Camp. jejuni and Camp. coli, with good amplification reaction parameters.

SIGNIFICANCE AND IMPACT OF THE STUDY

Following further validation, the qmPCR assay reported here has the potential to be applied to various sample types as an alternative and rapid methodology.

Occurrence of Campylobacter spp. in poultry and poultry products for sale on the Polish retail market

In 2007 and 2008, a monitoring study was carried out in Poland to examine the occurrence of thermotolerant Campylobacter spp. in raw and cooked chicken products available on the retail market. A total of 912 samples were tested: 443 samples of raw chicken meat, 146 samples of giblets, and 323 ready-to-eat poultry products (150 samples of spit-roasted chicken, 56 samples of smoked chicken, and 117 samples of pâté and cold meats). A high level of contamination of raw chicken meat (51.7% of samples) and chicken giblets (47.3% of samples) was detected. However, thermotolerant Campylobacter spp. were found in only 1.2% of the ready-to-eat poultry products.

Study of the molecular mechanisms involved in high-level macrolide resistance of Spanish Campylobacter jejuni and Campylobacter coli strains

OBJECTIVES

To investigate the molecular mechanisms involved in the high-level erythromycin resistance of clinical Spanish Campylobacter jejuni and Campylobacter coli strains.

METHODS

Overall susceptibilities of 678 C. jejuni and 119 C. coli strains, collected from 10 Spanish provinces during 2006 and 2007, were determined by Etest. In high-level erythromycin-resistant strains, molecular determinants were studied. The analysis was focused on region V of the 23S rRNA gene, the rplD and rplV ribosomal genes, and the regulatory region of the CmeABC efflux pump.

RESULTS

The global resistance rate to erythromycin was 3.8%. Among the resistant strains, 93% were C. coli and 7% were C. jejuni. The A2075G mutation in the 23S rRNA gene was detected in all of the resistant strains except for two, which carried the A2074G mutation. None of the ribosomal rplD and rplV genes harboured the described mutations that confer resistance to macrolides. Different mutations affecting the regulatory region of the CmeABC efflux pump were also found.

CONCLUSIONS

C. coli strains are clearly more resistant to erythromycin than C. jejuni. The mutation A2075G in the 23S rRNA gene was responsible for the resistance in most of the strains; A2074G was only found in two strains. Further studies are required to ascertain the effect of mutations in the regulatory region of cmeABC. Our data indicate that the rate of resistance was similar to that of other European countries.

Case-control study of risk factors for sporadic Campylobacter infections in northeastern Spain

BACKGROUND

An age-matched case-control study was conducted in northeastern Spain to identify major risk factors for sporadic Campylobacter infections and their relative importance.

METHODS

Cases were aged >6 months, residents of Sector Sanitario Huesca with diarrhea and confirmed culture of Campylobacter not related to outbreak. For each case <15 years of age, the patient closest in age to the case was selected from the medical records of the case's pediatrician to serve as a control. If the case was >or=15 years of age, the control was nominated by the case.

RESULTS

Eighty one cases (median age 2.3 years, 79% <15 years) and 81 controls were enrolled. Three exposures, in the 7 days prior to symptom onset, were independent predictors for illness after multivariate conditional logistic regression analysis: consuming three or more times chicken [odds ratio (OR)(adjusted) = 6.1; confidence interval (CI): 2.0-18.5; population attributable fraction (PAF) = 36.1%], consuming sliced deli meat unhygienically handled at retail stores (OR(adjusted) = 4.1; CI: 1.2-13.2; PAF = 24.5%) and contact with animals (OR(adjusted) = 2.8; CI: 1.1-7.3; PAF = 19. 0%). Among cases <15 years of age, only consuming chicken >or=3 times (OR(adjusted) = 7.8; CI: 2.2-26.7; PAF = 43.6%) and contact with animals (OR(adjusted) = 3.7; CI: 1.2-11.0; PAF = 25.1%) were independent predictors for disease. Consuming sliced deli meat unhygienically handled at retail stores was significantly more frequent among <15-year age group (56.3% versus 26.6.0%, P = 0.04).

CONCLUSION

A control programme for Campylobacter in the food chain and targeted food-safety education to prevent cross-contamination seem warranted to decrease the opportunity of human exposure to the pathogen in northeastern Spain.

Survival mechanisms and culturability of Campylobacter jejuni under stress conditions

Culture-based isolation and enumeration of bacterial human pathogens from environmental and human food samples has significant limitations.Many pathogens enter a viable but non-culturable(VBNC) state in response to stress, and cannot be detected via culturing methods. Favourable growth conditions with a source of energy and an ideal stoichiometric ratio of carbon to inorganic elements can reverse this VBNC state. This review will focus on the bacterium Campylobacter jejuni which is a leading cause of food borne illness in the developed world. C. jejuni can enter a VBNC state in response to extremes in: pH, moisture content, temperature,nutrient content and salinity. Once in a VBNC state,the organism must maintain an energy balance from substrate oxidation through respiration to grow,divide and remain viable. The goal of this review isa greater understanding of how abiotic stress and thermodynamics influence the viability of C. jejuni.

