New 1,3,4-oxadiazole compound with effective antibacterial and antibiofilm activity against Staphylococcus aureus.

Staphylococcus aureus is one of the main aetiological agents causing food-borne diseases. Some strains produce enterotoxins responsible for food poisoning. In addition, they can form biofilms on several surfaces such as plastics, glass and stainless steel making it difficult to eliminate them. The present study evaluated, for the first time, the antibacterial and antibiofilm activities of the synthetic compound LMM6 against S. aureus. The minimum inhibitory concentration was 0·97, 1·95 and 1·95 µg ml-1 against S. aureus ATCC 25923, S. aureus 629/94 and S. aureus FRI S-6, respectively. The time-kill curves showed that 96 h treatment with LMM6 reduced approximately 4 log CFU per ml at all tested concentrations. Furthermore, LMM6 reduced S. aureus preformed biofilm by approximately 1 log CFU per cm2 . During biofilm formation, a reduction of approximately 4 log CFU per cm2 was observed. LMM6 also reduced biofilm biomass during (~60%) and after biofilm formation (~25 to 45%), as shown by the crystal violet assay. Based on these results, we conclude that LMM6 exhibits antibacterial and antibiofilm activity and may be an innovative synthetic molecule for controlling S. aureus.

Antibacterial activity of Barbatimão (Stryphnodendron adstringens) against Staphylococcus aureus: in vitro and in silico studies.

We evaluated the activity of the aqueous fraction and the ethyl acetate fraction of Stryphnodendron adstringens against Staphylococcus aureus and proposed their mechanism of action. The antibacterial activity of S. adstringens fractions was evaluated against S. aureus and the cell targets were rated by docking. The fractions showed moderate antibacterial activity against S. aureus without toxicity on two mammalian cell lines. They also showed synergistic antibacterial activity with tannic acid (TA). In silico assays indicated FabG, FabZ and FabI as probable targets. The metabolic pathway for fatty acid biosynthesis in S. aureus was affected by components of S. adstringens. The synergistic effect when combining TA with S. adstringens fractions suggests a natural alternative to S. aureus control. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study describing the possible targets of action of Stryphnodendron adstringens on Staphylococcus aureus. Molecular dynamics simulations showed that the components of S. adstringens affected the metabolic pathway for fatty acid biosynthesis (FAS II) in S. aureus, inhibiting the FabI, FabG and FabZ enzymes. As tannic acid (TA) is a known inhibitor of some targets identified, we showed synergistic antibacterial activity of S. adstringens in combination with TA. This combination did not show toxicity against HaCaT and Vero cells and based on all these results we suggest that S. adstringens can be a natural and sustainable alternative to S. aureus control.

Photodynamic inactivation of foodborne bacteria by eosin Y.

AIMS: The aim of this study was evaluate the effect of photodynamic inactivation mediated by eosin Y in Salmonella enterica serotype Typhimurium ATCC 14028, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Bacillus cereus ATCC 11778. METHODS AND RESULTS: Bacteria (107 CFU per ml) were incubated with eosin Y at concentrations ranging from 0·1 to 10 µmol l-1 , irradiated by green LED (λmax 490-570 nm) for 5, 10 and 15 min and the cellular viability was determined. Pseudomonas aeruginosa was completely inactivated when treated with 10 µmol l-1 eosin Y for 10 min. Treatments reduced B. cereus and Salm. Typhimurium counts to 2·7 log CFU per ml and 1·7 log CFU per ml, respectively. Escherichia coli counts were slightly reduced. Staphylococcus aureus presented the highest sensitivity, being completely inactivated by eosin Y at 5 µmol l-1 and 5 min of illumination. The reduction of cellular viability of photoinactivated Staph. aureus was also demonstrated by flow cytometry and morphological changes were observed by scanning electron microscopy. CONCLUSIONS: Eosin Y in combination with LED produced bacterial inactivation, being a potential candidate for photodynamic inactivation. SIGNIFICANCE AND IMPACT OF THE STUDY: This study evidenced the efficacy of photodynamic inactivation as a novel and promising alternative to bacterial control.

