Quorum Sensing Genes lasI Research Articles

Down Regulation of Biofilm and Quorum Sensing Genes of Pseudomonas aeruginosa and Pasteurella multocida Isolated from Broiler Chicken Pericarditis Lesions by the Action of Some Essential Oils

Pseudomonas and Pasteurella species have variant of virulence factors as biofilm genetic elements that form a thick coat surface surround pathogen and prevent its phagocytosis; also, quorum sensing genes which responsible for cell-to-cell communication and its inhibition are considered a new approach of antimicrobial therapy. The present investigation successes to identify of P. aeruginosa (85.2%) and P. multocida (41.8%) from broiler chickens pericarditis lesions by using Vitek2 compact system. Disc diffusion antibiogram analysis showed that P. aeruginosa were complete resistant to amoxicillin, kanamycin and lincomycin, while P. multocida show complete resistance to amoxicillin, doxycycline, gentamycin, florofenicol and lincomycin 30% of the tested isolates for biofilm formation by Congo red assay showed positive results. Down regulation of biofilm genes pslA, tadG and quorum sensing genes lasI, luxS in P. aeruginosa and P. multocida, respectively after exposure to 0.01% concentration of cinnamon and clove oils were detected by using RT-PCR.

Investigation of Pseudomonas aeruginosa Biofilm Formation and Quorum Sensing Genes in Piperacillin/Tazobactam and Ciprofloxacin Sub-minimal Inhibitory Concentrations

Pseudomonas aeruginosa is a non-fermentative, oxidase-positive, motile gram-negative bacillus widespread in nature. The virulence factors of P.aeruginosa including the ability to grow under minimal growth conditions, the widespread presence in nature, and the ability to form biofilms make P.aeruginosa a highly important bacterium along with its resistance mechanisms against many antibiotics. The ability to form biofilms increases the symptom severity in diseases caused by P.aeruginosa and causes difficulties in the treatment. The aim of this study was to investigate the effects of sub-minimal inhibitory concentrations (sub-MIC) of piperacillin/tazobactam (TZP) and ciprofloxacin (CIP) which are used for the treatment of P.aeruginosa infections on biofilm formation and to investigate the relationship between the severity of biofilm formation and Quorum Sensing (QS) genes. The study included 24 P.aeruginosa isolates from the culture collection of Medical Microbiology Laboratory of Gazi University Faculty of Medicine. MIC values of TZP and CIP antibiotics were determined by the microdilution method. The biofilm layers in the antibiotic-free medium and in the sub-MIC (MIC/2, MIC/4 ve MIC/8) concentrations of antibiotics were visualized by using a scanning electron microscope (SEM). The QS genes (lasI, lasR, rhlI, and rhlR) of the 24 isolates with known biofilm characteristics were identified via the amplification of chromosomal DNA by using PCR method. In the study, it was foundthat both antibiotics reduced biofilm formation in a dose-dependent manner in sub-MIC concentrations compared to the antibiotic-free condition and that MIC/2 was the concentration, which reduced the biofilm formation most. These results were further confirmed by viewing the SEM images. The QS genes lasI, lasR, and rhlI were detected in a total of 19 isolates with moderately strong and strong biofilm formation, the rhlR gene was detected in six of the strong biofilm-forming isolates, in four of the moderately strong biofilm-forming isolates, and in three of the weak biofilm-forming isolates, respectively. The investigation of the effects of sub-MIC concentrations of antimicrobials, used for the treatment of P.aeruginosa infections, on the biofilm formation of P.aeruginosa and the investigation and better understanding of the QS systems associated with biofilm production will allow for finding out new treatment approaches and offer different options in combating infections with high morbidity and mortality.

Evaluating ginger extract, wild blueberry extract, and polysorbates (PS20, PS80) on Pseudomonas aeruginosa biofilm formation.

