"养鸡生产中沙门氏菌病的预防与控制策略"专栏(四)沙门氏杆菌和弯曲杆菌在家禽群体中的动态变化特征

难道我们不想掌控自身命运吗?虽然这是-个很广博的问题,但如果你在考虑幼龄肉鸡群沙门氏菌感染这个特定话题以及考虑它与人食源性疾病可能的关系时,这个问题就具有特殊的意义.出席美国国家家禽改良计划(the National Poultry Improvement Plan,NPIP)第40届年会(两年一次)的大多数代表,在投票是否采用美国肉鸡扩繁群肠炎沙门氏菌监测方案时,对该特殊问题给出了肯定回答.     

Examination of Australian backyard poultry for Salmonella,Campylobacter and Shigella spp., and related risk factors

Worldwide, foodborne illness is a significant public health issue in both developed and developing countries. Salmonellosis, campylobacteriosis and shigellosis are common foodborne gastrointestinal illnesses caused by the bacteria Salmonella spp., Campylobacter spp. and Shigella spp. respectively. These zoonotic diseases are frequently linked to eggs and poultry products. The aim of this study was to investigate the presence of these pathogens in Australian backyard poultry flocks and to determine risk factors for these pathogens. Poultry faeces samples were collected from 82 backyards and screened for Salmonella spp., Campylobacter spp. and Shigella spp. using qPCR. A questionnaire was administered to the backyard poultry owners to assess their knowledge regarding management of poultry and eggs and to identify potential risk factors that may contribute to the presence of zoonotic pathogens in the flocks. One composite faecal sample was collected from each backyard (82 samples). Composite sampling here means taking one or more grab samples from a backyard to make up approximately 10 grams. Four per cent of samples, that is 4% backyards tested, were positive for Salmonella spp., 10% were positive for Campylobacter spp. and none were positive for Shigella spp. A higher infection rate was seen in multi-aged flocks (24%) compared with the single-aged flocks (3%). The survey found that many participants were engaging in risky food safety behaviours with 46% of participants responding that they washed their eggs with running water or still water instead of wiping the dirt off with a damp cloth to clean the eggs and 19% stored their eggs at room temperature. This study demonstrated that backyard poultry may pose a potential risk for salmonellosis and campylobacteriosis. Additionally, Australian public health and food safety regulations should be modified and effectively implemented to address the risks associated with backyard poultry husbandry.     

Campylobacter spp. in broiler flocks at farm level and the potential for cross-contamination during slaughter

Screening of broiler flocks for their Campylobacter carriage on farm level and consequently the spread of Campylobacter spp. during slaughtering can help to identify hygiene control points. Therefore, between December 2001 and August 2002 in total 51 broiler flocks from three farms of different geographical regions in Germany were analysed for thermophilic Campylobacter. Campylobacter spp. were isolated from 45% of the broiler flocks examined. Subsequently, 1101 samples were taken from 22 flocks during different stages of processing. Samples were collected from: transport crates before and after cleaning/disinfection, evisceration, post-scalded and post-chilled carcasses and endproducts. Additionally, 45 selected Campylobacter isolates of droppings were genotyped by pulsed-field gel electrophoresis (PFGE). Campylobacter carriage of flocks showed seasonal variation, with the highest contamination rate during the period of June to August. No evidence was found for a horizontal transmission from one broiler flock to the next via a persistent house-contamination. In each positive flock, one to three different genotypes were found. One or two clones dominated isolations obtained from the farm level. The fact that in different flocks indistinguishable isolates of clonal origin were detected during the same rearing period suggested a transmission between the broiler flocks or an intermittent common external source. In one case, isolates of clonal origin were detected in various farms during different rearing periods. Sampling during processing confirmed that the entrance of a positive flock resulted in contamination of the abattoir environment. Campylobacter spp. were isolated from all sampling stages along the processing line, with a percentage of 91.1-100 of isolates at different stages of slaughtering.     

A pilot study on post-evisceration contamination of broiler carcasses and ready-to-sell livers and intestines (mala) with Campylobacter jejuni and Campylobacter coli in a high-throughput South African poultry abattoir

To assess post-evisceration contamination of broiler carcasses, 300 samples were randomly selected during routine slaughter in the winter of 2004. The samples originated from 50 chicken carcasses, taken directly after evisceration, as well as 25 samples from ready-to-sell packages of fresh intestines (mala) and livers. The samples were taken in batches over a period of 4 weeks to allow randomised sampling from different farms of origin. Conventional culture-based detection methods of Campylobacter spp. usually need 4-6 days to produce a result. The polymerase chain reaction (PCR) used for this study took less than 32 hours. The average contamination rates with Campylobacter in both the skin and liver samples were 24%, and 28% for intestines. Chicken and chicken products, especially livers and intestines, form an integral part of the traditional diet of many Black South Africans, as they are cheap and readily available in bulk and un-chilled for direct distribution, mainly through street vending and other informal retail outlets. This sudy showed that Campylobacter spp. are prevalent in poultry in South Africa. The handling of poultry meat and products contaminated with this organism in households and the potential for cross-contamination of other foods presents a high risk of infection to consumers in South Africa. The study also emphasised the need for further research in this field.     

