Enterotoxigenic Staphylococcus aureus strains that were isolated from foods were investigated for their ability to develop direct-tolerance and cross-tolerance to sodium chloride (NaCl), potassium chloride (KCl), lactic acid (LA) and acetic acid (AA) after habituation in sublethal amounts (1/2 of the minimum inhibitory concentration - 1/2 MIC and 1/4 of the minimum inhibitory concentration - 1/4 MIC) of Origanum vulgare L. essential oil (OVEO). The habituation of S. aureus to 1/2 MIC and 1/4 MIC of OVEO did not induce direct-tolerance or cross-tolerance in the tested strains, as assessed by modulation of MIC values. Otherwise, exposing the strains to OVEO at sublethal concentrations maintained or increased the sensitivity of the cells to the tested stressing agents because the MIC values of OVEO, NaCl, KCl, LA and AA against the cells that were previously habituated to OVEO remained the same or decreased when compared with non-habituated cells. These data indicate that OVEO does not have an inductive effect on the acquisition of direct-tolerance or cross-tolerance in the tested enterotoxigenic strains of S. aureus to antimicrobial agents that are typically used in food preservation.

This study assessed the capacity of adhesion, the detachment kinetic and the biofilm formation by Staphylococcus aureus isolated from food services on stainless steel and polypropylene surfaces (2 x 2 cm) when cultivated in a meat-based broth at 28 and 7 ºC. It was also to study the efficacy of the sanitizers sodium hypochlorite (250 mg/L) and peracetic acid (30 mg/L) in inactivating the bacterial cells in the preformed biofilm. S. aureus strains adhered in high numbers regardless the assayed surface kind and incubation temperature over 72 h. Cells detachment of surfaces revealed high persistence over the incubation period. Number of cells needed for biofilm formation was noted at all experimental systems already after 3 days. Peracetic acid and sodium hypochlorite were not efficient in completely removing the cells of S. aureus adhered on polypropylene and stainless steel surfaces. From these results, the assayed strains revealed high capacity to adhere and form biofilm on polypropylene and stainless steel surfaces under different growth conditions. Moreover, the cells in biofilm matrix were resistant for total removal when submitted to the exposure to sanitizers.

A avaliação antimicrobiana das partes aéreas de Kalanchoe brasiliensis Cambess, Crassulaceae, a qual é comumente utilizada para o tratamento de inflamações da mucosa oral, bronquites e congestão nasal, é relatada. Esta atividade foi avaliada em discos de Petri usando o método de difusão para a determinação da Concentração Inibitória Mínima (MIC) e cinética bactericida. Foram usadas amostras bacterianas gram-positivas, gram-negativas e cepas de fungos leveduriformes do gênero Cândida. Apenas o óleo essencial demonstrou ser efetivo, apresentando atividade frente amostras gram-positivas de Staphylococcus aureus (MRSA) meticilina resistente. A ação observada foi considerada bacteriostática por reduzir um log10 UFC/mL a partir da sexta hora de exposição da amostra ao óleo essencial nas concentrações de 4% e 8%. Compostos fenólicos estão presentes em óleo essencial, sugerindo que o efeito foi devido à presença dos mesmos. Por este motivo à planta Kalanchoe brasiliensis Cambess pode representar uma alternativa terapêutica para infecções provocadas por Staphylococcus aureus.

This study reports the antimicrobial evaluation of the aerial parts of Kalanchoe brasiliensis Cambess, Crassulaceae, commonly used for the treatment of the oral mucosa inflammation, bronchitis and nasal congestion. The antimicrobial activity was assayed in petri dishes using the diffusion method for determination of the minimal inhibitory concentration (MIC) and the kill curve kinetic methods. It were used gram-positive and gram-negative strain, leveduriforms fungi strain classified in genus Cândida. Only the essential oil showed activity against methicilin resistant Staphylococcus aureus (MRSA). This action was considered bacteriostatic with the reduction to one log10 CFU/ml after six hour of exhibition at the concentration of 4% and 8%. There are studies accounts that polyphenols are present in the essential oil and are active against bacteria. K. brasiliensis is rich in polyphenols suggering that the antimicrobial effect showed is due to this. For this reason, the plant Kalanchoe brasiliensis, can represent a therapeutic alternative against infections caused for Staphylococcus aureus.

Staphylococcus aureus apresenta-se como um microrganismo patogênico clássico sendo comumente reconhecido como agente etiológico de infecções comunitárias e hospitalares. Considerando o conhecimento acerca das propriedades biológicas apresentadas por Lippia sidoides Cham. (Verbenaceae), este estudo teve como objetivo avaliar a efetividade de seu óleo essencial em inibir o crescimento de cepas de S. aureus com diferentes perfis de resistência antibiótica isoladas de material clínico. Os resultados mostraram destacável atividade anti-S. aureus do óleo essencial de L. sidoides notada por grandes halos de inibição do crescimento bacteriano (15-21 mm). A CIM encontrada foi de 0.4 µL/mL para todas as cepas ensaiada. A CIM apresentou destacável efetividade de inibição da viabilidade de S. aureus em caldo durante vinte e quatro horas de interação caracterizando um efeito bacteriostático. Estes resultados mostram a destacável atividade antiestafilocócica do óleo essencial de L. sidoides, bem como suportam a possibilidade de seu uso racional como agente antimicrobiano alternativo.

Staphylococcus aureus is a classical pathogen microorganism and it is commonly recognized as etiological agent of many community and nosocomial infections. Regarding the knowledge about the biological properties of Lippia sidoides Cham. (Verbenaceae), this study aimed to evaluate the effectiveness of its essential oil in inhibiting the growth of S. aureus strains isolated from clinical materials and with different profiles of antibiotic resistance. The results showed prominent anti-S. aureus activity of L. sidoides essential oil noted by large growth inhibition zones (15-21 mm). MIC found was of 0.4 µL/mL for all assayed strains. MIC presented prominent effectiveness in inhibiting the viability of S. aureus in broth during twenty-four hours of exposure characterizing a bacteriostatic effect. These results show the promising anti-staphylococcal property of L. sidoides essential oil and support the possibility of its rational use as alternative antibacterial agent.