Bacteriophages as an alternative for biological control of biofilm-forming Salmonella enterica

Salmonellosis is one of the most common foodborne diseases worldwide. Surface adherence and biofilm formation are among the main strategies evolved by Salmonella to survive under harsh conditions and are risk factors for its spread through the food chain. Owing to the increase in antimicrobial resistance, there is a growing need to develop other methods to control foodborne pathogens, and bacteriophages have been suggested as a potential alternative for this purpose. The aim of this study was to evaluate bacteriophages as a biological control of Salmonella enterica serotypes to inhibit and remove bacterial biofilms. A total of 12 S. enterica isolates were selected for this study, all of which were biofilm producers. Seven bacteriophages were tested, individually and in a cocktail, for their host range and efficiency of plating (EOP). The phage cocktail was evaluated for its antibiofilm effect against the Salmonella biofilms. Phages UPF_BP1, UPF_BP2, UPF_BP3, UPF_BP6, and 10:2 possessed a broad lytic spectrum and could infect all S. enterica strains. Phages 10:2, UPF_BP6, and UPF_BP3 had high EOP in 10, 9, and 9 out of the 12 S. enterica strains, respectively. The cocktail was able to infect all S. enterica strains and had a high EOP in 10 out of 12 S. enterica isolates, presenting a broader host range than any of the tested single phages. A wide variation of inhibition among strains was observed, ranging from 14.72% to 88.53%. Multidrug-resistant and strong biofilm producer strains showed high biofilm inhibition levels by phage cocktail. Our findings demonstrate the ability of the cocktail to prevent biofilm formation and remove formed biofilms of Salmonella. These results indicate that the phage cocktail is a promising candidate to be used as an alternative for the control of Salmonella biofilms through surface conditioning.

Characterization of avian pathogenic Escherichia coli isolates based on biofilm formation, ESBL production, virulence-associated genes, and phylogenetic groups

Escherichia coli is a part of both animal and human commensal microbiota. Avian pathogenic E. coli (APEC) is responsible for colibacillosis in poultry, an economically important disease. However, the close similarities among APEC isolates make it difficult to differentiate between pathogenic and commensal bacteria. The aim of this study was to determine phenotypic and molecular characteristics of APEC isolates and to compare them with their in vivo pathogenicity indices. A total of 198 APEC isolates were evaluated for their biofilm-producing ability and extended-spectrum β-lactamase (ESBL) production phenotypes. In addition, 36 virulence-associated genes were detected, and the isolates were classified into seven phylogenetic groups using polymerase chain reaction. The sources of the isolates were not associated with biofilms, ESBL, genes, or phylogroups. Biofilm and ESBL production were not associated with pathogenicity. Group B2 had the highest pathogenicity index. Groups B2 and E were positively associated with high-pathogenicity isolates and negatively associated with low-pathogenicity isolates. In contrast, groups A and C were positively associated with apathogenic isolates, and group B1 was positively associated with low-pathogenicity isolates. Some virulence-associated genes showed positive or negative associations with specific phylogenetic groups. None of the individual techniques produced results that correlated with the in vivo pathogenicity index. However, the combination of two techniques, namely, detection of virulence-associated genes and the phylogenetic groups, could help the classification of the isolates as pathogenic or commensal.

Adhesion capacity of Salmonella Enteritidis, Escherichia coli and Campylobacter jejuni on polystyrene, stainless steel, and polyethylene surfaces

Poultry products are recognized as the main source of Salmonella and Campylobacter jejuni infections in humans, while avian pathogenic Escherichia coli may have zoonotic potential and can be transmitted from chicken meat to humans. Biofilm formation contributes to their spread through the food chain. This study aimed to compare the adhesion of Salmonella Enteritidis, E. coli, and C. jejuni strains isolated from poultry, food implicated in outbreaks, and poultry slaughterhouses on three surfaces widely used in poultry production (polystyrene, stainless steel, and polyethylene). S. Enteritidis and E. coli adhesion on the three surfaces tested were not significantly different (p > 0.05). Interestingly, the number of C. jejuni cells on stainless steel (4.51-4.67 log₁₀ CFU/cm.^-2) was significantly higher (p = 0.0004) than that on polystyrene (3.80-4.25 log₁₀ CFU/cm.^-2), but similar (p > 0.05) to that on polyethylene (4.03-4.36 log₁₀ CFU/cm.^-2). However, C. jejuni adhesion was significantly lower (p < 0.05) than S. Enteritidis and E. coli adhesion, regardless of the surface evaluated. In addition, scanning electron microscopy analyses have shown an increased irregularity of the stainless steel surface when compared to polyethylene and polystyrene. These irregularities form small spaces ideal for microbial adhesion.

Antibiofilm activity of electrochemically activated water (ECAW) in the control of Salmonella Heidelberg biofilms on industrial surfaces

Owing to its antimicrobial activity, electrochemically activated water (ECAW) is a potential alternative to chemical disinfectants for eliminating foodborne pathogens, including Salmonella Heidelberg, from food processing facilities. However, their antibiofilm activity remains unclear. This study aimed to evaluate the antibiofilm activity of ECAW against S. Heidelberg biofilms formed on stainless steel and polyethylene and to determine its corrosive capacity. ECAW (200 ppm) and a broad-spectrum disinfectant (0.2%) were tested for their antibiofilm activity against S. Heidelberg at 25 °C and 37 °C after 10 and 20 min of contact with stainless steel and polyethylene. Potentiostatic polarization tests were performed to compare the corrosive capacity of both compounds. Both compounds were effective in removing S. Heidelberg biofilms. Bacterial counts were significantly lower with ECAW than with disinfectant in polyethylene, regardless the time of contact. The time of contact and the surface significantly influenced the bacterial counts of S. Heidelberg. Temperature was not an important factor affecting the antibiofilm activities of the compounds. ECAW was less corrosive than the disinfectant. ECAW demonstrated a similar or even superior effect in the control of S. Heidelberg biofilms, when compared to disinfectants, reducing bacterial counts by up to 5 log10 CFU cm-2. The corrosion of stainless steel with ECAW was similar to that of commercial disinfectants. This technology is a possible alternative for controlling S. Heidelberg in the food production chain.

