Prevalence and persistence of Salmonella in broiler chicken flocks

An Approach to Describe Salmonella Serotypes of Concern for Outbreaks: Using Burden and Trajectory of Outbreak-related Illnesses Associated with Meat and Poultry

Over 40% of all U.S. Salmonella illnesses are attributed to consumption of contaminated meat and poultry products each year. Determining which serotypes cause the most outbreak illnesses associated with specific meat and poultry types can inform prevention measures. We developed an approach to categorize serotypes using outbreak illness burden (high, moderate, low) and trajectory (increased, stable, decreased). We used data from 192 foodborne Salmonella outbreaks resulting in 7,077 illnesses, 1,330 hospitalizations, and 9 deaths associated with chicken, turkey, beef, or pork during 2012-2021. We linked each meat and poultry type to 1-3 serotypes that we categorized as high outbreak illness burden and increased trajectory during 2021. Calculation and public display of outbreak illness burden and trajectory annually could facilitate the prioritization of serotypes for prevention by federal and state health and regulatory agencies and by the meat and poultry industry.

A systematic review and meta-analysis of the sources of Salmonella in poultry production (pre-harvest) and their relative contributions to the microbial risk of poultry meat

Salmonella is a major foodborne pathogen associated with poultry and poultry products and a leading cause for human salmonellosis. Salmonella is known to transmit in poultry flocks both vertically and horizontally. However, there is a lack of knowledge on relative contribution of the factors on Salmonella prevalence in poultry live production system including hatchery, feed, water, environment-interior, and -exterior. Therefore, a systematic review and meta-analysis was conducted to quantify the potential sources of Salmonella during preharvest and their relative contributions to the microbial risk of poultry meat. A total of 16,800 studies identified from Google Scholar and 37 relevant studies were included in the meta-analysis for relative contributions to Salmonella positivity on broilers after applying exclusion criteria. A generalized linear mixed model approach combined with logit transformation was used in the current study to stabilize the variance. The analysis revealed that the hatchery is the most significant contributor of Salmonella with a prevalence of 48.5%. Litter, feces, and poultry house internal environment were the other 3 major contributing factors with a prevalence of 25.4, 16.3, and 7.9%, respectively. Moreover, poultry house external environment (4.7%), feed (4.8%), chicks (4.7%), and drinker water also contributed to the Salmonella positivity. Results from this meta-analysis informed the urgent need for controls in live production to further reduce Salmonella in fresh, processed poultry. The control strategies can include eliminating the sources of Salmonella and incorporating interventions in live production to reduce Salmonella concentrations in broilers.

Prevalence, Serovars, and Antimicrobial Resistance of Salmonella in Cecal Samples of Chickens Slaughtered in Pluck Shops in Trinidad

The aim of the study was to determine the prevalence and zonal distribution of Salmonella serotypes in poultry and to determine the antimicrobial resistance profile of Salmonella isolates. A total of 1,503 cecal samples of poultry were randomly collected from 33 pluck shops across Trinidad. Isolation and identification of Salmonella followed standard methods, and the disk diffusion method was used to determine resistance of isolates to 14 antimicrobial agents. Ninety-one (6.1%) of the 1,503 samples collected from four zones were positive for Salmonella. The frequency of isolation of Salmonella from chicken ceca (6.5%) was higher than that detected in duck ceca (5.1%), but the difference was not statistically significant (P > 0.05). Ten serotypes were detected, with Salmonella Molade, Salmonella enterica subsp. enterica I, and Salmonella Typhimurium the most prevalent at 56.0, 11.0, and 8.8%, respectively. The highest frequency of isolation of Salmonella was recorded in the northeast zone (59.3%). All 91 isolates exhibited resistance to at least 1 of the 14 antimicrobial agents. The highest frequency of resistance was exhibited to ampicillin (51.0%), kanamycin (49.5%), and streptomycin (37.4%). A total of 22 resistance patterns were exhibited by the 91 isolates of Salmonella, and 13 isolates (14.3%) exhibited multiple drug resistance. The results emphasize the need to implement hygienic practices to reduce the levels of contamination at poultry pluck shops and the need for prudent use of antimicrobial agents in the poultry production system in Trinidad.

