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Spices as Eco-friendly Microbicides: From Kitchen to Clinic
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
The main purpose of using combinations of plant secondary metabolites with antibiotics is to increase the antimicrobial effect against the target pathogen. Although different methods are available for detecting the interactions between plant extracts/essential oils, the checkerboard technique is a method of choice. In this in vitro method concentrations of one substance are arranged horizontally and concentrations of another substance are arranged vertically in 96-well broth microdilution tray. Fractional Inhibitory Concentration Index (FICI) is then calculated and interaction of two antimicrobials is interpreted as synergistic, additive and antagonistic with FICI values of ≤ 0.5, > 0.5 and ≤ 2 and > 2 respectively (Table 5.5).
Antifungal Drugs and Susceptibility Testing of Fungi
Published in Rossana de Aguiar Cordeiro, Pocket Guide to Mycological Diagnosis, 2019
Débora de Souza Colares Maia Castelo-Branco, Glaucia Morgana de Melo Guedes, Marcos Fábio Gadelha Rocha
The same systems used for the phenotypical identification of fungal species, such as the Vitek 2 System (BioMérieux, France), can also be used to evaluate the antifungal susceptibility of the isolates. These devices are only able to identify and analyze yeast isolates belonging to the species they contain in their database. Thus, they can reliably perform antifungal susceptibility assay with Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata, and Candida krusei, and few others. The methodology applied by these devices is a broth microdilution using only three to five drug concentrations for each tested drug, which allows the evaluation of fungal growth inhibition and estimation of MIC values. These analyses are performed in manufactured cards or panels, which contain the drugs to be tested, that is, amphotericin B, flucytosine, fluconazole, voriconazole, caspofungin, and micafungin. The results are then released as MIC values, followed by the susceptibility category (S, I, or R) and epidemiological category (WT or NWT). These automated methods are very practical for the most prevalent yeast pathogens, but their major drawback is the lack of flexibility to perform the assays, as the tested species must be in the system database and the products and reagents used are developed, industrialized, and supplied by the companies.
Microbiological Diagnosis of Fungal Infections
Published in Nancy Khardori, Bench to Bedside, 2018
Gagandeep Singh, Immaculata Xess
Although the broth microdilution method by the CLSI is the recommended method for the susceptibility testing of yeasts and molds, it is expensive, demands technical expertise and is labor intensive. Automated systems can be used to perform susceptibility testing of yeasts. There are a few centers which use the disk diffusion method/E-test.
Effects of Calendula officinalis and Capsicum annum glycolic extracts on planktonic cells and biofilms of multidrug-resistant strains of Klebsiella pneumoniae and Pseudomonas aeruginosa
Published in Biofouling, 2023
Ana Luiza do Rosário Palma, Pamela Beatriz do Rosário Estevam dos Santos, Thais Cristine Pereira, Maria Cristina Marcucci, Alexandra Cristina Helena Frankland Sawaya, Luciane Dias de Oliveira
To determine the antimicrobial activity, the broth microdilution assay recommended by the Clinical and Laboratory Standards Institute (CLSI, M7–A6) was used. Bacteria were reactivated and microbial suspensions were prepared in sterile saline solution (NaCl 0.9%) with turbidity adjusted to 106 colony forming units per milliliter (CFU ml−1) in a spectrophotometer (Micronal, São Paulo, SP, Brazil). 96-well plates were used to perform the broth microdilution tests. For this, 100 µL of Mueller Hinton Broth (Himedia) was added to 10 wells, then 100 µL of glycolic extract (C. officinalis L. or C. annum) were added and serial dilutions (1:2) were performed sequentially until 10 decreasing concentrations were obtained. After that, 100 µL of bacterial suspension was added to all wells. After dilution of the extracts, the plates were incubated for 24 h (37 °C) to determine the minimum inhibitory concentration (MIC) of the evaluated extracts. To obtain the minimum bactericidal concentration (MBC), an aliquot containing 10 µL of the contents of each of the wells of the microdilution plates was transferred to BHI agar and incubated for 48 h (37 °C). MBC was determined as the lowest concentration without any colonial growth. All assays were performed in duplicate.
Jumping into the future: overcoming pharmacokinetic/pharmacodynamic hurdles to optimize the treatment of severe difficult to treat-Gram-negative infections with novel beta-lactams
Published in Expert Review of Anti-infective Therapy, 2023
The use of a precise MIC value may not always be appropriate for guiding antibacterial dosing because of imprecise and highly variable measurements associated with MIC determination, especially when using automated testing methods [47]. Broth microdilution is the most accurate method and is the reference standard for antimicrobial susceptibility testing according to both the European Committee for Antimicrobial Susceptibility Testing (EUCAST) and the Clinical and Laboratory Standards Institute (CLSI). Precise MIC values should be regarded as an estimate of pathogen’s susceptibility, and TDM-guided dosing adjustments should take care of any potential MIC variation [20]. Potential solutions for counteracting the issue of MIC imprecision could be the adoption a MIC value increased by twofold dilutions as referral MIC for PK/PD analysis [47].
Evaluation of association between parameters related to penetration into cerebrospinal fluid and the microbiological efficacy of vancomycin in patients with bacterial meningitis
Published in Journal of Chemotherapy, 2022
Masayuki Ishikawa, Masashi Uchida, Shingo Yamazaki, Yuki Shiko, Yohei Kawasaki, Takaaki Suzuki, Yasuo Iwadate, Itsuko Ishii
VMser and VMCSF were measured by a chemiluminescence immunoassay with an ARCHITECT® analyzer (Abbott Laboratories, Irving, TX). The method was fully validated over a concentration range of 3.0–100.0 μg/mL. The lower limit of quantification and the lower limit of detection were 3.0 μg/mL and 0.24 μg/mL, respectively. SA concentrations were measured by the bromocresol green or bromocresol purple method. The SA value measured by the bromocresol green method is known to be about 0.3 mg/dL higher than that measured by the bromocresol purple method. Therefore, if the SA was measured by the bromocresol green method, we subtracted 0.3 mg/dL from the measured value based on the guidelines [14]. CSF proteins and CSF glucose concentrations were measured by the pyrogallol red and hexokinase methods, respectively. CSF cell counts were performed manually. The MIC for bacteria was determined via the broth microdilution method of the Clinical and Laboratory Standards Institute. Creatinine clearance was calculated by the Cockcroft–Gault formula, using actual body weight [15].