Virulence determinants and biofilm production among Trueperella pyogenes recovered from abscesses of captive forest musk deer

Genetic diversity and virulence properties of caprine Trueperella pyogenes isolates

BACKGROUND

Trueperella pyogenes is an opportunistic pathogen that causes suppurative infections in various animal species, including goats. So far, only limited knowledge of phenotypic and genotypic properties of T. pyogenes isolates from goats has been gathered. In our study, we characterized the phenotypic and genotypic properties of caprine T. pyogenes isolates and established their relationship by Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR).

RESULTS

From 2015 to 2023, 104 T. pyogenes isolates were obtained from 1146 clinical materials. In addition, two T. pyogenes isolates were obtained from 306 swabs collected from healthy goats. A total of 51 T. pyogenes isolates were subjected to detailed phenotypic and genotypic characterization. The virulence genotype plo/nanH/nanP/fimA/fimC/luxS was predominant. All of the tested isolates showed the ability to form a biofilm but with different intensities, whereby most of them were classified as strong biofilm formers (72.5%). The high level of genetic diversity among tested caprine T. pyogenes isolates (19 different RAPD profiles) was observed. The same RAPD profiles were found for isolates obtained from one individual, as well as from other animals in the same herd, but also in various herds.

CONCLUSIONS

This study provided important data on the occurrence of T. pyogenes infections in goats. The assessment of virulence properties and genetic relationships of caprine T. pyogenes isolates contributed to the knowledge of the epidemiology of infections caused by this pathogen in small ruminants. Nevertheless, further investigations are warranted to clarify the routes of transmission and dissemination of the pathogen.

Role of biofilms in antimicrobial resistance of the bacterial bovine respiratory disease complex

An increase in chronic, non-responsive bovine respiratory disease (BRD) infections in North American feedlot cattle is observed each fall, a time when cattle are administered multiple antimicrobial treatments for BRD. A number of factors are responsible for BRD antimicrobial treatment failure, with formation of biofilms possibly being one. It is widely accepted that biofilms play a role in chronic infections in humans and it has been hypothesized that they are the default lifestyle of most bacteria. However, research on bacterial biofilms associated with livestock is scarce and significant knowledge gaps exist in our understanding of their role in AMR of the bacterial BRD complex. The four main bacterial species of the BRD complex, Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis are able to form biofilms in vitro and there is evidence that at least H. somni retains this ability in vivo. However, there is a need to elucidate whether their biofilm-forming ability contributes to pathogenicity and antimicrobial treatment failure of BRD. Overall, a better understanding of the possible role of BRD bacterial biofilms in clinical disease and AMR could assist in the prevention and management of respiratory infections in feedlot cattle. We review and discuss the current knowledge of BRD bacteria biofilm biology, study methodologies, and their possible relationship to AMR.

Detecting Forest Musk Deer Abscess Disease Pathogens Using 16S rRNA High-Throughput Sequencing Technology

Currently, researchers use bacterial culture and targeted PCR methods to classify, culture, and identify the pathogens causing abscess diseases. However, this method is limited by factors such as the type of culture medium and culture conditions, making it challenging to screen and proliferate many bacteria effectively. Fortunately, with the development of high-throughput sequencing technology, pathogen identification at the genetic level has become possible. Not only can this approach overcome the limitations of bacterial culture, but it can also accurately identify the types and relative abundance of pathogens. In this study, we used high-throughput sequencing of 16S rRNA to identify the pathogens in purulent fluid samples. Our results not only confirmed the presence of the main pathogen reported by previous researchers, Trueperella pyogenes, but also other obligate anaerobes, Fusobacterium necrophorum and Bacteroides fragilis as the dominant pathogens causing abscess diseases for the first time. Therefore, our findings suggest that high-throughput sequencing technology has the potential to replace traditional bacterial culture and targeted PCR methods.

Antimicrobial susceptibility, virulence genes and genomic characterization of Trueperella pyogenes isolated from abscesses in dairy cattle

Trueperella pyogenes is an opportunistic animal pathogen mainly associated with various suppurative infections in wild and domestic animals. Limited studies have investigated the pathogenesis of diseases caused by this pathogen. The main objective of the current study was to investigate the prevalence, phenotypic properties, virulence genotypes, antimicrobial susceptibility and genetic characterization of T. pyogenes isolated from abscess lesions in different tissues of on-farm dairy cattle. The study was performed on 150 postpartum cattle with clinical abscess symptoms on 22 farms around Tehran, Iran. Classical and disk diffusion methods are used for phenotypic characterization and antibiotic susceptibility. Detection of virulence factor encoding genes and genomic characterization of the isolates also are carried out by conventional PCR and BOX-PCR assays, respectively. Sixty-eight T. pyogenes strains (45.3%) were isolated, 12 were identified as pure cultures and the other 56 strains were isolated from mixed cultures. Seven distinct biotypes were identified among the T. pyogenes isolates. The isolates were mostly resistance to trimethoprim-sulfamethoxazole (70.6%), erythromycin (36.7%), tetracycline (26.5%) and tylosin (23.5%) antibiotics. Also, the genes plo, nanH, nanP and fimA were detected in all isolates. Forty-two isolates (61.7%) carried all virulence factor genes detected in this study. Three isolates only carried plo, nanH, nanP and fimA genes were identified as the least frequent genotype. All sixty-eight isolates and the reference strain were categorized into seven main clusters (A-G). A strong association was observed between virulence factor encoding genes, pathogenicity and biochemical biotypes in some specific clonal relationships.

