Lisa K. Williams

Enrichment culture can bias the isolation of Campylobacter subtypes

Enrichment culture is often used to isolate Campylobacter. This study compared isolation of Campylobacter spp. from 119 broiler chicken environments from two farms, using Preston and modified Exeter (mExeter) and modified Bolton (mBolton) enrichments. mExeter was significantly more effective in isolating Campylobacter spp. from the environmental samples compared to Preston (P<0.001) and mBolton (P<0.04) broths but there was no significant difference between the latter two methods (P>0.05). Enrichment broth type did not affect isolation from chicken faecal or soil and litter samples. C. jejuni was isolated from significantly more environmental samples using mExeter broth compared to Preston (P<0.01) and mBolton (P<0.003) broths; there was no difference between the latter two methods or between all methods for detection of C. coli (P>0.05). Only C. coli was isolated from the soil and litter samples and although both C. jejuni and C. coli were recovered from the faecal samples there was no effect of using different enrichment broths. The majority of samples where the same species had been isolated yielded the same or closely related genotypes as defined by pulsed-field gel electrophoresis. Isolates recovered using Preston and mBolton broths were less genetically diverse than those from mExeter broth. We conclude that the enrichment method used affects both the number and species of Campylobacter isolated from naturally contaminated samples.

Enrichment culture for the isolation of Campylobacter spp: Effects of incubation conditions and the inclusion of blood in selective broths

Isolation of Campylobacter spp. using enrichment culture is time consuming and complex. Reducing the time taken to confirm the presence or absence of Campylobacter spp. would have many advantages for diagnostic, commercial and research applications. Rapid techniques such as real-time PCR can detect campylobacters from complex samples but blood in enrichment culture can inhibit the PCR reaction, if applied directly to enriched samples. The aim of this study was to investigate the effect of blood in enrichment culture on the isolation of campylobacters from chicken caeca, carcass rinses and bootsock (gauze sock walked through a broiler chicken house) samples using Bolton broth. The effect of incubation temperature (37 degrees C or 41.5 degrees C for 48 h, or 37 degrees C for 4 h then transfer to 41.5 degrees C for 44 h) and method of generating atmosphere (incubation of container in jar gassed with microaerobic atmosphere or incubation of container with small headspace and tightly screwed lid in an aerobic atmosphere) with and without blood on isolation from chicken carcass rinses and chicken faeces was also investigated. The presence of blood in enrichment culture did not improve the isolation of campylobacters from chicken faeces or bootsock samples but significantly improved recovery from chicken carcass rinse samples. There was no significant effect of the method used to generate incubation atmosphere. Isolation rates did also not depend significantly on whether broths were incubated at 37 or 41.5 degrees C for 24 or 48 h. Overall, the presence of blood in such media is not essential, although isolation can vary depending on sample type and enrichment method used.

Campylobacter Infection Has Different Outcomes in Fast- and Slow-Growing Broiler Chickens