Bacteriological assessments of foodborne pathogens in poultry meat at different super shops in Dhaka, Bangladesh

Poultry is now considered as a major fast-growing source of meat in the world. The consumers demand safe and hygienic products without contamination with pathogenic microorganisms when the production and consumption of poultry meat is gradually increasing. The present study was conducted to assess the bacterial contamination of dressed chicken collected from different supershops in Dhaka, Bangladesh. The chicken samples from S₁, S₂, M1, M₂ and A supershops were analyzed to determine the enteropathogenic bacteria in poultry meat. Three genera of bacteria were isolated from all of the chicken meat samples. These enteropathogens from various organs of dressing chickens were also enumerated. The isolates were presumptively identified as E. coli, Salmonella spp., and Shigella spp. by conventional culture method. The three enteropathogens were subjected to PCR assay for their confirmation as virulent enteropathogens. Only E. coli isolates were confirmed as pathogenic E. coli (Enterotoxigenic), other isolates were not confirmed as virulent Salmonella spp., Shigella spp.. Results of this study demonstrated that more cautions are recommended for personnel hygiene in processing and handling of poultry and poultry products to prevent occurrence of enterotoxigenic E. coli in dressed poultry meat sold by the supershops in Bangladesh.

Occurrence, genotypes and antimicrobial susceptibility of Salmonella collected from the broiler production chain within an integrated poultry company

Salmonella is a common foodborne pathogen in the poultry production systems. Its presence in this food industry is determined by the fact that it can survive and pass throughout the different steps in the poultry production. In this study we aimed to study the occurrence, genotypes and antimicrobial resistance of Salmonella collected from the broiler production chain within an integrated poultry company. Three hundred fourteen samples were collected in the feeding plant, farms and the slaughterhouse. Samples were cultured for Salmonella isolation according to the ISO6579/Amd 1. Isolates were further typed by Kauffmann-White scheme and pulse field gel electrophoresis (PFGE). Antimicrobial resistance to 11 antimicrobials was studied by disk diffusion tests and sequencing of ESBL genes. From the collected samples 70 (22%) were found to be Salmonella positive. The lowest Salmonella rates were found in feed samples while in farm and slaughterhouse samples Salmonella presence ranged from 5% to 88%. S. Infantis was the most common serotype (94%, 66/70). PFGE demonstrated that isolates belonged to 11 genotypes. Some genotypes were continuously identified throughout the production chain. 97% of the isolates showed resistance to at least one antimicrobial. Moreover, all S. Infantis isolates and one auto-agglutinable isolate showed resistance to at least 6 antimicrobials. 30 and 8 isolates were positive to bla_CTX-M-65 and bla_CTX-M-14 genes respectively. No bla_KPC resistance genes were identified in any isolate. This study highlights the predominance of S. Infantis in the integrated poultry company. Genotypes showed that cross-contamination between stages of poultry production can occur, stressing the importance of implementing good hygiene practices in every level of the production. Moreover, multidrug resistance patterns and the presence of important ESBL genes have public health implications that need to be deeply discussed with a one health approach.

Salmonella control in poultry flocks and its public health impact

An increase in confirmed human salmonellosis cases in the EU after 2014 triggered investigation of contributory factors and control options in poultry production. Reconsideration of the five current target serovars for breeding hens showed that there is justification for retaining Salmonella Enteritidis, Salmonella Typhimurium (including monophasic variants) and Salmonella Infantis, while Salmonella Virchow and Salmonella Hadar could be replaced by Salmonella Kentucky and either Salmonella Heidelberg, Salmonella Thompson or a variable serovar in national prevalence targets. However, a target that incorporates all serovars is expected to be more effective as the most relevant serovars in breeding flocks vary between Member State (MS) and over time. Achievement of a 1% target for the current target serovars in laying hen flocks is estimated to be reduced by 254,400 CrI95[98,540; 602,700] compared to the situation in 2016. This translates to a reduction of 53.4% CrI95[39.1; 65.7] considering the layer-associated human salmonellosis true cases and 6.2% considering the overall human salmonellosis true cases in the 23 MSs included in attribution modelling. A review of risk factors for Salmonella in laying hens revealed that overall evidence points to a lower occurrence in non-cage compared to cage systems. A conclusion on the effect of outdoor access or impact of the shift from conventional to enriched cages could not be reached. A similar review for broiler chickens concluded that the evidence that outdoor access affects the occurrence of Salmonella is inconclusive. There is conclusive evidence that an increased stocking density, larger farms and stress result in increased occurrence, persistence and spread of Salmonella in laying hen flocks. Based on scientific evidence, an impact of Salmonella control programmes, apart from general hygiene procedures, on the prevalence of Campylobacter in broiler flocks at the holding and on broiler meat at the end of the slaughter process is not expected.

