Comparison of Oropharyngeal Microbiota in Healthy Piglets and Piglets With Respiratory Disease

Abstract

Porcine respiratory disease (PRD) is responsible for severe economic losses in the swine industry worldwide. Our objective was to characterize the oropharyngeal microbiota of suckling piglets and compare the microbiota of healthy piglets and piglets with PRD. Oropharyngeal swabs were collected from healthy (Healthy_A, n = 6; Healthy_B, n = 4) and diseased (PRD_A, n = 18; PRD_B, n = 5) piglets at 2–3 weeks of age from two swine farms in Guangdong province, China. Total DNA was extracted from each sample and the V3-V4 hypervariable region of the 16S rRNA gene was amplified and sequenced using the Illumina MiSeq platform. No statistically significant differences were observed in bacterial diversity and richness between the healthy and PRD groups in the two farms except for Shannon index in farm A. Principal coordinates analysis (PCoA) showed structural segregation between diseased and healthy groups and between groups of different farms. Among all samples, the phyla Firmicutes, Proteobacteria, and Bacteroidetes were predominant. At the genus level, Streptococcus, Lactobacillus, and Actinobacillus were the core genera in the oropharynx of healthy piglets from the two farms. Significant differences in bacterial taxa were found when the microbiota was compared regarding the health status. In farm A, the percentages of Moraxella and Veillonella were higher in the PRD group, while only Porphyromonas was significantly increased in the PRD group in farm B (p < 0.05). Compared to PRD groups, statistically significant predominance of Lactobacillus was observed in the healthy groups from both farms (p < 0.05). Our findings revealed that Moraxella, Veillonella, and Porphyromonas may play a potential role in PRD and Lactobacillus may have a protective role against respiratory diseases.

Interaction study of Pasteurella multocida with culturable aerobic bacteria isolated from porcine respiratory tracts using coculture in conditioned media

“…The identi cation of Acinetobacter, Klebsiella, and Weeksella in our study was consistent with their results, but only Klebsiella and Weeksella were reported as members of the core nasal microbiota. When compared to the study of oropharyngeal microbiota from healthy piglets in China [7], Streptococcus and Lactobacillus were the core microbiota in the oropharynx of these healthy piglets consistent with the studies in the UK and Spain [5]. This agreement showed that the nasal and oropharynx of the piglets shared more common bacterial genera compared to the tracheal isolates of the mature pigs in the present study.…”

“…From 116 isolates, our study identi ed 14 bacterial genera, which included four aerobic (Acidovorax, Acinetobacter, Weeksella, and Wohlfahrtiimonas) and ten facultative anaerobic (Aeromonas, Escherichia, Enterobacter, Hafnia, Klebsiella, Macrococcus, Proteus, Providencia, Shewanella, and Shigella) bacterial genera belonging to seven families (Aeromonadaceae, Comamonadaceae, Enterobacteriaceae, Flavobacteriaceae, Moraxellaceae, Shewanellaceae, and Staphylococcaceae) under three phyla (Proteobacteria, Firmicutes, and Bacteroidetes) from the respiratory tracts of healthy pigs. The isolation of Proteobacteria, Firmicutes, and Bacteroidetes could be due to their abundance in the porcine respiratory tract as previously shown from the metagenomic studies of the nasal, oropharyngeal, and lung microbiota [6][7][8][31][32][33][34][35]. Some of these 14 bacterial genera were reported in similar locations of the porcine respiratory tract [5][6][7][8][31][32][33][34][35][36][37][38][39][40].…”

“…Opportunistic bacteria, e.g., Pasteurella, Haemophilus, and Actinobacillus, were also abundant in the nasal, oropharynx, and tonsil of healthy pigs but were not isolated under aerobic conditions in this study, which seemed to be a limitation of the bacterial isolation method using the selective media compared to the metagenomics approach which was not required prior bacterial culture [5,7,34]. These in vitrocultured bacterial isolates were good candidates for the coculture assay to examine possible forms of interactions before investigating more complex bacterial interactions in the in vivo or in vivo-like experiments.…”

Microbiota Composition and Functional Profiling Throughout the Gastrointestinal Tract of Commercial Weaning Piglets

“…Up to now, the genus Actinobacillus has never been referenced as one of the most abundant in weaning piglet intestinal microbiota. Nonetheless, this taxon was identified to be predominant in piglet oropharynx which could explain its high abundance in stomach and small intestine samples of our study [39]. The Lactobacillus genus was already found to be predominant in the fecal microbiota of two weeks old suckling piglets [12].…”

Serotyping and pathotyping of Glaesserella parasuis isolated 2012–2019 in Germany comparing different PCR-based methods

“…Correct species identification is important especially when isolates are serologically non-typeable or pathotyped by the method according to Howell et al 2017. In both cases Actinobacillus species which are commensals of the respiratory tract might confound results [21,22]. However, the primers for the species marker identified by Howell et al [12] and originally used in their serotyping and pathotyping PCR erroneously identified six isolates in our collection as G. parasuis which could not be confirmed using primers designed by Oliveira et al 2001 [16] and were indeed closely related to Actinobacillus species by cpn60UT sequencing.…”