SUMMARY Campylobacter spp. are frequently carried by poultry, but they are not believed to cause significant disease in these animals. Modern poultry breeds have been selected to grow rapidly under intensive conditions, but recently, consumers have moved toward purchasing birds produced in higher welfare, free-range or organic systems. Birds reared in these systems tend to be a slower growing breed and are fed a different diet. Birds reared in such systems are stocked at a lower density compared with the standard conventional broilers, and they have access to environmental enrichment, such as perches. In previous research, these slower growing birds have been shown to have different levels of Campylobacter carriage in commercial rearing conditions, but the reasons for, and effect of, these different levels are unknown; is it the bird breed, diet, or environmental conditions? In this study, experimental flocks of fast- and slow-growing breeds of broiler chickens were reared to a standard commercial slaughter weight, with their weight gain being measured during the growing period. At 21 days, birds were either infected with Campylobacter jejuni or given a placebo as control. Cohorts of birds were euthanatized at various intervals, and samples were taken for examination for Campylobacter. The fast-growing birds gained weight more rapidly than the slow-growing birds. By 2 days postinfection (dpi), C. jejuni was detected in the caeca and by enrichment from the liver and spleen samples from both breeds of birds. Low-level colonization persisted in the spleen and liver samples but was undetectable by 28 dpi. Fast- and slow-growing birds did not show detectably different levels of Campylobacter carriage. Infection with C. jejuni affected the incidence of hock marks and pododermatitis in both breeds of birds, but the differences were greater with the fast-growing breed compared with the uninfected control birds. In addition, the incidence of pododermatitis was significantly higher in Campylobacter-positive fast-growing birds than in their slower-growing counterparts. The results show that infection with Campylobacter can have an indirect welfare effect on birds via increased incidence of hock marks and pododermatitis. RESUMEN La infección por Campylobacter muestra diferentes comportamientos en pollos de engorde de crecimiento rápido y lento. La bacteria Campylobacter spp. está presente frecuentemente en las aves comerciales, pero se cree que no causa una enfermedad significativa en estas aves. Las razas modernas de aves de corral han sido seleccionadas para crecer rápidamente bajo condiciones intensivas, pero recientemente, los consumidores se han desplazado hacia la compra de las aves producidas en sistemas de crianza al aire libre con mayor bienestar y de tipo orgánico. Las aves criadas en estos sistemas generalmente son razas de crecimiento más lento y son alimentadas con una dieta diferente. Las aves criadas en estos sistemas se alojan con una densidad más baja en comparación con los pollos convencionales estándar, y tienen acceso a medio ambiente enriquecido como perchas. En investigaciones anteriores, estas aves de crecimiento más lento han demostrado que tienen diferentes niveles de la presencia de Campylobacter en condiciones de crianza comercial, pero las razones y los efectos de estos distintos niveles no se conocen. ¿Esto estará relacionado con la raza de ave, la dieta, o con las condiciones ambientales? En este estudio, se criaron parvadas experimentales de razas de crecimiento rápido y lento de pollos de engorde a un peso final para procesamiento estándar, con el registro de su aumento de peso durante el período de crecimiento. A los 21 días, las aves fueron infectadas ya sea con Campylobacter jejuni o se les administró un placebo como control. Se sacrificaron grupos cohortes de aves en varios intervalos, y se tomaron muestras para la detección de Campylobacter. Las aves de rápido crecimiento aumentaron de peso más rápidamente que las aves de crecimiento lento. A los dos días después de la infección, se detectó C. jejuni en el ciego y por enriquecimiento en las muestras de hígado y de bazo procedentes de ambas razas de aves. Un bajo nivel de colonización persistió en el bazo y en las muestras de hígado, pero no fue detectable a los 28 días después de la inoculación. Las aves de crecimiento rápido y lento no mostraron niveles detectablemente diferentes con relación a la presencia de Campylobacter. La infección por C. jejuni afectó la incidencia de marcas en los corvejones y pododermatitis en ambas razas de aves, pero las diferencias fueron mayores con la raza de rápido crecimiento en comparación con las aves control no infectadas. Además, la incidencia de pododermatitis fue significativamente mayor en aves de crecimiento rápido positivas a Campylobacter en comparación de sus homólogos de crecimiento más lento. Los resultados muestran que la infección con Campylobacter puede tener un efecto indirecto sobre el bienestar de las aves a través de un aumento de la incidencia de las marcas en los corvejones y pododermatitis.

Detection of Campylobacter Jejuni and Campylobacter coli from broiler chicken related samples using BAX PCR and conventional international organization for standardization culture

In this study, the conventional International Organization for Standardization (ISO) culture method was compared with the DuPont Qualicon BAX system, a high-throughput, rapid molecular assay that can be used to detect several bacterial species, including Campylobacter jejuni and Campylobacter coli in diverse sample types. Standard enrichment culture is a time-consuming process, taking up to 6 days to obtain a confirmed result. Rapid molecular assays have been developed that provide results within 24 h. Naturally contaminated samples from the poultry production chain were examined for the presence of Campylobacter spp. Samples from broiler chicken ceca (n = 100), fresh chicken carcass rinses (n = 60), and bootsocks (gauze sock walked through a broiler chicken house; n = 50) were enriched according to the ISO 10272 method in Bolton broth specifically designed to detect Campylobacter spp. in complex sample types. Samples were enriched without blood for use with the BAX system using the Campylobacter BAX kits for the detection of C. jejuni and C. coli. Samples also were directly plated onto modified charcoal cefperazone deoxycholate agar, and results were compared with those from the enriched samples for the ability to detect Campylobacter spp. Campylobacter spp. were isolated from 49% of samples with conventional enrichment cultures, from 48% with direct culture, from 68% with the BAX system and enrichment cultures, and from 62% with the BAX system used directly with samples. Overall, the BAX system detected more positive samples than did the conventional culture method and is an effective methodology for the rapid and reliable detection of Campylobacter spp. from diverse sample types.

Pancreatic amylase is an environmental signal for regulation of biofilm formation and host interaction in Campylobacter jejuni.

ABSTRACT Campylobacter jejuni is a commensal bacterium in the intestines of animals and birds and a major cause of food-borne gastroenteritis in humans worldwide. Here we show that exposure to pancreatic amylase leads to secretion of an α-dextran by C. jejuni and that a secreted protease, Cj0511, is required. Exposure of C. jejuni to pancreatic amylase promotes biofilm formation in vitro, increases interaction with human epithelial cell lines, increases virulence in the Galleria mellonella infection model, and promotes colonization of the chicken ileum. We also show that exposure to pancreatic amylase protects C. jejuni from stress conditions in vitro, suggesting that the induced α-dextran may be important during transmission between hosts. This is the first evidence that pancreatic amylase functions as an interkingdom signal in an enteric microorganism.