Reliably colonising broiler chickens with Campylobacter spp. using a litter-based method

ABSTRACT

1. Chicken-associated Campylobacter spp. are the cause of most food poisoning cases in Europe. In order to study the host–pathogen interactions, a reliable and reproducible method of colonising chickens with the bacteria is required.

2. This study aimed to identify a more appropriate and less invasive method of colonisation (cf. gavaging) by seeding bedding material (litter) that commercial chickens are kept on with a mixture of Campylobacter spp., broth and faeces.

3. The first phase of the study tested the longevity of Campylobacter spp. recovery in seeded litter over 24 h: significantly more Campylobacter spp. was recovered at 0 or 3 h post-seeding than at 6 and 24 h post-seeding, indicating that the pathogen can survive to detectable levels for at least 3 h in this environment.

4. In the second phase, three groups of 10 broiler chickens (negative for Campylobacter spp. prior to exposure) were exposed at 21 days of age to one of three different Campylobacter jejuni and C. coli mixes (A, B, C), using the method above. At 28 days of age, birds were euthanised by overdose of barbiturate or cervical dislocation, and livers and caeca removed for Campylobacter spp. assessment.

5. All liver and 28/30 caeca samples tested positive for Campylobacter spp., with mix A and C giving higher counts in the caeca than mix B. The method of euthanasia did not affect Campylobacter spp. counts.

6. In conclusion, a successful method for reliably colonising broiler chickens with Campylobacter spp. has been developed which negates the need for gavaging and is more representative of how contamination occurs in the field.     

Surveillance of dairy production holdings supplying raw milk to the farmhouse cheese sector for Escherichia coli O157, O26 and O111

Clinically healthy domestic animals can harbour Escherichia coli O157 and other verocytotoxigenic E. coli (VTEC) strains in their faeces. Milk filters can be used to microbiologically monitor direct milk secretion and environmental contamination for these pathogens. The aim of this study was to establish baseline data on the prevalence and characteristics of VTEC organisms in lactating animals (bovine, ovine and caprine) supplying milk to the farmhouse cheese sector, with particular emphasis on serogroups O157, O111 and O26. Fifty-six bovine, 13 caprine and 5 ovine herds/flocks, the majority of which supplying milk for farmhouse cheese production, were surveyed from May 2004 to July 2005. Milk filters were analysed by immunomagnetic separation followed by PCR, on a serogroup-specific basis for E. coli O157, O26 and O111. Positive isolates were examined using a multiplex PCR protocol, for their potential to produce verocytotoxins (vt1/vt2), the haemolysin-encoding gene (hlyA) and the gene encoding attaching and effacement (eae). Five verocytotoxigenic and 22 non-virulent E. coli O157 isolates were detected. Seventeen E. coli O26 isolates were also detected, four of which were verocytotoxigenic, seven isolates contained the eae gene only and six isolates were devoid of any of the virulence factors. The VTEC O157 and O26 isolates contained the hlyA and eae genes along with the verocytotoxin genes. No E. coli O111 isolates were detected. Some of the herds were positive on more than one occasion and multiple E. coli serogroups were isolated from the same milk filter sample. Although all food products tested were VTEC negative, routine surveillance for such pathogens in raw milk/raw milk products is of public health importance. Herd-level surveillance along with subsequent risk management action may be a cost-effective component of risk reduction strategies for food production, drinking water supplies and the protection of public health.     

Biochemical composition and energy content of six species of phytoplankton used in mariculture of bivalves