Antilisterial activity of cinnamon essential oil, pomegranate extract, or strawberry tree extract against Listeria monocytogenes in slices of dry-cured ham and pork loin

Owing to concerns about the antimicrobial resistance of agents that can prevent the growth of Listeria monocytogenes in meat, researchers have investigated natural preservatives with antilisterial effects. However, in vivo application of essential oils and plant extracts usually results in reduced antimicrobial activity in meat products when compared to in vitro studies. This study aimed to evaluate the in vivo antimicrobial activity of cinnamon essential oil, pomegranate, and strawberry tree extracts in slices of dry-cured ham and pork loin against L. monocytogenes. Fragments of sterile dry-cured ham were inoculated with 100 μL cinnamon oil 0.5%, pomegranate, or strawberry crude extract. After 10 min, 100 μL of L. monocytogenes serotype 4b (104 colony-forming unit [CFU]/mL) was inoculated, and samples were incubated at 7 °C for 7 d to simulate the processing and storage temperature conditions of dry-cured meat products. L. monocytogenes was detected and quantified. Only strawberry extract presented significant differences (P < 0.05) from the control; thus, it was selected for the assay with 2% and 4% salt-treated pork loin. The strawberry tree extract significantly (P < 0.05) reduced the growth of L. monocytogenes in dry-cured ham. However, it could not reduce L. monocytogenes growth in pork loin, regardless of the salt concentration. This is the first report on the antimicrobial effect of strawberry tree leaf extract against L. monocytogenes in dry-cured ham.

Antimicrobial and antibiofilm activity of silver nanoparticles against Salmonella Enteritidis

Salmonella enterica serotype Enteritidis is one of the main pathogens associated with foodborne illnesses worldwide. Biofilm formation plays a significant role in the persistence of pathogens in food production environments. Owing to an increase in antimicrobial resistance, there is a growing need to identify alternative methods to control pathogenic microorganisms in poultry environments. Thus, this study aimed to synthesize silver nanoparticles (AgNPs) and evaluate their antibiofilm activity against poultry-origin Salmonella Enteritidis in comparison to a chemical disinfectant. AgNPs were synthesized, characterized, and tested for their minimum inhibitory concentration, minimum bactericidal concentration, and antibiofilm activity against S. Enteritidis strains on polyethylene surfaces. The synthesized AgNPs, dispersed in a liquid medium, were spherical in shape with a mean diameter of 6.2 nm. AgNPs exhibited concentration-dependent bactericidal action. The bacterial reduction was significantly higher with AgNPs (3.91 log10 CFU [Formula: see text] cm-2) than that with sanitizer (2.57 log10 CFU ∙ cm-2). Regarding the time of contact, the bacterial count after a contact time of 30 min was significantly lower than that after 10 min. The AgNPs exhibited antimicrobial and antibiofilm activity for the removal of biofilms produced by S. Enteritidis, demonstrating its potential as an alternative antimicrobial agent. The bactericidal mechanisms of AgNPs are complex; hence, the risk of bacterial resistance is minimal, making nanoparticles a potential alternative for microbial control in the poultry chain.

Different Multidrug-Resistant Salmonella spp. Serovars Isolated from Slaughter Calves in Southern Brazil

Bovines are carriers of Salmonella spp., a relevant foodborne pathogen, acting as contamination sources in slaughterhouses. Calves are prone to infection, and antimicrobial resistance may occur in such bacteria. This study aimed to determine the prevalence and virulence determinants of Salmonella spp. recovered from calves in the Rio Grande do Sul state, Brazil. Eighty-five calves' carcasses were evaluated (leather and veal meat). Thirteen Salmonella spp. isolates (8%) from 11 animals (13%) were obtained only from leather, indicating that contamination occurred before slaughter and that the meat was safe regarding this aspect. The serotypes S. Minnesota, S. Abony, S. Cerro, and S. Gafsa were identified, and all isolates were multidrug-resistant. The isolates had at least 19 virulence-related genes, and the bla_OXA-48 resistance gene was detected in three (23%). The data suggest that treating infections caused by these bacteria may be difficult in animals from these farms and can also be an extended human health problem.

The Prevalence and distribution of pathogenic genes in Campylobacter jejuni isolated from poultry and human sources

Introduction: Campylobacter jejuni is one of the most common bacterial causes of human gastroenteritis. Despite its public health importance, the virulence factors and mechanisms underlying C. jejuni pathogenesis remain poorly understood and the relationships between these genes and the sources of the strains are not clear. We aimed to determine the virulence profiles of C. jejuni isolated from poultry and human cases of Campylobacteriosis. Methodology: A total of 50 strains of C. jejuni isolated from poultry and human cases of Campylobacteriosis were screened by polymerase chain reaction (PCR) for the presence of six pathogenic genes (flaA, iam, wlaN, cdtA, cdtB, cdtC). Results: A total of 40% (10/25) of the human isolates presented only one virulence marker. In contrast, 64% (16/25) of the poultry-derived strains showed four or five virulence markers. cdtA and flaA occurred more frequently in poultry-derived strains than in human strains. Ten different virulence profiles were observed among the human isolates and 11 among the poultry strains. Only four profiles were common to both sources: profiles 3 (flaA, cdtA, cdtB, and cdtC), 5 (cdtA and cdtB), 7 (flaA and cdtB), and 10 (iam, flaA, cdtA, cdtB, and cdtC). The human-derived strains had a higher Shannon diversity index (1.9396) and Simpson index (0.8367), indicating a more diversified population than found in poultry (1.7742 and 0.7333, respectively). Conclusions: We found variations in the genetic profiles of the circulating strains based on the isolation source and genes that are potentially pathogenic to humans were detected in poultry-derived strains.

