Influence of lincomycin-spectinomycin treatment on the outcome of Enterococcus cecorum infection and on the cecal microbiota in broilers

Background Enterococcus cecorum (EC) is one of the main reasons for skeletal disease in meat type chickens. Intervention strategies are still rare and focus mainly on early antibiotic treatment of the disease, although there are no data available concerning the effectivity of this procedure. The present study aimed to investigate the effectivity of early lincomycin-spectinomycin treatment during the first week of life after EC-infection. Furthermore, the impact of lincomycin-spectinomycin treatment and EC infection on the development of cecal microbiota was investigated. Methods A total of 383 day-old broiler chicks were randomly assigned to four groups (non-infected and non-treated, non-infected and treated, EC-infected and non-treated, and EC-infected and treated). The EC-infected groups were inoculated orally with an EC suspension at the day of arrival and at study day 3. The treatment groups were treated with lincomycin-spectinomycin via the drinking water for six consecutive days, starting two hours after the first inoculation. Necropsy of 20 chickens per group was performed at study days 7, 14, 21, and 42. Bacteriological examination via culture and real-time PCR was performed to detect EC in different extraintestinal organs. Cecal samples of nine chickens per group and necropsy day were analyzed to characterize the composition of the cecal microbiota. Results No clinical signs or pathologic lesions were found at necropsy, and EC was not detected in extraintestinal organs of the EC-infected and treated birds. Lincomycin-spectinomycin promoted the growth of the bacterial genus Escherichia/Shigella and reduced the amount of potentially beneficial Lactobacillus spp. in the ceca regardless of EC-infection. Unexpectedly, the highest abundances of the genus Enterococcus were found directly after ending antibiotic treatment in both treatment groups, suggesting the growth of resistant enterococcal species. EC was not detected among the most abundant members of the genus Enterococcus. Oral EC-infection at the first day of life did not influence the development of cecal microbiota in the present study. Conclusions Lincomycin-spectinomycin treatment during the first week of life can prevent the EC-associated disease in broiler type chickens and has a direct impact on the development of the cecal microbiota. The low abundance of EC in the ceca of infected chickens underlines the pathogenic nature of the disease-causing EC strains. Further research on alternative prevention and intervention strategies is needed with regard to current efforts on reducing the use of antibiotics in livestock animals.

Biosynthesis-Guided Discovery of Enteropeptins, Unusual Sactipeptides Containing an N-Methylornithine

The combination of next-generation DNA sequencing technologies and bioinformatics have revitalized natural product discovery. Using a new bioinformatic search strategy, we recently identified ~600 gene clusters in animal microbiomes that code for ribosomal peptide natural products synthesized by radical S-adenosylmethionine enzymes. These grouped into 16 subfamilies and pointed to an unexplored microbiome biosynthetic landscape. Herein, we report the structure, biosynthesis, and function of one of these natural product groups, that we term enteropeptins, from the gut microbe Enterococcus cecorum. We elucidate three novel reactions, each catalyzed by a different family of metalloenzymes, in the biosynthesis of enteropeptins. Among these, we characterize the founding member of a widespread superfamily of Fe-S-containing methyltransferases, which, together with a di-Mn-dependent arginase, installs an N-methylornithine in the peptide sequence. Biological assays with the mature product revealed bacteriostatic activity only against the producing strain, extending an emerging theme of fratricidal or self-inhibitory metabolites in microbiome firmicutes.

Different virulence levels of Enterococcus cecorum strains in experimentally infected meat-type chickens

In recent years, pathogenic strains of Enterococcus cecorum (EC) have emerged as a causing agent of septicemia and skeletal infection in broiler chickens with a high economic impact worldwide. Although research has been conducted, many aspects of the pathogenesis of the EC-associated disease are still unknown. In the present study, an experimental infection model was established in broiler chickens. Two different EC strains (EC14 and EC15) were compared in two different concentrations of each strain (2 × 106 and 2 × 108 colony-forming units per milliliter (CFU/mL)) after oral infection of one-day-old chicks. Clinical signs and gross lesions of the EC-associated disease were monitored in the following seven weeks. Although both EC strains were originally isolated from clinical disease outbreaks and had a high embryonic lethality, only EC14 successfully induced the typical course of the EC-associated disease with characteristic clinical signs and gross lesions. In total, 23% of the birds in the two EC14-groups were EC-positive in extraintestinal organs on culture, and no differences were found between the two infectious doses. EC14 was frequently detected via real-time PCR in the free thoracic vertebra (FTV) and femoral heads without any detectable gross lesions. The number of EC positive spleens from infected broilers was comparable using bacterial isolation and a specific real-time PCR. Interestingly, EC15 was not detected in extraintestinal organs, although birds in the EC15 groups were colonized by EC in the ceca after experimental infection. The present study represents first proof that virulence differs among EC strains in experimentally infected chickens, and emphasizes the need to further characterize virulence factors and pathogenic mechanisms of EC. The strain EC14 at a dose of 106 CFU is suitable for reproduction of the EC-associated disease. The experimental infection model reported here provides the basis for further research on the EC pathogenesis and possible prevention and intervention strategies.