Estimation of the prevalence of Salmonella species on the slatted area compared to the scratch area of broiler breeder chicken houses

With the objective of detecting Salmonella species in the poultry house environment, sampling broiler breeder houses in the two-thirds slatted area and the one-third scratch area with pine shavings bedding can be difficult. The slatted area is where the females, consisting of approximately 90% of the population, eat, drink, and spend the majority of their time. The scratch area is where the males eat and drink, as well as where mating and mortality occur. Besides the nest boxes, the female feeders and water lines make the slatted areas more difficult to sample. However, it is important to take samples from the area with the greatest likelihood of isolating Salmonella. Therefore, boot swab samples were collected from 21 commercial broiler breeder chicken houses representing three different companies in north Georgia to estimate the prevalence of Salmonella on the slat vs. the scratch area in each chicken house. Every house sampled had a central scratch area covered with litter and two elevated slat areas constructed of wood. Four boot swab samples were collected on each side slat area by walking the entire length of the house for each swab. Eight samples were collected in the same manner from the scratch area. Results of 335 total samples were acquired, 167 of which were obtained from the slat area and 168 of which came from the scratch area, yielding 242 total Salmonella isolations. Salmonella was found in 117 of the slat samples, representing 70.1%, compared to 125 of the scratch area samples, representing 74.4%. Both the univariate (P = 0.311) and the multivariable (P = 0.303) analysis showed that sampling location was not associated with Salmonella prevalence.

Prevalence and fimbrial genotype distribution of poultry Salmonella isolates in China (2006 to 2012)

In this study, a total of 323 Salmonella enterica strains were isolated from 3,566 rectal swab samples of 51 poultry farms in seven regions of 12 provinces of China between 2006 and 2012. The prevalences of Salmonella sp. carriage were 12.4% in geese (66 positive/533 samples), 10.4% in turkeys (32/309), 9.8% in chickens (167/1,706), 6.8% in ducks (41/601), and 4.1% in pigeons (17/417), respectively. These isolates belonged to 20 serovars, in which the most frequent serovars were S. enterica serovar Gallinarum biovar Pullorum (herein, S. Pullorum) (55 isolates, 17.0%), S. enterica serovar Typhimurium (50 isolates, 15.5%), and S. enterica serovar Enteritidis (39 isolates, 12.1%). Overall, S. Typhimurium was the most commonly detected serovar; among the individual species, S. Pullorum was most commonly isolated from chickens, S. Enteritidis was most common in ducks, S. Typhimurium was most common in geese and pigeons, and S. enterica serovar Saintpaul was most common in turkeys. PCR determination of 20 fimbrial genes demonstrated the presence of bcfD, csgA, fimA, stdB, and sthE genes and the absence of staA and stgA genes in these isolates, and other loci were variably distributed, with frequency values ranging from 11.8 to 99.1%. These 323 Salmonella isolates were subdivided into 41 different fimbrial genotypes, and of these isolate, 285 strains (88.2%) had 12 to 14 fimbrial genes. Our findings indicated that the Salmonella isolates from different poultry species were phenotypically and genetically diverse and that some fimbrial genes are more frequently associated with serovars or serogroups.

Long-Term Prevalence of Antimicrobial-ResistantSalmonella entericaSubspeciesentericaSerovar Infantis in the Broiler Chicken Industry in Japan

Eleven broiler isolates of Salmonella Infantis obtained between 1989 and 1998 were examined for antimicrobial susceptibility and pulse field gel electrophoresis (PFGE) profiles. Seven strains of S. Infantis isolated after 1993 harbored similar antimicrobial susceptibilities to the recent isolates between 2001 and 2003. In comparison of PFGE profile with 22 isolates obtained from 22 apparently healthy broiler chickens between 2001 and 2003, the predominant cluster included the seven strains isolated after 1993. We could not clarify the reasons why the serovar has been prevalent in the broiler industry for a long time, but current antimicrobial usage is not always linked to its prevalence.

Expression of hilA in response to mild acid stress in Salmonella enterica is serovar and strain dependent

Salmonella enterica is the leading cause of foodborne illness with poultry and poultry products being primary sources of infection. The 2 most common S. enterica serovars associated with human infection are Typhimurium and Enteritidis. However, Kentucky and Heidelburg and the 2 most prevalent serovars isolated from poultry environments. Given the prevalence of other serovars in poultry products and environments, research is needed to understand virulence modulation in response to stress in serovars other than Typhimurium and Enteritidis. Thus, the objective of this research was to compare hilA gene expression (a master regulator of the virulence pathogenicity island) in response to acid stress among different strains and serovars of Salmonella. A total of 11 serovars consisting of 15 strains of S. enterica were utilized for these experiments. Cultures were suspended in tryptic soy broth (TSB) adjusted to pH 7.2, 6.2, or 5.5 with HCl or acetic acid. Total RNA was extracted from cultures at specific time points (0, 2, 4, and 24 h). Gene expression of hilA was measured with quantitative reverse transcriptase real time PCR (qRT-PCR). Growth and pH were measured throughout the 24 h time frame. Regulation of hilA in response to acid stress varied by serovar and strain and type of acid. The results of these experiments indicate that hilA regulation may have some impact on virulence and colonization of S. enterica. However, these results warrant further research to more fully understand the significance of hilA regulation in response to mild acid stress in S. enterica.