Antibiofilm activity of the biosurfactant and organic acids against foodborne pathogens at different temperatures, times of contact, and concentrations

Biofilm formation has been suggested to play a significant role in the survival of pathogens in food production. Interest in evaluating alternative products of natural origin for disinfectant use has increased. However, there is a lack of information regarding the effects of biosurfactants and organic acids on Salmonella enterica serotype Enteritidis, Escherichia coli, and Campylobacter jejuni biofilms, mainly considering temperatures found in environments of poultry processing, as well as simulating the contact times used for disinfection. The aim of this study was to evaluate the antibiofilm activity of rhamnolipid, malic acid, and citric acid on the adhesion of S. Enteritidis, E. coli, and C. jejuni on polystyrene surfaces at different temperatures (4, 12, and 25 °C), compound concentrations, and times of contact (5 and 10 min), and to analyze the potential use of these compounds to disrupt formed biofilms. All three compounds exhibited antibiofilm activity under all analyzed conditions, both in the prevention and removal of formed biofilms. Contact time was less important than temperature and concentration. The antibiofilm activity of the compounds also varied according to the pathogens involved. In the food industry, compound selection must consider the temperature found in each stage of product processing and the target pathogens to be controlled.

Detection and Quantification of Campylobacter in Poultry Slaughterhouses Using Conventional Microbiological Technique, Most Probable Number, and Real-Time PCR

Campylobacteriosis is one of the most common bacteria causing human gastroenteritis. Poultry is a major reservoir of Campylobacter spp. as well as the main source of transmission. Due to the increased occurrence of campylobacteriosis, poultry slaughterhouses are under pressure to deliver carcasses with low contamination. However, a few studies have been carried out to evaluate Campylobacter contamination of broiler carcasses in Brazilian slaughter lines. Therefore, in this study, we aimed at detecting and quantifying the thermotolerant Campylobacter spp. at different stages of the poultry slaughtering process. The samples were collected from 12 points in three slaughterhouses in southern Brazil, at an interval of 12 months, and were tested for Campylobacter spp. by conventional microbiological technique, the most probable number, and real-time PCR. A total of 432 samples were analyzed. The majority of strains belonged to Campylobacter jejuni (92%), and the flock positivity among the three techniques was similar in most cases. Campylobacter was detected in all slaughtering stages. Although contamination has remained similar (p > 0.05) throughout almost all the slaughter process, evisceration seemed to be an important source of contamination. Our results reinforce the idea that the final carcass quality after the slaughtering process is directly influenced by the level of contamination of the broiler flocks on arrival at the processing plant.

Avian pathogenic Escherichia coli (APEC) and uropathogenic Escherichia coli (UPEC): characterization and comparison

INTRODUCTION

Avian pathogenic E. coli (APEC) and uropathogenic E. coli (UPEC) are responsible for avian colibacillosis and human urinary tract infections, respectively. There are genetic similarities between the APEC and UPEC pathotypes, suggesting the APEC strains could be a potential reservoir of virulence and antimicrobial-resistance genes for the UPEC strains. This study aimed to characterize and compare APEC and UPEC strains regarding the phylogroup classification, pathogenicity and antimicrobial susceptibility.

METHODOLOGY

A total of 238 APEC and 184 UPEC strains were selected and characterized. The strains were assayed for antimicrobial susceptibility and classified into phylogenetic groups using a multiplex-PCR protocol. In addition, the APEC strains had previously been classified according to their in vivo pathogenicity.

RESULTS

The results showed that both pathotypes had variation in their susceptibility to most of the antimicrobial agents evaluated, with few strains classified as multidrug resistant. The highest resistance rate for both pathotypes was to amoxicillin. Classifying the APEC and UPEC strains into phylogenetic groups determined that the most frequently frequencies were for groups D and B2, respectively. These results reflect the pathogenic potential of these strains, as all the UPEC strains were isolated from unhealthy patients, and most of the APEC strains were previously classified as pathogenic.

CONCLUSIONS

The results indicate that distribution into phylogenetic groups provided, in part, similar classification to those of in vivo pathogenicity index, as it was possible to adequately differentiate most of the pathogenic and commensal or low-pathogenicity bacteria. However, no relationship could be found between the specific antimicrobial agents and pathogenicity or phylogenetic group for either pathotype.

Antimicrobial activity of copper surfaces against biofilm formation by Salmonella Enteritidis and its potential application in the poultry industry

As a consequence of developing antimicrobial resistance to disinfectants, copper, which exhibits antimicrobial activity, has been studied as a possible alternative to the use of stainless steel surfaces. The aim was to evaluate the antimicrobial activity of copper surfaces in preventing biofilm formation by Salmonella Enteritidis and to determine their corrosive capacity. Strains of S. Enteritidis were incubated at 4 °C, 12 °C, and 25 °C with 1 cm² coupons of electrolytic copper (99.9% Cu), brass (70% Cu), copper coated with tin, and stainless steel (control). A planktonic cell-suspension assay was used, followed by serial dilutions and bacterial counts. The corrosion test was performed with two disinfectants: benzalkonium chloride and sodium hypochlorite (100, 200, and 400 ppm). There was a significant reduction in biofilm production (log₁₀ CFU cm^-2) on the copper (2.64 at 4 °C, 4.20 at 12 °C, 4.56 at 25 °C) and brass (2.79 at 4 °C, 3.49 at 12 °C, 4.55 at 25 °C) surfaces compared to the control (5.68 at 4 °C, 5.89 at 12 °C, 6.01 at 25 °C). The antimicrobial surfaces showed uniform corrosion similar to that of surfaces generally used. These results demonstrated the effectiveness of copper surfaces in reducing S. Enteritidis and suggest they can be used as a complementary antimicrobial to control for this pathogen.

