Anti-Staphylococcal Activity of Cinnamomum zeylanicum Essential Oil against Planktonic and Biofilm Cells Isolated from Canine Otological Infections.

Vinicius De Queiroz Albuquerque,Rafaela Mesquita Bastos Cavalcante,Jesús Alberto Pérez Guerrero,Geovany Amorim Gomes,Victor Alves Carneiro,Tigressa Helena Soares Rodrigues,Maria Janeila Carvalho Soares,Débora De Souza Collares Maia Castelo-Branco,Isaac Neto Goes Da Silva,Maria Nágila Carneiro Matos,Rodrigo Fonseca De Medeiros Guedes

doi:10.3390/antibiotics11010004

Abstract

The aim of this study was to evaluate the phytochemical profile of Cinnamomum zeylanicum essential oil (CZEO) and their antimicrobial and antibiofilm activity against Staphylococcus strains isolated from canine otitis. First, the CZEO chemical composition was determined by gas chromatography-mass spectrometry (CG-MS). External otitis samples collected from dogs were submitted to staphylococcal isolation, followed by MALDI-TOF mass spectrometry identification. The antimicrobial action was tested against the isolates using the disk-diffusion and microdilution methods. The antibiofilm activity was evaluated by CZEO-based concentrations, subMIC for biofilm formation and supraMIC against preformed biofilm, quantified by crystal violet (CV) staining and CFU counting. The chemical analysis revealed that (E)-cinnamaldehyde, eugenol and (E)-cinnamyl acetate were the main compounds in the CZEO, representing 77.42, 8.17 and 4.50%, respectively. Two strains of three different species, S. saprophyticus, S. schleiferi and S. pseudintermedius, were identified. The disk-diffusion test showed an inhibitory zone diameter, ranging from 34.0 to 49.5 mm, while the MIC and MBC values were around 500 and 1000 µg/mL. SubMIC demonstrated an inhibition on biofilm formation against 4 out the 6 strains tested. On mature biofilm, the CZEO-based supraMIC groups had slightly change on biomass, however, the biofilm cell viability decreased the CFU in 3 magnitude orders.

Highlights

Otitis-related problems are one the most common diseases observed in canine patients, which cause inflammation of the ear membranes due to the uncontrolled growth of pathogenic bacteria and fungi [1]
Five of the six isolates presented resistance for at least one antibiotic, except for S. schleiferi 1, which was sensitive against all the antibiotics tested
We analyzed the Cinnamomum zeylanicum essential oil (CZEO) ability to inhibit biofilm formation and we found that CZEO interfered on most staphylococcal biofilm, five of six strains tested (Figure 2)

Summary

Introduction

Otitis-related problems are one the most common diseases observed in canine patients, which cause inflammation of the ear membranes due to the uncontrolled growth of pathogenic bacteria and fungi [1]. Staphylococcus strains are frequently associated with these infections, even though they are commensally present in small numbers on the skin and mucous membranes in healthy dogs [2]. When these bacteria become numerous, infections such as pyoderma and otitis media or externa may develop and prolong inflammation [3,4]. The prevalence of penicillinderived antibiotics resistance in Staphylococcus isolates obtained from canine and feline infections, such as methicillin-resistant Staphylococcus (MRS), has increased continuously over the last several decades [6] Another factor that contributes to antibiotic resistance of staphylococcal strains is the formation of biofilms [7]. Reducing or preventing the dissemination of antibiotic resistance genes into human pathogens is currently of high international importance

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