This study evaluated the rose bengal‐ and erythrosine‐mediated photoinactivation against Salmonella Typhimurium and Staphylococcus aureus planktonic and sessile cells using green LED as a light source. The free‐living or 2‐day‐old biofilm cells were treated with different concentrations of the photosensitizing agents and subjected to irradiation. Only 5 min photosensitization with rose bengal at 25 nmol L−1 and 75 μmol L−1 completely eliminated S. aureus and S. Typhimurium planktonic cells, respectively. Erythrosine at 500 nmol L−1 and 5 min of light exposure also reduced S. aureus planktonic cells to undetectable levels. Eradication of S. aureus biofilms was achieved when 500 μmol L−1 of erythrosine or 250 μmol L−1 of rose bengal was combined with 30 min of irradiation. Scanning electron microscopy allowed the observation of morphological changes in planktonic cells and disruption of the biofilm architecture after photodynamic treatment. The overall data demonstrate that rose bengal and erythrosine activated by green LED may be a targeted strategy for controlling foodborne pathogens in both planktonic and sessile states.
The present study evaluated the antibacterial and antibiofilm activity of carvacrol against Salmonella Typhimurium. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined and the time-kill curve and scanning electron microscopy (SEM) were performed to evaluate antibacterial activity. Antibiofilm activity was evaluated by quantifying total biomass using crystal violet assay, and metabolic activity was determined using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide] assay. The action of carvacrol against preformed biofilm on polypropylene and stainless steel was also evaluated by colony counting and SEM. The MIC and MBC was 312 µg mL-1. Carvacrol at MIC and 2 x MIC eliminated cells after 6 and 1 h of treatment, respectively, as exhibited in the time-kill curve. The greatest reduction in biofilm biomass and metabolic activity was 1,719 OD 550 and 0,089 OD 550 respectively, both at 4 x MIC of carvacrol. In carvacrol treated biofilms of S. Typhimurium on polypropylene, a reduction of 5.12 log was observed with 4 x MIC, while on stainless steel, carvacrol at 4 x MIC reduced bacterial counts by 5 log. The results showed that carvacrol exhibits antibacterial activity and can be used as an alternative for the control of S. Typhimurium biofilms.
Cutaneous leishmaniasis is caused by different species of
Leishmania. In domestic animals such as dogs and
cats, the diagnostic consists of clinical, epidemiological and serological
tests, which changes among countries all around the world. Because of this
diversity in the methods selected, we propose this systematic literature
review to identify the methods of laboratory diagnosis used to detect
cutaneous leishmaniasis in domestic dogs and cats in the Americas. Articles
published in the last 5 years were searched in PubMed, ISI Web of Science,
LILACS and Scielo, and we selected 10 papers about cutaneous leishmaniasis
in dogs and cats in the Americas. In Brazil, often the indirect
immunofluorescence and enzyme immunoassay (ELISA) have been applied. Other
countries like United States and Mexico have been using antigenic fractions
for antibodies detections by Western blot. ELISA and Western blot showed a
higher sensitivity and efficacy in the detection of leishmaniasis. Analysis
of sensibility and specificity of the methods was rarely used. Although
confirmatory to leishmaniasis, direct methods for parasites detection and
polymerase chain reaction showed low positivity in disease detection. We
suggested that more than one method should be used for the detection of
feline and canine leishmaniasis. Serological methods such as Western blot
and enzyme immunoassay have a high efficacy in the diagnosis of this
disease.
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