<div>Background: Mitigation process to curb the ever increasing problem of antimicrobial resistance through development of new class of antimicrobials is slow and costly affairs. Research on alternative to conventional antimicrobials using plant based products as good source of numerous phytochemicals have potential to cope up the antimicrobial resistance. The present study was formulated on detection of in vitro antimicrobial and antibiofilm properties of methanol leaf extract of Citrus maxima against clinical isolates of Staphylococcus aureus. 
 
Methods: Leaves of Citrus maxima plants were collected from the campus of College of Veterinary Sciences and Animal Husbandry, Central Agricultural University, Aizawl, Mizoram and processed for preparation of methanol crude extract. The plant extracts were evaluated for their phytochemical and antioxidant properties using DPPH (2, 2-Diphenyl-1-picrylhydrazyl) method. Twenty well characterized biofilm producing and multidrug resistant Staphylococcus aureus strains recovered from milk of mastitic cows from Mizoram were received from the cultural repository of the department. The plant extracts were subjected to determine their antimicrobial and antibiofilm activities against all the bacterial isolates including&nbsp;S. aureus (ATCC 29213) by in vitro agar well diffusion method and 96 well microtiter plate methods, respectively. The MIC value of the plant extracts were determined by microdilution method. 
 
Result: In the methanol leaf extract of C. maxima alkaloids, glycosides, terpenoids, tannin and phenol and flavonoids were detected by qualitative analysis. Saponin, protein, free amino acids, steroids and carbohydrates were not detected. The free radical scavenging potential of the extract was found to be 10.66&plusmn;1.84% to 36.10&plusmn;1.98%, which was comparatively lower than ascorbic acid (83.39&plusmn;0.13% to 89.76&plusmn;0.24%). A total of 8 (40.0%), 5 (25.0%) and 7 (35.0%) strains were recorded as weak, moderate and strong biofilm producer. Maximum antibacterial activity against standard culture was observed with the zone of inhibition of 18 mm at 200 mg/mL concentration and MIC value at 25 mg/mL. Maximum antimicrobial activities against clinical isolates were recorded with 11.8&plusmn;1.13 mm zone of inhibition at 200 mg/mL and MIC value at 25 mg/mL. The clinical isolates exhibited highest (85.94&plusmn;1.00%) biofilm inhibition at 6.25 mg/mL. To the best of our knowledge, this is the first-ever report on antibiofilm and antioxidative activities of C. maxima leaf extracts against any bacteria.</div>

Antimicrobial and Antibiofilm Activities of Methanol Leaf Extract of Citrus maxima against Clinical Isolates of Multidrug Resistant Staphylococcus aureus

<div>Background: Management of ever growing multidrug resistant (MDR) bacteria becomes one of the biggest threats to public health worldwide. The situation is worsening due to lack of new generation antimicrobials in the arsenal of the clinicians. Development of new alternatives to the conventional antimicrobial agents is the need of the hour to control the menace of AMR. Plants based products are attractive alternatives with proven efficacy but needs scientific investigation to explore their potential antimicrobial, antibiofilm and antiquorum sensing activities against major bacterial pathogens of human and animals. The present study was conducted to explore the antimicrobial, antibiofilm and antiquorum sensing activity of aqueous and methanol extracts of leaf, flower, fruit and stem of the Himalayan yellow raspberry (Rubus ellipticus) against clinical isolates of Staphylococcus aureus and Escherichia coli. 
 
Methods: E. coli and S. aureus were isolated and identified from diarrhoeic pigs and poultry and mastitic milk of cattle of Mizoram, respectively. Leaf, flower, fruit and stem/bark of R. ellipticus were collected from Mizoram and extracted by methanol and aqueous solvents. The antimicrobial activity and MIC was determined by well diffusion method and 96 wells microtiter plate method, respectively. Antibiofilm activity of plant extracts was determined in 96 well tissue culture plate. Antiquorum sensing activity was determined by disc diffusion method. 
 
Result: Methanol leaf extract exhibited antimicrobial activity against S. aureus with 19 mm and 7 mm zone of inhibition at 200 mg/mL and 12.5 mg/mL, respectively. Methanol fruit extract also showed antimicrobial activity against S. aureus only. Highest and lowest activities were observed at 200 mg/mL and 25 mg/mL concentrations with 15 mm and 7 mm zone of inhibition, respectively. No antimicrobial activities by either of the extracts were observed against E. coli isolates. The MIC of R. ellipticus methanol leaf and fruit extracts against S. aureus was 0.203125 mg/mL and 0.8125 mg/mL, respectively. The methanol leaf (86.60%) and stem (85.60%) extracts of R. ellipticus showed significant antibiofilm activity against S. aureus isolates, whereas methanol fruit (89.20%) extracts exhibited antibiofilm activity against E. coli isolates at the concentration of 0.05 mg/mL. Significant antiquorum sensing (QS) activities was exhibited by the methanol leaf extract of R. ellipticus at 200 mg/mL concentration against E. coli. This is the first ever report on antibiofilm and anti QS activities of the R. ellipticus plant extracts against E. coli and S. aureus bacteria.</div>

