Genotypic Diversity of
            <i>Haemophilus parasuis</i>
            Field Strains

Olvera, Àlex; Calsamiglia, María; Aragón, Virginia

doi:10.1128/aem.02834-05

Cited by 38 publications

(47 citation statements)

References 39 publications

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“…The majority of them are fingerprinting methods, and, even though the reported techniques have a higher level of discrimination than serotyping, they present application problems, such as limited resolution (de la Puente-Redondo et al, del Rio et al, 2006) or difficulty in comparing results from different laboratories (Rafiee et al, 2000;Smart et al, 1988). To improve the epidemiological study of H. parasuis strains, a single-locus sequence typing method was recently used by our group (Olvera et al, 2006). The heterogeneity of H. parasuis field isolates was confirmed by hsp60 partial sequencing, but although a virulent cluster was detected, the classification of the strains was not satisfactory.…”

Section: Introductionmentioning

confidence: 99%

Study of the population structure of Haemophilus parasuis by multilocus sequence typing

2006

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Haemophilus parasuis is the aetiological agent of Glä sser's disease in swine. In addition, this bacterium causes other clinical outcomes and can also be isolated from the upper respiratory tract of healthy pigs. Isolates of H. parasuis differ in phenotypic features (e.g. protein profiles, colony morphology or capsule production) and pathogenic capacity. Differences among strains have also been demonstrated at the genetic level. Several typing methods have been used to classify H. parasuis field strains, but they had resolution or implementation problems. To overcome these limitations, a multilocus sequence typing (MLST) system, using partial sequences of the house-keeping genes mdh, 6pgd, atpD, g3pd, frdB, infB and rpoB, was developed. Eleven reference strains and 120 field strains were included in this study. The number of alleles per locus ranged from 14 to 41, 6pgd being the locus with the highest diversity. The high genetic heterogeneity of this bacterium was confirmed with MLST, since the strains were divided into 109 sequence types, and only 13 small clonal complexes were detected by the Burst algorithm. Further analysis by unweighted-pair group method with arithmetic mean (UPGMA) identified six clusters. When the clinical background of the isolates was examined, one cluster was statistically associated with nasal isolation (putative non-virulent), while another cluster showed a significant association with isolation from clinical lesions (putative virulent). The remaining clusters did not show a statistical association with the clinical background of the isolates. Finally, although recombination among H. parasuis strains was detected, two divergent branches were found when a neighbour-joining tree was constructed with the concatenated sequences. Interestingly, one branch included almost all isolates of the putative virulent UPGMA cluster. INTRODUCTIONHaemophilus parasuis is a member of the family Pasteurellaceae and the causative agent of Glässer's disease in pigs, which is pathologically characterized by fibrinous to fibrinopurulent polyserositis and polyarthritis (RappGabrielson et al., 2006). In addition to Glässer's disease, H. parasuis produces other clinical outcomes, such as pneumonia, and colonizes the upper respiratory tract of healthy animals (Rapp-Gabrielson et al., 2006). Although it is commonly accepted that one strain is responsible for each clinical outbreak, diagnosis of H. parasuis infection is complicated by the fact that it is usual to detect several strains in a farm and even within a single animal. Therefore, it is essential to determine the causative strain by its isolation from organs with the characteristic lesions of the disease.Differences among strains in phenotypic and genotypic characteristics have been reported, although no clear association with virulence could be determined (Oliveira & Pijoan, 2004;Rapp-Gabrielson et al., 2006). However, several studies have confirmed that different strains of H. parasuis have different pathogenic capacity (Kielstein & Rapp-Gabrielson, 199...

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Section: Introductionmentioning

confidence: 99%

Study of the population structure of Haemophilus parasuis by multilocus sequence typing

2006

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“…Embora esse método seja relativamente útil para caracterização de cepas e preparo de vacinas, não é discriminativo o bastante para epidemiologia (OLVERA et al, 2006a). Importante levar em consideração que é possível e normal isolar mais de um sorotipo do mesmo rebanho e até de um mesmo animal (SMART et al, 1988).…”

Section: Sorotiposunclassified

“…De acordo com outros autores (SMART et al, 1988;OLIVEIRA et al, 2003;OLVERA et al, 2006a), os resultados de OLVERA et al (2006b) confirmam que várias amostras (entre uma e cinco) podem circular em uma granja. Além disso, diferentes amostras podem ser isoladas do mesmo animal, até mesmo da mesma lesão sistêmica, o que indica que mais de uma amostra pode estar envolvida em um surto da doença.…”

Section: Restriction Fragment Length Polymorphism (Pcr-rflp)unclassified

Epidemiologia molecular de Haemophilus parasuis

et al. 2009

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“…Single-locus sequence typing (SLST) applications is the sequence analysis of a single gene with sufficient sequence variations for typing bacterial isolates (Beall et al, 1996;Frenay et al, 1996;Olvera et al, 2006;Bennett et al, 2007). Typing the polymorphic X region of the staphylo- …”

Section: Single-locus Sequence Typing (Slst)mentioning

confidence: 99%

Molecular typing of bacteria for epidemiological surveillance and outbreak investigation / Molekulare Typisierung von Bakterien für die epidemiologische Überwachung und Ausbruchsabklärung

Ruppitsch

2016

Die Bodenkultur: Journal of Land Management, Food and Environment

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SummaryConstant confrontations with microbial threats pose major challenges to human and animal health, agricultural and food production, and public safety. Identifying pathogenic bacteria (species) and tracking strains (by series of well-characterized isolates) to their sources are especially important in outbreak investigations. Compared to the identification of the species, the identification of the source and spread of microbial infections represents a major-and many times futile-challenge. This is due to the multitude of ways microorganisms can occur and spread within healthcare facilities and in the community; how, when, and where they can contaminate the complex nutrition chain, leading to natural and man-made outbreaks. Typing is the characterization of isolates or strains below species or subspecies level. Typing of bacterial isolates is an essential procedure to identify the microbe causing the illness or to track down an outbreak to the suspected source. In the genomic era, the introduction of molecular methods has largely replaced phenotypic methods and "molecular epidemiology" has emerged as a new discipline. The current molecular typing methods can be classified into three categories: (a) PCR-based methods, (b) DNA fragment analysis-based methods, and (c) DNA sequence-based methods, including the new exciting era of high-throughput genome sequencing. Keywords

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Genotypic Diversity of Haemophilus parasuis Field Strains

Cited by 38 publications

References 39 publications

Study of the population structure of Haemophilus parasuis by multilocus sequence typing

Study of the population structure of Haemophilus parasuis by multilocus sequence typing

Epidemiologia molecular de Haemophilus parasuis

Molecular typing of bacteria for epidemiological surveillance and outbreak investigation / Molekulare Typisierung von Bakterien für die epidemiologische Überwachung und Ausbruchsabklärung

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