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Infectious Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Susanna J. Dunachie, Hanif Esmail, Ruth Corrigan, Maria Dudareva
There are two important concepts in understanding antibacterial chemotherapy: Minimum inhibitory concentration (MIC): The lowest concentration at which the growth of the organism is inhibited. The concentration of antimicrobials at the site of the infection should exceed the MIC.Minimum bactericidal concentration (MBC): The lowest concentration at which the organism is killed. Some antimicrobials are not bactericidal (kill bacteria) but are only bacteriostatic (prevent growth of bacteria but do not kill).
Saussurea costus (Kust) and Senna alexandrina (Senna)
Published in Azamal Husen, Herbs, Shrubs, and Trees of Potential Medicinal Benefits, 2022
Amita Dubey, Soni Gupta, Mushfa Khatoon, Anil Kumar Gupta
Several reports show antibacterial activity of leaves and pods of S. alexandrina (Selim et al., 2013; Al Saiym et al., 2015). The extracts of pods of S. alexandrina showed high antibacterial activity against gram-positive and gram-negative bacteria, including Listeria monocytogenes (clinical isolate), Staphylococcus aureus (ATCC 6538), Bacillus cereus (ATCC 14579), Micrococcus flavus (ATCC 10240), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (ATCC 35210). The minimum inhibitory (MIC) and bactericidal concentration (MBC) ranged from 0.02 to 0.12 mg/mL and 0.04 to 0.29 mg/mL, respectively (Elansary et al., 2018). Ahmed et al. (2016) tested the antibacterial activity of Senna aqueous and organic extracts against Acinetobacter junii IARS2, Enterobacter cloacae IARS7, Pseudomonas aeroginosa IARS8, Salmonella typhi ATCC 14079, and Serratia mercescens IARS6 and found the highest bactericidal activity against S. mercescens in the ethyl acetate extract. Methanol extract showed inhibitory effects against all bacterial strains tested whereas aqueous extract was ineffective against A. junni, E. cloacae, and P. aeroginosa. Significant antibacterial activity against some human pathogenic bacteria, E. coli, Klebsiella pneumoniae, and Shigella shinga has been reported by Bameri et al., 2013. Antibacterial potential of n-butanol extract of Senna against S. aureus and typhi was also reported by Gnanavel et al. (2012).
Hirak Bhasma: A Potential Ayurvedic Antibacterial Drug Assessed by In Vitro Pre-Clinical Studies
Published in P. Mereena Luke, K. R. Dhanya, Didier Rouxel, Nandakumar Kalarikkal, Sabu Thomas, Advanced Studies in Experimental and Clinical Medicine, 2021
Sutapa Som Chaudhury, Bhuban Ruidas, Prasanta Kumar Sarkar, Chitrangada Das Mukhopadhyay
The in vitro antibacterial ability of the HB was appraised using the disc diffusion method following the protocol by Zaidan et al. [20]. HB extract was tested (at 25 µg/ml–10 mg/ml) against clinically isolated E. coli, S. aureus, and C. intermedia by incubating them at 37°C for 24 h in LB agar and yeast extracts peptone dextrose (YPD) agar (HiMedia Laboratories, India), respectively keeping ampicillin as the positive control. Broth turbidimetric analyses were performed following a modified method by Berridge and colleagues to determine minimal inhibitory concentration (MIC) via the measurement of OD600 [21]. From the tubes where the respective cultures were first inhibited (determined by the absence of visible growth) by HB a 100 µl broth was taken and spread on a fresh LB agar plate each. Thus, the minimal bactericidal concentration (MBC) was determined. In addition, a bacterial cell viability assay was performed with an improved MTT assay, i.e., 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay (MTT assay kit, Invitrogen, Thermo Fisher Scientific Corporation) [22].
Impact of chronic medications in the perioperative period: mechanisms of action and adverse drug effects (Part I)
Published in Postgraduate Medicine, 2021
Ofelia Loani Elvir-Lazo, Paul F White, Hillenn Cruz Eng, Firuz Yumul, Raissa Chua, Roya Yumul
Preoperative antibiotic prophylaxis is a common clinical practice to reduce postoperative infections, shorten the length of the hospital stay, and reduce health care costs [45]. Antibiotics and anesthetic drugs are often administered concurrently despite limited knowledge of their interactions. Antibiotics are usually organized into one of the two main categories, namely bactericidal, or bacteriostatic, based on their effect on bacteria. Minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) are used to define their level of bacteriostatic and/or bactericidal activity. Bacteriostatic is defined as having an MBC-to-MIC ratio greater than 4, and bactericidal is defined as a ≥ 99% reduction in viable bacterial density in an 18–24-hour period (an MBC-to-MIC ratio less than or equal to 4) [46,47].
Antimicrobial properties of rosin acids-loaded nanoparticles against antibiotic-sensitive and antibiotic-resistant foodborne pathogens
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Elisa Santovito, José das Neves, Donato Greco, Vito D’Ascanio, Bruno Sarmento, Antonio Francesco Logrieco, Giuseppina Avantaggiato
To determine the minimum inhibitory concentration (MIC) the microtitre broth dilution method [24] was used, with the workflow proposed by Wiegand et al. [25]. Antimicrobials were tested in two-fold dilution series in the range of 0.01–0.4% w/v (125–4000 mg/L) for RA, and 0.65–10% v/v for the suspension of RA-NPs (containing 30–430 mg/L of RA). A final concentration of ca. 5 × 105 CFU/mL per well was used for each tested bacterium. Growth controls and blanks were obtained as described above. Plates were incubated at 37 °C for 24 h in the required conditions. Growth was monitored by analyzing the turbidity in each well using a microtiter plate reader as described above. The cell viability was confirmed by resazurin staining [26]. The experimental MIC (MICe) is the concentration of the higher dilution well in which the absence of bacterial growth occurred, with no visible turbidity and no significant change in the OD600nm value, and a blue staining observed after resazurin addition. The minimum bactericidal concentration (MBC) was determined as the highest dilution at which no growth occurred in media. MBC was confirmed by plate counting. Each test was replicated in three wells, while three independent experiments were repeated in different days.
Engineering of polymer–surfactant nanoparticles of doxycycline hydrochloride for ocular drug delivery
Published in Drug Delivery, 2015
Varsha Pokharkar, Vikram Patil, Leenata Mandpe
The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by microdilution or serial dilution method. Briefly, E. coli and S. aureus bacterial culture containing 0.5 McFarland (1.5 × 108 CFU/ml) of organisms in Luria broth was added to various concentrations of DXY aqueous solution and DNPs (1–8 µg/ml). The MIC concentration of DXY was defined as the lowest concentration inhibiting visible growth of bacteria after overnight incubation of the cultures at 37 °C. The MBC is measured by subculturing the broths used for MIC determination onto fresh agar plates. The MBC is the lowest concentration of a drug that results in killing 99.9% of the bacteria being tested.