Serovar profiling of <i>Haemophilus parasuis</i> on Australian farms by sampling live pigs

Turni, Conny; Blackall, P. J.

doi:10.1111/j.1751-0813.2010.00592.x

Cited by 29 publications

(34 citation statements)

References 11 publications

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“…The site of isolation is also very important, as isolates cultured from the joints or from meninges have survived serum killing and phagocytosis and so are highly likely to be virulent; however, if samples are taken from the upper respiratory tract or the lung, there is a higher chance of the isolate being part of a coinfection rather than the isolate responsible for the disease. This might well introduce sampling bias, and the relative proportions of different serovars among isolates actively causing disease and carriage isolates in pig populations may vary from the commonly reported serovars 4, 5, and 13 (24)(25)(26)(27).…”

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“…The current serotyping scheme, based on reactions between antisera and surface antigens, classifies the bacteria into 15 serovars, with a considerable number of nontypeable (NT) isolates observed (22,23). Most commonly isolated from the field are serovars 4, 5, and 13 (24)(25)(26)(27). However, isolates are collected predominantly from severely affected individuals or clinical cases from within a herd, with only a single colony studied from those cultured from a swab.…”

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“…However, isolates are collected predominantly from severely affected individuals or clinical cases from within a herd, with only a single colony studied from those cultured from a swab. As multiple infections of the same individual and within herds can occur (25,(27)(28)(29), there may be additional isolates that contribute to disease in animals that are not commonly investigated. The site of isolation is also very important, as isolates cultured from the joints or from meninges have survived serum killing and phagocytosis and so are highly likely to be virulent; however, if samples are taken from the upper respiratory tract or the lung, there is a higher chance of the isolate being part of a coinfection rather than the isolate responsible for the disease.…”

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Development of a Multiplex PCR Assay for Rapid Molecular Serotyping of Haemophilus parasuis

et al. 2015

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iHaemophilus parasuis causes Glässer's disease and pneumonia in pigs. Indirect hemagglutination (IHA) is typically used to serotype this bacterium, distinguishing 15 serovars with some nontypeable isolates. The capsule loci of the 15 reference strains have been annotated, and significant genetic variation was identified between serovars, with the exception of serovars 5 and 12. A capsule locus and in silico serovar were identified for all but two nontypeable isolates in our collection of >200 isolates. Here, we describe the development of a multiplex PCR, based on variation within the capsule loci of the 15 serovars of H. parasuis, for rapid molecular serotyping. The multiplex PCR (mPCR) distinguished between all previously described serovars except 5 and 12, which were detected by the same pair of primers. The detection limit of the mPCR was 4.29 ؋ 10 5 ng/l bacterial genomic DNA, and high specificity was indicated by the absence of reactivity against closely related commensal Pasteurellaceae and other bacterial pathogens of pigs. A subset of 150 isolates from a previously sequenced H. parasuis collection was used to validate the mPCR with 100% accuracy compared to the in silico results. In addition, the two in silico-nontypeable isolates were typeable using the mPCR. A further 84 isolates were analyzed by mPCR and compared to the IHA serotyping results with 90% concordance (excluding those that were nontypeable by IHA). The mPCR was faster, more sensitive, and more specific than IHA, enabling the differentiation of 14 of the 15 serovars of H. parasuis. Haemophilus parasuis is a Gram-negative bacterium commonly found in the upper respiratory tract of the pig, and it was identified in 1910 as the causative agent of a globally prevalent systemic disease of pigs known as Glässer's disease. The more severe presentations of this disease include arthritis, meningitis, polyserositis, septicemia, and pneumonia (1-5). Based on statistics from the United States, H. parasuis is the leading cause of mortality (alongside the porcine reproductive and respiratory syndrome [PRRS] virus) in nursery herds, and it is the third most important bacterial pathogen affecting finisher herds (6). H. parasuis also contributes to a multifactorial porcine respiratory disease complex, the leading cause of mortality in grower-finisher pigs in the United States (7). Diagnostic submissions to veterinary investigation centers of the Animal and Plant Health Agency (APHA) in 2013 and 2014 recorded the highest annual rates of diagnosis of disease incidents due to H. parasuis in England and Wales since 2002 (8, 9). In the third quarter of 2013, the diagnostic rate reached nearly 8% of diagnosable submissions (8,9). This disease characteristically manifests postweaning and is associated with the loss of maternally derived antibodies and the endemic presence of the bacterium in herds (1, 5).Treatment and prevention of Glässer's disease are implemented via strategic delivery of penicillin-based antimicrobials in feed or water. Ongoing treatment may be...