Diatoms Thalassiosira pseudonana (Hustedt) Hasle and Heimdal, Chaetoceros calcitrans (Paulsen) Takano and Chaetoceros sp. (Aquaculture Research Corporation), and phytoflagellates Isochrysis galbana Parke, Isochrysis aff. galbana Green (T-Iso) and Tetraselmis suecica (Kylin) Butcher were harvested at exponential and stationary phases of growth and biochemical compositions determined. Moisture content declined in all species at the stationary phase of growth. The siliceous nature of the diatom reduced inherent organic content relative to that of the flagellate. Total pigments were more concentrated in the stationary phases of all species except Tetraselmis. Inclusion of cellular lipid and protein was highest in species of Isochrysis with the carbohydrate constituents of the phytoflagellates presenting a complex mixture of glucose, galactose, mannose, xylose, arabinose, ribose, fucose, and rhamnose. Content of carbohydrates was generally higher in diatoms than phytoflagellates, with glucose the dominant sugar originating from a reserve glucan considered digestible by bivalves. Caloric content of lipid, carbohydrate and protein in phytoplankton allowed for ranking as sources of energy in the following decreasing order: Isochrysis aff. galbana (T-Iso), Isochrysis galbana, Chaetoceros calcitrans, Tetraselmis suecica, Thalassiosira pseudonana, and Chaetoceros sp. (ARC), with all but Thalassiosira exhibiting higher energy levels in the stationary cells.     

The effect of commercial steam pasteurization on the levels of Enterobacteriaceae and Escherichia coli on naturally contaminated beef carcasses

The aim of the study was to assess the reduction achieved by steam pasteurization of beef carcasses of Escherichia coli, Enterobacteriaceae and total aerobic mesophilic plate counts (APCs). In total, 30 carcass halves were exposed to steam pasteurization (90 degrees C, 10 s exposure time) and the 30 corresponding carcass halves remained as untreated controls. The neck, midline and rump were sampled on each carcass half. Significant reductions in E. coli incidence (P < 0.05) and counts, 0.5 log10 CFU 1000 cm(-2) (P < 0.05), were observed on rump sites only. Significant reductions (>0.8 log10 CFU 1000 cm(-2)) of Enterobacteriaceae were observed at all carcass sites sampled (P < 0.05). Enterobacteriaceae reductions (>2 log10 CFU 1000 cm(-2)) were highly significant at the more contaminated sites (P < 0.001). Reductions in total APCs were inconsistent. Steam pasteurization significantly reduced the level of E. coli and Enterobacteriaceae at more contaminated sites, but did not result in complete decontamination. Therefore, steam pasteurization should be classed as an aid to hygienic beef processing, but not as a critical control point.     

Occupational exposure of poultry stockmen in current barn systems for egg production in the United Kingdom

1. The occupational exposure to inhalable dust and ammonia of 12 stockmen working in barn systems conforming to the UK Royal Society for the Prevention of Cruelty to Animals (RSPCA) Freedom Foods requirements was measured and compared with established limits for occupational exposure. The influence of the type of task upon the daily exposure was assessed and comparisons of daily exposure were made with that of battery cage system stockmen. 2. The mean inhalable dust exposures experienced by poultry stockmen working in barn systems was 10.8 mg/m3 (9.5 mg/m3, time-weighted average), for a complete working day. This was greater (P < 0.01) than the mean dust exposure measured in current cage systems of 4.8 mg/m3 (4.4 mg/m3, time-weighted average). The individual values of dust exposure for 4 of the 12 barn stockmen exceeded the occupational exposure standard (OES) of 10.0 mg/m3 for inhalable dust, whereas that of all of the individual cage stockmen taking part in this study did not. 3. The mean ammonia exposure experienced by poultry stockmen working in barn systems was 14 ppm (11 ppm, time-weighted average), for a complete working day. This also was greater (P < 0.01) than the mean ammonia exposure measured in current cage systems of 8 ppm (7 ppm, time-weighted average). None of the individual values of ammonia exposures for both barn and cage system stockmen taking part in this study exceeded the OESs of 25 ppm, although the short-term limit of 35 ppm for 15 min was exceeded on a number of occasions. 4. Current methods for assessing the combined effects of dust and ammonia indicated that 8 of the 12 barn stockmen were at risk compared with 1 of the 8 cage system stockmen. 5. The average dust burden in daily common tasks such as maintenance and collecting floor eggs ranged from 5 to 15 mg/m3, while intermittent common tasks such as nest box checks and litter spreading ranged from 13 to 35 mg/m3. Tasks that had the highest exposure values included sweeping and partition removal, ranging from 63.3 to 70.7 mg/m3. 6. Designs of the typical barn systems investigated offer little scope for reducing airborne dust for common daily tasks. Personal respiratory protection while carrying out tasks that result in high dust concentrations in barns is advisable.     