Embryo Lethality Assay for Evaluating Virulence of Isolates from Bacterial Chondronecrosis with Osteomyelitis in Broilers

We used an embryo lethality assay (ELA) to assess virulence for different isolates from cases of bacterial chondronecrosis with osteomyelitis (BCO) in broilers. ELA has been used to measure virulence and lethal dosage of Enterococcus faecalis and Enterococcus cecorum. We hypothesized that ELA could substitute for more laborious and costly assessments of BCO isolate pathogenicity using live birds. We evaluated two different levels of bacteria injected into eggs from layer and commercial broiler embryos. Significant findings include a) Escherichia coli from neighboring farms operated by the same integrator had very different embryo lethality, b) isolate Staphylococcus agnetis 908 had low virulence in ELA, even though this isolate can induce more than 50% BCO lameness, c) Enterococcus cecorum 1415 also had low pathogenicity; even though it was recovered from severe bilateral tibial dyschondroplasia, d) human and chicken isolates of S. aureus had significant pathogenicity, e) virulence for some isolates was highly variable possibly corresponding with quality of the embryos/fertile eggs used, and f) ELA pathogenicity was much lower for our BCO isolates than previous reports which may reflect maternal environment. Overall, ELA virulence and BCO virulence are not always concordant indicating that that ELA may not be an effective measure for assessing virulence with respect to BCO.ImportanceLameness is among the most significant animal welfare issues in the poultry industry. Bacterial infections are a major cause of lameness and different bacterial species have been obtained from lame broilers. Reliable lab-based assays are required to assess relative virulence of bacteria obtained from lame broilers. Embryo Lethality Assays have been used to compare virulence. Our results suggest that this assay may not be an effective measure of virulence related to lameness.

РЕШЕНИЕ ПРОБЛЕМЫ СУСТАВНОЙ ПАТОЛОГИИ ПУТЕМ РАЦИОНАЛЬНОГО ПОДХОДА К ПРИМЕНЕНИЮ ЛЕЧЕБНЫХ АНТИБИОТИКОВ Попова Т.В., Хошафян Л.С., Аносов Д.Е., Валишин Р.Р.

КЛЮЧЕВЫЕ СЛОВА: ЦЫПЛЯТА-БРОЙЛЕРЫ, СУСТАВНЫЕ ПАТОЛОГИИ, БАКТЕРИАЛЬНЫЕ ПАТОГЕНЫ, ЧУВСТВИТЕЛЬНОСТЬ К АНТИБИОТИКАМ, КОЛИКВИНОЛ, СОХРАННОСТЬ, ПРИБЫЛЬ АННОТАЦИЯ: Суставные патологии (артриты, некроз головки бедренной кости, искривление конечностей), вызванные бактериальными патогенами - частая проблема, встречающаяся среди птицепоголовья по всей территории РФ. Приведены данные опыта, проведенного в 2021 г. в условиях крупной птицефабрики Юго-Западного региона с относительно высокой частотой суставных патологий у цыплят-бройлеров кросса Кобб-500. У бройлеров были выделены изоляты Streptococcus pluranimalium, Enterococcus cecorum, Enterococcus gallinarum, Staphylococcus spp., E. coli. В опыте in vitro в независимой лаборатории была определена их чувствительность к действующим веществам препаратов производства компании «ВИК - здоровье животных»; лучшие результаты получены с комплексным препаратом Коликвинол (чувствительность установлена у 20 из 21 выделенного изолята). Последующий опыт in vivo был проведен на 2 группах бройлеров (свыше 400 тыс. голов в каждой). С 1 по 5 день опытной группе давали Коликвинол, контрольной - препарат на основе энрофлоксацина 10%; вторая лечебная обработка в 20-24 дня в обеих группах была одинаковой (препаратом на основе флорфеникола). Схема терапии, использованная в опытной группе, оказалась эффективнее контрольной: сохранность цыплят возросла на 2,21%, что составило более 2 млн. руб. дополнительной прибыли при реализации мяса. Таким образом, применение индивидуальной схемы терапии, основанной на определении циркулирующих в стаде патогенов и их чувствительности к различным антибиотикам, дает значительно лучшие результаты, чем стандартные схемы, как с точки зрения экономической эффективности производства, так и с точки зрения ответственного использования антибиотиков.