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Development of a Multiplex PCR Assay for Rapid Molecular Serotyping of Haemophilus parasuis

et al. 2015

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“…Low detection rates and difficulties diagnosing H. parasuis have been previously reported. 20,21 Only limited information is available on the virulence determinants of H. parasuis. 4,15 A recent report suggested the existence of a putative hemolysin gene operon hhdBA, which has been found only in virulent reference serovars and could be a novel virulence factor for H. parasuis.…”

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“…1,14 An improved sensitivity of PCR over bacterial culture has been reported when using the newly developed real-time PCR. 21 The fact that H. parasuis is a commensal bacterium, found in the upper respiratory tract of clinical healthy pigs, 20 restricts the use of the 16S rRNA PCR as a diagnostic tool. 24 trimeric autotransporters, 15 and outer membrane proteins.…”

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Detection of a putative hemolysin operon, hhdBA, of Haemophilus parasuis from pigs with Glässer disease

Assavacheep

Turni

2012

J VET Diagn Invest

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The aim of the current study was to investigate whether polymerase chain reaction amplification of 16S ribosomal (r)RNA and a putative hemolysin gene operon, hhdBA, can be used to monitor live pigs for the presence of Haemophilus parasuis and predict the virulence of the strains present. Nasal cavity swabs were taken from 30 live, healthy, 1- to 8-week-old pigs on a weekly cycle from a commercial Thai nursery pig herd. A total of 27 of these pigs (90%) tested positive for H. parasuis as early as week 1 of age. None of the H. parasuis–positive samples from healthy pigs was positive for the hhdBA genes. At the same pig nursery, swab samples from nasal cavity, tonsil, trachea, and lung, and exudate samples from pleural/peritoneal cavity were taken from 30 dead pigs displaying typical pathological lesions consistent with Glässer disease. Twenty-two of 140 samples (15.7%) taken from 30 diseased pigs yielded a positive result for H. parasuis. Samples from the exudate (27%) yielded the most positive results, followed by lung, tracheal swab, tonsil, and nasal swab, respectively. Out of 22 positive samples, 12 samples (54.5%) harbored hhdA and/or hhdB genes. Detection rates of hhdA were higher than hhdB. None of the H. parasuis–positive samples taken from nasal cavity of diseased pigs tested positive for hhdBA genes. More work is required to determine if the detection of hhdBA genes is useful for identifying the virulence potential of H. parasuis field isolates.

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Glässer's Disease

Aragón¹,

Segalés²,

Tucker³

2019

Diseases of Swine

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Serovar profiling of Haemophilus parasuis on Australian farms by sampling live pigs

Abstract: Healthy pigs contain a range of Hps serovars, even on farms free of Glässer's disease. Nasal swabbing of both healthy and sick pigs seems a useful method of serovar profiling of farms.

Cited by 29 publications

References 11 publications

Development of a Multiplex PCR Assay for Rapid Molecular Serotyping of Haemophilus parasuis

Development of a Multiplex PCR Assay for Rapid Molecular Serotyping of Haemophilus parasuis

Detection of a putative hemolysin operon, hhdBA, of Haemophilus parasuis from pigs with Glässer disease

Glässer's Disease

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