Exploration of Antimicrobial, Antibiofilm and Antiquorum Sensing Activity of the Himalayan Yellow Raspberry (Rubus ellipticus) against Clinical Isolates of Escherichia coli and Staphylococcus aureus

<div>Background: Development and persistence of multidrug resistant (MDR) bacteria is considered to be one of the biggest threats to public health worldwide. Development of new antimicrobial agents and alternatives to the conventional antimicrobial agents to control the menace of AMR is the need of the hour. Plants based products can be effectively explored as potential antimicrobial, antibiofilm and antiquorum sensing agents against major bacterial pathogens of human and animals. This present study was conducted to explore the antimicrobial, antibiofilm and antiquorum sensing activity of aqueous and methanol extracts of leaf, flower, fruit and stem of Melastoma malabathricum against clinical isolates of Staphylococcus aureus and Escherichia coli. 
 
Methods: E. coli and S. aureus were isolated and identified from diarrhoeic pigs and poultry and mastitic milk of cattle of Mizoram, respectively. Leaf, flower, fruit and stem of M. malabathricum were collected from Mizoram and extracted by methanol and aqueous solvents. The antimicrobial activity and MIC was determined by using well diffusion method and 96 wells microtiter plate method, respectively. Antibiofilm activity of plant extracts was determined in 96 well tissue culture plate. Antiquorum sensing activity was determined by disc diffusion method. 
 
Result: Methanol leaf extract exhibited antimicrobial activity against E. coli but not against S. aureus with 18 mm and 6 mm zone of inhibition at 200 mg/mL and 12.5 mg/mL, respectively. Methanol flower extract showed antimicrobial activity against S. aureus but not against E. coli with 14 mm and 6 mm zone of inhibitions at 200 mg/ml and 12.5 mg/mL, respectively. Similarly, the aqueous leaf extract showed antimicrobial activity against S. aureus but not against E. coli with 12 mm and 6 mm zone of inhibition at 200 mg/mL and 100 mg/mL, respectively. The MIC of M. malabathricum methanol leaf extract against E. coli was 3.125 mg/mL, whereas the MIC value of methanol flower and leaf extracts was 6.25 mg/mL against S. aureus. Antibiofilm activity of M. malabathricum methanol leaf, methanol flower and aqueous leaf extracts was recorded only against S. aureus isolates with maximum inhibition at 0.05 mg/mL concentration. Good antiquorum sensing activities was exhibited by the M. malabathricum methanol leaf, methanol flower and aqueous leaf extracts against S. aureus isolates at 200 mg/mL concentration.</div>

<div>In vitro Antimicrobial, Antibiofilm and Antiquorum Sensing Activity of Indian Rhododendron (Melastoma malabathricum) against Clinical Isolates of Escherichia coli and Staphylococcus aureus</div>

Background: Dairy sector is a leading industry in our country. Mastitis being most concerned and frightful disease, not only affecting health of animals but also the economy of the livestock owner. Prevailing status of the antimicrobial resistance makes the treatment of mastitis much more difficult. Biofilm formation in mastitis milk could place difficulty in the treatment of animals as it further increases the possibility of antimicrobial resistance. Essential oils generally being less toxic, could be optimal alternatives to conventional antibiotics, most of these essential oils higher MIC values than antibiotics, needed to be given in increased concentration in feed/water. 
 
Methods: Different dairy farms were screened for mastitis (164 dairy cattle and buffalo) Staphylococcus aureus isolates were identified and characterized phenotypically by standard biochemical tests. The biofilm formation ability was studied by different methods along with the quantitative analysis and MIC of standard drug cefoperazone. 
 
Result: Out of total milk samples 17 samples were identified Staphylococcus aureus positive with Congo red agar (70% positive), Light Microscopy method (52% positive) and Microtiter plate (Crystal Violet) method. (100% sensitivity). The antimicrobial and antibiofilm effect of Cinnamon oil were studied by Microtiter plate method, SEM analysis and confocal techniques. Cinnamon oil gave antibiofilm activity in all the concentration used (1%, 2%, 3%). The MIC of Cefoperazone was in the range of 64 &igrave;g/to 16 &igrave;g/ml. No significant changes were observed on biofilm production at sub-MIC of cefoperazone.

Antimicrobial and Antibiofilm Activity of Cinnamon Oil on Staphylococcus aureus Isolated from Cattle Milk with Mastitis

<div>Background: Bovine mastitis is a multifactorial and is one of the most challenging disease. It can be caused by many different bacterial species, the most common of which are Staphylococcus species and Streptococcus species. The prevalence of different species varies temporally, geographically and also due to control measures adopted in herds. The present study is on the biofilm forming Streptococcus uberis causing mastitis and the effect of antibiofilm agents on the antimicrobial resistance of the microorganisms.&nbsp; 
 
Methods: The isolates were identified by Polymerase chain reaction (PCR). Two antibiofilm agents, resveratrol and ursolic acid (UA) each at two concentrations (30 &mu;g/ml, 100 &mu;g/ml) were used for the study. Biofilm formation and rate of biofilm inhibition was detected using quantitative microtiter plate (MTP) assay and biofilm gene (lux S) was detected using PCR. The isolates treated with antibiofilm agents were subjected to standard disc diffusion test with 7 antibiotics and the change in antibiotic resistance was studied.&nbsp; 
 
