Antimicrobials minimum inhibitory concentration

The minimum inhibitory concentration (MIC) is the lowest concentration of an antimicrobial agent that prevents growth. The lower the MIC value, the more active the agent. 

The goal of antimicrobial dosing for surgical prophylaxis is to maintain antibiotic concentrations above the minimum inhibitory concentration (MIC) of suspected organisms for the duration of the operation. 

To compare the bactericidal efficacy of silver nanoparticles and silver ions, the minimum inhibitory concentration (MIC) assays were conducted for gram-negative bacterium E. coli, gram-positive bacteria S. aureus and B. subtilis and fungus P. phoeniceum. The data on MICs are summarized in Table 18.1. The results demonstrated that the antimicrobial activity of silver ions was superior to that of silver nanoparticles against all microbes tested. 

The activity of penicillin G was originally defined in units. Crystalline sodium penicillin G contains approximately 1600 units per mg (1 unit = 0.6 meg 1 million units of penicillin = 0.6 g). Semisynthetic penicillins are prescribed by weight rather than units. The minimum inhibitory concentration (MIC) of any penicillin (or other antimicrobial) is usually given in mcg/mL. Most penicillins are dispensed as the sodium or potassium salt of the free acid. Potassium penicillin G contains about 1.7 mEq of K+ per million units of penicillin (2.8 mEq/g). Nafcillin contains Na +, 2.8 mEq/g. Procaine salts and benzathine salts of penicillin G provide repository forms for intramuscular injection. In dry crystalline form, penicillin salts are stable for years at 4°C. Solutions lose their activity rapidly (eg, 24 hours at 20°C) and must be prepared fresh for administration. 

Table 9. Antimicrobial activity of compounds 11 and 49-53 Minimum Inhibitory Concentration, Minimum Bactericidal Concentration is reported in parentheses (fig/ml)...

The fact that an accurate animal model does not exist has not precluded the use of other systems to make estimates of the potential of residues to select for resistance. In the absence of in vivo data, in vitro data such as the minimum inhibitory concentrations (MIC) may be used, on a temporary basis, for safety evaluations. Tire MIC has been defined as the minimum concentration of an antimicrobial drug giving complete inhibition of growth of a particular microorganism, as judged by the naked eye after a given period of incubation. 

In vitro antimicrobial spectrum of TC as minimum inhibitory concentration in jug/ml can be given as following (89a) ... 

ADME-tox absorption, distribution, metabolism, and excretion/toxicologic properties ECS0 median effective concentration IC50 median inhibitory concentration MIC minimum inhibitory concentration MLSMR Molecular Libraries Small Molecule Repository TAACF-NIAID Tuberculosis Antimicrobial Acquisition and Coordinating Facility/ National Institute of Allergy and Infectious Diseases... 

Cinnamon oil and extracts possess various antimicrobial activities against several bacteria, fungi, etc. Aqueous extract from cinnamon (C. zeylanicum, Blume) inhibited the replication of the influenza virus (Mancini et al., 1999). Oral administration of t-cinnamaldehyde and Omethoxycinnamaldehyde inhibited candidiasis at a MIC (minimum inhibitory concentration) value of 0.03-0.05 mg/ml. 

The importance of tissue penetration varies with the site of infection. The CNS is one body site where the importance of antimicrobial penetration is relatively well defined and correlations with clinical outcomes are established. Drugs that do not reach significant concentrations in cerebrospinal fluid should either be avoided or instilled directly when treating meningitis. Apart from the bloodstream, other body fluids where drug concentration data are clinically relevant include urine, synovial fluid, and peritoneal fluid. Pharmacokinetic parameters such as area under the concentration-time curve (AUC) and maximal plasma concentration can be predictive of treatment outcome when specific ratios of AUC or maximal plasma concentration to the minimum inhibitory concentration (MIC) are achieved. For... 

Antimicrobial activity optimum antimicrobial activity occurs between pH 4-10. Preservative efficacy is enhanced by ethanol and reduced by soaps and other anionic surfactants. For typical minimum inhibitory concentrations (MICs) see Table II.< >... 

Antimicrobial activity potassium sorbate is predominantly used as an antifungal preservative although it also has antibacterial properties. Similarly to sorbic acid, the antimicrobial activity is dependent on the degree of dissociation there is practically no antibacterial activity above pH 6. Preservative efficacy is increased with increasing temperature, and increasing concentration of potassium sorbate. The efficacy of potassium sorbate is also increased when used in combination with other antimicrobial preservatives or glycols since synergistic effects occur. Reported minimum inhibitory concentrations (MICs) at the pH values indicated are shown in Table... 

The maximum plasma concentration reflects the extent of drug bioavailability. It can be used in relation to minimum inhibitory concentration (MIC) to predict the efficacy of concentration-dependent antimicrobial agents (e.g. fluoroquinolones, aminoglycosides). Both the maximum (peak) and minimum (trough) plasma concentrations are used during therapeutic drug monitoring to maximize efficacy and minimize the occurrence of undesirable effects. 

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