Thermophilic Campylobacter spp. in salad vegetables in Malaysia

The main aim of this study was to combine the techniques of most probable number (MPN) and polymerase chain reaction (PCR) for quantifying the prevalence and numbers of Campylobacter spp. in ulam, a popular Malaysian salad dish, from a traditional wet market and two modern supermarkets in Selangor, Malaysia. A total of 309 samples of raw vegetables which are used in ulam were examined in the study. The prevalences of campylobacters in raw vegetables were, for supermarket I, Campylobacter spp., 51.9%; Campylobacter jejuni, 40.7%; and Campylobacter coli, 35.2%: for supermarket II, Campylobacter spp., 67.7%; C. jejuni, 67.7%; and C. coli, 65.7%: and for the wet market, Campylobacter spp., 29.4%; C. jejuni, 25.5%; and C. coli, 22.6%. In addition Campylobacter fetus was detected in 1.9% of raw vegetables from supermarket I. The maximum numbers of Campylobacter spp. in raw vegetables from supermarkets and the wet market were >2400 and 460 MPN/g, respectively.

Detection of Campylobacter jejuni and Campylobacter coli in chicken meat samples by real-time nucleic acid sequence-based amplification with molecular beacons

A nucleic acid sequence-based amplification (NASBA) assay based on molecular beacons was used for real-time detection of Campylobacter jejuni and Campylobacter coli in samples of chicken meat. A set of specific primers and beacon probe were designed to target the 16S rRNA of both species. The real-time NASBA protocol including the RNA isolation was valid for both of the cell suspensions in buffered saline and the artificially contaminated chicken meat samples. The presence of rRNA could be correlated with cellular viability, following inactivation of the bacteria by heating, in inoculated chicken meat samples but not in RNase-free cell suspensions.

Effect of oral administration of bismuth compounds on Campylobacter colonization in broilers

Bismuth compounds have been used since the 18th century to treat gastrointestinal ailments in man. Colloidal bismuth subcitrate (De-Nol) is currently used in combination with antibiotics to reduce enteric Helicobacter pylori colonization as a treatment of stomach ulcers. We investigated whether bismuth citrate or its parent compound, colloidal bismuth subcitrate, would reduce colonization of the closely related foodborne pathogen, Campylobacter jejuni in chickens. In 2 studies, birds were either fed 0, 50, or 200 ppm bismuth citrate or bismuth subcitrate (De-Nol) for 10 or 21 d and were orally challenged with 7 combined strains of C. jejuni (n = 6 birds/treatment). For both treatment groups, cecal Campylobacter colonization was reduced when birds were fed 200 ppm for 10 d but not 21 d. For the 50 ppm treatment group, only birds dosed with bismuth citrate for 21 d demonstrated any reduction in cecal Campylobacter concentrations when compared with controls. These data suggest that bismuth citrate and colloidal bismuth subcitrate may reduce cecal colonization by Campylobacter in broilers, but these effects are inconsistent.

Detection and identification of food-borne pathogens of the genera Campylobacter, Arcobacter and Helicobacter by multiplex PCR in poultry and poultry products

The objective of this study was to develop a multiplex polymerase chain reaction (PCR) to detect and differentiate food-borne pathogens of the three genera Campylobacter, Arcobacter and Helicobacter in a single step procedure. One common reverse primer and three genus-specific forward primers were designed by hybridizing to the 16S rRNA of selected reference strains. Besides the species with significance as food-borne pathogens isolated from poultry meat--Campylobacter jejuni, Campylobacter coli, Arcobacter butzleri and Helicobacter pullorum--several other members of these genera were tested to determine the specificity of the designed multiplex PCR. In total, 20 ATCC and NCTC reference strains of Campyobacter, Arcobacter and Helicobacter were used to evaluate the PCR. Specific amplificates were obtained from all thermophilic species of Campylobacter as well as from species of Arcobacter and Helicobacter. No amplification product was obtained from the non-thermophilic Campylobacter, C. hyointestinalis and C. fetus. Furthermore, a total of 43 field strains of the three genera isolated from poultry, pigs, cattle and humans were investigated using this PCR. To confirm the classification of 10 H. pullorum strains the 16S rRNAs were sequenced. The developed PCR is a helpful diagnostic tool to detect and differentiate Campylobacter, Arcobacter and Helicobacter isolated from poultry and poultry products.