Effect of two lytic bacteriophages against multidrug-resistant and biofilm-forming Salmonella Gallinarum from poultry

1. Salmonella Gallinarum (SG) infections cause fowl typhoid, which leads to important economic losses. Multidrug resistance (MDR) and the capacity for bacteria to form biofilms could play an important role in the persistence of SG in poultry flocks resulting in intermittent disease outbreaks. The aim of the following study was to assess the lytic activity of two new bacteriophages (Salmonella phages UPF_BP1 and UPF_BP2) against MDR and biofilm-forming SG. 2. Forty-six strains of SG, isolated in 2015, were characterised by antimicrobial resistance, biofilm formation profiles and susceptibility to two new bacteriophages. 3. Of these strains, 24% were multidrug resistant and more than 80% formed biofilm, with no statistical difference between incubation temperatures (42°C or 22°C). With regard to the lytic activity of the phages, 85% of strains were susceptible to at least one phage. Of these, 74% were lysed by both phages, including MDR and biofilm producing strains. 4. The use of salmonella phages UPF_BP1 and UPF_BP2 were shown to be promising alternatives for the biological control of fowl typhoid.

Evaluation of peroxide index and oxidative rancidity of broiler diets and the occurrence of breast muscle anomalies

The incidence of breast muscle anomalies, such as white striping (WS) and wooden breast (WB), has increased over the last two decades. These myopathies have different implications on the quality of poultry meat, which depending on the degree of the anomaly, may be rejected due to undesirable appearance or lower technological and nutritional characteristics. Despite the high economic impact, the causes of these myopathies have not yet been defined. The increased susceptibility of poultry to the oxidation process may influence the occurrence of hemorrhagic disorders and muscular dystrophies, necrosis, and fibrosis associated with myopathy with unknown etiology development. Coagulants such as ferric chloride (FC) used in the treatment of effluents can be involved in the feed peroxidation process. Our aim was to evaluate whether the peroxides generated by the presence of FC in poultries’ diets are related to myopathies. Broilers were treated with feed supplemented with 4, 8, or 12 mL FC/Kg of feed. The presence of WS and WB, feed peroxide indices (PI), mean weights, and feed conversion ratios were evaluated. The highest FC concentration indicated higher peroxide production. Addition of 4, 8 and 12 mL of FC yielded 60.0%, 70.0%, and 70.7% of myopathies, respectively, which indicated a possible relationship between food peroxidation and myopathies. Lipoperoxidation resulted in the lowest mean final weight and worsening of the feed conversion in the birds treated with 12 mL of FC. Feed with a high peroxide index is a factor that can increase the incidence of WB and WS.

Antimicrobial susceptibility and detection of virulence-associated genes of Escherichia coli and Salmonella spp. isolated from domestic pigeons (Columba livia) in Brazil

Overpopulation of domestic pigeons is considered to be one of the major problems of urban centers, as these birds are responsible for the dissemination of relevant pathogens to animal and human health. The aim of this study was to detect potentially pathogenic Escherichia coli and Salmonella spp. in domestic pigeons captured in areas near silos used for grain and feed storage, analyzing the antimicrobial sensitivity and the presence of virulence-associated genes. We evaluated 41 pigeons. From each bird, cecal contents and a pool of viscera (heart, spleen, and liver) were collected. Fifty strains of E. coli and three strains of S. Typhimurium were isolated. The antimicrobial susceptibility assay showed that 2% of the isolates of E. coli were resistant to chloramphenicol and the combination of sulfamethoxazole + trimethoprim and 4% to tetracycline, doxycycline, and sulfonamide. The three S. Typhimurium strains were sensitive to all antimicrobials tested. The pathogenicity profile demonstrated that no E. coli isolates showed a STEC compatible profile. Regarding the APEC pathotype, all genes were observed in 8% of E. coli, 6% had only the iss gene and 4% presented ompT, hlyF, and iutA genes. invA, hilA, avrA, and lpfA genes were detected in 100% of Salmonella isolates. The sitC and pefA genes were only present in one strain and the remaining genes were detected in two. In conclusion, it was found that pigeons living in the vicinity of silos are carriers of important pathogens, and control measures should be taken to minimize animal and human health risks.

Development of Copper Hatch Baskets and Evaluation of the Productive Indexes of a Commercial Hatchery

Background: The dissemination of pathogenic microorganisms in hatcheries leads to a higher number of contaminated eggs, causing reduction in hatchability and increase of discarded chicks. Sanitation programs are crucial for maximum hatchability and chick quality. Efforts have been made to find alternative approaches to the conventional disinfectants, and surfaces with copper, which have antimicrobial properties, could assist in this process. However, the possible adverse effects of copper surfaces on chicks in hatcheries have not yet been evaluated. The present study aimed at developing hatch baskets composed of copper and evaluating the effect of these baskets on the productive indexes of a hatchery.Materials, Methods and Results: For this experiment, 3.15 kg hatch tray prototypes with 99.9% Cu (Cu11000) were developed to fit inside conventional polypropylene hatch baskets (580 × 755 × 83 mm). Six polypropylene hatch baskets (control group) and 6 polypropylene hatch baskets covered by 99.9% copper (Cu11000) hatch trays (test group) were evaluated during 5 hatchings. Hatched eggs and chicks remained in contact with the hatch basket surfaces for at least 72 h, corresponding to the entire period in which they were located in the hatcher. Cleaning and disinfection programs of the hatchery were not modified. The level of microbial contamination on the hatch baskets was evaluated at 6 different periods: 0 h (initial contamination after disinfection and egg transfer to the trays); 24 h, 30 h, 45 h and 60 h after the first sampling; and at the moment when chicks were removed from the hatching cabinet and transferred to the chick-holding room (> 60 h). Counting of total moulds and yeasts, mesophilic microorganisms, Enterobacteria and Escherichia coli colonies was performed. The number of hatched chicks, non-hatched eggs, and chicks discarded were registered for each hatching. Microbiologic analyses showed no growth on hatch baskets neither of the test group nor on those of the control group, regardless of the period evaluated. No significant difference was found between the two groups in the counts of hatched chicks, non-hatched eggs, and chicks discarded. Discussion: The antimicrobial efficacy of copper surfaces has been established for a variety of bacteria and fungi, including in the healthcare environment. In addition, antimicrobial resistance to copper is extremely rare because of copper’s multisite kill mechanism and other mostly nonspecific damage mechanisms. Several copper applications have been established; however, the potential adverse effects of using copper surfaces in hatcheries on chicks or on hatchery productive indexes had not yet been evaluated. The analyses performed in this study did not show microbiological growth. The results showed that the copper surface did not cause any significant adverse effects on chicks. The hatched chicks were visually healthy, and no significant difference was found between the numbers of chicks discarded in the control and test groups. Since the production parameters were not altered or impaired in the present study, it is possible to conclude that the use of copper surfaces in hatcheries can be an effective tool in the microbiological control of these environments. Nevertheless, copper alloys lend themselves to the creation of self-sanitizing surfaces that should be used as a complement and not as a substitute for standard cleaning and disinfection practices.

