Altered Nasal Microbiota Composition Associated with Development of Polyserositis by Mycoplasma hyorhinis

Fibrinous polyserositis in swine farming is a common pathological finding in nursery animals. The differential diagnosis of this finding should include Glaesserella parasuis (aetiological agent of Glässer’s disease) and Mycoplasma hyorhinis, among others. These microorganisms are early colonizers of the upper respiratory tract of piglets. The composition of the nasal microbiota at weaning was shown to constitute a predisposing factor for the development of Glässer’s disease. Here, we unravel the role of the nasal microbiota in the subsequent systemic infection by M. hyorhinis, and the similarities and differences with Glässer’s disease. Nasal samples from farms with recurrent problems with polyserositis associated with M. hyorhinis (MH) or Glässer’s disease (GD) were included in this study, together with healthy control farms (HC). Nasal swabs were taken from piglets in MH farms at weaning, before the onset of the clinical outbreaks, and were submitted to 16S rRNA gene amplicon sequencing (V3–V4 region). These sequences were analyzed together with sequences from similar samples previously obtained in GD and HC farms. Animals from farms with disease (MH and GD) had a nasal microbiota with lower diversity than those from the HC farms. However, the composition of the nasal microbiota of the piglets from these disease farms was different, suggesting that divergent microbiota imbalances may predispose the animals to the two systemic infections. We also found variants of the pathogens that were associated with the farms with the corresponding disease, highlighting the importance of studying the microbiome at strain-level resolution.

Outbreak of peracute Glässer’s disease in suckling piglets in a self-recruiting high health farrow to grower herd: A Case report

BackgroundGlässer’s disease is caused by a bacterial infection where the causative agent is Glaesserella parasuis and is of rising concern in Norwegian high health pig herds. Different factors can trigger the onset of Glässer’s disease, including management practices such as unstable room temperature, poor ventilation or impaired immunity. Outbreaks of peracute Glässer’s disease in suckling piglets are rarely described. Case presentationIn a high health, farrow to grower pig herd 270 suckling piglets out of 920 died in a peracute to acute manner during a 20-day period. Post-mortem examinations revealed findings consistent with congestion and oedema and histopathological examination found no signs of inflammation or intravascular microthrombi. Bacteriological examination detected G. parasuis in relevant tissues. Emesis in half of the piglets and central nervous signs in a few was found after first intramuscular injection of procaine penicillin. Anaemia, poor temperature regulation in the farrowing unit and poor hygiene were factors contributing to the disease outbreak.ConclusionsIn the present case, it was concluded that an outbreak with high mortality and predominantly peracute to acute clinical disease in 3-5 week old suckling piglets was caused by Glässer’s disease (G. parasuis).

Glässer’s disease in swine from Northeastern Brazil

ABSTRACT: Glässer’s disease is an important infectious disorder of swine caused by Haemophilus parasuis. Although well recognized in most regions of Brazil, outbreaks of Glässer’s disease have not been described in Northeastern region. For this reason, three municipalities of the Pernambuco State were visited in order to identify histories of high mortality in growing and finishing pigs. The main clinical signs consisted of dry cough, apathy, fever, anorexia, paresis, muscle tremors, motor incoordination, seizures leading to high mortality rates. Nine pigs were necropsied, and fragments of the nervous system, organs of the abdominal and thoracic cavities were collected for histological analysis. In addition, lung and brain fragments were used for DNA extraction and molecular testing by real-time Polymerase Chain Reaction (PCR). Grossly, the main lesions consisted of petechial hemorrhages or ecchymosis on the skin of the face, abdomen, forelimbs, and hind limbs. The main severe lesions consisted of hydropericardium, hemopericardium, fibrinous pericarditis and pleuropneumonia. Microscopically, pericarditis, epicarditis and subepicardial myocarditis, followed by a moderate to severe multifocal pleuropneumonia, fibrinosuppurative and necrotizing were the most frequent lesions observed. Real-time PCR amplified H. parasuis infB gene in all samples analyzed, confirming the presence of this etiologic agent.

Development and application of an antibody detection ELISA for Haemophilus parasuis based on a monomeric autotransporter passenger domain