Sialolitíase em equino: relato de caso / Sialolithiasis in equine: case report

Sialolitíase é uma afecção que afeta as glândulas salivares ou seus ductos, caracterizada pela presença de estruturas calcificadas, denominadas de sialolitos, com crescimento lento e gradual, geralmente assintomático, dificultando ou impedindo o fluxo normal de saliva. Devido à ausência de relatos na literatura nacional, descreve-se o caso de uma égua de 15 anos, que apresentava um sialolito de 13cm no ducto parotídico havia mais de dois anos, próximo à crista facial. O diagnóstico foi realizado por meio do exame clínico: visualização do aumento de volume, palpação do sialolito, avaliação odontológica; e de exames complementares: radiografia e ultrassonografia. Optou-se pelo tratamento cirúrgico, através do acesso percutâneo, pois é o mais indicado para cálculos grandes, realizando-se sutura do ducto de Stenon, sem presença de fístulas no pós-operatório. Foi de extrema importância a avaliação e os cuidados odontológicos durante a realização do procedimento, pois as pontas dentárias facilitam a formação dos cálculos.(AU)

Sialolithiasis is a condition that affects the salivary glands or their ducts, characterized by the presence of calcified structures, called sialolites, with slow and gradual growth, usually asymptomatic, hindering or impeding the normal flow of saliva. Due to the absence of reports in the national literature, the case of a 15-year-old mare who had a 13cm sialolite in the parotid duct near the face ridge for more than 2 years is described. The diagnosis was made through clinical examination: with visualization and palpation of the sialolite, dental evaluation; and complementary exams: radiography and ultrasonography. We chose surgical treatment through percutaneous access, which is the most appropriate for large stones, and Stenon's duct suture was performed, without postoperative fistulas. The assessment and dental care during the procedure was extremely important, since the dental tips facilitate the formation of the stones.(AU)

Pyrazinamide susceptibility testing in Mycobacterium tuberculosis using the fast resazurin microtiter assay plate.

SETTING: Department of Clinical Analysis and Biomedicine, State University of Maringa, Maringa, PR, Brazil. OBJECTIVE: To evaluate the performance of the resazurin microtiter assay (REMA) plate at pH 5.5 in detecting Mycobacterium tuberculosis susceptibility to pyrazinamide (PZA). DESIGN: The minimal inhibitory concentration (MIC) of PZA in M. tuberculosis H37Rv and M. bovis AN5 reference strains and in 34 clinical M. tuberculosis isolates (26 PZA-susceptible and eight PZA-resistant) was determined using REMA at pH 5.5 and compared to REMA at pH 6.0. RESULTS: REMA at pH 5.5 was helpful in discriminating PZA-susceptible from resistant M. tuberculosis isolates when â©¿50 µg/ml PZA was considered as the cut-off for PZA susceptibility. Furthermore, it provided results in 8 days. However, two PZA-resistant isolates failed to grow at pH 5.5. CONCLUSION: As the REMA method is rapid, inexpensive, easy to perform and read, it would be of great usefulness in low-income countries for detecting PZA-resistant M. tuberculosis. REMA at pH 5.6-5.9 should be evaluated on an extended panel of clinical M. tuberculosis isolates with a greater range of MIC values in different laboratories for a better understanding of its utility in differentiating PZA-resistant from PZA-susceptible isolates.

Comparative study between atropine and hyoscine-N-butylbromide for reversal of detomidine induced bradycardia in horses.

REASONS FOR PERFORMING STUDY: Bradycardia may be implicated as a cause of cardiovascular instability during anaesthesia. HYPOTHESIS: Hyoscine would induce positive chronotropism of shorter duration than atropine, without adversely impairing intestinal motility in detomidine sedated horses. METHODS: Ten minutes after detomidine (0.02 mg/kg bwt, i.v.), physiological saline (control), atropine (0.02 mg/kg bwt) or hyoscine (0.2 mg/kg bwt) were randomly administered i.v. to 6 horses, allowing one week intervals between treatments. Investigators blinded to the treatments monitored cardiopulmonary data and intestinal auscultation for 90 min and 24 h after detomidine, respectively. Gastrointestinal transit was assessed for 96 h via chromium detection in dry faeces. RESULTS: Detomidine significantly decreased heart rate (HR) and cardiac index (CI) from baseline for 30 and 60 min, respectively (control). Mean ± s.d. HR increased significantly 5 min after atropine (79 ± 5 beats/min) and hyoscine (75 ± 8 beats/min). After this time, HR was significantly higher after atropine in comparison to other treatments, while hyoscine resulted in intermediate values (lower than atropine but higher than controls). Hyoscine and atropine resulted in significantly higher CI than controls for 5 and 20 min, respectively; but this effect coincided with significant hypertension (mean arterial pressures >180 mmHg). Auscultation scores decreased from baseline in all treatments. Time to return to auscultation scores ≥12 (medians) did not differ between hyoscine (4 h) and controls (4 h) but atropine resulted in significantly longer time (10 h). Atropine induced colic in one horse. Gastrointestinal transit times did not differ between treatments. CONCLUSION: Hyoscine is a shorter acting positive chronotropic agent than atropine, but does not potentiate the impairment in intestinal motility induced by detomidine. Because of severe hypertension, routine use of anticholinergics combined with detomidine is not recommended. POTENTIAL RELEVANCE: Hyoscine may represent an alternative to atropine for treating bradycardia.