Molecular Basis for Luteolin as a Natural TatD DNase Inhibitor in Trueperella pyogenes

TatD960 and TatD825 are DNases that contribute to biofilm formation and virulence in Trueperella pyogenes (T. pyogenes). Luteolin is a natural flavonoid commonly found in plants that exhibits antimicrobial capacity. Our study aims to investigate the effects of luteolin on TatD DNases as a natural inhibitor. In this research, the expression of tatD genes and TatD proteins in T. pyogenes treated with luteolin was detected, and then the effect of luteolin on the hydrolysis of DNA by TatD DNases was analyzed using agarose gel electrophoresis. Moreover, the interactions between luteolin and TatD DNases were tested using surface plasmon resonance (SPR) assays and molecular docking analysis. After 1/2 MIC luteolin treatment, the transcription of tatD genes and expression of TatD proteins appeared to be reduced in 80–90% of T. pyogenes (n = 20). The gel assay revealed that luteolin can inhibit the activity of TatD DNases. The SPR assay showed that the KD values of luteolin to TatD960 and TatD825 were 6.268 × 10⁻⁶ M and 5.654 × 10⁻⁶ M, respectively. We found through molecular docking that hydrogen bonding is predominant in the interaction of luteolin and TatD DNases. Our data indicate that luteolin inhibited the ability of TatD DNases by decreasing their binding to DNA. The current study provides an insight into the development of luteolin as a DNase inhibitor in preventing biofilm formation and virulence in T. pyogenes.

Prevalence and Genetic Diversity of Trueperella pyogenes Isolated from Infections in European Bison (Bison bonasus)

Simple Summary

In the European bison, Trueperella pyogenes is associated with different suppurative infections of mainly the urogenital tract or with abscesses in various tissues. Our research showed that in the studied population of European bison in Poland, the prevalence of T. pyogenes infections is relatively high. The significant genetic diversity of isolated strains was observed. However, in a few cases, the same RAPD profile was obtained for strains isolated from individuals living in the same area. Our study indicated that different virulence factors are related to the pathogenicity of this bacterium. The results obtained in this study provide valuable data about the prevalence, pathogenicity and genetic diversity of T. pyogenes in the European bison. Thus, it improves the knowledge on treatment for the European bison’s health and proves the importance of continuous monitoring for the protection of these wild ruminants.

Abstract

Trueperella pyogenes is a Gram-positive bacterium causing purulent infections in many animal species, including the European bison. However, the data about the virulence and genetic relationships of T. pyogenes strains isolated from these wild ruminants are strongly limited. The aim of this study was to investigate the prevalence of T. pyogenes infections in the European bison, and to evaluate the genetic diversity of isolates from these animals. In the time span of 10 years, 328 European bison from 16 different locations were examined. The standard bacteriological methods were used for T. pyogenes isolation and identification from clinical specimens obtained from urogenital tract infections and abscesses of different locations. The presence of genes encoding known virulence factors was investigated by PCR, and the genetic diversity of T. pyogenes strains was examined with the RAPD-PCR method. The prevalence of T. pyogenes infections was 14.6%, and the pathogen was isolated from both female (47.9% of isolates) and male (52.1% of isolates) European bison. It should be highlighted that a considerable number of strains were isolated from the prepuce and penis infections. Therefore, the role of T. pyogenes in the pathogenesis of balanoposthitis should be seriously perceived. A total of 39 T. pyogenes strains were subjected to genetic characterization. All studied strains carried the plo gene, while the nanH (25.6%), nanP (23.1%), cbpA (7.7%), fimA (97.4%), fimC (69.2%), fimE (92.3%) and fimG (15.4%) genes were present with a variable frequency among the tested strains. The virulence genotype plo/fimA/fimC/fimE was dominant. RAPD-PCR typing showed a high level of genetic diversity among European bison T. pyogenes strains, and a total of 31 different RAPD profiles were distinguished. In a few cases, the same RAPD profile was found in strains obtained from animals living in the same area. This study provided the first data about the prevalence and genetic relationships of T. pyogenes in the Polish population of European bison. However, further epidemiological investigations are needed to understand the routes of transmission and dissemination of the pathogen in these wild animals.

