Recent approaches for control of E. coli and respiratory complex in Middle East

The synergy effect of matrine and berberine hydrochloride on treating colibacillosis caused by an avian highly pathogenic multidrug-resistant Escherichia coli

Infection by multidrug-resistant avian pathogenic Escherichia coli (APEC) in chickens always leads to the uselessness of antibiotics, highlighting the need for alternative antibacterial agents. Sophora flavescens and Coptis chinensis have been a classical combination used together in Traditional Chinese Medicine (TCM) formulas to treat diseases with similar symptoms to colibacillosis for an extended period, but the effect of their active ingredients' combination on APEC infection remains unstudied. The objective of this study was to explore the synergistic effect of matrine and berberine hydrochloride on colibacillosis caused by an isolated multidrug-resistant APEC. In this study, a highly pathogenic E. coli was isolated from the liver of a diseased chicken in a farm suspected of colibacillosis, and it was resistant to multiple antibiotics. The LD50 of the strain was approximately 3.759×108 CFU/mL. The strain harbored several antibiotic resistance genes and virulence genes. Matrine and berberine hydrochloride have synergistic antibacterial effect against the isolated strain in vitro. The combined use of matrine and berberine hydrochloride exhibited synergistic effects in the treatment of APEC infection by regulating the organ indices, improving the pathological situation, decreasing the bacterial load, and regulating the inflammatory factors to enhance the survival rate of chickens in vivo. These results provided a foundation for revealing the effective effects and possible mechanisms of matrine and berberine hydrochloride as potential antimicrobial agents on diseases caused by multidrug-resistant APEC in chickens.

A systematic review and meta-analysis on the efficacy of vaccination against colibacillosis in broiler production

Colibacillosis, a disease caused by Escherichia coli in broiler chickens has serious implications on food safety, security, and economic sustainability. Antibiotics are required for treating the disease, while vaccination and biosecurity are used for its prevention. This systematic review and meta-analysis, conducted under the COST Action CA18217-European Network for Optimization of Veterinary Antimicrobial Treatment (ENOVAT), aimed to assess the efficacy of E. coli vaccination in broiler production and provide evidence-based recommendations. A comprehensive search of bibliographic databases, including, PubMed, CAB Abstracts, Web of Science and Agricola, yielded 2,722 articles. Following a defined protocol, 39 studies were selected for data extraction. Most of the studies were experimental infection trials, with only three field studies identified, underscoring the need for more field-based research. The selected studies reported various types of vaccines, including killed (n = 5), subunit (n = 8), outer membrane vesicles/protein-based (n = 4), live/live-attenuated (n = 16), and CpG oligodeoxynucleotides (ODN) (n = 6) vaccines. The risk of bias assessment revealed that a significant proportion of studies reporting mortality (92.3%) or feed conversion ratio (94.8%) as outcomes, had "unclear" regarding bias. The meta-analysis, focused on live-attenuated and CpG ODN vaccines, demonstrated a significant trend favoring both vaccination types in reducing mortality. However, the review also highlighted the challenges in reproducing colibacillosis in experimental setups, due to considerable variation in challenge models involving different routes of infection, predisposing factors, and challenge doses. This highlights the need for standardizing the challenge model to facilitate comparisons between studies and ensure consistent evaluation of vaccine candidates. While progress has been made in the development of E. coli vaccines for broilers, further research is needed to address concerns such as limited heterologous protection, practicability for application, evaluation of efficacy in field conditions and adoption of novel approaches.

Antimicrobial Efficacy of Cinnamon Essential Oil against Avian Pathogenic Escherichia coli from Poultry

Colibacillosis, caused by E. coli, is responsible for economic losses in the poultry industry due to mortality, decreased production, and the cost of antibiotic treatments. Prevention of colibacillosis is based on improved biosecurity measures and the use of the vaccine performed with O78 E. coli strains, which is responsible for most cases of colibacillosis. Recently, there has been increased interest in other infection control methods, such as the use of natural compounds. The aim of this study was to evaluate the antimicrobial efficacy of cinnamon essential oil (CEO) against E. coli strains isolated from poultry. The MIC50 and MIC90 of CEO were determined by testing 117 strains belonging to serogroups O78, O2, O128, O139, isolated from laying hens (91 strains), broilers (10 strains), and turkeys (16 strains). The bacterial strains were tested at cell densities of 108 and 106 CFU/mL. At the cell density of 108 CFU/mL, MIC50 and MIC90 were 0.4 and 0.5 µL/mL for most of the tested strains, while they corresponded to 0.5 µL/mL for all strains isolated from broilers and for strains belonging to serogroup O139. At the cell density of 106 CFU/mL, MIC50 and MIC90 were 0.3 and 0.4 µL/mL, regardless of bird species of origin and for strains belonging to serogroups O78 and O2. In addition, a concentration of 0.04 µL/mL of CEO corresponded both to MIC50 and MIC90 for strains belonging to serogroups O139 and O128. Based on these results, cinnamon essential oil showed an effective antibacterial activity against E. coli strains from poultry and could find field application for the prevention of colibacillosis.

