Treatment of Streptococcus mutans biofilms with a nonthermal atmospheric plasma

Aims: A nonthermal atm. plasma, designed for biomedical applications, was tested for its antimicrobial activity against biofilm cultures of a key cariogenic bacterium Streptococcus mutans. Methods and Results: The Strep. mutans biofilms were grown with and without 0.15% sucrose. A chlorhexidine digluconate rinse (0.2%) was used as a pos. antimicrobial ref. The presence of sucrose and the frequency of plasma application during growth were shown to have a significant effect on the response to treatment and antibacterial activity. Conclusions: A single plasma treatment for 1 min on biofilms cultured without sucrose caused no re-growth within the observation period. However, with either single or repeated plasma treatments of 1 min, on biofilms cultured with 0.15% sucrose, growth was only reduced. Significance and Impact of the Study: In summary, there may be a role for nonthermal plasma therapies in dental procedures. Sucrose and assocd. growth conditions may be a factor in the survival of oral biofilms after treatment

Can mouth washes containing chlorhexidine 0.12% be used as synonym of a water solution of chlorhexidine 0.12%?

Chlorhexidine digluconate (CHX) is a gold standard drug in dentistry and is widely used as a reference in both in vitro and in vivoexperiments. Due to ease of access, mouth washes containing CHX 0.12% are used as a substitute for aqueous CHX 0.12% solution in laboratory experiments. Additionally, it is well known that for product flavor purposes, volatile compounds are added to mouth washes formulations. Volatiles added to CHX 0.12% may improve wash's antibacterial ability. Volatiles add potency to the mouth wash formulation. Compared with an aqueous CHX 0.12% solution, it is proposed that CHX solutions and Periogard® would have antimicrobial activity. Antimicrobial activity was assessed in the present study via disk diffusion assays against Streptococcus mutans, Streptococcus sanguinisand Escherichia coli. Periogard® showed a significantly higher antibacterial activity in relation to CHX 0.12% (p0.05). Periogard(r) volatiles were analyzed by gas-chromatography/mass spectrometry (GCMS) and the presence of antibacterial menthol, menthone, isomenthol, menthyl acetate, trans-anethol and eugenol was verified. Finally, the use of Periogard® as a synonym of CHX 0.12% must be avoided, because its antibacterial activity is closely related to CHX 1%.</p

Atividade antimicrobiana de óleos essenciais em bactérias patogênicas de origem alimentar Antimicrobial activity of essential oils against sessile and planktonic pathogens of food source

Objetivou-se identificar e quantificar os constituintes e avaliar a atividade antimicrobiana dos óleos essenciais de Mentha piperita, Cymbopogon citratus, Ocimum basilicum e Origanum majorana contra cepas de Escherichia coli enteropatogênica, Salmonella enterica Enteritidis, Listeria monocytogenes e Enterobacter sakazaki. A obtenção dos óleos essenciais foi realizada a partir de folhas secas, empregando-se a técnica de hidrodestilação e utilizando-se a aparelho de Clevenger modificado. A atividade antibacteriana dos óleos essenciais foi determinada pelo método de difusão em ágar. Observou-se que os óleos essenciais inibiram o crescimento bacteriano, mas a efetividade foi variada. Entre os óleos essenciais testados, M. piperita apresentou maior atividade antibacteriana para E. coli, (8.106 UA mL-1) quando comparada as demais bactérias, atividade moderada para Salmonella enterica Enteritidis e Enterobacter sakazakii (1.706 e 3.200 UA mL-1 respectivamente) e baixa atividade para Listeria monocytogenes (106,67 UA mL-1). Já óleo essencial de Cymbopogon citratus apresentou maior atividade antimicrobiana frente a E. coli (9.386 UA mL-1) e atividade moderada frente a Enterobacter sakazakii, Salmonella enterica Enteritidis e Listeria monocytogenes (2.773 UA mL-1 para ambas). Ocimum basilicum apresentou maior atividade antibacteriana frente E. coli e Enterobacter sakazakii (6.826 e 8.106 UA mL-1 respectivamente), moderada atividade frente a Salmonella enterica Enteritidis (1.600 UA mL-1) e não apresentou atividade frente a Listeria monocytogenes.Origanum majorana também foi testado neste estudo e apresentou maior atividade antimicrobiana frente E. coli (5.973 UA mL-1), atividade moderada para Salmonella enterica Enteritidis e Enterobacter sakazakii (1.706 e 2.346 UA mL-1 , respectivamente) e não apresentou atividade para Listeria monocytogenes.<br>ABSTRACT The objective of this work was to identify and quantify the constituents, and to evaluate the antimicrobial activity of the essential oils from Mentha piperita, Cymbopogon citratus, Ocimum basilicum and Origanum majorana, against enteropathogenic Escherichia coli, Salmonella enterica Enteritidis, Listeria monocytogenes and Enterobacter sakazakii. The essential oils were obtained from dried leaves by using the hydrodistillation technique and the modified Clevenger apparatus, and their bacterial activity was determined by using the agar diffusion technique. The essential oils inhibited bacterial growth, but their effectiveness was varied. Among the essential oils tested, that from M. piperita showed a greater antimicrobial activity against E. coli (8.106 UA mL-1), moderate activity for S. enterica Enteritidis and E. sakazakii (1.706 e 3.200 UA mL-1 respectively) and low activity for L. monocytogenes (106,67 UA mL-1). However, the essential oil from C. citratus presented a greater antimicrobial activity against E. coli (9.386 UA mL-1) and a moderate activity against E. sakazakii, S. enterica Enteritidis and L. monocytogenes (2.773 UA mL-1 for both). The essential oil from O. basilicum showed a greater antimicrobial activity against E. coli and E. sakazakii (6.826 e 8.106 UA mL-1 respectively),moderate activity against S. enterica Enteritidis (1.600 UA mL-1), and was inactive against L, monocytogenes. Origanum majorana, which was also tested in our work, showed a greater antibacterial activity against E. coli, (5.973 UA mL-1) moderate activity against S. enterica Enteritidis and E. sakazakii (1.706 e 2.346 UA mL-1 , respectively), and was inactive against L. monocytogenes