Heterologous Prime-Boost Immunization with DNA Vaccine and Modified Recombinant Proteins Enhances Immune Response against Trueperella pyogenes in Mice

Trueperella pyogenes (T. pyogenes) is a crucial opportunistic pathogen normally causing mastitis, abscesses and pneumonia in economically important ruminants. Although only one commercial vaccine of T. pyogenes is currently obtainable, its immunoprotective effect is limited. Pyolysin (PLO) is the most predominant virulence factor highly expressed in T. pyogenes and is an excellent target for the development of novel vaccines against T. pyogenes. In this study, we designed a heterologous prime-boost vaccination scheme combining a DNA vaccine pVAX1-PLO and a subunit vaccine His-PLO to maximize host responses in mice. Humoral and cellular immune responses and protective effects were evaluated in mice to compare the immunogenicity induced by different immunization schemes. Compared to the PBS-control group, in vivo immunization results showed that better immune responses of mice immunized with the pVAX1-PLO plasmids and His-PLO proteins were induced. The residual bacterial burdens from the liver and peritoneal fluid were remarkably decreased in the immunized mice compared with the PBS group. Notably, the heterologous prime-boost vaccination groups significantly enhanced host humoral and cellular immune responses and protected mice from different virulent T. pyogenes strains infection. Conclusively, this study provides a favorable strategy for the further development of next-generation vaccines against T. pyogenes infections.

RAPD-PCR-Based Fingerprinting Method as a Tool for Epidemiological Analysis of Trueperella pyogenes Infections

In this study, a Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) method for genetic typing of Trueperella pyogenes, an opportunistic bacterial pathogen, was designed. The method optimization was performed for 37 clinical T. pyogenes strains isolated from various infections in different animal species. Optimal conditions for reliable and reproducible DNA fingerprinting were determined according to the modified Taguchi method. The developed method was assessed regarding its typeability, reproducibility, and discriminatory power using the Hunter’s and Gatsons’ index of discrimination. A high degree of genetic diversity was shown between the studied strains, which represented 31 genotypes. The generated RAPD profiles were relatively complex and simultaneously easy to interpret due to the wide size range of amplicons. The discriminatory index of the designed method was sufficiently high; thus, only strains epidemiologically related displayed identical RAPD genotypes. In conclusion, the DNA fingerprinting of T. pyogenes by the developed RAPD-PCR method is a reliable typing tool that may allow a better understanding of the epidemiology as well as pathogenesis of infections caused by this pathogen.

TatD DNases Contribute to Biofilm Formation and Virulence in Trueperella pyogenes

TatD DNases are conserved proteins in a variety of organisms and are considered potential virulence factors in Plasmodium falciparum and Streptococcus pneumoniae. However, the function of TatD DNases has not yet been determined in Trueperella pyogenes, which causes various infections in animals and leads to economic losses. In this study, we describe the roles of TatD DNases in T. pyogenes (TpTatDs). A bioinformatics analysis was performed to investigate the sequence characteristics of TpTatDs, and then the ability of recombinant TatD proteins to hydrolyze DNA was determined in the presence of divalent cations. Moreover, we constructed tatD-deficient mutants. The biofilms formed by the wild-type and mutant strains were observed under a microscope. The mortality and bacterial load in the spleen of mice infected with the wild-type strain and tatD-deficient mutants were determined to obtain insights into the role of TatDs in the virulence of T. pyogenes. Two TatD DNases were identified in T. pyogenes. They were Mg²⁺-dependent DNases and exhibited DNA endonuclease activity. Compared with those formed by the parental strain, biofilms formed by mutants showed a significantly reduced thickness and biomass. Moreover, mutants produced a lower bacterial load in the spleen of mice and compromised virulence. Our data indicated that TatD DNases in T. pyogenes are involved in biofilm formation and required for virulence during infections.

vB-ApyS-JF1, the First Trueperella pyogenes Phage, Shows Potential as an Alternative Treatment Strategy for Trueperella pyogenes Infections

Trueperella pyogenes (T. pyogenes) is an important opportunistic animal pathogen that causes huge economic losses to the animal husbandry industry. The emergence of bacterial resistance and the unsatisfactory effect of the vaccine have prompted investigators to explore alternative strategies for controlling T. pyogenes infection. Due to the ability of phages to kill multidrug-resistant bacteria, the use of phage therapy to combat multidrug-resistant bacterial infections has attracted attention. In this study, a T. pyogenes phage, vB-ApyS-JF1 (JF1), was isolated from sewage samples, and its whole genome and biological characteristics were elucidated. Moreover, the protective effect of phage JF1 on a mouse bacteremic model caused by T. pyogenes was studied. JF1 harbors a double-stranded DNA genome with a length of 90,130 bp (30.57% G + C). The genome of JF1 lacked bacterial virulence-, antibiotic resistance- and lysogenesis-related genes. Moreover, the genome sequence of JF1 exhibited low coverage (<6%) with all published phages in the NCBI database, and a phylogenetic analysis of the terminase large subunits and capsid indicated that JF1 was evolutionarily distinct from known phages. In addition, JF1 was stable over a wide range of pH values (3 to 11) and temperatures (4 to 50°C) and exhibited strong lytic activity against T. pyogenes in vitro. In murine experiments, a single intraperitoneal administration of JF1 30 min post-inoculation provided 100% protection for mice against T. pyogenes infection. Compared to the phosphate-buffered saline (PBS) treatment group, JF1 significantly (P < 0.01) reduced the bacterial load in the blood and tissues of infected mice. Meanwhile, treatment with phage JF1 relieved the pathological symptoms observed in each tissue. Furthermore, the levels of the inflammatory cytokines tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin-6 (IL-6) in the blood of infected mice were significantly (P < 0.01) decreased in the phage-treated group. Taken together, these results indicate that phage JF1 demonstrated great potential as an alternative therapeutic treatment against T. pyogenes infection.