Prevalence and antimicrobial susceptibility of Salmonella in Japanese broiler flocks

This study determined the prevalence and antimicrobial susceptibility of Salmonella isolated from broiler flocks in Japan. Caecal dropping samples were collected from 288 broiler flocks between November 2007 and February 2010. Salmonella was prevalent in 248 (86·1%) broiler flocks. The top three serovars were S. Infantis, S. Manhattan and S. Schwarzengrund. S. Infantis was found in all regions tested in this study. However, S. Manhattan and S. Schwarzengrund were frequently found only in the western part of Japan. High antimicrobial resistance rates were observed against oxytetracycline (90·2%), dihydrostreptomycin (86·7%) and ampicillin (36·5%), and 258 (90·5%) of 285 isolates were resistant to two or more antimicrobial agents. Interestingly, 26·3% of isolates were resistant to ceftiofur, especially 38·1% of S. Infantis isolates, although its use in broilers has not been approved in Japan. This study showed that Salmonella is highly prevalent (86·1%) in Japanese broiler flocks, that 90·5% of Salmonella isolates were multidrug-resistant, and that S. Infantis frequently exhibited resistance to cephalosporin antimicrobial agents.

Prevalence of Salmonella isolates and antimicrobial resistance patterns in chicken meat throughout Japan

We investigated the prevalence of Salmonella in chicken meat from northern, central, and southern Japan. Between 2006 and 2008, 821 samples from these three regions were collected and examined. Salmonella isolates were detected in 164 (20.0%) of these samples, with 15 (10.0%) of 150, 113 (27.5%) of 411, and 36 (13.8%) of 260 recovered from the northern, central, and southern regions, respectively. We recovered 452 Salmonella isolates. From the isolates, 27 serovars were identified; the predominant serovars isolated were Salmonella Infantis (n=81), Salmonella Kalamu (n=56), and Salmonella Schwarzengrund (n=43). Of the 452 isolates, 443 (98.0%) were resistant to one or more antibiotics, and 221 (48.9%) showed multiple-antibiotic resistance, thereby implying that multiple-antibiotic resistant Salmonella organisms are widespread in chicken meat in Japan. Resistance to oxytetracycline was most common (72.6%), followed by dihydrostreptomycin (69.2%) and bicozamycin (49.1%). This study, the first to report Salmonella prevalence in chicken meat throughout Japan, could provide valuable data for monitoring and controlling Salmonella infection in the future.

Prevalence and antimicrobial resistance of Salmonella serotypes in chickens from retail markets in Yaounde (Cameroon)

From February 2006 to January 2007, 150 chickens were collected from eight retail markets in Yaounde, and 90 (60%) tested positive for Salmonella. Seventy-nine chickens were contaminated with only one Salmonella serotype, 10 with two different serotypes, and 1 with four serotypes. The most prevalent serotypes were Enteritidis (47 strains) and Hadar (29 strains). The isolates were tested for their susceptibilities to amoxicillin, amoxicillin/clavulanic acid, cefoxitin, cefotaxime, gentamicin, streptomycin, tetracycline, chloramphenicol, sulfonamides, nalidixic acid, ciprofloxacin, and trimethoprim/sulfamethazole by disk diffusion assay. Minimum inhibitory concentrations of ampicillin, streptomycin, tetracycline, sulfonamides, and nalidixic acid were determined for the resistant strains by agar dilution method. Eleven isolates (10.7%) of the 103 tested were susceptible to all antimicrobials. Resistance was most observed to tetracycline (84.5%), streptomycin (44.7%), and nalidixic acid (34%). Forty-one isolates (39.8%) were multidrug resistant (resistant to three or more antimicrobials from different classes), of which 68.3% were Hadar and 21.9% Enteritidis. The most frequent resistant pattern in Hadar was streptomycin-tetracycline-nalidixic acid. These results highlight once more the need for surveillance of Salmonella contamination in poultry.

Characterization of 13 multi-drug resistant Salmonella serovars from different broiler chickens associated with those of human isolates

Background

Salmonella are frequently isolated from chickens and their products. Prevalent serogroups and serovars of Salmonella as well as their genotypes and antibiograms were determined for cloacal samples from 1595 chickens. To understand the possible serovar and H antigens for transmission between chicken and human, serovars and their H antigens of 164 chicken and 5314 human isolates were compared.

