Many gram-negative bacteria employ N -acylhomoserine lactone (AHL)-mediated quorum sensing to control virulence. To determine whether gram-positive bacteria such as Staphylococcus aureus respond to AHLs, we used a growth-dependent lux reporter fusion. Exposure of S. aureus to different AHLs revealed that 3-oxo-substituted AHLs with C ₁₀ to C ₁₄ acyl chains inhibited light output and growth in a concentration-dependent manner, while short-chain AHLs had no effect. N -(3-Oxododecanoyl)- l -homoserine lactone (3-oxo-C ₁₂ -HSL) inhibited the production of exotoxins and cell wall fibronectin-binding proteins but enhanced protein A expression. Since these processes are reciprocally regulated via the S. aureus agr quorum-sensing system, which in turn, is regulated via sar , we examined the effect of AHLs on sarA and agr . At sub-growth-inhibitory concentrations of 3-oxo-C ₁₂ -HSL, both sarA expression and agr expression were inhibited, indicating that the action of 3-oxo-C ₁₂ -HSL is mediated at least in part through antagonism of quorum sensing in S. aureus . Spent culture supernatants from Pseudomonas aeruginosa , which produces both 3-oxo-C ₁₂ -HSL and N -butanoyl-homoserine lactone (C ₄ -HSL), also inhibited agr expression, although C ₄ -HSL itself was inactive in this assay. Since quorum sensing in S. aureus depends on the activities of membrane-associated proteins, such as AgrB, AgrC, and AgrD, we investigated whether AHLs perturbed S. aureus membrane functionality by determining their influence on the membrane dipole potential. From the binding curves obtained, a dissociation constant of 7 μM was obtained for 3-oxo-C ₁₂ -HSL, indicating the presence of a specific saturable receptor, whereas no binding was observed for C ₄ -HSL. These data demonstrate that long-chain 3-oxo-substituted AHLs, such as 3-oxo-C ₁₂ -HSL, are capable of interacting with the S. aureus cytoplasmic membrane in a saturable, specific manner and at sub-growth-inhibitory concentrations, down-regulating exotoxin production and both sarA and agr expression.

We aimed to assess antibiotic usage and knowledge regarding antibiotics and antimicrobial resistance (AMR) among undergraduate students of the Universiti Brunei Darussalam (UBD), public university located in Brunei Darussalam. A cross-sectional study was performed using a self-administered questionnaire. The questionnaire was adapted from the World Health Organization’s (WHO) “Antibiotic resistance: Multi-country public awareness” survey distributed online. Students at the UBD were invited to participate in the online survey through internal email. The questionnaire consisted of five sections: demographic information, antibiotic usage, knowledge on antibiotics, antibiotic resistance (AMR), and use of antibiotics in agriculture. The data were analyzed descriptively and appropriate inferential statistics were used accordingly. A total of 130 students returned a completed questionnaire. The result of the study found that 51% (n = 66) of the students had good level of knowledge of antibiotic and antimicrobial resistance with a mean total knowledge score of nine out of 14. Of note, 76% (n = 99) of the respondents mistakenly believed that antibiotic resistance is the result of the body becoming resistant to antibiotics. Only 14% (n = 18) of the respondents were found to have poor knowledge on antibiotics and antimicrobial resistance in the study. Misconceptions in regards to the use of antibiotics for conditions related to viral illnesses like cold and flu (41%, n = 53) were noticed among the respondents in our study. Thus, improving knowledge on antibiotics is crucial to address these beliefs.

Background: Public misconception and demand for the indication of antibiotics could lead to inappropriate prescribing and consumption. Successful treatment can only be achieved when the public and industrial users have knowledge on antibiotic use and resistance. This survey is aimed to assess antibiotic usage and knowledge regarding antibiotics and antimicrobial resistance (AMR) among undergraduate students of Universiti Brunei Darussalam (UBD), public university located in Brunei Darussalam. Methods: A cross-sectional study was performed using a self-administered questionnaire. The questionnaire was adapted from the World Health Organization (WHO) Antibiotic Resistance, Multi-country public awareness survey distributed online. Students at UBD were invited to participate in the online survey through internal email. The questionnaire consisted of 5 sections: demographic information, antibiotic usage, knowledge on antibiotics, antibiotic resistance (AMR) and use of antibiotics in agriculture. Data were analyzed descriptively and appropriate inferential statistics was used accordingly. Cronbach’s alpha was also done to determine the internal consistency. The section on antibiotic use and knowledge showed good internal consistency of Cronbach’s alpha 0.66 and 0.86 respectively. Research ethics approval was obtained from the PAPRSB Institute of Health Sciences, Universiti Brunei Darussalam (UBD). Results: A total of 145 students returned the complete questionnaire. The result of the study found that 50% of the students had good level of knowledge of antibiotic and antimicrobial resistance with a mean total knowledge score of 11.4 out of 14. Respondents reported the use of antibiotic in the past (69%). Many of the students could identify the use of antibiotics for the treatment of bacterial infection. However, there were also students who incorrectly thought that antibiotics can be used for cold and flu (43%) and fever (41%). Moreover, 76% of the respondents mistakenly believed that antibiotic resistance is the result of the body becoming resistant to antibiotics. Only 12% of the respondents were found to have poor knowledge in the study. Conclusions: Misconceptions in regards to the use of antibiotics for conditions related to viral illnesses was noticed among the respondents in our study. Thus, improving knowledge on antibiotics is crucial to address those beliefs.