Investigation of antimicrobial susceptibility and virulence factor genes in Trueperella pyogenes isolated from clinical mastitis cases of dairy cows

Trueperella pyogenes is an opportunistic pathogen causing important diseases including mastitis and metritis in domestic animals such as dairy cows leading to prominent economic losses in food production industry. The aim of this study was to investigate bacterial species, antimicrobial susceptibility, and presence of virulence factor genes and genotyping of T. pyogenes isolates associated with summer mastitis cases from 22 different farms around Tehran, Iran. Fifty-five percent of dairy cows with clinical mastitis symptoms was infected by T. pyogenesis indicated that this pathogen is the most important contributor to clinical mastitis in dairy cows in the present study. A significant correlation was illustrated between presence of virulence factor genes of isolated pathogen, biochemical patterns, and the utter infected types. Multidrug resistance susceptibility observed between isolates indicated the important need for prudent use of antimicrobials in treatment of mastitis caused by T. pyogenes and increased concerning of consumer health associated with recent problems of antimicrobial resistance. The categorization of isolates was implemented into seven different clonal related types by COX-PCR at 80% of similarity cutoff with significance relationship to clonal types, CAMP test result and sampling time and biochemical profile. Regarding to the results obtained at the present study, T. pyogenes can be considered as an important typically cause of purulent and acute form of clinical bovine mastitis and loss of dairy productivity. Further studies with more sample size and high-throughput omic methods in various sampling time and areas are suggested for study of this pathogen precisely.

A case of Trueperella pyogenes causing prosthetic joint infection

We present the first reported case of prosthetic joint infection caused by Trueperella pyogenes. This animal pathogen rarely causes human infection. Our patient was successfully treated with single-stage exchange and 12 weeks of rifampicin and moxifloxacin.

Metagenomics analysis of the gut microbiome in healthy and bacterial pneumonia forest musk deer

BACKGROUND

The forest musk deer (FMD, Moschus berezovskii) is an threatened species in China. Bacterial pneumonia was found to seriously restrict the development of FMD captive breeding. Historical evidence has demonstrated the relationship between immune system and intestinal Lactobacillus in FMD.

OBJECTIVE

We sought to elucidate the differences in the gut microbiota of healthy and bacterial pneumonia FMD.

METHODS

The bacterial pneumonia FMD was demonstrated by bacterial and pathological diagnosis, and the gut microbiome of healthy and bacterial pneumonia FMD was sequenced and analysed.

RESULTS

There are three pathogens (Pseudomonas aeruginosa, Streptococcus equinus and Trueperella pyogenes) isolated from the bacterial pneumonia FMD individuals. Compared with the healthy group, the abundance of Firmicutes and Proteobacteria in the pneumonia group was changed, and a high level of Proteobacteria was found in the pneumonia group. In addition, a higher abundance of Acinetobacter (p = 0.01) was observed in the population of the pneumonia group compared with the healthy group. Several potentially harmful bacteria and disease-related KEGG subsystems were only found in the gut of the bacterial pneumonia group. Analysis of KEGG revealed that many genes related to type IV secretion system, type IV pilus, lipopolysaccharide export system, HTH-type transcriptional regulator/antitoxin MqsA, and ArsR family transcriptional regulator were significantly enriched in the metagenome of the bacterial pneumonia FMD.

CONCLUSION

Our results demonstrated that the gut microbiome was significantly altered in the bacterial pneumonia group. Overall, our research improves the understanding of the potential role of the gut microbiota in the FMD bacterial pneumonia.

Viral metagenomics revealed diverse CRESS-DNA virus genomes in faeces of forest musk deer

Background

Musk deer can produce musk which has high medicinal value and is closely related to human health. Viruses in forest musk deer both threaten the health of forest musk deer and human beings.

Methods

Using viral metagenomics we investigated the virome in 85 faeces samples collected from forest musk deer.

