Streptococcus suis: occurrence, identification and characteristics in Swedish pigs

Anna Werinder

Streptococcus suis: occurrence, identification and characteristics in Swedish pigs

Bidragets översatta titel: Streptococcus suis – studier av bakteriens egenskaper, dess diagnostik och förekomst hos svenska grisar

Anna Werinder

Publikation: Avhandling › Doktorsavhandling

4 Nedladdningar

Sammanfattning

Streptococcus suis är ett av de viktigaste bakteriella smittämnena inom grisproduktionen världen över, och bakterien har också en zoonotisk potential. Syftet med den här avhandlingen var att fördjupa kunskapen om bakteriens egenskaper och dess förekomst hos svenska grisar. Prover togs från tonsiller på friska grisar, från obducerade grisar med meningit, sepsis eller endokardit, och från vildsvin. S. suis hittades hos 95% av grisarna, och isolerades också från vildsvin. Totalt ingick 348 bakterieisolat i studierna som presenteras i avhandlingen. Uppgifter gällande skötselrutiner, produktionsdata och miljöparametrar samlades in och analyserades, men inga riskfaktorer kunde kopplas till sjukdomen. En utvärdering av MALDI-TOF MS, en vanlig artbestämningmetod för bakterier, resulterade i bedömningen att konfirmerande artbestämning med andra metoder behövs, eftersom närbesläktade bakterier felaktigt kan identifieras som S. suis. Isolatens antibiotikakänslighet testades, och resistens mot penicillin och tetracyklin identifierades. DNA isolerades och hel-genom sekvenserades för att studera bakteriernas populationsstruktur. Isolat från friska och sjuka grisar uppvisade genetiska skillnader och bildade separata kluster, och flera nya gener förmodat kopplade till virulens identifierades. Sammanfattningsvis visade resultaten att S. suis är vanligt förekommande hos svenska grisar, inklusive potentiellt zoonotiska serotyper och sekvenstyper. Penicillinresistenta isolat identifieradesför första gången i Sverige, och nya virulensassocierade gener identifierades för framtida studier

Bidragets översatta titel	Streptococcus suis – studier av bakteriens egenskaper, dess diagnostik och förekomst hos svenska grisar
Originalspråk	Engelska
Kvalifikation	Doktor i filosofi
Förlag	Swedish University of Agricultural Sciences
Tryckta ISBN	978-91-8046-020-0
Elektroniska ISBN	978-91-8046-021-7
Status	Publicerad - 2022

FN:s SDG:er

Detta resultat bidrar till följande hållbara utvecklingsmål:

SDG 2 – Ingen hunger

Nyckelord

MALDI-TOF MS
MLST
Streptococcus suis
antimicrobial resistance
endocarditis
meningitis
pigs
virulence
wholegenome sequencing
wild boar

SLU-serie

Acta Universitatis Agriculturae Sueciae

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title = "Streptococcus suis: occurrence, identification and characteristics in Swedish pigs",

abstract = "Streptococcus suis is one of the most important bacterial pathogens in pigs globally, and it is also an emerging zoonotic agent. The aim of this thesis was to gain further knowledge of the occurrence and characteristics of S. suis in Swedish pigs.Samples were taken from the tonsils of healthy pigs, from necropsies of pigs suffering from meningitis, sepsis, and endocarditis, and from wild boar. S. suis was found in 95\% of the pigs and was also isolated from wild boar. In total, 348 isolates were included in the studies presented in this thesis. Farm records on management practices, production data, and environmental parameters were gathered and analysed, but no potential risk factors were associated with disease. The commonly used MALDI-TOF MS method of species identification was evaluated, and it was concluded that additional confirmatory methods are needed, since closely related bacteria may be misidentified as S. suis. The isolates were tested for antibiotic susceptibility, and resistance to penicillin and tetracycline was identified. DNA was isolated and whole-genome sequencing was performed in order to study the population structure. Isolates from healthy and sick pigs exhibited genomic differences and clustered separately, and several new, possibly virulence-associated genes were identified.In conclusion, the results showed that S. suis was commonly found in Swedish pigs, including potentially zoonotic serotypes and sequence types. Isolates resistant to penicillin were identified for the first time in Sweden, and new virulenceassociated genes were proposed for further studies.",

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N2 - Streptococcus suis is one of the most important bacterial pathogens in pigs globally, and it is also an emerging zoonotic agent. The aim of this thesis was to gain further knowledge of the occurrence and characteristics of S. suis in Swedish pigs.Samples were taken from the tonsils of healthy pigs, from necropsies of pigs suffering from meningitis, sepsis, and endocarditis, and from wild boar. S. suis was found in 95% of the pigs and was also isolated from wild boar. In total, 348 isolates were included in the studies presented in this thesis. Farm records on management practices, production data, and environmental parameters were gathered and analysed, but no potential risk factors were associated with disease. The commonly used MALDI-TOF MS method of species identification was evaluated, and it was concluded that additional confirmatory methods are needed, since closely related bacteria may be misidentified as S. suis. The isolates were tested for antibiotic susceptibility, and resistance to penicillin and tetracycline was identified. DNA was isolated and whole-genome sequencing was performed in order to study the population structure. Isolates from healthy and sick pigs exhibited genomic differences and clustered separately, and several new, possibly virulence-associated genes were identified.In conclusion, the results showed that S. suis was commonly found in Swedish pigs, including potentially zoonotic serotypes and sequence types. Isolates resistant to penicillin were identified for the first time in Sweden, and new virulenceassociated genes were proposed for further studies.

AB - Streptococcus suis is one of the most important bacterial pathogens in pigs globally, and it is also an emerging zoonotic agent. The aim of this thesis was to gain further knowledge of the occurrence and characteristics of S. suis in Swedish pigs.Samples were taken from the tonsils of healthy pigs, from necropsies of pigs suffering from meningitis, sepsis, and endocarditis, and from wild boar. S. suis was found in 95% of the pigs and was also isolated from wild boar. In total, 348 isolates were included in the studies presented in this thesis. Farm records on management practices, production data, and environmental parameters were gathered and analysed, but no potential risk factors were associated with disease. The commonly used MALDI-TOF MS method of species identification was evaluated, and it was concluded that additional confirmatory methods are needed, since closely related bacteria may be misidentified as S. suis. The isolates were tested for antibiotic susceptibility, and resistance to penicillin and tetracycline was identified. DNA was isolated and whole-genome sequencing was performed in order to study the population structure. Isolates from healthy and sick pigs exhibited genomic differences and clustered separately, and several new, possibly virulence-associated genes were identified.In conclusion, the results showed that S. suis was commonly found in Swedish pigs, including potentially zoonotic serotypes and sequence types. Isolates resistant to penicillin were identified for the first time in Sweden, and new virulenceassociated genes were proposed for further studies.

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