Antibacterial effect of water-soluble chitosan on representative dental pathogens Streptococcus mutans and Lactobacilli brevis

Dental caries is still a major oral health problem in most industrialized countries. The development of dental caries primarily involves Lactobacilli spp. and Streptococcus mutans. Although antibacterial ingredients are used against oral bacteria to reduce dental caries, some reports that show partial antibacterial ingredients could result in side effects. OBJECTIVES: The main objective is to test the antibacterial effect of water-soluble chitosan while the evaluation of the mouthwash appears as a secondary aim. MATERIAL AND METHODS: The chitosan was obtained from the Application Chemistry Company (Taiwan). The authors investigated the antibacterial effects of water-soluble chitosan against oral bacteria at different temperatures (25-37ºC) and pH values (pH 5-8), and evaluated the antibacterial activities of a self-made water-soluble chitosan-containing mouthwash by in vitro and in vivo experiments, and analyzed the acute toxicity of the mouthwashes. The acute toxicity was analyzed with the pollen tube growth (PTG) test. The growth inhibition values against the logarithmic scale of the test concentrations produced a concentrationresponse curve. The IC50 value was calculated by interpolation from the data. RESULTS: The effect of the pH variation (5-8) on the antibacterial activity of water-soluble chitosan against tested oral bacteria was not significant. The maximal antibacterial activity of water-soluble chitosan occurred at 37ºC. The minimum bactericidal concentration (MBC) of water-soluble chitosan on Streptococcus mutans and Lactobacilli brevis were 400 µg/mL and 500 µg/mL, respectively. Only 5 s of contact between water-soluble chitosan and oral bacteria attained at least 99.60% antibacterial activity at a concentration of 500 µg/mL. The water-soluble chitosan-containing mouthwash significantly demonstrated antibacterial activity that was similar to that of commercial mouthwashes (>99.91%) in both in vitro and in vivo experiments. In addition, the alcohol-free mouthwash exhibited no cytotoxicity and no oral stinging. To the best of our knowledge, this was the first study to combine in vitro and in vivo investigations to analyze the antibacterial properties of water-soluble chitosan-containing mouthwash. CONCLUSIONS: This study illustrated that water-soluble chitosan may be a viable alternative to commercial mouthwashes in the future.

Evaluation of silicon oil on bacterial growth / Avaliação dos efeitos do óleo de silicone no crescimento bacteriano

PURPOSE: To analyze the antimicrobial properties of silicon oil (Óleo de Silicone®, Ophthalmos, Brazil) on in vitro bacterial growth of different microorganisms related to endophthalmitis. METHODS: The following microorganisms were analyzed: (1) Pseudomonas aeruginosa (ATCC 27583); (2) Escherichia coli (ATCC 25922); (3) Staphylococcus aureus (ATCC 25923); (4) Staphylococcus epidermidis (ATCC 12228); (5) Candida albicans (ATCC 10231); (6) Klebsiella pneumoniae (ATCC 13883); and (7) Streptococcus pneumoniae (ATCC 49619). The plates were incubated at 35 ± 2ºC and its growth examined after 24 hours. An empty disk was placed in the center of each plate as a control. RESULTS: No inhibition halos were verified in any of the plates containing the four different concentrations of the bacterial inocula. CONCLUSIONS: The silicon oil 1000 cps does not have any effect on bacterial growth of any of the studied microrganisms.

OBJETIVO: Analisar as propriedades antimicrobianas do óleo de silicone (Óleo de Silicone®, Ophthalmos, Brazil) no crescimento in vitro de diferentes microrganismos relacionados à endoftalmite. MÉTODOS: Os seguintes microrganismos foram analisados: (1) Pseudomonas aeruginosa (ATCC 27583); (2) Escherichia coli (ATCC 25922); (3) Staphylococcus aureus (ATCC 25923); (4) Staphylococcus epidermidis (ATCC 12228); (5) Candida albicans (ATCC 10231); (6) Klebsiella pneumoniae (ATCC 13883); and (7) Streptococcus pneumoniae (ATCC 49619). As placas foram incubadas à temperatura de 35 ± 2ºC e o seu crescimento examinado após 24 horas. Um disco de papel filtro neutro, sem óleo de silicone, foi posicionado no centro de cada placa como controle. RESULTADOS: Não foram encontrados halos de inibição em nenhuma das placas contendo as diferentes concentrações de inóculo bacteriano estudadas. CONCLUSÕES: O Óleo de Silicone® 1000 cps não apresenta efeito no crescimento bacteriano de nenhum dos microrganismos estudados.

Estudo in vitro da ação bactericida e/ou bacteriostática da papaína / Study in vitro of bactericidal and/or bacteriostatic action of the papaíne

OBJETIVO: avaliar a atividade bactericida e/ou bacteriostática de soluções de papaína, em diferentes volumes, à 2%, 4%, 6%, 8%, 10%, 16% e 20% em culturas de S. aureus, P. aeruginosa, E. faecalis, K. pneumoniae e S. typhi, obtidas e identificadas de materiais biológicos provenientes de pacientes atendidos em um laboratório particular de Belém - Pará. MÉTODO: colhidas amostras de cada uma das colônias de bactérias e realizado o repique das mesmas para tubos de ensaio contendo caldo Casoy, até obter-se uma suspensão com turbidez correspondente a 0,5% na escala de Mac Farland, denominada suspensão-mãe. Foram, então, preparados 08 tubos contendo 1,8ml de caldo Casoy, um grupo para cada espécie de bactéria e, em seguida, feito o repique de 200?l da suspensão-mãe em cada tubo. Posteriormente, adicionou-se 200?l, 400?l, 500?l, 1ml ou 2ml de solução de papaína nas concentrações a serem analisadas. Os controles foram realizados somente com as suspensões bacterianas, sem papaína, incubados a 37ºC por 24 horas. Após esta incubação foi feito o repique de cada tubo para placas de Petri contendo Ágar Cled e incubação a 37ºC por 24 horas. RESULTADOS: evidenciou-se crescimento bacteriano em todas as placas semeadas. CONCLUSÃO: não foi observado efeito bactericida ou bacteriostático, in vitro, associado à papaina.

OBJECTIVES: evaluate the bactericidal and/or bacteriostatic activities of 2, 4, 6, 8, 10, 16 and 20% solutions of papaine on cultures of S. aureus, P. aeruginosa, E. faecalis, K. pneumoniae and S. typhi, obtained from biological samples collected from patients attended at the laboratory in Belém, Pará. METHODS: the previously-isolated bacteria were grown in test tubes containing Casoy medium broth, till the broth attained a turbidity of 0.5% on the Mac Farland scale, to form the stock suspensions. Then, 200?l of the stock suspension of each bacteria was inoculated into each of eight test tubes, each containing 1.8 ml of Casoy broth. Various volumes (200?l, 400?l, 500?l, 1ml or 2ml) of each of the papaine solutions were added to the inoculated broth in the tubes. Controls consisted of bacteria-inoculated broth, without papaine. All the tubes were incubated at 37ºC for 24 hours. After incubation, the bacteria from the tubes were inoculated onto Petri dishes containing Cled agar and incubated at 37ºC for 24 hours. RESULTS: was evidenced bacteria grew in all of the inoculated plates. CONCLUSIONS: no bactericidal or bacteriostatic effects, in vitro, associated papaine.