ABSTRACT
Staphylococcus aureus is often associated worldwide with foodborne illnesses, and the elimination of biofilms formed by this bacterium from industrial surfaces is very challenging. To date, there have been few attempts to investigate plant oils obtained by recent green technologies, applied against biofilms on usual surfaces of the food industry and bacteria isolated from such environment. Therefore, this study evaluated the activity of Moringa oleifera seed oil (MOSO), extracted with pressurized n-propane, against standard and environmental S. aureus biofilms. Additionally, a genotypic and phenotypic study of the environmental S. aureus was proposed. It was found that this bacterium was a MSSA (methicillin-sensitive S. aureus), a carrier of icaA and icaD genes that has strong adhesion (OD550=1.86 ± 0.19) during biofilm formation. The use of pressurized n-propane as a solvent was efficient in obtaining MOSO, achieving a yield of 60.9%. Gas chromatography analyses revealed the presence of a rich source of fatty acids in MOSO, mainly oleic acid (62.47%), behenic acid (10.5%) and palmitic acid (7.32%). On polystyrene surface, MOSO at 0.5% and 1% showed inhibitory and bactericidal activity, respectively, against S. aureus biofilms. MOSO at 1% allowed a maximum reduction of 2.38 log UFC/cm² of S. aureus biofilms formed on PVC (polyvinyl chloride) surface. Scanning electron microscopy showed disturbances on the surface of S. aureus after exposure to MOSO. These unprecedented findings suggest that MOSO extracted with pressurized n-propane is potentially capable of inhibiting biofilms of different S. aureus strains, thus, contributing to microbiological safety during food processing.
Subject(s)
Moringa oleifera , Staphylococcus aureus , Propane/pharmacology , Biofilms , Plant Oils/pharmacology , Anti-Bacterial Agents/pharmacology , Microbial Sensitivity TestsABSTRACT
BACKGROUND: The influence of the Hawthorne effect on hand hygiene compliance in an intensive care unit was assessed using covert and overt direct observation. METHODS: The observational study was conducted from February to November 2018 in a 24-bed adult intensive care unit in a 243-bed tertiary care hospital, in four periods (P): P-1, February 5-March 3, 29 h (covert) and P-2, March 15-April 16, 33 h (overt), prior to an educational campaign on hand hygiene; and P-3, August 27-September 28, 33 h (covert) and P-4, October 3-November 6, 35 h (overt), after the campaign. Three 20-min observation sessions were performed daily, randomly distributed in the morning, afternoon and evening shifts, including holidays and weekends. Hand hygiene compliance rates observed in Periods 2 and 4 were displayed on an electronic panel installed in the unit. Hand hygiene compliance was assessed according to the World Health Organization "My Five Moments for Hand Hygiene" guidelines. RESULTS: Before the campaign, the overall hand hygiene compliance rate was 31.95% (340/1064, covert) versus 68.10% (790/1160, overt), and afterwards was 56.11% (615/1096, covert) versus 80.98% (1086/1341, overt). The infection rate was reduced by 22.62% (18.87% versus 14.60%). CONCLUSIONS: The Hawthorne effect and educational campaign markedly influenced compliance with hand hygiene recommendations. The results suggest that combining overt and covert observation methods, including regular feedback on hand hygiene compliance displayed on an electronic panel, may be a valid alternative to increase real hand hygiene compliance rates in hospital practice.
