RESUMO
Persistent apical periodontitis occurs when the endodontic treatment fails to eradicate the intraradicular infection, and is mainly caused by Gram-positive bacteria and yeasts, such as Enterococcus faecalis and Candida albicans, respectively. Phenothiazines have been described as potential antimicrobials against bacteria and fungi. This study aimed to investigate the antimicrobial potential of promethazine (PMZ) and chlorpromazine (CPZ) against E. faecalis and C. albicans dual-species biofilms. The susceptibility of planktonic cells to phenothiazines, chlorhexidine (CHX) and sodium hypochlorite (NaOCl) was initially analyzed by broth microdilution. Interaction between phenothiazines and CHX was examined by chequerboard assay. The effect of NaOCl, PMZ, CPZ, CHX, PMZ + CHX, and CPZ + CHX on biofilms was investigated by susceptibility assays, biochemical and morphological analyses. Results were evaluated through one-way ANOVA and Tukey's multiple comparison post-test. PMZ, alone or in combination with irrigants, was the most efficient phenothiazine, capable of reducing cell counts, biomass, biovolume, carbohydrate and protein contents of dual-species biofilms. Neither PMZ nor CPZ increased the antimicrobial activity of CHX. Further investigations of the properties of phenothiazines should be performed to encourage their use in endodontic clinical practice.
RESUMO
Introdução: Psidium guajava L. (Myrtaceae), conhecida como goiabeira, é uma planta muito utilizada popularmente na forma de chá das folhas jovens (brotos), para o tratamento de enfermidades, como infecções do trato gastrointestinal. Objetivos: Avaliar a atividade antimicrobiana do extrato hidroalcoólico das folhas maduras de P. guajava assim como seu potencial modulador sobre a ação de antibióticos comerciais. Métodos: O potencial antimicrobiano do extrato hidroalcoólico das folhas maduras de P. guajava foi determinado sobre as cepas Staphylococcus aureus ATCC 6538P, Escherichia coli ATCC 10536, Pseudomonas aeruginosa ATCC 9027, Salmonella choleraesuis ATCC 10708 e Candida albicans ATCC 10231, utilizando os métodos de difusão em ágar e de microdiluição em caldo de cultura. Foi utilizada a técnica de difusão em ágar para avaliação do efeito modulador do extrato sobre os fármacos gentamicina, cefoxitina, ciprofloxacino e amicacina. Resultados: Testes fitoquímicos mostraram que o extrato apresentou flavonóides, taninos pirogálicos, saponinas e triterpenóides. O extrato inibiu o crescimento de 60 % (n=3) das cepas, apresentando melhor ação sobre P. aeruginosa ATCC 9027 es. choleraesuis ATCC 10708, com concentração inibitória mínima igual a 5mg/mL para ambas as cepas. A maioria das associações foi aditiva (n=7; 58,33 %), mas destaca-se o importante sinergismo encontrado na associação com ampicilina sobre P. aeruginosa ATCC 9027 e S. choleraesuis ATCC 10708, com reduçãoda resistência destas cepas ao fármaco. Conclusão: Portanto, o extrato das folhas maduras de P. guajava possui boa ação antimicrobiana que deve continuar sendo investigada, além de potencializar a ação de fármacos convencionais, restaurando sua eficácia sobre cepas de importância clínica.
Introduction: Psidium guajava L. (Myrtaceae), known as guava, is a plant commonly used in the form of tea of young leaves (shoots) to treat gastrointestinal infections. Objectives: Evaluate the antimicrobial activity of the hydroalcoholic extract of mature P. guajava leaves, as well as its potential effect upon the action of commercial antibiotics. Methods: Determination was performed of the antimicrobial potential of P. guajava mature leaves against strains of Staphylococcus aureus ATCC 6538P, Escherichia coli ATCC 10536, Pseudomonas aeruginosa ATCC 9027, Salmonella choleraesuis ATCC 10708 and Candida albicans ATCC 10231 by the agar diffusion test and broth culture microdilution. The agar diffusion technique was used to evaluate the modifying effect of the extract upon the drugs gentamicin, cefoxitin, ciprofloxacin and amikacin. Results: Phytochemical tests found that the extract contained flavonoids, pyrogallic tannins, saponins and triterpenoids. The extract inhibited growth in 60 % (n = 3) of the strains, displaying better activity in P. aeruginosa ATCC 9027 and S. choleraesuis ATCC 10708, with a minimum inhibitory concentration of 5 mg/ml for both strains. Most combinations were additive (n = 7, 58.33%), but the combination with ampicillin displayed considerable synergy in P. aeruginosa ATCC 9027 and S. choleraesuis ATCC 10708, reducing the resistance of these strains to the plant drug. Conclusions: The extract of P. guajava mature leaves was found to display good antimicrobial activity which should be the object of further research. The extract also boosts the action of conventional drugs, reinforcing their efficacy against strains of clinical importance.