Results

Prevalence of Salmonella differed among chicken lines and ages. Chicken and human isolates belonged mainly to serogroup B, C1, C2-C3, D, and E. 13 serovars and 66 serovars were identified for chicken and human isolates respectively. The common serovars for chicken and human isolates were S. Typhimurium, S. Enteritidis, S. Albany, S. Derby, and S. Anatum and shared common H1 antigens "g complex; i; e,h; and z4,z24" and H2 antigens "1 complex and -". In human isolates, H1 antigen "i" and H2 antigen "-" were common in all serogroups. In chicken, antimicrobial susceptibility differed among serogroups, serovars and three counties. All isolates were susceptible to cefazolin and ceftriaxone, but highly resistant to ampicillin, chloramphenicol, flumequine, streptomycin, sulfamethoxazole-trimethoprim, and tetracycline. Except those isolates of serogroup C1 of Chick group and serogroup G, all isolates were multi-drug resistance. Only S. Kubacha, S. Typhimurium, S. Grampian, and S. Mons were resistant to ciprofloxacin and/or enrofloxacin.

Conclusion

In chicken, prevalent serogroups and serovars were associated with chicken ages, lines and regions; and flouroquinolone-resistant and MDR isolates emerged. H1 antigens "g complex and i" and H2 antigens "1 complex and -" might be important for transmission of Salmonella between chicken and human.

Prophylactic Supplementation of Caprylic Acid in Feed Reduces Salmonella Enteritidis Colonization in Commercial Broiler Chicks†

Salmonella Enteritidis is a major foodborne pathogen for which chickens serve as reservoir hosts. Reducing Salmonella Enteritidis carriage in chickens would reduce contamination of poultry meat and eggs with this pathogen. We investigated the prophylactic efficacy of feed supplemented with caprylic acid (CA), a natural, generally recognized as safe eight-carbon fatty acid, for reducing Salmonella Enteritidis colonization in chicks. One hundred commercial day-old chicks were randomly divided into five groups of 20 birds each: CA control (no Salmonella Enteritidis, CA), positive control (Salmonella Enteritidis, no CA), negative control (no Salmonella Enteritidis, no CA), and 0.7 or 1% CA. Water and feed were provided ad libitum. On day 8, birds were inoculated with 5.0 log CFU of Salmonella Enteritidis by crop gavage. Six birds from each group were euthanized on days 1, 7, and 10 after challenge, and Salmonella Enteritidis populations in the cecum, small intestine, cloaca, crop, liver, and spleen were enumerated. The study was replicated three times. CA supplementation at 0.7 and 1% consistently decreased Salmonella Enteritidis populations recovered from the treated birds. Salmonella Enteritidis counts in the tissue samples of CA-treated chicks were significantly lower (P < 0.05) than those of control birds on days 7 and 10 after challenge. Feed intake and body weight did not differ between the groups. Histological examination revealed no pathological changes in the cecum and liver of CA-supplemented birds. The results suggest that prophylactic CA supplementation through feed can reduce Salmonella Enteritidis colonization in day-old chicks and may be a useful treatment for reducing Salmonella Enteritidis carriage in chickens.

International spread of multidrug-resistant Salmonella Schwarzengrund in food products

This serovar was isolated from persons, food, and food animals in Thailand, Denmark, and the United States.

We compared 581 Salmonella enterica serotype Schwarzengrund isolates from persons, food, and food animals in Denmark, Thailand, and the United States by antimicrobial drug susceptibility and pulsed-field gel electrophoresis (PFGE) typing. Resistance, including resistance to nalidixic acid, was frequent among isolates from persons and chickens in Thailand, persons in the United States, and food imported from Thailand to Denmark and the United States. A total of 183 PFGE patterns were observed, and 136 (23.4%) isolates had the 3 most common patterns. Seven of 14 isolates from persons in Denmark had patterns found in persons and chicken meat in Thailand; 22 of 390 human isolates from the United States had patterns found in Denmark and Thailand. This study suggests spread of multidrug-resistant S. Schwarzengrund from chickens to persons in Thailand, and from imported Thai food products to persons in Denmark and the United States.

Prevalence and characterization of multidrug-resistant (type ACSSuT) Salmonella enterica serovar Typhimurium strains in isolates from four gosling farms and a hatchery farm