Results

In this article, eight novel CRESS-DNA viruses were characterized, whole genomes were 2148 nt–3852 nt in length. Phylogenetic analysis indicated that some viral genomes were part of four different groups of CRESS-DNA virus belonging in the unclassified CRESS-DNA virus, Smacoviridae, pCPa-like virus and pPAPh2-like virus. UJSL001 (MN621482), UJSL003 (MN621469) and UJSL017 (MN621476) fall into the branch of unclassified CRESS-DNA virus (CRESSV1–2), UJSL002 (MN621468), UJSL004 (MN621481) and UJSL007 (MN621470) belong to the cluster of Smacoviridae, UJSL005 (MN604398) showing close relationship with pCPa-like (pCRESS4–8) clusters and UJSL006 (MN621480) clustered into the branch of pPAPh2-like (pCRESS9) virus, respectively.

Conclusion

The virome in faeces samples of forest musk deer from Chengdu, Sichuan province, China was revealed, which further characterized the diversity of viruses in forest musk deer intestinal tract.

Phenotypic and molecular characterization of antimicrobial resistance in Trueperella pyogenes strains isolated from bovine mastitis and metritis

Background

Trueperella pyogenes is one of the most clinically imperative bacteria responsible for severe cases of mastitis and metritis, particularly in postpartum dairy cows. The bacterium has emergence of antibiotic resistance and virulence characters. The existing research was done to apprise the phenotypic and genotypic evaluation of antibiotic resistance and characterization of virulence factors in the T. pyogenes bacteria of bovine mastitis and metritis in postpartum cows.

Methods

Two-hundred and twenty-six bovine mastitic milk and 172 uterine swabs were collected and transferred to laboratory. Samples were cultured and T. pyogenes isolates were subjected to disk diffusion and DNA extraction. Distribution of virulence and antibiotic resistance genes was studied by PCR.

Results

Thirty-two out of 226 (14.15%) mastitic milk and forty-one out of 172 (23.83%) uterine swab samples were positive for T. pyogenes. Isolates of mastitic milk harbored the highest prevalence of resistance toward gentamicin (100%), penicillin (100%), ampicillin (90.62%), amoxicillin (87.50%) and trimethoprim-sulfamethoxazole (87.50%), while those of metritis harbored the highest prevalence of resistance toward ampicillin (100%), amoxicillin (100%), gentamicin (97.56%), penicillin (97.56%) and cefalexin (97.56%). AacC, aadA1, aadA2 and tetW were the most generally perceived antibiotic resistance genes. All bacteria harbored plo (100%) and fimA (100%) virulence factors. NanP, nanH, fimC and fimE were also the most generally perceived virulence factors.

Conclusions

All bacteria harbored plo and fimA virulence factors which showed that they can use as specific genetic markers with their important roles in pathogenicity of T. pyogenes bacteria. Phenotypic pattern of antibiotic resistance was confirmed by genotypic characterization of antibiotic resistance genes.

INTERDIGITAL NECROBACILLOSIS ASSOCIATED WITH TRUEPERELLA PYOGENES IN GOITERED GAZELLES ( GAZELLA SUBGUTTUROSA)

  This study presents the clinical findings, treatment results, and gross pathology of Trueperella pyogenes-associated interdigital necrobacillosis in captive goitered gazelles ( Gazella subgutturosa). Four male and two female gazelles presented with weight loss, front limb swelling, and persistent lameness despite antibiotic treatment. The animals were reluctant to bear weight on the affected limbs, and the diagnosis of interdigital necrobacillosis was made based on physical exam, bacteriologic evaluation, and radiographic imaging. In all cases, the interdigital skin and subcutaneous tissues were affected in both forelimbs. Exungulation (loss of the hoof) occurred in one female gazelle. Despite aggressive topical and systemic treatment, the two female gazelles died. Gross pathology detected abscesses in the heart, lung, and liver. T. pyogenes was isolated as the major pathogen. This is the first report of interdigital necrobacillosis caused by T. pyogenes in Gazella subgutturosa.

MTOR involved in bacterial elimination against Trueperella pyogenes infection based on mice model by transcriptome and biochemical analysis

Trueperella pyogenes is an importantly opportunistic and commensal pathogen that causes suppurative lesions of most economically important livestock. To understand the molecular mechanism underlying the infection by T. pyogenes, we carried out a large-scale transcriptome sequencing of mice livers intraperitoneally infected with T. pyogenes using RNA-sequencing. A total of 47 G clean bases were obtained and 136 differentially expressed genes were detected between the control and the infection groups in the liver transcriptomes. Additionally, we found that the expression of a key autophagy regulator, mTOR (mechanistic target of rapamycin) was significantly up-regulated in the infection groups. Mechanistically, T. pyogenes infection induced the expression of mTOR and subsequently inhibited the autophagy of host cell. Blocking autophagy with inhibitor 3-methyladenine (3-MA) or silencing autophagy-related gene 7 (Atg7) reduced the effect of bacterial elimination. Interestingly, inhibition of mTOR induced autophagy and reduced T. pyogenes viability in RAW264.7 murine macrophages. The silencing mTOR regulated oxidation and cytokines (interleukin-1β, IL-6 and tumor necrosis factro-α) against T. pyogenes in macrophages and significantly protected mice from T. pyogenes challenge. These findings indicate that mTOR is a novel functional regulator in autophagy-mediated T. pyogenes elimination and will be useful to further knowledge on the development of effective therapeutic strategy to control T. pyogenes-related diseases.