The Influence of Vaccination of Broiler Chickens and Turkeys with Live E. coli Attenuated Vaccine on E. coli Population Properties and TRT Vaccination Efficacy

Simple Summary

Escherichia coli infections are considered one of the major causes of economic loss in the poultry industry. The reasons for the magnitude of the problem are the numerous sources of infection with these bacteria for birds and the need for an effective prevention method. Vaccination is one of the strategies for minimizing the consequences of E. coli infection. In this study, we performed three independent experiments at farm level using a live vaccine against E. coli. Antibiotic-free broiler chickens, conventional broiler chickens and broiler turkeys were examined in different experiments. The most meaningful results and conclusions of these experiments are that vaccination against colibacillosis decreases the population count of E. coli, increases the antibiotic susceptibility of field E. coli isolates and has no impact on the efficacy of vaccination against another significant poultry upper respiratory tract disease—TRT. We believe that the vaccination of broiler chickens and turkeys against E. coli can improve bird health and should be considered in terms of routine immunoprophylaxis.

Abstract

Colibacillosis is one of the major causes of economic losses in the poultry industry. Vaccination against E. coli is attracting increasing interest. The aim of the study was to evaluate the influence of vaccination with live, aroA gene-deleted vaccine on the structure and properties of field E. coli population and its potential impact on TRT vaccination efficacy in broiler chickens and turkeys. We performed three independent experiments on farms: (1) with antibiotic-free broiler chickens, (2) with conventional broiler chickens and (3) with broiler turkeys. In experiment 1, we have recorded an approx. 0–15% prevalence of multi-susceptible E. coli strains in the first production cycle. Starting from production cycle number two, after vaccination introduction, successive significant increases in E. coli susceptibility emerged, reaching 100% of strains at the end of production cycle 3. Increased E. coli susceptibility remained for three production cycles after vaccination withdrawal. In experiments 2 (2 production cycles) and 3 (1 production cycle), we recorded similar tendencies of E. coli susceptibility profile change. In experiments 1 and 2, the E. coli population count was lower after vaccination. In experiments 2 and 3, no negative influence of E. coli vaccination on the level of specific antibodies against TRT was recorded.

Effects of the Probiotic Candidate E. faecalis-1, the Poulvac E. coli Vaccine, and their Combination on Growth Performance, Caecal Microbial Composition, Immune Response, and Protection against E. coli O78 Challenge in Broiler Chickens

The present study was performed on 180-day-old commercial Cobb chicks to assess the effects of the probiotic candidate Enterococcus faecalis-1, the Poulvac Escherichia coli vaccine, and their combination on growth parameters, intestinal microbial composition, immune response, and protection against challenge with the avian pathogen E. coli O78. The experimental groups were as follows: G1, basal diet; G2, basal diet and challenge with O78 at 28 days of growth; G3, basal diet, vaccination with Poulvac (1 and 15 days), and challenge with O78 at 28 days of growth; G4, basal diet, E. faecalis-1 supplementation for the first 3 days of growth, and challenge with O78 at 28 days of growth; G5, basal diet, E. faecalis-1 supplementation for the first 3 days of growth, vaccination with Poulvac (1 and 15 days), and challenge with O78 at 28 days of growth; G6, basal diet and E. faecalis-1 supplementation for the first 3 days of growth. The results showed that E. faecalis-1 in drinking water significantly improved the growth performance and immune response, increased the total Enterococcus counts, reduced the mortality, and decreased the visceral invasion by O78 in challenged broilers. While the effect of the Poulvac vaccine alone or with E. faecalis-1 was not significant compared with that of the E. faecalis-1 supplement, the vaccine improved the growth rate and decreased the mortality and visceral invasion by APEC O78 in challenged broilers. These results showed that E. faecalis-1 supplementation and routine vaccination with the Poulvac vaccine could improve the growth performance and immune response of broiler chickens and protect against challenge with APEC O78.