Salmonella enterica serovar Typhimurium strains of phage types DT104 and U302 are often resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline (the ACSSuT resistance type) and are major zoonotic pathogens. Increased consumption of goose meat may enhance the risk of transferring S. enterica serovar Typhimurium and other enteric pathogens from geese to human due to the consumption of meats from infected geese or improper preparation of meats. Therefore, we characterized S. enterica serovar Typhimurium strains isolated from four goose farms (farms A, B, C, and D) and one hatchery farm (farm E) to determine the epidemic and genetic differences among them. Antibiotic susceptibility tests and multiplex PCR confirmed that 77.6% (52/67) of strains were ACSSuT strains isolated from farms A, C, and E. Antibiotic-susceptible strains were isolated mostly from farm B, and no strain was observed in farm D. All ACSSuT strains harbored a 94.7-kb virulence plasmid and contained one 1.1-kb conserved segment identical to that of Salmonella genomic island 1. Four genotypes were determined among these S. enterica serovar Typhimurium isolates by pulsed-field gel electrophoresis analysis of XbaI-digested DNA fragments. Most isolates (85.29%; 29/34) of major genotype Ib were ACSSuT strains isolated mainly from goslings of farm C and egg membranes of farm E, a hatchery farm, suggesting that S. enterica serovar Typhimurium strains in isolates from goslings might originate from its hatchery, from the egg membranes to the gosling fluff after hatching. Multiple phage types, types 8, 12, U283, DT104, and U302, were identified. In conclusion, geese were a reservoir of diverse multidrug-resistant (type ACSSuT) S. enterica serovar Typhimurium strains, and each farm was colonized with genetically closely related S. enterica serovar Typhimurium strains.

Assessing the prevalence of Salmonella enterica in poultry hatcheries by using hatched eggshell membranes

Salmonella enterica causes a number of significant poultry diseases and is also a major pathogen in humans. Most poultry infected by Salmonella become carriers; infection may also be fatal, depending on the particular serovar and the age of the bird at infection. Younger birds are more susceptible to infection by Salmonella, so it is critical that hatcheries monitor birds. We developed a method to use hatched eggshell membranes (HEM) to assess contamination by Salmonella in poultry hatching cabinets and to evaluate the prevalence of Salmonella in a goose hatchery and rearing farm. Comparison of the Salmonella isolation rate in hatching cabinets using 3 sampling methods showed that the highest Salmonella contamination was detected in HEM, and that these results differed significantly from those obtained from fluff samples and cabinet swab samples (P < 0.05). Analysis of HEM was also used to evaluate Salmonella contamination in goose, chicken, and duck hatcheries. The lowest Salmonella-positive rate was found for the chicken hatchery, followed by the goose and the duck hatcheries (P < 0.05). Six serogroups of Salmonella were detected in the 3 hatcheries: A, B, C1, C2, D, and E. The distribution of these serogroups differed among the hatcheries. Salmonella serogroup C1 was the major serogroup found in geese, compared with serogroup B in chickens and ducks. However, Salmonella Typhimurium was dominant in 1 goose hatchery and also in geese from this hatchery that had been transferred to a farm. Antibiotic susceptibility analysis showed that Salmonella Typhimurium strains isolated from the farm geese with diarrhea showed significantly higher resistance to doxycycline, colistin, sulfamethoxazole-trimethoprin, and cephalothin than those isolated from the hatchery (P < 0.05). Therefore, HEM as a detection target can be used to monitor Salmonella contamination in hatching cabinets and also be used to assess Salmonella prevalence in poultry hatcheries and rearing farms.

The distribution of Salmonella serovars in chicken and humans in Lithuania

We studied serovars of Salmonella strains isolated from chicken and humans in Lithuania over the period from 2000 to 2004. Salmonella strains were isolated and identified according to the techniques recommended by International Organisation for Standardization (Microbiology of Food and Animal Feeding Stuff--Horizontal Method for the Detection of Salmonella, 1998, ISO, Geneva). The per cent of infected flocks with Salmonella in separate years was between 1.01% and 3.2% during the period of investigation. The contamination rate of broiler legs and breasts was higher (2.36% and 4.25%) than that of wings (0.82%). Eighteen serovars of Salmonella were identified from the total 300 isolated samples. The most prevalent serovars in chicken were Salmonella Enteritidis, Salmonella Infantis and Salmonella Typhimurium. Other serovars such as Salmonella Montevideo, Salmonella Djugu, Salmonella Isangi, Salmonella Bovismorbificans, Salmonella Mbankada, Salmonella Hadar were detected only in one to two samples. In general, similar serovars of Salmonella were found in humans and chicken (S. Enteritidis and S. Typhimurium), although distinct serovars were found only in humans or only in chicken. Analysis of the distribution of Salmonella serovars in humans during the seasons of the year indicated that the highest incidence of Salmonella was in Summer and in the beginning of Autumn. Analysis of the distribution of serovars during the study period indicated that there is a shift over time in both humans and chicken.

Emergence ofSalmonellaBlockley, possible association with long-term reactive arthritis, and antimicrobial resistance

We previously reported the case of a patient who became ill with Salmonella serotype Blockley after eating a chicken meal and who was still suffering symptoms of salmonella-reactive arthritis 10 years after the initial infection. The immunological consequences of infection were of concern and prompted a literature review because of the possibility that Salmonella Blockley may be more likely to cause long-term illness in certain patients than more common serovars. The review revealed the additional cause for concern of plasmid-borne extended spectrum beta-lactamases and the high frequency of integron-associated multidrug resistance in some isolates. The serovar was described in 1955 in the USA and Europe. It has become common in South East Asia and recently has been reported more often in Europe. A review of reactive arthritis outbreaks shows that information on the incidence and duration of the condition caused by serovars other than Salmonella serotype Enteritidis and Salmonella serotype Typhimurium is very limited. Rheumatologists can assist microbiologists and epidemiologists by reporting relevant cases of long-term reactive arthritis.