Occurrence of Salmonella,Campylobacter, Yersinia enterocolitica,Escherichia coli O157 and Listeria monocytogenes in Swine

The objective of this study was to investigate the occurrence of major bacterial foodborne pathogens in swine. In total, 359 samples from manure storage tanks (91) and fresh pooled faeces (268) obtained from finisher (110), sows (78) and weanlings (80) were collected and tested. Campylobacter, Salmonella, Yersinia enterocolitica, Escherichia coli O157 and Listeria monocytogenes were isolated from 36.5%, 31.5%, 5.8%, 3.3% and 3.3% of samples respectively. All E. coli O157 isolates found on 10 farms were tested but none was determined to be E. coli O157:H7. Salmonella and Campylobacter were more likely to be detected from stored manure rather than from fresh faecal samples. Yersinia enterocolitica tended to be detected more commonly from fresh samples than from manure pits. Listeria monocytogenes was not recovered from manure pits or from sow faecal samples and only infrequently found in the faeces of weanling pigs and finisher pigs. The proportion of positive samples showed a seasonal change. Salmonella was twice as likely not be recovered in winter, whereas the chance of culturing Campylobacter was higher in winter. The 113 Salmonella isolates recovered on 24 farms and the four most common serovars were Salmonella Typhimurium var. Copenhagen (31.0%), Salmonella Derby (12.4%), S. Typhimurium (10.6%) and Salmonella Agona (10.6%). Of 131 Campylobacter isolates recovered on 21 farms, 118 isolates were Campylobacter coli and 13 isolates could not be speciated. Fifteen of 21 Y. enterocolitica isolates found on 15 farms were detected in finisher pigs. The sero/biogroups of Y. enterocolitica were O3/biotype 4 (16 isolates), O6,30/biotype 1A (three isolates), O5/biotype 1A (one isolate) and O8/biotype 1B (one isolate). These findings provide baseline information on the distribution of important zoonotic pathogens in swine and indicate that pigs should be considered as a possible source of foodborne diseases in humans.     

Prevalence, numbers and antimicrobial susceptibilities of Salmonella serovars and Campylobacter spp. in retail poultry in Phnom Penh, Cambodia

Salmonella and Campylobacter are common bacterial pathogens associated with human gastro-enteritis; and raw poultry is considered to be an important source of these bacteria. To evaluate whether the Salmonella serovars and Campylobacter spp. bacteria could be monitored for the purpose of microbial presence, enumeration and antimicrobial resistance in raw poultry, 152 poultry carcasses were randomly selected from 10 markets in retail outlets of Phnom Penh during March 2006 to February 2007. The majority of poultry samples was contaminated by Salmonella serovars (88.2%) and Campylobacter spp. (80.9%). A very high contamination of Salmonella was found at 3-4 log?? CFU/g for 22.4% of samples and of Campylobacter at 7-8 log?? CFU/g for 1.3% of samples. Fifty nine different Salmonella serovars contaminated 134 poultry carcasses; five most prevalent serovars covered 29.1% of serovars isolates (Anatum, Typhimurium, Corvallis, Stanley and Enteritidis). Three Campylobacter species contaminating 123 raw poultry were Campylobacter jejuni (50.0%), Campylobacter coli (29.0%) and Campylobacter lari (21.0%). High antibiotic resistance percentages were found among Salmonella serovars and Campylobacter spp. isolates. This study revealed that raw poultry at the retail outlets in Phnom Penh markets are contaminated with high prevalences of food-borne pathogens, and communicating the importance of minimizing this risk in reducing human infections.     