Efeitos do modo ventilatório sobre variáveis hemogasométricas em equinos submetidos à mudança de decúbito durante a anestesia geral inalatória com halotano / Effects of the ventilatory regimen on arterial blood gas variables in horses that underwent a change in body position during halothane anesthesia

Compararam-se os efeitos da ventilação espontânea (V E) e controlada (V C) em equinos submetidos à mudança de decúbito durante anestesia. Dezesseis animais foram equitativamente divididos em dois grupos: V E e V C. Os procedimentos cirúrgicos foram iniciados com os animais em decúbito lateral esquerdo (DLE) e, após 75 minutos, os animais foram reposicionados em decúbito lateral direito (DLD). Análises hemogasométricas do sangue arterial foram realizadas após 30 e 75 minutos com os animais posicionados em cada decúbito (M1 e M2 no DLE e M3 e M4 no DLD, respectivamente). Durante a V E, observaram-se hipercapnia (PaCO2 >45mmHg), acidose respiratória (pH <7,35), redução significativa da oxigenação sanguínea após 75min da mudança de decúbito (M4: 205,8±124,7mmHg) em relação aos valores de PaO2 observados antes da mudança de posicionamento (M1: 271,8±84,8mmHg). A Vc foi associada a valores de PaCO2 e pH mais próximos da normalidade bem como resultou em valores de PaO2 significativamente maiores (52 a 96 por cento de elevação nos valores médios) que a V E. Conclui-se que a mudança de decúbito, em equinos anestesiados com halotano e mantidos sob V E, resulta em hipercapnia, acidose respiratória e diminuição dos valores de PaO2. A instituição de V C, desde o início da anestesia, previne a acidose respiratória, além de resultar em valores de PaO2 mais próximos do ideal para animais respirando O2 a 100 por cento.

The effects of spontaneous (SV) and controlled ventilation (CV) were compared in horses undergoing changes in body position during anesthesia. Sixteen animals were equally distributed in two groups: SV and CV. All surgical procedures were commenced on left lateral recumbency (LLR) and 75 minutes later the animals were repositioned on right lateral recumbency (RLR). Arterial blood gas analyses were performed at 30 and 75 minutes after each recumbency (M1 and M2 for LLR and M3 and M4 for RLR). Hypercapnia (PaCO2 >45mmHg), respiratory acidosis (pH <7.35), and significant decrease in PaO2 after 75min of change in body position (M4: 205.8±124.7mmHg) in comparison to PaO2 values before the change of position (M1: 271.8±84.8mmHg) were observed during SV. When compared to the SV group, CV resulted in significantly higher PaO2 levels (52 to 96 percent increase). It was concluded that the change in the body position in spontaneously ventilating halothane-anesthetized horses causes impairment in arterial oxygenation. The use of CV since the beginning of anesthesia prevents the respiratory acidosis and maintains arterial oxygen levels that are closer to values expected during the use of 100 percent O2.

Relaxation of the electron energy distribution function in the afterglow of a N2 microwave discharge including space-charge field effects.

The relaxation of the electron energy distribution function (EEDF) in the post-discharge of an omega/(2pi)=2.45 GHz microwave discharge in N2 has been investigated by solving the time-dependent Boltzmann equation, including a term taking into account electron losses by diffusion under the presence of a space-charge field. It is shown that although the high-energy tail of the EEDF is rapidly depleted in times of 10(-7) s (p=2 and 10 Torr), the electron density n(e)(t), the electron transport parameters, and the rate coefficients for some processes induced by electron impact, with energy thresholds typically smaller than approximately 2-3 eV, such as, e.g., stepwise excitation of N2(B (3)Pi(g)) and N2(C (3)Pi(u)) states from N2(A (3)Sigma(+)(u)) metastables and excitation of N2(X (1)Sigma(+)(g),v) levels, are only slowly modified in the time interval t approximately 10(-7)-3 x 10(-4) s due to the large characteristic times for ambipolar diffusion. As a result of modifications in n(e)(t), the change from ambipolar to free diffusion regimes occurs abruptly at t approximately 3 x 10(-4) and approximately 10(-3) s for p=2 and 10 Torr, respectively.