Result: The mean&plusmn;SE values of inhibition rates of 29 S. uberis isolates by 30 &mu;g/ml UA, 100 &mu;g/ml UA, 30 &mu;g/ml resveratrol, 100 &mu;g/ml resveratrol were 33.96&plusmn;3.17%, 57.40&plusmn;2.8%, 31.35&plusmn;3.12% and 46.28&plusmn;3.47%, respectively. Biofilm inhibiting agents along with all antibiotics had reduced antimicrobial resistance by 1.5-2 times on in vitro antibiotic resistance testing by disc diffusion at 100 &mu;g/ml concentration. The antibiofilm agents were found to be very effective to control antibiotic resistance of S. uberis from mastitic milk samples in vitro.</div>

​Efficacy of Resveratrol and Ursolic Acid on Biofilm Inhibition and Antimicrobial Resistance of Streptococcus uberis

Background: Colibacillosis is an infectious disease that affects livestock such as cattle, pigs, goats, sheep, horses and poultry caused by the bacterium Escherichia coli. E. coli can form biofilms when environmental conditions are unfavorable. The purpose of this research is to determine the effect of honeybee propolis on the formation of E. coli biofilm in vitro.&nbsp; 
 
Methods: The research began with the dilution of propolis using the microdilution technique and determination of concentration values with a modified minimum inhibitory concentration (MIC). Biofilm inhibition assays were conducted in microplates with five propolis concentration treatments: 0.39 mg/mL, 0.78 mg/mL, 1.56 mg/mL, 3.125 mg/mL and 6.25 mg/mL, along with negative and positive controls, with eight replications. Subsequently, crystal violet quantification and absorbance value readings were done using an ELISA reader with a wavelength of 595 nm. 
 
Result: The results showed that between concentrations of 3.125 mg/mL, 6.25 mg/mL and the negative control, there was no significant difference with mean values of 0.09963, 0.078857 and 0.079375, respectively. Honeybee propolis extract has the potential to act as an antibiofilm against E. coli in vitro, with the minimum concentrations capable of inhibiting biofilm formation being 3.125 mg/mL and 6.25 mg/mL.

The Effect of Honeybee Propolis on Escherichia coli Biofilm Formation in vitro

Background: Cassia fistula L., a flowering plant of the leguminous family (Fabaceae), has been explored for its potential in synthesizing silver nanoparticles. This plant is known for its medicinal properties, making it a promising candidate for applications in nanobiotechnology. 
 
Methods: The researchers employed a combination of hot and cold extraction procedures to synthesize silver nanoparticles using seed extracts of C.fistula. The identity and characteristics of these nanoparticles were verified through various techniques, including chromatography, imaging microscopy, X-ray diffraction and scanning electron microscopy. Biological activities such as antioxidant and antibacterial properties were tested. For antioxidant activity, a reaction mixture consisting of 50 &mu;l of seed extract and 5 ml of a 0.04% (w/v) DPPH solution was used. Antibacterial activity was evaluated against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes at concentrations of 0.125, 0.25, 0.5 and 1 mg/ml of AgNPs. Additionally, the antibiofilm effect and hemolysis impact were studied. 
 
Result: The synthesized silver nanoparticles demonstrated significant biological activities, including antioxidant and antibacterial effects. The diameters of the zones of inhibition for P.aeruginosa at a concentration of 1 mg/ml were 20 mm for cold extract and 18 mm for E.coli using hot extract. These findings highlight the potential of C. fistula as a sustainable source for environmentally friendly nanomaterials, contributing to advancements in medical and environmental sciences. Finally, the use of silver nanoparticles from Cassia fistula encourages sustainable and productive agricultural practices, by improving plant health and yield, potentially revolutionizing agricultural methods. 
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Antimicrobial and Antibiofilm Activities of Methanol Leaf Extract of Citrus maxima against Clinical Isolates of Multidrug Resistant Staphylococcus aureus

Exploration of Antimicrobial, Antibiofilm and Antiquorum Sensing Activity of the Himalayan Yellow Raspberry (Rubus ellipticus) against Clinical Isolates of Escherichia coli and Staphylococcus aureus

In vitro Antimicrobial, Antibiofilm and Antiquorum Sensing Activity of Indian Rhododendron (Melastoma malabathricum) against Clinical Isolates of Escherichia coli and Staphylococcus aureus

Antimicrobial and Antibiofilm Activity of Cinnamon Oil on Staphylococcus aureus Isolated from Cattle Milk with Mastitis

​Efficacy of Resveratrol and Ursolic Acid on Biofilm Inhibition and Antimicrobial Resistance of Streptococcus uberis

The Effect of Honeybee Propolis on Escherichia coli Biofilm Formation in vitro

Bioactive Nanoparticles from Cassia fistula L. Seed Aqueous Extract: Assessment of Multiple Biological Activities

Efficacy of Resveratrol and Ursolic Acid on Biofilm Inhibition and Antimicrobial Resistance of Streptococcus uberis