Artificial Neural Networks on Eggs Production Data Management

Background: Eggs have acquired a greater importance as an inexpensive and high-quality protein. The Brazilian egg industry has been characterized by a constant production expansion in the last decade, increasing the number of housed animals and facilitating the spread of many diseases. In order to reduce the sanitary and financial risks, decisions regard­ing the production and the health status of the flock must be made based on objective criteria. The use of Artificial Neural Networks (ANN) is a valuable tool to reduce the subjectivity of the analysis. In this context, the aim of this study was at validating the ANNs as viable tool to be employed in the prediction and management of commercial egg production flocks.Materials, Methods & Results: Data from 42 flocks of commercial layer hens from a poultry company were selected. The data refer to the period between 2010 and 2018 and it represents a total of 600,000 layers. Six parameters were selected as “output” data (number of dead birds per week, feed consumption, number of eggs, weekly weight, weekly egg produc­tion and flock uniformity) and a total of 13 parameters were selected as “input” data (flock age, flock identification, total hens in the flock, weekly weight, flock uniformity, lineage, weekly mortality, absolute number of dead birds, eggs/hen, weekly egg production, feed consumption, flock location, creation phase). ANNs were elaborated by software programs NeuroShell Predictor and NeuroShell Classifier. The programs identified input variables for the assembly of the networks seeking the prediction of the variables called outgoing that are subsequently validated. This validation goes through the comparison between the predictions and the real data present in the database that was the basis for the work. Validation of each ANN is expressed by the specific statistical parameters multiple determination (R2) and Mean Squared Error (MSE). For instance, R2 above 0.70 expresses a good validation. ANN developed for the output variable “number of dead birds per week” presented R2= 0.9533 and MSE= 256.88. For “feed consumption”, the results were R2= 0.7382 and MSE= 274.56. For “number of eggs (eggs/hen)”, the results were R2= 0.9901 and MSE= 172.26. For “weekly weight”, R2= 0.9712 and MSE= 11154.41. For “weekly egg production”, R2= 0.8015 and MSE= 72.60. For “flock uniformity”, R2= -2.9955 and MSE= 431.82.Discussion: From the six ANN designed in this study, in five it was possible to validate the predictions by comparing predictions with the real data. In one output parameter (“flock uniformity”), it was not possible to have adequate validation due to insufficient data in our database. For “number of dead birds per week”, “feed consumption”, “weekly weight” and “uniformity”, the most important variable was “flock age” (27.5%, 52.5%, 55.2% and 37.9%, respectively). For “number of eggs (eggs/hen)”, “uniformity” (52.1%) was the most relevant variable for prediction. For “weekly egg production”, “flock age” and “number of eggs (eggs/hen)” were the most important zootechnical parameters, both with a relative contribution of 38.2%. The results showed that even with the use of a robust tool such as ANNs, it is necessary to have well-noted and clear information that expresses the reality of the flocks. In any case, the results presented allow us to state that ANNs are capable for the management of data generated in a commercial egg production facility. The process of evaluation of these data would be improved if ANNs were routinely used by the professionals linked to this activity.

Electrochemically-Activated Water Presents Bactericidal Effect Against Salmonella Heidelberg Isolated from Poultry Origin

Salmonella spp. are among the most important pathogens in poultry farming, and Salmonella Heidelberg (SH) is one of the most frequent serotypes isolated in Brazil. SH has a zoonotic potential and stands out as a pathogen that is difficult to eliminate from the poultry chain due to its resistance to disinfectants. One alternative to traditional disinfectants is the electrochemically-activated water (ECA), a bactericidal compound produced from the electrolysis of salt and water. ECA generators produce a compound that consists of free chlorine, hypochlorous acid, and other free radicals. This alternative control method is safe for human health and reduces environmental contamination. The present study aimed at evaluating the efficacy of ECA against 30 SH isolates from poultry origin in scenarios that simulated the chiller environment (4°C, 5 and 50 parts per million [ppm], 5 and 40 min of exposure) and the cleaning and disinfection process (25°C, 200 ppm, 5 and 10 min of exposure). In the quantitative test, SH was susceptible to ECA. The mean bacterial counts decreased significantly compared to the control group, especially at 200 ppm. At this concentration, ECA inhibited the growth of almost 87% of the Salmonella strains, and the results showed a significant decrease in the mean bacterial counts for both exposure times (5 and 10 min). These findings demonstrate that ECA is effective against SH in vitro and it is a possible alternative to disinfection in the poultry industry for the control of this pathogen. However, in situ tests in the food industry are needed.