Pathogenicity and Virulence of Trueperella pyogenes: A Review

Bacteria from the species Trueperella pyogenes are a part of the biota of skin and mucous membranes of the upper respiratory, gastrointestinal, or urogenital tracts of animals, but also, opportunistic pathogens. T. pyogenes causes a variety of purulent infections, such as metritis, mastitis, pneumonia, and abscesses, which, in livestock breeding, generate significant economic losses. Although this species has been known for a long time, many questions concerning the mechanisms of infection pathogenesis, as well as reservoirs and routes of transmission of bacteria, remain poorly understood. Pyolysin is a major known virulence factor of T. pyogenes that belongs to the family of cholesterol-dependent cytolysins. Its cytolytic activity is associated with transmembrane pore formation. Other putative virulence factors, including neuraminidases, extracellular matrix-binding proteins, fimbriae, and biofilm formation ability, contribute to the adhesion and colonization of the host tissues. However, data about the pathogen–host interactions that may be involved in the development of T. pyogenes infection are still limited. The aim of this review is to present the current knowledge about the pathogenic potential and virulence of T. pyogenes.

A T4virus prevents biofilm formation by Trueperella pyogenes

Trueperella pyogenes is an opportunistic pathogen of many animal species. It causes economic losses worldwide, through mastitis, metritis and mainly endometritis in dairy cows. The ability of this bacterium to form biofilms is implicated in chronic infections through hampering immune system recognition and antibiotic penetration. Since it is difficult to eradicate T. pyogenes infections with antibiotics, phage therapy presents itself as a non-toxic, effective and economically viable alternative. The present study evaluated the use of the bacteriophage vB_EcoM-UFV13 (UFV13) in the prevention of T. pyogenes biofilm development. Based upon two different approaches (crystal violet and sessile cell counting) we observed that only a multiplicity of infection (MOI) of 10 showed a statistically significant reduction in biofilm formation. Although the exact mechanisms of biofilm disruption and cell-adhesion inhibition have not been determined, genome sequence analysis of the Escherichia phage UFV13 revealed a repertoire of virion-associated peptidoglycan hydrolases (VAPGHs). The present study presents new findings regarding the disruption of biofilm formation of a Gram-positive bacterium. Subsequent transcriptomic and proteomic research will help us to understand the exact interaction mechanisms between UFV13 and T. pyogenes.

Chitosan-DNA nanoparticles enhanced the immunogenicity of multivalent DNA vaccination on mice against Trueperella pyogenes infection

BACKGROUND

Trueperella pyogenes is a commensal and opportunistic pathogen that normally causes mastitis, liver abscesses and pneumonia of economically important livestock. To develop efficacious and potent vaccine against T. pyogenes, chimeric gene DNA vaccines were constructed and encapsulated in chitosan nanoparticles (pPCFN-CpG-CS-NPs).

RESULTS

The pPCFN-CpG-CS-NPs consists of the plo, cbpA, fimA, and nanH gene of T. pyogenes and CpG ODN1826. It was produced with good morphology, high stability, a mean diameter of 93.58 nm, and a zeta potential of + 5.27 mV. Additionally, chitosan encapsulation was confirmed to protect the DNA plasmid from DNase I digestion. The immunofluorescence assay indicated that the four-chimeric gene could synchronously express in HEK293T cells and maintain good bioactivity. Compared to the mice immunized with the control plasmid, in vivo immunization showed that mice immunized with the pPCFN-CpG-CS-NPs had better immune responses, and release of the plasmid DNA was prolonged. Importantly, immunization with pPCFN-CpG-CS-NPs could significantly protect mice from highly virulent T. pyogenes TP7 infection.

CONCLUSIONS

This study indicates that chitosan-DNA nanoparticles are potent immunization candidates against T. pyogenes infection and provides strategies for the further development of novel vaccines encapsulated in chitosan nanoparticles.

Quorum-sensing molecules N-acyl homoserine lactones inhibit Trueperella pyogenes infection in mouse model

