In vitro activity of tea-tree oil against clinical skin isolates of meticillin-resistant and -sensitive Staphylococcus aureus and coagulase-negative staphylococci growing planktonically and as biofilms

The susceptibility of Staphylococcus aureus [meticillin-resistant (MRSA) and meticillin-sensitive (MSSA)] and coagulase-negative staphylococci (CoNS), which respectively form part of the transient and commensal skin flora, to tea-tree oil (TTO) was compared using broth microdilution and quantitative in vitro time-kill test methods. MRSA and MSSA isolates were significantly less susceptible than CoNS isolates, as measured by both MIC and minimum bactericidal concentration. A significant decrease in the mean viable count of all isolates in comparison with the control was seen at each time interval in time-kill assays. However, the only significant difference in the overall mean log(10) reduction in viable count between the groups of isolates was between CoNS and MSSA at 3 h, with CoNS isolates demonstrating a significantly lower mean reduction. To provide a better simulation of in vivo conditions on the skin, where bacteria are reported to grow as microcolonies encased in glycocalyx, the bactericidal activity of TTO against isolates grown as biofilms was also compared. Biofilms formed by MSSA and MRSA isolates were completely eradicated following exposure to 5 % TTO for 1 h. In contrast, of the biofilms formed by the nine CoNS isolates tested, only five were completely killed, although a reduction in viable count was apparent for the other four isolates. These results suggest that TTO exerts a greater bactericidal activity against biofilm-grown MRSA and MSSA isolates than against some biofilm-grown CoNS isolates.

Effect of roasting on the antioxidant activity of coffee brews

Colombian Arabica coffee beans were roasted to give light, medium, and dark samples. Their aqueous extracts were analyzed by gel filtration chromatography, UV-visible spectrophotometry, capillary electrophoresis, and the ABTS(.+) assay. A progressive decrease in antioxidant activity (associated mainly with chlorogenic acids in the green beans) with degree of roasting was observed with the simultaneous generation of high (HMM) and low molecular mass (LMM) compounds possessing antioxidant activity. Maximum antioxidant activity was observed for the medium-roasted coffee; the dark coffee had a lower antioxidant activity despite the increase in color. Analysis of the gel filtration chromatography fractions showed that the LMM fraction made a greater contribution to total antioxidant activity than the HMM components.

Antioxidant activity of coffee model systems

Coffee model systems prepared from combinations of chlorogenic acid (CGA), N-alpha-acetyl-1-arginine (A), sucrose (S), and cellulose (C) were roasted at 240 degreesC for 4 min prior to analysis by UV-visible spectrophotometry, capillary zone electrophoresis (CZE), and the ABTS radical cation decolorization assay. The A/CGA/S/C and A/S/C systems were also fractionated by gel filtration chromatography. Antioxidant activity of the systems showed a positive, nonlinear relationship with the amount of CGA remaining after roasting. Sucrose degradation was a major source of color in the heated systems. There was no relationship between antioxidant activity and color generation.

The effect of feeder type and change of feeder type on growing and finishing pig performance and behaviour

Reduced feed intake and hence lower growth rates commonly occur when the environment of the pig changes, e.g. at weaning and when pigs are moved from growing accommodation to finishing accommodation. It is hypothesised that if environmental factors, such as feeder type, remain the same in the weaning and finishing accommodation this 'growth check' may be reduced. A total of 640 pigs in 32 pens of 20 pigs per pen were used to investigate the effects of two feeder types and changing or not changing the feeder type at 10 weeks of age on growth performance and behaviour in the periods from 4 to 10, 10 to finish (22) and from 4 to finish (22) weeks of age, respectively. The two feeder types tested were a 'wet and dry' single-space (S) feeder and a 'dry' multi-space feeder (M).

Influence of social status on the welfare of growing pigs housed in barren and enriched environments

One hundred and twenty-eight pigs were reared in barren or enriched environments from birth to slaughter at 21 weeks of age. Pigs remained as litter-mate groups until 8 weeks of age when they were mixed into groups of eight animals. These groups were balanced for gender and weight and contained two pigs from each of four different litters. Each pig was assigned high or low social status on the basis of relative success in aggressive interactions at mixing. Injury levels were assessed on a weekly basis from 8 to 2 1 weeks of age. Pigs were exposed to two group food competition tests after a period of food restriction at 10 weeks of age, and to an individual novel pen test at 11 weeks of age. Behavioural and plasma cortisol responses to both types of test were recorded. Low social status was associated with increased injuries to the head, neck and ears, and therefore reduced welfare. Pigs with low social status showed reduced resource-holding ability in the food competition test, and greater avoidance of a novel object during the novel pen test. It is suggested that avoidance of the novel object reflected 'learned' fearfulness in these individuals. Environmental enrichment did not negate the effect of low social status on injury levels, but did appear to reduce the negative influence of low social status on stress during food restriction, and led to a reduction in fearfulness in response to the novel pen test. These results suggest that environmental enrichment may improve the we/fare of growing pigs with low social status.