In Vitro and In Vivo Anti-Candida albicans Activity of a Scorpion-Derived Peptide.

The increasing infection and drug resistance frequency has encouraged the exploration of new and effective anti-Candida albicans agents. In this study, CT-K3K7, a scorpion antimicrobial peptide derivative, effectively inhibit the growth of C. albicans. CT-K3K7 killed C. albicans cells in a dose-dependent manner, mainly by damaging the plasma membrane. CT-K3K7 could also disrupt the nucleus and interact with nucleic acid. Moreover, CT-K3K7 induced C. albicans cells necrosis via a reactive oxygen species (ROS)-related pathway. Furthermore, CT-K3K7 inhibited the hyphal and biofilm formation of C. albicans. In the mouse skin subcutaneous infection model, CT-K3K7 significantly prevented skin abscess formation and reduced the number of C. albicans cells recovered from the infection area. Taken together, CT-K3K7 has the potential to be a therapeutic for C. albicans skin infections.

Antifungal efficacy of scorpion derived peptide K1K8 against Candida albicans in vitro and in vivo.

As an alternative class of antimicrobial agents, antimicrobial peptides (AMPs) have gained significant attention. In this study, K1K8, a scorpion AMP derivative, showed effective activity against Candida albicans including clinically resistant strains. K1K8 killed C. albicans cells mainly by damaging the cell membrane and inducing necrosis via an ROS-related pathway. K1K8 could also interact with DNA after damaging the nuclear envelope. Moreover, K1K8 inhibited hyphal development and biofilm formation of C. albicans in a dose-dependent manner. In the mouse skin infection model, K1K8 significantly decreased the counts of C. albicans cells in the infection area. Overall, K1K8 is a potential anti-infective agent against skin infections caused by C. albicans.

Transcriptome analysis of sRNA responses to four different antibiotics in Pseudomonas aeruginosa PAO1.

A large number of evidence showed that regulatory sRNAs could modulate antibiotic resistance and sensitivity. In this study, we used RNA-sequencing to profile sRNAs in wild type and antibiotic-resistant PAO1 selected by four antibiotics (polymyxin B, ciprofloxacin, doxycycline, and ceftriaxone). Totally, we found 113, 25, 91 and 12 differentially expressed sRNAs in polymyxin B-, ciprofloxacin-, doxycycline-, and ceftriaxone-resistant P. aeruginosa, respectively. To elucidate functions of differentially expressed sRNA, we predicated their target genes and obtained pathways enriched by their target genes. In addition, our results indicated that the downregulated sRNA spae884.1, spae3443.1, and spae5681.1 might involve in polymyxin B resistance by enhancing their target genes arnA, arnD, and arnT expression in PAO1, respectively. The upregulated sRNA spae3443.1 and spae649.2 might implicate in ciprofloxacin resistance by promoting their target gene pslK expression to increase biofilm formation in PAO1. The upregulated spae1558.1 might increase oprJ expression, as well as spae3959.1 and spae3706.1 might increase mexC expression to modulate doxycycline resistance in PAO1. The sRNA novel-N714 might involve in virulence in ceftriaxone-resistant PAO1 by activating its target gene PA1429 expression. Our study might provide bases of the underlying mechanism of sRNA in regulating antibiotic resistance of PAO1 against different antibiotics.

Antimicrobial activity of CT-K3K7, a modified peptide by lysine substitutions from ctry2459 - A Chaerilus tryznai scorpion venom peptide.

Antimicrobial peptides (AMPs) have started to garner more interest as novel antimicrobial agents. The scorpion venom peptide ctry2459 was modified to CT-K3K7 by lysine substitutions at the 3rd and 7th positions to increase the cationic properties. We discovered that the modified peptides CT-K3K7 had improved antibacterial activity, higher thermal stability, as well as lower hemolytic activity. It can kill S. aureus and P. aeruginosa rapidly, and reduce the production of biofilm and live bacterial residues in biofilm in vitro. CT-K3K7 has also been demonstrated to decrease bacterial counts, abscess area, and inflammatory cell infiltration in the mouse subcutaneous abscess models that were duplicated by S. aureus and P. aeruginosa. CT-K3K7 has difficulty in inducing S. aureus and P. aeruginosa to develop drug resistance, which may be related to the bactericidal properties. CT-K3K7 increases cationic properties by lysine substitutions can increase the electrostatic force between the peptides and the bacterial surface, which can lead to an increase in bacterial membrane permeability and DNA binding. In conclusion, the modified peptide CT-K3K7 enhances the antimicrobial activity and can be a novel antimicrobial agent candidate for the treatment of infections by S. aureus and P. aeruginosa.

In vitro and in vivo Activity of Phibilin Against Candida albicans.

The increase in the occurrence of antifungal-resistant Candida albicans infections necessitates more research to explore alternative effective and safe agents against this fungus. In this work, Phibilin, a new antimicrobial peptide obtained from Philomycus bilineatus and used in traditional Chinese medicine, effectively inhibits the growth and activities of C. albicans, including the clinical resistant strains. Phibilin is a fungicidal antimicrobial peptide that exhibited its antimicrobial effect against C. albicans mainly by disrupting the membrane and interacting with the DNA of the fungi. In particular, Phibilin induces the necrosis of C. albicans via the ROS-related pathway. Moreover, this antifungal compound inhibited the biofilm formation of C. albicans by preventing the development of hyphae in a dose-dependent manner. Furthermore, Phibilin and clotrimazole displayed a synergistic effect in inhibiting the growth of the fungi. In the mouse cutaneous infection model, Phibilin significantly inhibited the formation of skin abscesses and decreased the counts of C. albicans cells in the infected area. Overall, Phibilin is potentially an effective agent against skin infections caused by C. albicans.