Pseudomonas aeruginosa is a biofilm forming pathogen that challenges clinical and industrial settings. Many natural products and surfactants have been screened and valued for their anti-biofilm capacity. In this study we assessed the inhibitory effect and molecular mechanism of action of ginger extract (Zingiber officinale Rosc.), wild blueberry extract (Vaccinium angustifolium), and polysorbates (PS20/PS80) on biofilm formation. Ginger and wild blueberry extractions were done using ethanol and distilled water, respectively. Hexane and methanol were used for extracts' liquid-liquid portioning. LC-HRMS was performed to obtain extract fractions. Efficacy of the crude extracts, fractions, and polysorbates was assessed on P. aeruginosa PAN14 growth and biofilm. Transcription levels of biofilm encoding genes ndvB, pelC, algC and quorum sensing genes lasI, lasR, rhlI, rhlR were evaluated by RT-qPCR. Extracts and polysorbates concentrations did not affect P. aeruginosa growth. Biofilm assay showed a reduction in biofilm when 5% ginger, 25% wild blueberry extracts, 0.2% PS20, and 0.25% PS80 were added. LC-HRMS analysis of ginger extract showed abundant gingerol in the hexane layer. Wild blueberry chromatograms showed various constituents differing between their peel and pulp, and pulp extracts. RT-qPCR showed decreased transcription levels of exopolysaccharide and quorum sensing genes with a 363.6 folds reduction in ndvB upon treatment with 25% wild blueberry peel and pulp extract. These results shed light on the mechanism of action of ginger and wild blueberry constituents as well as PS20/80 on P. aeruginosa biofilm formation. Future mouse model experiments are useful to test biofilm inhibition in-vivo.

Quorum Sensing - Dependent Virulence Factors and Biofilm Formation of Pseudomonas Aeruginosa Isolates from Retrieved Orthopedic Implants

Background: Quorum sensing (QS) plays a crucial role in medical device-related infections. However, epidemiological analysis of QS- dependent virulence factors among Pseudomonas aeruginosa (P. aeruginosa) isolates from orthopedic implants-related infections has rarely been reported. Objective: to assess some QS-dependent virulence factors (as pyocyanin, elastase, protease, rhamnolipid, and biofilm production) in P. aeruginosa isolates from retrieved different orthopedic implants. Methodology: Twenty-four P. aeruginosa isolates obtained from 300 retrieved orthopedic implants with proven diagnosis of osteoarticular infection directly related to orthopedic implants were investigated for production of QS-dependent virulence factors. The pyocyanin production was assayed using King A media, rhamnolipid production was checked utilizing cetyltrimethylammonium bromide (CTAB) agar test. Elastin lytic activity was assayed using elastin Congo red, total protease was estimated using the modified skimmed milk assay technique, and the biofilm forming ability was assayed by microtiter plate assay. N-acyl homoserine lactones (3-oxo-C 12 -HSL, C 4 -HSL) were detected by Cross-feeding bioassay. Polymerase chain reaction (PCR) was used to assess the presence of the QS genes lasI, lasR, rhlI, and rhlR in P. aeruginosa isolates. Results: Seventeen isolates (70.8%) displayed the QS-dependent phenotypes and seven isolates were found to be lacking all tested virulence factors. The lack of production of pyocyanin, Rhamnolipid, las B elastase, total protease, and biofilm formation by the seven isolates proposed that they might have a defective QS system. Among the Seven isolates exhibiting impaired QS-dependent phenotypes, AHLs autoinducers were present in three isolates, though the residual four isolates were lacking both autoinducers and therefore are considered QS-deficient. PCR analysis declared that two isolates contained lasI, lasR, rhlI and rhlR genes while one isolate lacked lasR gene, and one isolate was lacking the four tested genes. Conclusion: Although QS seems to be a crucial regulator of virulence factors and biofilm formation in P. aeruginosa, it is equipped to produce implant infection in humans despite an impaired QS system. These results do not challenge the concept that QS plays a foremost role in P. aeruginosa pathogenicity, but highlight that along with known virulence factors, perhaps there are other virulence factors, that may not be strictly under QS control.