International approach to plant exploration and introduction

These is a need to review the theories of N. I. Vavilov on the basis of modern knowledge on the nature and genetics of variability, ecogenetics, environmental archaeology and related subjects.Greater care should be taken in the preliminary planning of plant collecting expeditions, so that collectors may be better informed on the ecology of the species they are to collect, and of the types of vegetation in which they are likely to occur. The best method of sampling populations should be evolved so that plant introduction stations shall not be swamped with vast collections.Current interest is widespread with regard both to species and to the countries concerned. There is a great need for new material of herbage and fodder plants, grain legumes, cereals, potato, coffee, cacao, rubber and other crops. Time is short, as the centres of origin are suffering from clearance of vegetation and development.There is a recent tendency to propose the establishment of Plant Exploration Centres within the centres of origin.

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Samenvatting Er bestaat aanleiding de theorieën van N. I. Vavilov te herzien op grond van nieuwe kennis omtrent de aard en de genetische achtergrond van de variabiliteit, de ecogenetica, de archeologie van het milieu en dergelijke.Meer zorg dient te worden besteed aan de voorbereiding van expedities opdat de plantenzoekers beter ingelicht zijn over de ecologie van de soorten, die ze gaan verzamelen, en over de vegetatie-typen waarin ze waarschijnlijk voorkomen. De beste methoden dienen te worden ontwikkeld om monsters uit populaties te verzamelen opdat de planten-introductie-centra niet overstelpt worden met materiaal.De belangstelling richt zich overal op de soorten zowel als op de landen. Er is grote behoefte aan nieuw materiaal van voedergewassen, peulvruchten, granen, aardappels, koffie, cacao, rubber en andere gewassen.De tijd dringt, aangezien de genencentra bedreigd worden met uitputting door het opruimen van vegetaties en door ontwikkeling.Er is thans een tendens merkbaar om voorstellen te doen tot het vestigen van verzamelcentra in de oorsprongsgebieden zelf.

     

The protein kinase complement of the human genome

We have catalogued the protein kinase complement of the human genome (the "kinome") using public and proprietary genomic, complementary DNA, and expressed sequence tag (EST) sequences. This provides a starting point for comprehensive analysis of protein phosphorylation in normal and disease states, as well as a detailed view of the current state of human genome analysis through a focus on one large gene family. We identify 518 putative protein kinase genes, of which 71 have not previously been reported or described as kinases, and we extend or correct the protein sequences of 56 more kinases. New genes include members of well-studied families as well as previously unidentified families, some of which are conserved in model organisms. Classification and comparison with model organism kinomes identified orthologous groups and highlighted expansions specific to human and other lineages. We also identified 106 protein kinase pseudogenes. Chromosomal mapping revealed several small clusters of kinase genes and revealed that 244 kinases map to disease loci or cancer amplicons.     

Nonsurgical videolaparoscopy for determination of reproductive status of the Arctic charr.

The efficient commercial production of Arctic charr is hampered by the limited and subtle sexual dimorphism shown by this species. This project examined the feasibility of low-cost videoendoscopy through the genital pore to determine sex, stage of maturity, and safety for 80, randomly selected, anesthetized Arctic charr. The sensitivity and specificity for correct assignment of male sex were 90% and 100%, respectively, among 3 observers in a single-blind design. Sensitivity and specificity for relative sexual maturity in the same fish were 96% and 54%, respectively. The observed mortality rate of 7% at the end of 3 weeks was confounded by the presence of unrelated disease. We conclude that the technique holds promise for application by producers to improve production efficiency.     

Properties of the immunosuppressive factor induced by murine cytomegalovirus

Murine cytomegalovirus infection of spleen cultures induced the production of a small (less than 10,000 molecular weight) immunosuppressive factor (VISF), which suppressed concanavalin-A mitogenesis in fresh mouse spleen cells, and in fresh human peripheral blood leukocytes. The factor did not affect the growth of two murine T-cell lines or of mouse fibroblasts. A similar factor was also found in the serum of infected mice, at the time of maximum immune suppression. The properties of VISF indicate that the mechanism of MCMV immune suppression is different from that caused by several other viruses which are important in human and veterinary medicine.