Influence of the norepinephrine and medium acidification in the growth and adhesion of Salmonella Heidelberg isolated from poultry

Salmonella spp. are among the leading pathogens responsible for foodborne illnesses worldwide. Bacterial communities use a quorum sensing (QS) system to control biofilm formation. QS is a cell-to-cell signaling mechanism involving compounds called auto-inducers (AI). Norepinephrine utilizes the same bacterial signaling of AI-3 and serves as a signal of QS. Acid stress is a challenge encountered by microorganisms in food processing environments and in the gastrointestinal tracts of hosts. Thus, adaptation to acidic environments may increase the pathogenicity of the strain. The aim of this study was to evaluate the influence of two concentrations of norepinephrine (100 μM and 250 μM) and acidification (pH 3.0) of the medium on the growth and adhesion of Salmonella Heidelberg strains isolated from poultry sources at 12 °C and 25 °C. Furthermore, three genes associated with the biofilm formation process were detected (adrA, csgD, and sidA). Norepinephrine stimulation did not influence the growth or adhesion of Salmonella Heidelberg strains, regardless of the catecholamine concentration and temperature. On the other hand, the use of acidified medium (pH 3.0) resulted in a significant reduction of growth and a significant increase of S. Heidelberg adhesion at both temperatures, indicating that the acidified medium favors the biofilm formation process. The adrA and sidA genes showed higher detection frequencies than csgD. Experiments analyzing the biofilm production process by S. Heidelberg strains are not common, and further studies are necessary to understand this complex process.

Detection of virulence genes in Salmonella Heidelberg isolated from chicken carcasses

During the last years, Brazilian government control programs have detected an increase of Salmonella Heidelberg in poultry slaughterhouses a condition that poses a threat to human health However, the reasons remain unclear. Differences in genetic virulence profiles may be a possible justification. In addition, effective control of Salmonella is related to an efficient epidemiological surveillance system through genotyping techniques. In this context, the aim of this study was the detection of 24 virulence-associated genes in 126 S. Heidelberg isolates. We classified the isolates into 56 different genetic profiles. None of the isolates presented all the virulence genes. The prevalence of these genes was high in all tested samples as the lowest number of genes detected in one isolate was 10/24. The lpfA and csgA (fimbriae), invA and sivH (TTSS), and msgA and tolC (intracellular survival) genes were present in 100% of the isolates analyzed. Genes encoding effector proteins were detected in the majority of SH isolates. No single isolate had the sefA gene. The pefA gene was found in only four isolates. We have also performed a screening of genes associated with iron metabolism: 88.9% of isolates had the iroN geneand 79.4% the sitC gene . Although all the isolates belong to the same serotype, several genotypic profiles were observed. These findings suggest that there is a diversity of S. Heidelberg isolates in poultry products. The fact that a single predominant profile was not found in this study indicates the presence of variable sources of contamination caused by SH. The detection of genetic profiles of Salmonella strains can be used to determine the virulence patterns of SH isolates.

Detection and quantification of Salmonella spp. in poultry slaughterhouses of southern Brazil

INTRODUCTION

Salmonella is a major cause of foodborne illness throughout the world. The use of quantitative techniques is important for assessing the risk and determining the capacity of each step of the slaughtering process to decrease or increase bacterial contamination. We aimed to detect and to quantify the presence of Salmonella in Brazilian processing plants by real-time quantitative polymerase chain reaction (qPCR).

METHODOLOGY

A total of 139 poultry slaughterhouses samples were collected in order to detect to and quantify Salmonella by qPCR.

RESULTS

Almost all collection points (3/18), except water from pre-chiller tank, carcasses after pre-chiller, and carcasses frozen at -12ºC for 60 days, and 49% (68/139) of samples were positive for Salmonella. Quantification means varied equally among all of the tested sources, and we could not establish any pattern of variation. A large proportion (52.6%) of cloacal swabs was Salmonella-positive. Also, contamination in transport cages was increased after the cleaning process, indicating that the process was ineffective. The overall prevalence in samples obtained during the slaughtering process was 48.9%, and on the whole rinsed carcasses, this proportion was 50%. The detection of Salmonella in frozen carcasses, even after long periods of storage, indicates that the carcasses are a potential source of infection for consumers.

CONCLUSIONS

We found that contamination levels remain similar throughout the slaughtering. qPCR proved to be an efficient method for the detection of Salmonella.

Biofilm formation by Salmonella Enteritidis and Salmonella Typhimurium isolated from avian sources is partially related with their in vivo pathogenicity

Salmonella Enteritidis and Salmonella Typhimurium are among the most prevalent serotypes isolated from salmonellosis outbreaks and poultry. Salmonella spp. have the capacity to form biofilms on several surfaces, which can favour survival in hostile environments, such as slaughterhouses. Salmonella strains present differences in pathogenicity. However, there is little information regarding the pathogenicity of S. Enteritidis and S. Typhimurium isolated from avian sources and their relationship to biofilm production. The aim of this study was to use a novel pathogenicity index and a biofilm production assay to evaluate their relationships within these serotypes. In addition, we detected the presence of the spiA and agfA genes in these strains. Biofilm formation was investigated at two temperatures (37 °C and 28 °C) using microtiter plate assay, and the results were compared with the individual pathogenicity index of each strain. PCR was used to detect spiA and agfA, virulence genes associated with biofilm production. S. Enteritidis and S. Typhimurium strains were capable of producing biofilm at 37 °C and 28 °C. Sixty-two percent and 59.5% of S. Enteritidis and 73.8% and 46.2% of S. Typhimurium produced biofilm at 37 °C and 28 °C, respectively. Biofilm production at 37 °C was significantly higher in both serotypes. Only S. Enteritidis was capable of adhering strongly at both temperatures. Biofilm production was related to pathogenicity index only at 28 °C for S. Enteritidis. spiA and agfA were found in almost all strains and were not statistically associated with biofilm production.