Trueperella pyogenes is a gram-positive opportunistic pathogen normally causes mastitis, liver abscesses and pneumonia of economically important livestock. It has been suggested that gram-negative bacteria can suppress the growth and virulence of T. pyogenes in vitro by using the quorum-sensing (QS) signal molecules and cause the transition of predominant species. However, whether these QS signals can be used as potential anti-virulence drugs against T. pyogenes infection is unclear. In this study, the in vivo inhibitory effect N-acyl homoserine lactones (AHLs) from Escherichia coli and Pseudomonas aeruginosa on T. pyogenes was tested by using mouse model. Mice were first peritoneally infected with T. pyogenes followed by intravenous injection of N-Octanoyl-DL-homoserine lactone (C8HSL) or N-(3-oxododecanoyl) homoserine-l-lactone (C12HSL). The results showed that C8HSL and C12HSL significantly reduced bacterial load and increased the survival rate of mice against T. pyogenes challenge. Additionally, the treatment of AHLs promoted the secretion of IL-1β, IL-6, IL-8 and TNF-α in mouse peritoneal fluid, and significantly decreased the expression levels of virulence genes of residual T. pyogenes. Importantly, murine macrophages rapidly phagocytosed bacteria when they were treated with AHLs compared to untreated cells. Collectively, our findings provide a major advance in understanding the inhibitory effect of AHLs in vivo and a promise for developing new clinical or veterinary treatments of T. pyogenes-related infection.

Fatal infection in three Grey Slender Lorises (Loris lydekkerianus nordicus) caused by clonally related Trueperella pyogenes

Background

Trueperella pyogenes is a worldwide known bacterium causing mastitis, abortion and various other pyogenic infections in domestic animals like ruminants and pigs. In this study we represent the first case report of three unusual fatal infections of Grey Slender Lorises caused by Trueperella pyogenes. Meanwhile, this study represents the first in-depth description of the multilocus sequence analysis (MLSA) on T. pyogenes species.

Case presentation

Three Trueperella pyogenes were isolated from three different Grey Slender Lorises, which died within a period of two years at Frankfurt Zoo (Frankfurt am Main - Germany). The three Grey Slender Loris cases were suffering from severe sepsis and died from its complication. During the bacteriological investigation of the three cases, the T. pyogenes were isolated from different organisms in each case. The epidemiological relationship between the three isolates could be shown by four genomic DNA fingerprint methods (ERIC-PCR, BOX-PCR, (GTG)₅-PCR, and RAPD-PCR) and by multilocus sequence analysis (MLSA) investigating four different housekeeping genes (fusA-tuf-metG-gyrA).

Conclusion

In this study, we clearly showed by means of using three different rep-PCRs, by RAPD-PCR and by MLSA that the genomic fingerprinting of the investigated three T. pyogenes have the same clonal origin and are genetically identical. These results suggest that the same isolate contaminated the animal’s facility and subsequently caused cross infection between the three different Grey Slender Lorises. To the best of our knowledge, this is the first epidemiological approach concentrating on T. pyogenes using MLSA.

Trueperella pyogenes isolated from a brain abscess of an adult roebuck (Capreolus capreolus)

The present study was designed to characterize phenotypically and genotypically a Trueperella pyogenes strain isolated from a brain abscess of an adult roebuck (Capreolus capreolus). The species identity could be confirmed by phenotypical investigations, by MALDI-TOF MS analysis, and by sequencing the 16S ribosomal RNA (rRNA) gene, the 16S-23S rRNA intergenic spacer region (ISR); by sequencing the target genes rpoB, gap, and tuf; and by detection of T. pyogenes chaperonin-encoding gene cpn60 with a previously developed loop-mediated isothermal amplification (LAMP) assay. The T. pyogenes strain could additionally be characterized by PCR-mediated amplification of several known and putative virulence factor-encoding genes which revealed the presence of the genes plo encoding pyolysin and nanH and nanP encoding neuraminidases; the genes fimA, fimC, and fimE encoding the fimbrial subunits FimA, FimC, and FimE; and the gene cbpA encoding collagen-binding protein CbpA. The present data give a detailed characterization of a T. pyogenes strain isolated from a brain abscess of a roebuck. However, the route of infection of the roebuck remains unclear.

Characterization of porcine Trueperella pyogenes by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), molecular typing and antimicrobial susceptibility profiling in Sao Paulo State

Trueperella pyogenes can be found as a commensal or pathogenic bacterium among animals causing a variety of pyogenic infections in several species. The agent appears to act primarily as an opportunistic pathogen but may disseminate and produce metastatic abscesses accompanied or not by mastitis, metritis or pneumonia. In this study, 30 porcine T. pyogenes strains were identified by MALDI-TOF MS and 16S rRNA sequencing and further evaluated in relation to their resistance and genetic profiles through broth microdilution and single enzyme AFLP. All strains were susceptible to β-lactams, florfenicol, gentamicin, spectinomycin and tiamulin. The highest resistance rates were observed for sulfonamides, tetracyclines and clindamycin. All isolates could be characterized by SE-AFLP presenting more than 80% of similarity, despite their distinct origins. Four genotypes were detected with the segregation of T. pyogenes ATCC 19411 from Brazilian T. pyogenes strains. No correlation between genotypes and isolates origins and susceptibility profile was observed.