Assessing evidence of a potential Salmonella transmission across the poultry food chain

Enhanced Salmonella surveillance programmes in poultry were implemented in all European Member States, with minimum prevalence targets for a list of targeted serotypes to safeguard food and public health. Based on the Belgian Salmonella surveillance programme and focusing on poultry, the overarching aim of this study was to highlight possible Salmonella transmissions across the food chain (FC). For this purpose, firstly, the prevalence patterns of Salmonella (targeted and the most prevalent non-targeted) serotypes along the FC were described over time. Secondly, the effectiveness of the control measures against vertical transmission (breeders to 1-day-old broiler and layer chicks) was indirectly assessed by looking into the odds of targeted serotypes detection. Thirdly, it was appraised if Salmonella prevalence can significantly increase during broilers and layers production. In addition, it was tested if being tested negative at the end of production in broilers when tested positive at the entrance is serotype dependent (targeted vs. non-targeted serotypes). Results showed that, firstly, the prevalence patterns of the listed serotypes were inconstant over time and across the FC. Secondly, the odds of Salmonella targeted serotype detection in 1-day-old broiler and in 1-day-old layer flocks were lower than in breeder flocks while, thirdly, infection during broiler and layer production can lead to significant increase in positivity in subsequent samples. Finally, being infected by a targeted or by non-targeted serotype at the entrance of the flock poorly reflects the Salmonella status at the end of production. Note that this study did not make a distinction between the different sources of contamination and the effects of sampling methods and isolation methods should be subject to further investigation.     

Salmonella Infantis and Salmonella Enteritidis specific bacteriophages isolated form poultry faeces as a complementary tool for cleaning and disinfection against Salmonella

Salmonellosis represents an important public health concern. Several authors point out the inefficiency of the cleaning and disinfection protocols to remove the bacteria from the field. For this reason, innovative techniques, as bacteriophages, could be implemented to control the bacteria. The main objectives of this study were to assess the effect of bacteriophages against Salmonella Infantis and Salmonella Enteritidis on farm surfaces, and to evaluate bacteriophage procedure application as sanitiser against Salmonella in field conditions. Thus, most prevalent serovars in poultry production were selected (Salmonella Infantis and Salmonella Enteritidis) to contaminate farm facilities. Then, two specific bacteriophages isolated from poultry faeces were applied against them. Results showed Salmonella Infantis and Salmonella Enteritidis decreased of 4.55 log₁₀CFU/mL and 3.85 log₁₀CFU/mL, respectively; the maximum reduction in Salmonella was the 5^th day, after 10⁸ PFU/mL and 10³ PFU/mL bacteriophage application. These results highlight bacteriophages as a promising tool together with cleaning and disinfection.     

The role of litter beetles as potential reservoir for Salmonella enterica and thermophilic Campylobacter spp. between broiler flocks

We evaluated the role of beetles infesting broiler chicken rearing facilities as potential reservoirs for Salmonella enterica infections between successive broiler flocks. In addition, their role as potential reservoirs for thermophilic Campylobacter spp. was also investigated. Fourteen broiler houses located at 11 different farms were included in the study. The houses were nonrandomly selected on the basis of their salmonella status; nine were persistently contaminated with salmonella whereas five were salmonella negative. For each broiler house, two consecutive broiler flocks (i.e., 28 broiler flocks in all) as well as beetles collected during both rotations of production and in the empty period (after cleaning and disinfection) between these flocks were monitored for the presence of salmonella. Examinations for the presence of campylobacter in the same sample materials were also performed. Beetles sampled during production were positive for salmonella or campylobacter or both. Furthermore, in one house, the occurrence of Salmonella indiana in two consecutive broiler flocks coincided with the presence of S. indiana-contaminated beetles in the empty period between the flocks. The genotype of the identified S. indiana was in all cases identical when analyzed by pulsed-field gel electrophoresis. However, our results also suggest that salmonella from beetles may not always be transmitted to the chickens and that beetles living in contaminated houses can remain free of infection. All cases of campylobacter-positive beetle samples were detected in connection with a positive chicken flock; in no case was campylobacter isolated from beetles taken from the empty period between rotations. Four beetle species were identified during this study. Alphitobius diaperinus was found in all houses and was relatively abundant in most. Typhaea stercorea and Ahasverus advena were found in eight and nine houses, respectively, and were abundant in most of these. Carcinops pumilio was found in small numbers in eight houses. No other insect species was identified. These investigations have shown that beetles in broiler houses infrequently are positive for salmonella. However, transmission of S. indiana between two consecutive broiler flocks can coincide with the presence of salmonella-contaminated beetles in the empty period, indicating that the beetles were the reservoir of S. indiana between the two flocks. Concerning campylobacter, the results suggest that beetles do not play a significant role as a reservoir of campylobacter from one rotation to the next.     

