E-Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2021

Nasal microbiota diversity and abundance in shelter dogs carrying methicillin-resistant and -sensitive Staphylococcus species (#313)

Sara Horsman 1 , Deirdre Mikkelsen 2 , John Mallyon 1 , Ricardo Soares Magalhães 1 3 , Erika Meler 1 , Justine Gibson 1
  1. School of Veterinary Science, The University of Queensland, Gatton, QLD, Australia
  2. School of Agriculture and Food Sciences, The University of Queensland, Brisbane, QLD, Australia
  3. Children's Health and Environment Program, Child Health Research Centre, The University of Queensland, Brisbane, QLD, Australia

Introduction

Methicillin-resistant or -sensitive Staphylococcus species are carried in the nares of dogs and may cause opportunistic infections. The protective roles of the resident nasal microbiota need to be explored to guide antimicrobial therapy or techniques which can maintain or restore indigenous microbiota to decrease nasal carriage and reduce canine infections. This study aimed to investigate the associations between resident nasal microbiota of dogs on methicillin-resistant and -sensitive Staphylococcus spp. nasal carriage in shelter dogs.

Methods

Nasal samples were taken from 70 dogs classified as “strays”, “owner surrendered” and “humane officer seized” on admission to the shelter, then twice a week until discharge. Samples were both cultured (Staphylococcus spp.) and sequenced (microbiota) with isolates corresponding to a nasal microbiota sample identified by matrix-assisted laser desorption ionisation–time of flight mass spectrometry. All staphylococci were subjected to antimicrobial susceptibility testing. Differences in microbiota was investigated in 52 samples from 40 dogs after 16S rRNA gene sequencing using bioinformatics, including alpha and beta diversity plots using Operational Taxonomic Units (OTUs) and heat maps.  

Results

At admission 37% (N=26/70) of dogs carried Staphylococcus spp. and upon discharge 64% (N=45/70) carried combinations of methicillin-resistant (n=9) and -sensitive (n=24) S. pseudintermedius, methicillin-resistant (n=2) and sensitive (n=6) S. aureus and coagulase-negative Staphylococcus spp. (n=16). From admission to discharge, 13% (N=9/70) of dogs remained culture negative to staphylococci and close to 30% of positive dogs (N=12/45) carried multiple Staphylococcus spp. Seven methicillin-resistant Staphylococcus spp. were multidrug resistant.

Our preliminary microbiota analysis revealed that the most abundant phyla were Proteobacteria, Firmicutes, Actinobacteriota and Bacteroidota. The most abundant genera included Moraxella, Psychrobacter and Leucobacter. Our results indicate no detectable differences in OTUs between nasal carriage status, sex, sampling location and dog population type.

Conclusion

Staphylococcus spp. carriage and diversity increased as dogs remained in the shelter. Preliminary microbiota analysis indicated no significant associations between type of Staphylococcus spp. nasal carriage and resident nasal microbiota, but these results require further investigations.