Citral modulates virulence factors in methicillin-resistant Staphylococcus aureus

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for high morbidity and mortality rates. Citral has been studied in the pharmaceutical industry and has shown antimicrobial activity. This study aimed to analyze the antimicrobial activity of citral in inhibiting biofilm formation and modulating virulence genes, with the ultimate goal of finding a strategy for treating infections caused by MRSA strains. Citral showed antimicrobial activity against MRSA isolates with minimum inhibitory concentration (MIC) values between 5 mg/mL (0.5%) and 40 mg/mL (4%), and minimum bactericidal concentration (MBC) values between 10 mg/mL (1%) and 40 mg/mL (4%). The sub-inhibitory dose was 2.5 mg/mL (0.25%). Citral, in an antibiogram, modulated synergistically, antagonistically, or indifferent to the different antibiotics tested. Prior to evaluating the antibiofilm effects of citral, we classified the bacteria according to their biofilm production capacity. Citral showed greater efficacy in the initial stage, and there was a significant reduction in biofilm formation compared to the mature biofilm. qPCR was used to assess the modulation of virulence factor genes, and icaA underexpression was observed in isolates 20 and 48. For icaD, seg, and sei, an increase was observed in the expression of ATCC 33,591. No significant differences were found for eta and etb. Citral could be used as a supplement to conventional antibiotics for MRSA infections.

Composition, Anti-MRSA Activity and Toxicity of Essential Oils from Cymbopogon Species

“…Therefore, it has been suggested that biofilm prevention is preferable to disruption and removal. The inability of antimicrobial compounds to remove biofilm deposits has also been observed by other authors [36,41]. As biofilms develop, the cells undergo irreversible attachment, leading to maturation.…”

“…In turn, a study by Oliveira et al of antistaphylococcal activity [41] indicated that the lowest concentration of citral that inhibited MRSA growth was 5 mg/mL, while the highest was 40 mg/mL, whereas bactericidal concentrations varied between 10 mg/mL and 40 mg/ mL. Oliveira et al [41] showed the bioflm formation capacity of MRSA in a quantitative way in MRSA isolates using citral in the initial phase of bioflm formation from 0 to 24 h, along with the addition of citral in the mature phase of the bioflm, corresponding to 24 h after inoculation. A concentration of 25 mg/mL of citral was more effective in isolates with citral added in the initial phase of bioflm formation than in the mature phase.…”

Chemical Composition, Antioxidant, Antibacterial, and Antibiofilm Activities of Backhousia citriodora Essential Oil

“…Based on this observation, it can be speculated that the strong antibacterial activity exerted by BCEO can be attributed to the high amounts of oxygenated monoterpenes, especially geranial and neral. Citral, or one of its isomers (geranial or neral), has been reported to be a molecule that inhibits the growth of several pathogenic and food-spoilage bacteria, such as S. aureus , E. coli, Salmonella enterica , and Bacillus cereus [ 76 , 77 ]. Chueca et al [ 78 ] demonstrated that oxygenated monoterpenes of citral (a mixture of geranial and neral) exhibited antimicrobial activity by causing oxidative stress in E. coli .…”

β-caryophyllene and docosahexaenoic acid, isolated or associated, have potential antinociceptive and anti-inflammatory effects in vitro and in vivo

“…PBMCs were separated using centrifugation in with a Ficol column (200× g for 10 min at 4 °C) and resuspended in RPMI 1640 medium with 10% fetal bovine serum (FBS, GIBCO BRL). After the evaluation of the quantity and adequate viability of the cells, monocytes were inoculated and/or treated with BPC and DHA 8 , 68 , 69 .…”

“…Since the discovery of penicillin in the 1990s, the interest in natural products has increased with regard to the inhibition of free radicals, attenuation of inflammation, and in the antibiotics sector. Simultaneously, bacterial resistance has increased due to the frequent prescription of an against non-bacterial infections and its indiscriminate and irregular use, leading to sublethal doses that allow an increase in the resistance spectrum of microorganisms 4 , 8 . Therefore, the choice of antibiotics to treat MRSA infections is restricted 7 , 9 .…”