Occurrence of Pasteurella multocida among pigs with respiratory disease in China between 2011 and 2015

Huisheng Liu,Qiao Xue,Xiaojian Xi,Zhanqin Zhao,Yun Xue,Ta Long

doi:10.1186/s13620-016-0080-7

Huisheng Liu, Qiao Xue + Show 4 more

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https://doi.org/10.1186/s13620-016-0080-7

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Abstract

BackgroundPrior to the 1990s, P. multocida capsular serogroup A was the most prevalent in China, followed by serogroups B and D. Thirty years later, serogroup D became the most prevalent, followed by serogroups A and B. However, the P. multocida capsular serogroups currently circulating in China remain unclear. Therefore, the aim of the present study was to provide an update on P. multocida serogroups isolated from diagnostic samples collected from clinically diseased pigs in Central and Eastern China from 2011 to 2015.ResultsBetween February 2011 and October 2015, 296 isolates of Pasteurella multocida were collected from 3212 pigs with clinical respiratory disease in 12 provinces of China (isolation rate of 9.2%). Of the 296 collected isolates, 146 (49.3%) were P. multocida capsular type A, 141 (47.6%) were capsular type D, and one was capsular type B. Streptococcus suis (94/193; 48.7%), Haemophilus parasuis (76/193; 39.3%), Escherichia coli (53/193; 27.5%), and Bordetella bronchiseptica (26/193; 13.5%) were frequently isolated together with P. multocida. A total of 14 toxigenic P. multocida strains co-isolated with other pathogens from 32 cases of atrophic rhinitis were classified into serogroup D. The virulence of P. multocida capsular type A isolates was higher than that of capsular type D isolates based on LD50 studies in mice.ConclusionsOver the past 5 years, P. multocida capsular type A was the most frequently isolated from diagnostic submissions in Central and Eastern China, followed by serogroups D and B.

Highlights

Prior to the 1990s, P. multocida capsular serogroup A was the most prevalent in China, followed by serogroups B and D
The results showed that the virulence of only one isolate of P. multocida capsular type A was relatively weak with a 50% lethal dose (LD50) of 2.1 × 105, and the virulence of PM-30 of P. multocida capsular type D strain was lowest with a LD50 of > 4.9 × 107
Our findings suggest that strains of P. multocida are widely prevalent on pig farms, and there were no differences in the prevalence (p > 0.05, χ2 test) of P. multocida of capsular type A (49.3%) and D (47.6%), which was different from the results of previous report from China (39.5% vs. 54.9%, p < 0.05) [8] and different from the report by Rajkhowa et al [26]

Summary

Introduction

Prior to the 1990s, P. multocida capsular serogroup A was the most prevalent in China, followed by serogroups B and D. The P. multocida capsular serogroups currently circulating in China remain unclear. The aim of the present study was to provide an update on P. multocida serogroups isolated from diagnostic samples collected from clinically diseased pigs in Central and Eastern China from 2011 to 2015. P. multocida strains are classified into five capsular serogroups (A, B, D, E, and F) and 16 somatic serotypes (1 to 16) based on lipopolysaccharide antigens [6,7,8]. P. multocida possesses various virulence factors, including fimbriae, adhesins, and toxins, especially dermonecrotic toxin. Of these virulence factors, toxins produced by serogroups A and D play important roles in the pathogenicity of P. multocida. Data on P. multocida toxins can provide better understanding of pasteurellosis in pigs

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