Current Issue : October-December Volume : 2022 Issue Number : 4 Articles : 5 Articles
Methicillin-resistant Staphylococcus aureus (MRSA) has led to serious infections, especially in hospitals and clinics, where treatment and prevention have become more difficult due to the formation of biofilms. Owing to biofilm-derived antibiotic tolerance, the currently available traditional antibiotics have failed to treat MRSA infections. Hence, there is a urgent need to develop novel antibiotics for treating life-threatening MRSA infections. Lugdunin (cyclic peptide-1), a nonribosomal cyclic peptide produced by Staphylococcus lugdunensis, exhibits potent antimicrobial activity against MRSA. Amazingly, cyclic peptide-1 and its analogues cyclic peptide-11 and cyclic peptide-14 have the ability to disperse mature MRSA biofilms and show anti-clinical MRSA activity, including MRSA persister cells. In addition, these three cyclic peptide compounds have non-toxicity, lower hemolytic activity and lack of resistance development. Our results indicate that cyclic peptide-1, cyclic peptide- 11, and cyclic peptide-14 have great potential as new antimicrobial drug candidates for the treatment of clinical MRSA infections....
The spread of extended-spectrum β-lactamase-producing Escherichia coli and methicillinresistant Staphylococcus aureus has caused a reduction in antibiotic effectiveness and an increase in mortality rates. Essential oils (EOs), known for their therapeutic efficacy, can be configured as novel broad-spectrum biocides. Accordingly, the bacteriostatic–bactericidal activity of Citrus Lemon (LEO), Pinus Sylvestris (PEO), Foeniculum Vulgaris (FEO), Ocimum Basilicum (BEO), Melissa Officinalis (MEO), Thymus Vulgaris (TEO), and Zingiber Officinalis Rosc. (GEO), at concentrations ranging from 1.25 to 40% (v/v), were tested in vitro against different E. coli and S. aureus strains using minimal inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). The chemical compositions of the EOs were analyzed using GC/MS. The major components of all seven tested oils were limonene, α-pinene, anethole, estragole, citral, thymol, and zingiberene, respectively. We found that the bacteriostatic–bactericidal activity of the EOs was related to their chemotypes and concentrations, as well as the strain of the bacteria. A dose–effect correlation was found when testing GEO against S. aureus strains, whilst FEO was found to have no activity regardless of concentration. PEO, MEO, and BEO were found to have bactericidal effect with a MIC and MBC of 1.25% (v/v) against S. aureus strains, and LEO was found to have values of 1.25% (v/v) and 5% (v/v) against ATCC and clinical isolate, respectively. Interestingly, the antimicrobial activity of TEO was not related to oil concentration and the complete inhibition of growth across all E. coli and S. aureus was observed. Although preliminary, our data demonstrate the efficacy of EOs and pave the way for further investigations on their potential synergistic use with traditional drugs in the human and veterinary fields....
Microorganisms are one of the main sources of antimicrobial agents and over 50% of antibiotics currently used in hospitals are metabolites from microbes. This study aimed to isolate microorganisms from the Dompoase landfill site, Kwame Nkrumah University Physics Garden, Kosiko River, and Ada Foah seashore of Ghana and screen their metabolites for antimicrobial activity. Forty-eight (48) microorganisms were isolated and their metabolites were screened against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Vibrio cholerae, Salmonella typhi, Pseudomonas aeruginosa, Streptococcus pyogenes, Proteus mirabilis, and Candida albicans using the agar well diffusion method. Ten (10) of the isolates exhibited antimicrobial activity. Isolate DO5, identified as P. aeruginosa isolate, from the Dompoase landfill site was selected for fermentation because it exhibited the highest activity against all the test organisms. DO5 produced optimum antimicrobial activity when fermented for 11 days at 30°C. In the agar diffusion method, the extract of isolate DO5 recorded zones of inhibition ranging between 11.67 ± 0.23 and 21.50 ± 0.71 mm. The MIC and MBC recorded for the DO5 extract ranged from 3.13–25.0 mg/mL and from 6.25–50.0 mg/mL, respectively. Column chromatography analysis yielded eight (8) subfractions from the DO5 extract. IR analysis revealed the presence of functional groups such as alcohols, esters, and hydrocarbons in the fractions. GC-MS analysis identified nine compounds that have been reported to have antimicrobial agents. The DO5 metabolites stand the chance to be developed into potent antibiotics for infection treatment....
Investigation of the cytotoxic fractions of the ethyl acetate extract of the fermentation broth of the tunicate-derived Aspergillus sp. DY001 afforded two new dipeptides, asperopiperazines A and B (1 and 2), along with the previously reported compounds (+)-citreoisocoumarin (3) and (−)-6,8-di-O-methylcitreoisocoumarin (4). Analyses of the 1D and 2D NMR spectroscopic data of the compounds supported their structural assignments. Asperopiperazine A (1) is a cyclic dipeptide of leucine and phenylalanine moieties, which are substituted with an N-methyl and an N-acetyl group, respectively. On the other hand, asperopiperazine B (2) is a cyclic dipeptide of proline and phenylalanine moieties with a hydroxyl group at C-2 of the proline part. The absolute configuration of the amino acid moieties in 1 and 2 were determined by Marfey’s analyses and DFT NMR chemical shift calculations, leading to their assignment as cyclo(L-NMe-Leu-L-NAc-Phe) and cyclo(D-6-OHPro- L-Phe), respectively. Asperopiperazines A and B displayed higher antimicrobial effects against Escherichia coli and Staphylococcus aureus than Candida albicans. Furthermore, compounds 1–4 displayed variable growth inhibitory effects towards HCT 116 and MDA-MB-231 cells, with asperopiperazine A as the most active one towards HCT 116....
Antimicrobial resistance is a serious threat to global health, causing increased mortality and morbidity especially among critically ill patients. This toll is expected to rise following the COVID- 19 pandemic. Carbapenem-resistant Acinetobacter baumannii (CRAb) is among the Gram-negative pathogens leading antimicrobial resistance globally; it is listed as a critical priority pathogen by the WHO and is implicated in hospital-acquired infections and outbreaks, particularly in critically ill patients. Recent reports from Lebanon describe increasing rates of infection with CRAb, hence the need to develop concerted interventions to control its spread. We set to describe the impact of combining antimicrobial stewardship and infection control measures on resistance rates and colonization pressure of CRAb in the intensive care units of a tertiary care center in Lebanon before the COVID-19 pandemic. The antimicrobial stewardship program introduced a carbapenem-sparing initiative in April 2019. During the same period, infection control interventions involved focused screening, monitoring, and tracking of CRAb, as well as compliance with specific measures. From January 2018 to January 2020, we report a statistically significant decrease in carbapenem consumption and a decrease in resistance rates of isolated A. baumannii. The colonization pressure of CRAb also decreased significantly, reaching record low levels at the end of the intervention period. The results indicate that a multidisciplinary approach and combined interventions between the stewardship and infection control teams can lead to a sustained reduction in resistance rates and CRAb spread in ICUs....
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