Classification of Avian Pathogenic Escherichia coli (APEC) and Human Uropathogenic Escherichia coli (UPEC) in Phylogenetic Groups and Association with Pathogenicity In Vivo

Background: Avian pathogenic E. coli (APEC) and uropathogenic E. coli (UPEC) are responsible, respectively, for avian colibacillosis and for 80% of urinary tract infections in humans. E. coli control is difficult due to the absence of a reliable method to differentiate pathogenic and commensal strains. Genetic similarity between APEC and UPEC suggests a common ancestral origin and the capability of potentially pathogenic strains to affect human health. The classification in phylogenetic groups facilitates the identification of pathogenic strains. The objective of this work was to classify APEC and UPEC E. coli strains into phylogenetic groups and to associate it with in vivo pathogenicity.Materials, Methods & Results: 460 APEC and 450 UPEC strains, stored in BHI with glycerol at -80°C, were selected. APEC strains were isolated from cellulitis, respiratory tract and poultry litter of broiler flocks from Southern Brazil. The UPEC strains from urinary tract infection were provided by a hospital in Porto Alegre. After DNA extraction, APEC and UPEC strains were classified into four phylogenetic groups (A, B1, B2 and D) by a multiplex-PCR protocol for the detection of the chuA and yjaA genes and the TspE4.C2 DNA fragment. Phylogenetic groups were associated with pathogenicity indexes (PI), presented on a scale of 0 to 10, which were previously obtained through the inoculation of APEC strains in one-day-old chicks. Phylogenetic groups were also associated with the presence of 38 virulence-associated genes. The multiplex-PCR protocol was able to differentiate 100% of the APEC and UPEC strains in the four phylogenetic groups. The majority of APEC strains were classified into phylogenetic groups D (31.1%) and B2 (24.1%). On the other hand, the majority of UPEC strains were classified into B2 (53.6%). Among APEC strains, five genes (crl, mat, ompA, fimC and fimH) were detected in more than 80% of strains in all groups. Some genes showed a significant association with specific phylogenetic groups. Gene ireA was exclusively to group D, kpsMT II and cvaC to B2 and sat was exclusively to B1. Four genes (ireA, sfa/focCD, ibeA, tsh) were detected in more than 70% of UPEC strains in all phylogenetic groups. Gene iroN1 showed a significant association exclusively to group A, and iucD, papC and irp2 to B1 group. APEC isolated from poultry litter presented significantly lower PIs than those isolated from cellulitis and from birds with respiratory signs. The average PI from B2 group was significantly higher than that of D group. In addition, the PIs of the two groups were significantly higher than those of A and B1.Discussion: The high frequency of UPEC classified as B2 is in agreement with the literature. More virulent strains are usually classified into B2 group and some of them may be classified into D group. On the other hand, the distribution of APEC isolates in phylogenetic groups is characterized by variability and it is usually related to the origin of the isolates, as observed in the study. Since E. coli strains isolated from human and poultry face similar challenges in infection establishment of extraintestinal sites, they may share some virulence genes. In this study, most of the 38 genes presented a high frequency in both APEC and UPEC strains. As the distribution of APEC strains in phylogenetic groups showed a significant association with pathogenicity, multiplex-PCR becomes an important tool for screening the pathogenicity of strains isolated from the poultry production chain.

Phenotypic and Molecular Characterization of Salmonella Enteritidis SE86 Isolated from Poultry and Salmonellosis Outbreaks

Salmonella Enteritidis remains a standout among the leading causes of foodborne diseases worldwide. Previous studies have demonstrated that a unique clonal group of Salmonella Enteritidis, named SE86, is involved in foodborne outbreaks in southern Brazil and is frequently identified among strains isolated from poultry. The aim of this study was to determine the influence of the isolation source (food products involved in salmonellosis outbreaks and poultry sources) on the phenotypic and molecular characteristics of Salmonella Enteritidis SE86. A biofilm formation assay, antimicrobial susceptibility test, polymerase chain reaction identification of virulence-associated genes, and phage type 4 (PT4) assessment were performed to characterize Salmonella Enteritidis SE86. The human strains presented less antimicrobial resistance than the poultry strains. Resistance to some substances was related to the isolation source of the strain. Strains of the same clonal group presented different biofilm production abilities. Biofilm formation was independent of the isolation source at all temperatures. Temperature influenced biofilm formation only by the poultry strains. Most of the investigated genes presented a high frequency and a regular distribution, regardless of the isolation source. The spvB, spiA, pagC, sipB, prgH, spaN, sitC, and lpfC genes were associated with the avian strains, whereas iroN was associated with the strains isolated from food products involved in salmonellosis outbreaks. Most strains belonged to PT4. No relationship was found between biofilm production and antimicrobial resistance or between the virulence profile and biofilm production or antimicrobial resistance.

Spread of a Major Clone of Salmonella enterica Serotype Enteritidis in Poultry and in Salmonellosis Outbreaks in Southern Brazil

Salmonella spp. are among the most important agents of foodborne diseases all over the world. Human Salmonella outbreaks are often associated with the consumption of poultry products (meat and eggs), and one of the most prevalent serotypes associated with these products is Salmonella Enteritidis. Brazil is one of the most important poultry exporters in the world. In southern Brazil, three closely related clones of Salmonella Enteritidis have been responsible for the majority of foodborne Salmonella outbreaks over the past decade. However, until now, there has been little information regarding the clonal relationship among the Brazilian Salmonella strains of avian origin and those involved in foodborne outbreaks. Therefore, the aim of the present study was to complete the molecular characterization of Salmonella Enteritidis strains isolated from poultry and food sources involved in Salmonella outbreaks. PCR ribotyping was performed to discriminate the strains into different ribotype profiles according to the banding pattern amplification. This technique was able to differentiate the Salmonella Enteritidis strains into two banding patterns: R2 and R4. R2 accounted for 98.7% of the strains. DNA sequencing of the 600-bp fragment, present in all ribotypes, was applied to confirm this result. The sequences generated showed high levels of similarity, ranging from 99.7 to 100%, and were grouped into a single cluster. These results suggest that there is a clonal relationship among the Salmonella Enteritidis strains responsible for several salmonellosis outbreaks and the strains collected from poultry sources.