Background Haemophilus parasuis is a commensal pathogen in the swine upper respiratory tract and causes Glässer’s disease. Surveillance, screening for infection, and vaccination response of H. parasuis is hindered by the lack of a rapid antibody detection method. Results In the present study, a monomeric autotransporter was identified as a novel antigen for developing an indirect ELISA. The autotransporter passenger domain (Apd) was expressed, purified, and demonstrated to be specific in ELISA and western blotting. Mouse antiserum of recombinant Apd (rApd) recognized native Apd in the 15 serotype reference strains and five non-typeable isolate stains, but showed no reaction with seven other bacterial pathogens. The rApd ELISA was optimized and validated using 67 serum samples with known background, including 27 positive sera from experimentally infected and vaccinated pigs along with 40 negative sera that had been screened with H. parasuis whole cell ELISA from clinically healthy herds. The rApd ELISA provided positive and negative percent agreements of 96.4 and 94.9%, respectively, and an AUC value of 0.961, indicating that the assay produced accurate results. Conclusion Apd was a universal antigen component among 15 serotype and non-typeable strains of H. parasuis and was also specific to this pathogen. The rApd ELISA could detect antibodies elicited by H. parasuis infection and vaccination, thereby exhibiting the potential to be applied for Glässer’s disease diagnosis, H. parasuis vaccination evaluation, and large-scale serological surveillance.

Molecular serotyping of clinical strains ofHaemophilus (Glaesserella) parasuisbrings new insights regarding Glässer’s disease outbreaks in Brazil

Glässer’s disease (GD) is an important infectious disease of swine caused byHaemophilus (Glaesserella) parasuis. Vaccination with inactivated whole cell vaccines is the major approach for prevention ofH. parasuisinfection worldwide, but the immunity induced is predominantly against the specific polysaccharide capsule. As a consequence, the available vaccines may not induce adequate protection against the field strains, when the capsules present in the vaccine strains are different from those in strains isolated from the farms. Therefore, it is crucial to mapH. parasuisserovars associated with regional outbreaks so that appropriate bacterin vaccines can be developed and distributed for prevention of infection. In this study, 459H. parasuisfield strains isolated from different Glässer’s disease outbreaks that occurred in 10 different Brazilian States were analyzed for serotype using PCR-based approaches. Surprisingly, non-typeable (NT) strains were the second most prevalent group of field strains and along with serovars 4, 5 and 1 comprised more than 70% of the isolates. A PCR-based approach designed to amplify the entire polysaccharide capsule locus revealed 9 different band patterns in the NT strains, and 75% of the NT strains belonged to three clusters, suggesting that a number of new serovars are responsible for a substantial proportion of disease. These results indicate that commercially available vaccines in Brazil do not cover the most prevalentH. parasuisserovars associated with GD.

Antimicrobial susceptibility of porcine bacterial pathogens

A retrospective review of antimicrobial susceptibility to the fluoroquinolones and potentiated sulfonamides of 120 isolates of the most typical porcine bacterial pathogens isolated from animals of different age groups from 2009 to 2019 at FGBI «ARRIAH» was carried out. According to the results, P. multocida, H. parasuis are highly susceptible to enrofloxacin, which can be used for empirical treatment of pasteurellosis and Glasser's disease. A. pleuropneumoniae and S. suis are also susceptible to enrofloxacin, so it can be recommended for the treatment of A. pleuropneumonia and streptococcosis. 50% of isolates of S. suis isolated from the brain tissues are susceptible to the potentiated sulfonamides, so this medication can be recommended for the treatment of streptococcosis only after susceptibility testing.

Molecular serotyping ofHaemophilus parasuisisolated from diseased pigs and the relationship between serovars and pathological patterns in Taiwan

BackgroundHaemophilus parasuisis the etiological agent of Glässer’s disease, and causes severe economic losses in the swine industry. Serovar classification is intended as an indicator of virulence and pathotype and is also crucial for vaccination programs and vaccine development. According to a polysaccharide biosynthesis locus analysis,H. parasuisisolates could be classified by a molecular serotyping assay except serovars 5 and 12 detected by the same primer pair. The aim of this study was to identifyH. parasuisisolates from diseased pigs in Taiwan by using a molecular serotyping assay and to analyze the relationship between serovars and pathological patterns.MethodsFrom August 2013 to February 2017, a total of 133 isolates from 277 lesions on 155 diseased animals from 124 infected herds serotyped by multiplex PCR and analyzed with pathological data.ResultsThe dominant serovars ofH. parasuisin Taiwan were serovars 5/12 (37.6%), 4 (27.8%) and 13 (15%) followed by molecular serotyping non-typable (MSNT) isolates (13.5%). Nevertheless, the serovar-specific amplicons were not precisely the same sizes as previously indicated in the original publication, and MSNT isolates appeared with unexpected amplicons or lacked serovar-specific amplicons. MostH. parasuisisolates were isolated from nursery pigs infected with porcine reproductive and respiratory syndrome virus. The percentage of lung lesions (30.4%) showingH. parasuisinfection was significantly higher than that of serosal lesions.DiscussionCollectively, the distribution of serovars in Taiwan is similar to that found in other countries, but MSNT isolates remain due to genetic variations. Furthermore, pulmonary lesions may be optimum sites forH. parasuisisolation, the diagnosis of Glässer’s disease, and may also serve as points of origin for systemicH. parasuisinfections in hosts.