In vitro antimicrobial resistance and oral microbiota of dogs diagnosed by next generation sequencing and mass spectrometry

Author(s)

Fábio Vinícius Ramos Portilho

• Document type: Master's Dissertation
• Press: Botucatu. 2020-06-26.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Medicina Veterinária e Zootecnia. Botucatu
• Defense date: 2020-04-24
• Advisor: Márcio Garcia Ribeiro

Abstract

The close relationship between humans and companion animals in recent decades has strongly increased the risk of transmission of pathogens from pets-to-humans. The microbiota of the oral cavity from companion animals is polymicrobial and these agents may potentially infect humans through bites or by direct contact with mucous membranes or cutaneous lesions. Nonetheless, the identification of these microorganisms by molecular techniques (microbiome, proteomics) is scarce. Besides, the in vitro microbial susceptibility pattern of oral bacterial microbiota from dogs and the etiology of agents involved in human bites are not fully understood, since many dogs are homeless and/or evade after aggression. The present study investigated the presence of bacterial and fungal agents in the oral cavity of 100 healthy dogs based on conventional microbiological culture, large-scale DNA sequencing (microbiome), and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). In vitro antimicrobial susceptibility profile of the isolates was assessed as well. A total of 213 bacterial and 20 fungal microorganisms were identified. The most prevalent bacterial agents diagnosed by microbiological culture and mass spectrometry were Staphylococcus pseudintermedius (40/100=40%), α-hemolytic Streptococcus (37/100=37%), and Pasteurella stomatis (22/100=22%), whereas the most common genus of fungi was Aspergillus (10/100=10%). Imipenem (207/213=97.2%), ceftiofur (196/213=92%), and amoxicillin/clavulanic acid (194/213=91.1%) were the most effective antimicrobials. Conversely, the highest resistance of isolates was observed to sulfamethoxazole/trimethoprim (77/213=36.1%), penicillin (75/213=35.2%), and azithromycin (48/213=22.5%). Multidrug resistance was identified in 18.8% of the bacterial isolates (40/213), in addition to the detection of the resistance gene mecA in three isolates of coagulase-positive staphylococci (3/49=6.1%) (one S. aureus and two S. pseudintermedius). In large-scale sequencing, the most predominant genera were Porphyromonas (32.5%), Moraxella (16.3%), Fusobacterium (12.8%), and Conchiformibius (9.5%). Less frequently, there were identified Bergeyella spp. (5%), Campylobacter spp. (3.8%), and Capnocytophaga spp. (3.4%). High complexity of agents was identified in oral microbiota of apparently healthy dogs, including pathogens with zoonotic potential. Also, isolates revealed a high multidrug resistance to conventional antimicrobials, an emergent public health issue. Overall, the polymicrobial nature of oral microbiota of dogs and multi-resistance of the agents to conventional drugs highlights the potential risk of contaminated lesions caused by bites from dogs-to-humans, and need for treatment of these lesions based on etiology identification with a combination of methods, and antimicrobial susceptibility pattern. (AU)

• FAPESP's process: 18/07345-7 - Oral microbiota (microbiome) and antimicrobial resistance in microorganisms potentially transmissible by dog bite
• Grantee: Fábio Vinícius Ramos Portilho
• Support Opportunities: Scholarships in Brazil - Master