Ways to minimize bacterial infections, with special reference to Escherichia coli, to cope with the first-week mortality in chicks: an updated overview

On the commercial level, the poultry industry strives to find new techniques to combat bird's infection. During the first week, mortality rate increases in birds because of several bacterial infections of about ten bacterial species, especially colisepticemia. This affects the flock production, uniformity, and suitability for slaughter because of chronic infections. Escherichia coli (E. coli) causes various disease syndromes in poultry, including yolk sac infection (omphalitis), respiratory tract infection, and septicemia. The E. coli infections in the neonatal poultry are being characterized by septicemia. The acute septicemia may cause death, while the subacute form could be characterized through pericarditis, airsacculitis, and perihepatitis. Many E. coli isolates are commonly isolated from commercial broiler chickens as serogroups O₁, O₂, and O₇₈. Although prophylactic antibiotics were used to control mortality associated with bacterial infections of neonatal poultry in the past, the commercial poultry industry is searching for alternatives. This is because of the consumer's demand for reduced antibiotic-resistant bacteria. Despite the vast and rapid development in vaccine technologies against common chicken infectious diseases, no antibiotic alternatives are commercially available to prevent bacterial infections of neonatal chicks. Recent research confirmed the utility of probiotics to improve the health of neonatal poultry. However, probiotics were not efficacious to minimize death and clinical signs associated with neonatal chicks' bacterial infections. This review focuses on the causes of the increased mortality in broiler chicks during the first week of age and the methods used to minimize death.

Evaluation of commercially available aroA delated gene E. coli O78 vaccine in commercial broiler chickens under Middle East simulating field conditions

The broiler industry in the Middle East (ME) faces many challenges related to bacterial infections, including M. gallisepticum, M. synoviae, E. coli, and other gram-negative bacteria, exacerbated by various errors in the brooding process. Antibiotics use in the first three days of life, such as Linco-Spectin 100 SP, tilmicosin, enrofloxacin, tylosin, colistin, and doxycycline, is the trend in the market to control such challenges. This study aimed to evaluate the efficacy of the newly introduced aroA E. coli vaccine (Poulvac E. coli) and its ability to reduce over-reliance on the heavy use of antibiotics in the ME. The study was conducted on 160 broiler chicks, divided into eight even groups. Each group was treated differently in terms of antibiotic therapy and ages at the time of Poulvac E. coli administration and the challenge of virulent avian pathogenic E. coli (APEC), serotype O78. Spray application of Poulvac E. coli at seven days of age plus Linco-Spectin 100 SP during the first three days provided the best results for zero mortality after challenge with APEC, while Poulvac E. coli at seven days with enrofloxacin during the early three days resulted in 10% mortality. Poulvac E. coli hatchery vaccination protected birds against mortality but reduced body weight gain compared to the 7-day group vaccinated with Linco-Spectin 100 SP during the first three days. Poulvac E. coli given on day one or day seven did not affect the immune response to concurrent respiratory viral vaccines and, in some cases, improved response. This study shows that Poulvac E. coli at seven days of age, together with Linco-Spectin 100 during the first three days, has produced the best results in terms of protection and performance in the ME high presence of avian pathogenic E. coli field challenge.

Influence of vaccination of broiler chickens against Escherichia coli with live attenuated vaccine on general properties of E. coli population, IBV vaccination efficiency, and production parameters-a field experiment

Poultry colibacillosis has been one of the major causes behind economic losses in the poultry production; however, no effective method for its prevention has been developed so far. Vaccination against colibacillosis is capturing increasing interest. The aim of this study was to demonstrate benefits from using a live, aroA gene–deleted vaccine against colibacillosis in broiler chickens and its potential impact on reduced use of antibiotics, the efficacy of vaccination against infectious bronchitis (IB), and the structure and properties of Escherichia coli population in broilers under commercial farm conditions. In 2 experiments, carried out on 3 farms, broiler chickens of one chicken house from each farm were vaccinated against Escherichia coli (E. coli), whereas birds of other chicken houses of each farm were not vaccinated against E. coli. In experiment 1, which was carried out on 2 farms, for 3 consecutive production cycles, spray vaccination of day-old broilers against E. coli decreased the number of E. coli isolates from internal organs but not from the respiratory system in the sixth week of birds' life. In experiment 1, E. coli–vaccinated broilers did not receive the antimicrobials until 14 d after the vaccination. Escherichia coli isolates from the E. coli–vaccinated birds were more susceptible to the antimicrobials. Escherichia coli vaccination had no impact on the IB vaccination efficiency; it has reduced the mean number of days of the antimicrobial treatment and improved broiler production parameters. In experiment 2, chickens of both houses received the antimicrobials for the first 4 d of their life. Birds of chicken house 1 were vaccinated against E. coli on the ninth day of life, whereas birds of chicken house 2 were not vaccinated. In both houses, further antimicrobial usage was the same, and antimicrobials were not used until 14 d after E. coli vaccination. Similar to experiment 1, in experiment 2, vaccination decreased the number of E. coli isolates, and these isolates were more susceptible to the antimicrobials. Vaccination of broilers against E. coli should be considered in terms of routine immunoprophylaxis.