Investigation of the concurrent colonization with Campylobacter and Salmonella in poultry flocks and assessment of the sampling site for status determination at slaughter

Fifty six broiler flocks and 20 laying hen and breeder flocks were sampled in six slaughterhouses for the presence of Campylobacter and Salmonella. Samples were taken from three different sites of the gastrointestinal tract, namely from the crop, the duodenum and the ceca. The prevalence of flocks colonized with Campylobacter and Salmonella was determined and an association between the concurrent colonization with these two pathogens was investigated. Furthermore, the best sampling site for status determination at the slaughterhouse level was evaluated. Of the broiler flocks, 73% were colonized with Campylobacter, whereas 13% were Salmonella-positive at slaughter. Concerning the laying hen and breeder flocks, all flocks were colonized with Campylobacter and 65% of the flocks were Salmonella-positive. No association was found between Campylobacter and Salmonella occurrence in broiler flocks. Since all laying hen and breeder flocks were colonized with Campylobacter, no association between the concurrent colonization with the two pathogens could be determined. At the slaughterhouse level, sampling only the duodena was sufficient to determine the Campylobacter status of poultry flocks, whereas the three sampling sites had to be analyzed to detect all flocks colonized with Salmonella.     

Heat resistance in liquids of Enterococcus spp., Listeria spp., Escherichia coli, Yersinia enterocolitica, Salmonella spp. and Campylobacter spp

The aim of the work was to collect, evaluate, summarize and compare heat resistance data reported for Campylobacter, Enterococcus, Escherichia, Listeria, Salmonella and Yersinia spp. The work was limited to resistance in liquids with pH values 6-8. Results obtained under similar experimental conditions were sought. Thermal destruction lines for the various bacterial groups studied were constructed using log10 D values and treatment temperatures. There was a good linear relationship between log10 D and temperature with Escherichia coli, listerias and salmonellas. For campylobacters, enterococci and yersinias the relationships were weaker but, nevertheless, present. Using the slopes of the lines and their 95% confidence limits, z values and their 95% confidence limits were calculated. z values were compared with z values obtained from reports. The equations for the lines were also used for calculation of predicted means of D values at various treatment temperatures. 95% confidence limits on predicted means of D values and on predicted individual D values were also calculated. Lines and values are shown in figures and tables. Differences in heat resistance noted between and within the bacterial groups studied are discussed.     

Bacteriological and serological examination and risk factor analysis of Salmonella occurrence in sow herds, including risk factors for high Salmonella seroprevalence in receiver finishing herds

A strong association between the seroprevalence in sows and the occurrence of Salmonella Typhimurium among weaners has been shown. As shown several times for finisher herds, the risk-factors, ready mixed pelleted feed and health status also apply to sow herds. Risk factors on the sow level, for high seroprevalence in finishers have been quantified. It has been shown, that isolating Salmonella in weaners is a risk factor for high seroprevalence in finishers. Feed factors; ready-mixed pelleted feed for both sows and finishers, dry feed for sows, have been shown to have a significant effect on high seroprevalence, monitored by meat juice samples at slaughter. The etiological fraction of ready-mixed pelleted feed for sows and for finishers is of the same magnitude, indicating that intervention on the sow level could prove to contribute considerably to the effect of intervention programs.     

Use of delayed secondary enrichment for the isolation of Salmonella in poultry and poultry environments

A conventional method of isolating Salmonella was compared with isolation using novobiocin-supplemented plating media and delayed secondary enrichment (DSE). The DSE greatly increased the ability to isolate Salmonella from poultry and environmental samples. Four hundred sixty-four isolations of Salmonella were made from a total of 4377 cultures (11%). Two hundred sixty-nine (58%) isolations of Salmonella were made following the 24-hour incubation; of these, 43 (9%) isolates were isolated only at this time. In comparison, a total of 421 (91%) Salmonella were isolated by DSE, of which 195 isolates (42%) were isolated only with DSE. The addition of novobiocin to the selective plating medium increased the isolation rate for Salmonella and reduced the level of contaminating bacteria growing on the plate.     

A survey of carcass condemnation at a poultry abattoir and its application to disease management

During a five year period, slaughter records were maintained on flocks of broiler chickens sent to a federally-inspected abattoir in New Brunswick. These records, including data regarding condemnation of both carcasses and portions of broilers, were maintained at the level of the individual producer. Annual meetings and ad hoc consultations with producers, a veterinary poultry specialist, and support groups in the poultry industry (feed mills, breeders, etc.) were used to relay to the various interested parties, information relating to disease conditions.

Following the implementation of this system, condemnation rates dropped by one full percentage point during the first three years, with a slight increase observed during the last two years of the study. At the end of the survey, condemnation rates were 20% less than those of the national average.