Relationships between antimicrobial resistance, distribution of virulence factor genes and the origin of Trueperella pyogenes isolated from domestic animals and European bison (Bison bonasus)

Trueperella pyogenes is an opportunistic pathogen causing suppurative infections in livestock and wild animals. Although this bacterium is known for a long time, our knowledge about its pathogenicity is still insufficient. In this study the relationships between antimicrobial resistance profiles, distribution of virulence factor genes and the origin of T. pyogenes isolates were investigated. Isolates (n = 97) from various infections in domestic animals and European bison were studied. Minimal inhibitory concentrations of 12 antimicrobials were determined by a strip diffusion method, and PCR was used for detection of genes encoding seven putative virulence factors. All strains were susceptible to tested beta-lactams, and a statistically significant correlation between the resistance to enrofloxacin, tetracycline, macrolides, clindamycin, and a strain origin was found. The isolates from European bison were more susceptible than those from livestock, however the resistance to tetracycline and fluoroquinolones was observed. The plo and fimA genes were detected in all strains. There was no statistically significant association between the distribution of particular virulence factor genes and the type of infection, but the nanH, nanP and fimG genes were less frequently found in the isolates from European bison. The presence of three genes, nanP, nanH and cbpA, was found to be related to the resistance to tetracycline and ciprofloxacin. In conclusion, the resistance patterns of T. pyogenes were correlated with an isolate origin, but our findings did not allow to indicate which of the putative virulence factors may play a crucial role in the pathogenesis of particular types of T. pyogenes infection.

DNA vaccination based on pyolysin co-immunized with IL-1β enhances host antibacterial immunity against Trueperella pyogenes infection

Trueperella pyogenes is a commensal and opportunistic pathogen normally causes mastitis, liver abscesses and pneumonia of economically important livestock. To date, no specific control measure was reported to prevent T. pyogenes infections. In this study, we first constructed a recombinant plasmid pVAX1-PLO based on the main virulent factor pyolysin gene as DNA vaccine against T. pyogenes infection. Subsequently, transient expression of pVAX1-PLO and pcDNA3.1/V5-fIL-1β were identified in Human embryonic kidney cells (HEK293T) by immunofluorescence assay. Humoral and cellular immune responses were evaluated in mice to compare the immunogenicity between different immunized groups. The results showed that the successful expression of PLO or fIL-1β protein was detected by confocal microscopy for cells transfected with plasmid pVAX1-PLO and/or pcDNA3.1/V5-fIL-1β. The mice immunized with pVAX1-PLO elicited a higher titer of PLO-specific antibody than the control group. The levels of IFN-γ and IL-2 were significantly increased in the pVAX1-PLO immunized mice, while the expression level of IL-4 was slightly increased but not significant. These findings suggested that the DNA vaccine pVAX1-PLO can primarily induce Th1 immune response. The residual Colony-Forming Units (CFUs) from the liver and peritoneal fluid were decreased obviously in the pVAX1-PLO treated mice compared with the control. Importantly, co-immunization with pcDNA3.1/V5-fIL-1β and pVAX1-PLO could enhance host humoral and cellular immune responses and significantly protect mouse from T. pyogenes infection. In conclusion, our study provides a promising strategy against T. pyogenes infections and implies the potential clinical application of combined DNA vaccines in diseases control.

Isolation and genotypic characterization of Trueperella (Arcanobacterium) pyogenes recovered from active cranial abscess infections of male white-tailed deer (Odocoileus virginianus)

Trueperella (Arcanobacterium) pyogenes is a causative agent of suppurative infections in domestic and wild animals. In some populations of captive or free-ranging white-tailed deer (Odocoileus virginianus), cranial abscess disease is an important source of mortality in adult males. Although the pathogenesis of this disease is poorly understood, T. pyogenes has been isolated from active infections with other opportunistic bacteria. In this study, bacteria associated with cranial abscess infections were identified, the prevalence of T. pyogenes associated with these infections was determined, and the presence of known virulence determinants in T. pyogenes isolates was ascertained. Using routine biochemical techniques seven bacterial species were identified from 65 samples taken from active cranial abscess infections of 65 male white-tailed deer. Trueperellapyogenes was recovered from 46 samples; in 32 samples it was the only bacterium species detected. Staphylococcus aureus was detected in 26 samples. From these samples, the presence of known and putative virulence genes of T. pyogenes--plo, nanH, nanP, cbpA, fimA, fimC, fimE, and fimG--was examined by conventional polymerase chain reaction. All T. pyogenes isolates were positive for the pyolysin genes plo, nanP, and fimA. Furthermore, nanH, fimA, fimC, and fimE were detected in over 70% of isolates. Of the isolates tested, 48% had genotypes containing all virulence genes except cbpA. The suggestive virulence potential of all isolates, coupled with the large number of pure cultures obtained, implies that T. pyogenes is a causative agent of cranial abscess disease.

Complete Genome Sequence of Trueperella pyogenes, an Important Opportunistic Pathogen of Livestock

Here, we report the complete genome sequence of Trueperella pyogenes TP6375, a strain isolated from the uterus of a dairy cow affected with metritis. The complete circular genome is 2,338,390 bp and contains several genes needed for pathogenicity.