Investigating the Antimicrobial Effects of a Novel Peptide Derived From Listeriolysin S on S aureus, E coli, and L plantarum: An In Silico and In Vitro Study.

Aims: The emergence of antibiotic resistance is one of the most significant issues today. Modifying antimicrobial peptides (AMPs) can improve their effects. In this study, the active region of Listeriolysin S (LLS) as a peptidic toxin has been recognized, and its antibacterial properties have been evaluated by modifying that region. Methods: After extracting the sequence, the structure of LLS was predicted by PEP-FOLD3. AntiBP and AMPA servers identified its antimicrobial active site. It was modified by adding arginine residue to its 3- and N-terminal regions. Its antimicrobial properties on Staphylococcus aureus, Escherichia coli, and Lactobacillus Plantarum were estimated. Findings: The results of AntiBP and AntiBP servers demonstrated that a region of 15 amino acids has the most antimicrobial properties (score = 1.696). After adding arginine to the chosen region, the physicochemical evaluation and antimicrobial properties revealed that the designed peptide is a stable AMP with a positive charge of 4, which is not toxic to human erythrocyte cells and has antigenic properties. The results of in vitro and colony counting indicated that at different hours, it caused a significant reduction in the count of S aureus, E coli, and L Plantarum compared with the control sample. Conclusions: Upcoming research implies that identifying and enhancing the active sites of natural peptides can help combat bacteria.

Investigating the effects of zinc oxide and titanium dioxide nanoparticles on the formation of biofilm and persister cells in Klebsiella pneumoniae.

The biofilm formation in klebsiella pneumoniae isolates poses a significant problem as it can result in treatment failure and the development of chronic infections. These biofilms act as protective barriers, rendering the bacteria resistant to antibiotics. Additionally, persister cells, which make up a small fraction of the bacterial population, have the ability to enter a dormant state after treatment with high doses of antibiotics. These persister cells play a crucial role in the high level of biofilm-mediated tolerance to antibiotics. The present study aimed to investigate the impact of Zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles on the formation of biofilm and persister cells in K. pneumoniae. The minimum inhibitory concentration (MIC) of colistin in K. pneumoniae ATCC 13883 was determined using the microdilution method. The formation of persister cells was evaluated by introducing sub-MIC of colistin. Subsequently, the MIC of ZnO NPs and TiO2 NPs in these persister cells was assessed using the microdilution method. Furthermore, the effects of nanoparticles on the expression levels of biofilm-associated genes were analyzed using real-time polymer chain reaction (PCR). The MIC values for colistin, ZnO, and TiO2 were determined at 2, 12.5, and 6.25 µg/mL, respectively. In the presence of nanoparticles, biofilm formation decreased. Real-time PCR results showed the messenger RNA (mRNA) level of mrkH and fimH were decreased and the expression of luxS and mazF were increased. Biofilm formation of K. pneumoniae ATCC 1383 was inhibited in response to nanoparticles. According to the results of the present study use of nanoparticles may help control multidrug-resistant (MDR) infections in hospitalized patients.

Tetracyclines resistance in Mycoplasma and Ureaplasma urogenital isolates derived from human: a systematic review and meta-analysis.

BACKGROUND: Urogenital Mycoplasma infections are considered an important public health problem, owing to the presence of antibiotic resistance or decreased susceptibility, the treatment options are limited. OBJECTIVE: Therefore, this meta-analysis aimed to estimate resistance rates of genital Mycoplasmas to tetracyclines (tetracycline, doxycycline, and minocycline). METHODS: We searched the relevant published studies in PubMed, Scopus, and Embase until 3, March 2022. All statistical analyses were carried out using the statistical package R. RESULTS: The 26 studies included in the analysis were performed in 15 countries. In the metadata, the proportions of tetracycline, doxycycline, and minocycline resistance in Mycoplasma and Ureaplasma urogenital isolates were reported 14.2% (95% CI 8.2-23.2%), 5% (95% CI 3-8.1%), and 11.9% (95% CI 6.3-21.5%), respectively. According to the meta-regression, the tetracycline and minocycline resistance rate decreased over time. Although, the doxycycline resistance rate increased over time. There was a statistically significant difference in the tetracyclines resistance rates between different continents/countries (P < 0.05). CONCLUSION: The prevalence rate and antibiotic susceptibility profiles vary geographically. Therefore, rigorous or improved antimicrobial stewardship, contact tracing, and enhanced intensive surveillance systems are necessitated for preventing the emergence and further spreading of tetracyclines resistance in genital Mycoplasmas.