Classification of Avian Pathogenic Escherichia coli by a Novel Pathogenicity Index Based on an Animal Model

Background: Avian Pathogenic Escherichia coli is the main agent of colibacillosis, a systemic disease that causes considerable economic losses to the poultry industry. In vivo experiments are used to measure the ability of E. coli to be pathogenic. Generally, these experiments have proposed different criteria for results interpretation and did not take into account the death time. The aim of this study was to propose a new methodology for the classification of E. coli pathogenicity by the establishment of a pathogenicity index based in the lethality, death time and the ability of the strain to cause colibacillosis lesions in challenged animals.Materials, Methods & Results: A total of 293 isolates of E. coli were randomly selected to this study. The strains were isolated from cellulitis lesions, broiler bedding material or respiratory diseases and were previously confirmed through biochemical profile. The bacterial isolates were kept frozen at -20°C. The strains were retrieved from stocks and cultured in brain-heart infusion broth overnight at 37°C to obtain a final concentration of 109 UFC/mL. A total of 2940 one-dayold chicks from commercial breeding hens were randomly assigned to groups containing 10 animals and each group was subcutaneously inoculated in the abdominal region with 0.1 mL of the standard inoculum solution containing each of the strains. A control group of 10 broilers were inoculated with 0.1 mL of brain-heart infusion broth by the same route. The chicks were kept for seven days. They were observed at intervals of 6, 12 and 24 h post-inoculation during the first days. From the second day on, the chicks were observed at intervals of 12 h. According to the death time and to the scores of each lesion (aerosaculitis, pericarditis, perihepatitis, peritonitis and cellulitis), a formula to determine the Individual Pathogenicity Index was established. A value of 10 was established as the maximum pathogenicity rate for an inoculated bird. From this rate, 5 points corresponded to scores for gross lesions present at necropsy. For each lesion present, it represents 1 point. The remaining 5 points corresponded to the death time. To obtain the death time value, an index of 1, corresponding to the maximum value assigned to a death on the first day, was divided by the number of days that the birds were evaluated, resulting in a value of 0.1428, which corresponded to a survival bonus factor. It was possible to classify E. coli strains into four pathogenicity groups according to the pathogenicity index: high pathogenicity (pathogenicity index ranging from 7 to 10), intermediate pathogenicity (pathogenicity index ranging from 4 to 6.99), low pathogenicity (pathogenicity index ranging from 1 to 3.99) and apathogenic (pathogenicity index ranging from 0 to 0.99). The analysis of the strains according to their origin revealed that isolates from broiler bedding material presented a lower pathogenicity index.Discussion: It is possible that the source of isolation implies in different results, depending on the criteria adopted. This data reinforces the importance of use a more accurate mathematical model to represents the biological phenomenon. In the study, all avian pathogenic Escherichia coli strains were classified based on a pathogenicity index and the concept of the death time represents an interesting parameter to measure the ability of the strain to promote acute and septicemic manifestation. The use of a support method for poultry veterinary diagnostic accompanying the fluctuation of the bacteria pathogenicity inside the farms may indicate a rational use of antimicrobial in poultry industry.

Virulence genes and antimicrobial resistance of Pasteurella multocida isolated from poultry and swine

Pasteurella multocida causes atrophic rhinitis in swine and fowl cholera in birds, and is a secondary agent in respiratory syndromes. Pathogenesis and virulence factors involved are still poorly understood. The aim of this study was to detect 22 virulence-associated genes by PCR, including capsular serogroups A, B and D genes and to evaluate the antimicrobial susceptibility of P. multocida strains from poultry and swine. ompH, oma87, plpB, psl, exbD-tonB, fur, hgbA, nanB, sodA, sodC, ptfA were detected in more than 90% of the strains of both hosts. 91% and 92% of avian and swine strains, respectively, were classified in serogroup A. toxA and hsf-1 showed a significant association to serogroup D; pmHAS and pfhA to serogroup A. Gentamicin and amoxicillin were the most effective drugs with susceptibility higher than 97%; however, 76.79% of poultry strains and 85% of swine strains were resistant to sulphonamides. Furthermore, 19.64% and 36.58% of avian and swine strains, respectively, were multi-resistant. Virulence genes studied were not specific to a host and may be the result of horizontal transmission throughout evolution. High multidrug resistance demonstrates the need for responsible use of antimicrobials in animals intended for human consumption, in addition to antimicrobial susceptibility testing to P. multocida.

Cloning of a complementary DNA for rabbit proactivator. A metalloproteinase that activates synovial cell collagenase, shares homology with stromelysin and transin, and is coordinately regulated with collagenase

Rabbit proactivator is a neutral metalloproteinase that activates another metalloproteinase, procollagenase, and degrades noncollagenous matrix. We describe the construction of an activator complementary DNA (cDNA) clone, which is 1.9 kb, that selects a 2.1-kb messenger RNA (mRNA) in Northern blot hybridizations. Nucleic acid sequence studies of the activator cDNA indicate 1) that it encodes protein Mr 53,881, 2) that this protein exhibits approximately 80% homology with rat transin, an oncogene-induced protein with a previously unknown function, and 3) that, in the first 172 residues, it is virtually identical to the rabbit metalloproteinase, stromelysin. Homology between rabbit activator and human skin collagenase is approximately 50%. Activator and collagenase mRNA are coordinately regulated; untreated cultures of rabbit synovial fibroblasts produce low levels of each protein, but addition of phorbol myristate acetate (10(-8)M) results in an increase in mRNA for both proteins by 2.5-5 hours. Adding all-trans-retinoic acid (10(-6)M) or dexamethasone (10(-7)M) to phorbol-stimulated cells coordinately suppresses both activator and collagenase mRNA. Our data suggest the existence of coordinately regulated metalloproteinases that are important in the modulation of connective tissue metabolism.