Prevalence of Campylobacter and Salmonella Species on Farm, After Transport, and at Processing in Specialty Market Poultry

The prevalence of Campylobacter and Salmonella spp. was determined from live bird to prepackaged carcass for 3 flocks from each of 6 types of California niche-market poultry. Commodities sampled included squab, quail, guinea fowl, duck, poussin (young chicken), and free-range broiler chickens. Campylobacter on-farm prevalence was lowest for squab, followed by guinea fowl, duck, quail, and free-range chickens. Poussin had the highest prevalence of Campylobacter. No Salmonella was isolated from guinea fowl or quail flocks. A few positive samples were observed in duck and squab, predominately of S. Typhimurium. Free-range and poussin chickens had the highest prevalence of Salmonella. Post-transport prevalence was not significantly higher than on-farm, except in free-range flocks, where a higher prevalence of positive chickens was found after 6 to 8 h holding before processing. In most cases, the prevalence of Campylobacter- and Salmonella-positive birds was lower on the final product than on-farm or during processing. Odds ratio analysis indicated that the risk of a positive final product carcass was not increased by the prevalence of a positive sample at an upstream point in the processing line, or by on-farm prevalence (i.e., none of the common sampling stations among the 6 commodities could be acknowledged as critical control points). This suggests that hazard analysis critical control point plans for Campylobacter and Salmonella control in the niche-market poultry commodities will need to be specifically determined for each species and each processing facility.

Salmonella serovars from humans and other sources in Thailand, 1993-2002

We serotyped 44,087 Salmonella isolates from humans and 26,148 from other sources from 1993 through 2002. The most common serovar causing human salmonellosis in Thailand was Salmonella enterica Weltevreden. Serovars causing human infections in Thailand differ from those in other countries and seem to be related to Salmonella serovars in different food products and reservoirs.

Prevalence of Salmonella spp. in Pigs, Chickens and Ducks in the Mekong Delta, Vietnam

In order to determine the prevalence of Salmonella spp. in domestic animals in 6 provinces of the Mekong Delta, Vietnam, 1,098 fecal or intestinal content samples from pigs, chickens, and ducks were examined in the period from July to October, 2000. Salmonella spp. were isolated from 78 (7.1%) of the total samples, which included 23 (5.2%) of 439 pigs, 24 (7.9%) of 302 chickens, and 31 (8.7%) of 357 ducks. From those samples, 80 Salmonella strains were isolated and 25 serovars were identified. The predominant serovars were S. Javiana, S. Derby, and S. Weltevreden. S. Javiana and S. Weltevreden were detected together in pigs, chickens, and ducks. These results indicate that the serovars of Salmonella are widely distributed in domestic animals in the Mekong Delta, Vietnam.

Cross-contamination with Salmonella on a broiler slaughterhouse line demonstrated by use of epidemiological markers

AIMS

To investigate contamination of surfaces on a poultry slaughter line from infected poultry and subsequent cross-contamination of non-infected poultry.

METHODS AND RESULTS

A broiler slaughterhouse was investigated for the presence of Salmonella on 17 defined points over two 1-week periods. Flocks supplied to slaughter and neck skin samples from processed chicken were likewise investigated. Salmonella was detected in 10 out of 18 flocks at ante-mortem inspection, while seven flocks tested positive in the finished products. Equipment at all but one control point at the slaughter line tested positive at least once during the study. The chicken receiving area was the most contaminated. By comparison of typing results from serotyping, plasmid profile typing and phage typing, direct evidence for cross-contamination with Salm. serotype Typhimurium, Salm. Serotype 4.12:b:- and Salm. serotype Virchow on the slaughter line was obtained for four of the flocks. The cleaning procedure in place did not remove all Salmonella from the contaminated areas.

CONCLUSIONS

Evidence for contamination of equipment on a slaughter line and subsequent cross-contamination to non-infected chicken was provided by typing methods.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study has provided detailed information on cross-contamination on a slaughter line by the use of phage typing and plasmid profiling. The study stresses the importance of controlling Salmonella in the primary production, as contamination of the equipment on the slaughter line will act as a vehicle to contaminate finished products. Cleaning procedures on slaughter lines cannot be expected to control this problem with the current equipment.

