Objective Silybin and curcumin have potential antimicrobial effects. This study aimed to evaluate the synergistic antimicrobial effects of silybin and curcumin on virulence and carbapenemase genes expression among multidrug-resistant (MDR) Klebsiella oxytoca. Results A total of 70 MDR K. oxytoca (carrying blaIMP and blaOXA-48-like genes) were included. The antibiotic susceptibility and biofilm production of isolates were determined. The silybin and curcumin at concentrations 10–500 mg/mL alone and in combination were exposed to bacterial isolates in Mueller Hinton broth medium for 24 h. The expression of blaIMP, blaOXA-48-like, mrkA, pilQ, matB and fimA genes was evaluated using quantitative real-time polymerase chain reaction (qRT-PCR). The mean minimum inhibitory concentration (MIC) of curcumin and silybin were 250 mg/mL and 500 mg/mL, respectively. The anti-virulent effect of 100 mg/mL of silybin and curcumin was shown by significant reduction in the expression of fimA (2.1-fold, P < 0.0001) and mrkA (2.1 fold, P < 0.0001) genes. Moreover, these compounds significantly decreased the expression of blaIMP1 (3.2-fold, P < 0.0001) gene. Notably, there was no significant effect on pilQ, matB and blaOXA-48-like genes. The results showed that silybin and curcumin can be candidate as natural way for control the MDR virulent strains of K. oxytoca.

The present investigative study revealed the inhibitory effect of Alternaria isolates on selectively tested gram-positive and negative bacteria used in this study. Isolate-4 was distinguished by its ability to induce the highest inhibitory effect among the four isolates on E. coli bacteria, followed by isolation-2 as the inhibitory diameter of two isolates was (14 and 10.5) respectively, while the inhibitory diameter of the two isolates (4 and 2) was less. Effect on Proteus Vulgaris bacteria by reaching the inhibitory diameter of 12 mm to isolate-4, followed by isolate-2, isolate-3 and finally isolation-1, as it reached respectively (11.5, 9 and 7) mm, while no significant effect was observed for the four isolates on Bacillus substiles except for the two isolates (3 and 1), they had a clear effect, as it reached a diameter Inhibition (7 and 9), while no effect on staphylococcus aureus was observed.

The present study has shown the screening test of Hawthorn fruits (Crataegus spp.) using crude hydroalcoholic extract and in vitro antimicrobial activity of extracted flavonoid which has shown more antibacterial activity than crude extract with minimal inhibitory concentration (MIC) values ranged from 5% to 2.5%. The amount of total flavonoid and antioxidant activity of Hawthorn fruits (Crataegus spp) in various concentration extracts and antioxidant activities of different concentration extracts were determined by radical scavenging by 2, 2-diphenyl-1-picrylhydrazyl (DPPH • ). The output showed that the contents of flavonoid were found to be 0.386 mg quercet in equivalents (QUE/g). Dried extract displayed remarkable antioxidant activity according to (DPPH • ) assays.

Microbial biofilms are collections of grouped microbial cells enmeshed in an extracellular polymeric substances (EPS) matrix that they have self-assembled. Biofilms are resistant to harsh environments and can serve as "protective clothing" for bacteria by shielding them from ultraviolet (UV) radiation, extreme temperatures, pH ranges, high salinity, high pressure, inadequate nutrition, antibiotics, etc. Research on biofilms in recent years has mostly concentrated on biofilm-associated illnesses and methods for eradicating microbial biofilms.