Virulence traits and antibiotic resistance among enterococci isolated from dogs with periodontal disease

https://doi.org/10.1016/j.cimid.2016.04.002Get rights and content

Highlights

  • The presence of enterococci in the oral mucosa was dogs with periodontal disease (PD) was investigated.

  • Pathogenicity potential of the PD-enterococci was evaluated.

  • PD-isolates harbor virulence traits, form biofilm and present antibioressistances.

  • Owners must be alerted of this hazard and informed on preventive actions.

Abstract

Periodontal disease – PD – is one of the most widespread diseases in dogs, but the role of this odontogenic infection in the dissemination of pathogenic bacteria present in the oral mucosa to other animals or pet owners is understudied.

Trying to unveil the putative pathogenicity of enterococci present in the gums of dogs diagnosed with PD, thirty-two animals were investigated during routine visits to a private veterinary clinic. Seventy-one enterococci were recovered and characterized regarding species, genomic variability, virulence traits, antimicrobial resistance and biofilm-forming ability.

Isolates were mainly identified as Enterococcus faecalis, with the large majority (95%) being able to produce biofilm. Regarding antibiotic resistance, all dog-enterococci were susceptible to ampicillin, amoxicillin/clavulanate, gentamicin-120, imipenem and vancomycin; while distinct levels of resistance were observed for chloramphenicol (10%), erythromycin (20%), streptomycin-300 (35%) and tetracycline (95%).

For virulence traits incidence levels of 35% were observed for β-hemolysis and 25% for cylA, 25% for gelatinase and 35% for gelE; 85% harbor efaAfs and ebpABC; while ace, agg and esp are present respectively in 50, 30 and 10% of the dog-enterococci; efaAfm and acm were detected in all the Enterococcus faecium.

Overall, the widespread prevalence of PD in dogs, associated with the close contact between companion animals, other animals and humans, may act as source for the dissemination of opportunistic pathogenic bacteria. Hence, aforementioned data on virulence and resistance features, emphasizes the need for active surveillance measures, such as the diagnose of PD in companion animals during routine visits to the veterinary clinic.

Introduction

Due to the close contact between pets and owners, the emergence of virulent and/or antimicrobial resistant bacteria in companion animals can be considered a major public health concern [1]. The spread of microbial pathogenic variants should not be disregarded; especially considering that improvement in veterinary medical assistance increased the administration of antimicrobials to animals, many times based on human medicine [2]. Additionally, pets interact with other animals, sometimes engaging in fights resulting in dog-bites, which can potentiate the spread of microorganisms. Hence, companion animals constitute important intervenients in the dissemination of pathogenic bacteria [3], justifying the implementation of effective surveillance measures, essential to allow the development of new strategies to confine this increasing problem.

In this context, pathogenicity assessment of bacteria present in pets diagnosed with periodontal disease (PD) plays a major role. Particularly considering that it is one of the most widespread diseases in dogs, with a prevalence of 44–80% [4], [5], affecting animals from 2 years old [4], especially small and brachycephalics breeds [5]. PD has a multifactorial etiology, depending on several factors, related with the host and the environment [6]. It requires the formation of a plaque, defined as a microbial biofilm in the oral cavity that leads to the inflammation of tooth supporting structures, progressing from a mild gingivitis to severe periodontitis reaching the periodontal ligament and alveolar bone [4], [6].

Several aerobic and anaerobic microorganisms that colonize dogs’ oral cavity have been associated with PD development and progression, including Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, Proteus spp., Fusobacterium spp., Veillonella spp., Prevotella spp., Porphyromonas spp., Capnocytophaga spp. and Actinobacillus actinomycetemcomitans, and Gram-positive bacteria such as streptococci, staphylococci, Corynebacterium spp., Actinomyces spp., Bacillus spp., Peptostreptococcus spp., Eubacterium spp., Propionibacterium spp. and Lactobacillus spp. [7]. Enterococcus spp., known to be natural inhabitants of the gastrointestinal tract of humans, mammals and birds, are also frequently found in the canine oral environment [8], being increasingly associated with severe diseases in human and veterinary medicine, including bacteremia, meningitis, infective endocarditis, intra-abdominal, wound, urinary tract and healthcare associated infections [9], [10]. Enterococci are also known to be intrinsically resistant to several antimicrobials, having the ability to acquire additional antibiotic resistances via genetic mobile elements [10], [11], constituting a major challenge for effective antimicrobial therapy. Additionally, several virulence factors, responsible for the establishment and/or severity of enterococci-related infections, have been described over the years [12], [13].

The close contact between animals, as well as amongst pets and owners, associated with the scarce available data regarding the role of enterococci in dogs’ PD, led the present study. Hence, enterococcal isolates obtained from gum swabs of dogs diagnosed with PD were screened for the presence of antibiotic resistance, virulence factors and biofilm-forming ability.

Section snippets

Sampling and enterococcal isolation

Samples were collected at a private veterinary hospital located in Cascais, Portugal, from 31 dogs (17 males and 14 females, ages between 7 and 17 years). After the detailed observation of the oral cavity, to allow classifying the stage of PD, swab sampling was performed, including gingivitis and periodontitis lesions.

Swabs with Stuart transport medium (Deltalab®) were used to collect samples from the gums of each animal, stored at 4 °C and immediately transported to the Laboratory of

Results and discussion

Characterization of the oral microbiota of dogs with PD is extremely relevant, not only to assess oral health and prevent bacteria systemic dissemination [24], but also due to the potential of pathogen transmission to humans and others animals [2], [25], predominantly via bite wounds [26].

Many bacterial pathogens have been associated with dog-PD, among which members of the genus Enterococcus. Traditionally regarded as low grade pathogens, these bacteria have emerged in the last decades as

Conclusions

To summarize, the implementation of surveillance measures, such as the diagnose of PD-disease in companion animals during routine visits to the veterinary is essential. Owners must be alerted to this hazard and taught how to perform preventive actions, such as avoiding close contact with the animals mouth and saliva, as well as execute pet’s dental hygiene on regular basis.

Acknowledgements

This study was performed on “Centro de Investigação Interdisciplinar em Sanidade Animal” (CIISA/FMV) from Faculdade de Medicina Veterinária da Universidade de Lisboa (Faculty of Veterinary Medicine, University of Lisbon), through Project UID/CVT/00276/2013 from “Fundação para a Ciência e Tecnologia-FCT”. Teresa Semedo-Lemsaddek is financially supported by FCT, Portugal (SFRH/BPD/108123/2015).

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