Salmonella enterica serotype Bredeney: antimicrobial susceptibility and molecular diversity of isolates from Ireland and Northern Ireland

Salmonella enterica serotype Bredeney has emerged as the third most commonly identified serotype among human clinical isolates referred to the Irish National Salmonella Reference Laboratory in the years 1998 to 2000. A collection of 112 isolates of S. enterica serotype Bredeney collected during the period 1995 to 1999 from animal, food, and human sources from both Ireland and Northern Ireland were studied. Antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and DNA amplification fingerprinting (DAF) were performed on all isolates. Plasmid profiles were examined on a subset of 33 isolates. A high proportion (74%) of isolates were susceptible to all antimicrobial agents tested. Resistance to both sulfonamide and trimethoprim was observed in 21% of isolates, and resistance to multiple (five) antimicrobial agents was observed in a single isolate (0.9%). Eight different PFGE patterns were obtained, with 87% of isolates grouping as PFGE type A. PFGE type A was predominant in animals, food, and humans. There was good overall concordance between the groups identified by PFGE and DAF. Overall results indicate that most S. enterica serotype Bredeney isolates in Ireland and Northern Ireland from animal and human sources are clonally related.

Prevalence of Salmonella serovars in chickens in Turkey

In this study, 151 (18.6%) of 814 ceca obtained during in-line processing of 28 broiler (Hybro G, Avian, Arbor acres, and Cobb breeds) and 5 layer (Ross, Tetra SL, Isa Brown, and Brown Nick breeds) flocks in Turkey were found to be contaminated with four different Salmonella serovars. Only Salmonella enterica subsp. enterica Serovar Enteritidis (Salmonella Enteritidis) was recovered from layer birds, whereas Salmonella Enteritidis (81.5%). Salmonella Agona (7.6%), Salmonella Thompson (10.1%), and Salmonella Sarajane (0.8%) were isolated from broiler birds. Isolations of Salmonella Agona and Salmonella Thompson from poultry are reported for the first time in Turkey. The isolation of Salmonella Sarajane from chickens is the first report in the world. The standard method of National Poultry Improvement Plan, U.S. Department of Agriculture, was used to detect Salmonella from chicken cecal samples. Primary and delayed secondary enrichments (PE and DSE) were done in tetrathionate-Hajna broth (TTHB). Two different agar media, xylose lysine tergitol 4 (XLT4) and brilliant green with novobiocin (BGN) were used to observe, and compared for their isolation and selective differentiation of, Salmonella-suspected colonies. Isolated salmonellae were then biotyped and serotyped. Ninety-one and 151 salmonellae were isolated with XLT4 agar after PE and DSE, respectively. From the same samples, BGN agar was able to detect only 50 and 131 Salmonella after PE and DSE, respectively. The isolation rate with XLT4 was 11.2% (P < 0.01) with PE, and this rate increased to 18.6% after DSE. Also, the PE isolation rate (11.2%) with XLT4 agar was significantly higher (P < 0.01) than PE with BGN agar (6.1%). Salmonella was isolated from 39.3% (11 of 28) of the broiler flocks and from 60.0% (3 of 5) of the layers. The detection sensitivity of the isolation method was determined as 1 CFU g(-1) experimentally. These data demonstrate the presence of Salmonella Enteritidis, Salmonella Thompson, Salmonella Agona, and Salmonella Sarajane in chicken flocks in Turkey.

Observations on the distribution and control of Salmonella species in two integrated broiler companies

The effectiveness of cleaning and disinfecting broiler farms and the persistence of Salmonella species in two integrated broiler companies was investigated for two years. Both companies used a cleaning and disinfection regime which included the application of a spray of phenolic disinfectant followed by fogging with formaldehyde solution, and this was highly effective in preventing carry-over of infection in the broiler houses. The disinfection of service areas and areas outside the houses was less effective but it had no influence on the Salmonella status of later flocks. Both companies had persistent problems with the contamination of pellet cooling systems in their feedmills with Salmonella 4, 12:d:- in company A, and with Salmonella binza and Salmonella ohio in company B. The hatcher incubators of both companies were also persistently contaminated with Salmonella livingstone and Salmonella thomasville in company A and with Salmonella senftenberg in company B. At both companies sites Salmonella enteritidis and Salmonella typhimurium Tr104 were also isolated occasionally from various locations.

Molecular typing of multidrug-resistant Salmonella Blockley outbreak isolates from Greece

During 1998, a marked increase (35 cases) in human gastroenteritis due to Salmonella Blockley, a serotype rarely isolated from humans in the Western Hemisphere, was noted in Greece. The two dominant multidrug-resistance phenotypes (23 of the 29 isolates studied) were associated with two distinct DNA fingerprints, obtained by pulsed-field gel electrophoresis of genomic DNA.