An Assessment of the Level of Protection Against Colibacillosis Conferred by Several Autogenous and/or Commercial Vaccination Programs in Conventional Pullets upon Experimental Challenge

The prevention of avian colibacillosis has historically been investigated through vaccination, with variable outcomes. Commercial live (attenuated) and inactivated vaccines are reported to have limited efficacy in the context of heterologous challenge. Autogenous vaccination, using field isolates, is widely used, but scarcely documented. Different vaccination programs, including a live commercial vaccine and/or an inactivated autogenous vaccine, were compared for three different avian pathogenic Escherichia coli (APEC) strain (serotypes O78, O18 and O111) challenges. On the pullet farm, four groups of conventional pullets received different vaccination protocols. Group A was kept unvaccinated (control group). Group B was vaccinated three times with a live commercial O78 E. coli vaccine (at one day old, 59 and 110 days of age). Group C was immunized twice (at 79 and 110 days) with a three-valence autogenous vaccine (O78, O18 and O111). Group D was vaccinated first with the commercial vaccine (at one day old and 59 days), then with the autogenous vaccine (110 days). Birds were transferred to the experimental facility at 121 days of age and were challenged 10 days later. In each group, 20 birds were challenged with one of the three APEC strains (O78, O18, O111); in total, 80 birds were challenged by the same strains (20 per group). The recorded outcomes were: mortality rate, macroscopic lesion score in target organs and the bacterial recovery of the challenge strain from bone marrow and pooled organs. When challenged with O78 or O111 strains, birds from groups C and D proved to be significantly better protected, in terms of lesion scoring and bacteriological isolation, than those of groups A and B. With the O18 challenge, only birds of group D presented a statistically significant reduction of their lesion score. To the authors’ knowledge, this is the first report on the efficacy of an immunization program in poultry that combines commercial and autogenous vaccines.

Effect of colibacillosis on the immune response to a rabbit viral haemorrhagic disease vaccine

Viral haemorrhagic disease (VHD) and colibacillosis are common diseases in rabbits that cause economic losses worldwide. The effect of colibacillosis on the immune response of vaccinated rabbits against rabbit haemorrhagic disease virus (RHDV) was studied. Four groups (G1-G4) were included. G1 was the negative control group; G2 was the RHDV vaccine group; G3 was the E. coli-infected group; and G4 was the E. coli-infected + RHDV vaccine group. The E. coli infection and RHDV vaccination were simultaneously performed, with another previous infection, 3 days before vaccination. At 28 days post-vaccination (PV), the rabbits (G2-G4) were challenged intramuscularly with 0.5 ml of RHDV at a dose of 10³ 50% median lethal dose (LD₅₀)/rabbit. The rabbits were observed for clinical signs, body weight gain and mortality rates. Tissue, blood, serum, and faecal samples and rectal swabs were collected at 3, 5, 7, 14, 21 and 28 days PV. Significant clinical signs and mortality and a decrease in BW were observed in the infected + RHDV vaccine group. On the 3^rd day post-infection (PI), compared with all the other groups, the vaccinated group (G2) had significantly upregulated hepatic tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels; however, the infected + RHDV vaccine group had significantly higher intestinal levels of TNF-α and IL-6 than the other groups. Furthermore, E. coli infection in vaccinated rabbits led to immunosuppression, as shown by significant decreases (P < 0.05) in heterophil phagocytic activity, the CD4+/CD8+ ratio, and HI antibody responses to RHDV and a significant increase in the heterophil to lymphocyte (H/L) ratio. In conclusion, colibacillosis leads to immunosuppression involving a shift in the equilibrium of cytokines and reduced weight gain and mortality in vaccinated rabbits and could be a contributing factor in RHDV vaccination failure in rabbit farming.