Minimum growth inhibitory concentration

Fig. 11.9 Isobologram ( - ) drawn from minimum growth inhibitory concentrations (MIC values) of chlorocresol and phenylmercuric acetate used alone and in combination against Staph, aureus, showing synergy. A, result if combination was merely additive B, result if combination was antagonistic.

A mode of action study of azalomvcin P on Candida adbicans indicates that at its minimum growth inhibitory concentration the antibiotic strongly inhibited amino acid incorporation into cellular protein and prevented generally the substrate respiration of amino acids.This same article contains a brief bibliography of mode of action studies on antifungal... 

Activities are expressed as minimum inhibitory concentration (MIC, pg mL ) defined as the lowest concentration required for complete inhibition of growth of bacterial strain. 

Graded doses ofthe test substance are incorporated into broth dispensed in McCartney boules and the bottles inoculated with the test organism and incubated. The point at which no growth occurs is taken as the bacteriostatic concentration (minimum inhibitory concentration, MIC). It is essential when performing these tests to determine the size of the inoculum as the position of the end-point varies considerably with inoculum size, which should always be defined in any description of result. 

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. 

Minimum inhibitory concentration The lowest concentration of a drug that will visually inhibit the growth of a microorganism. 

The values reported In Table III represent readings taken after incubation times of 24 hr for all organisms except M. smegmatis. which was read at 72 hr. The concentration of the tube of highest dilution that was free from growth was recorded as the minimum inhibitory concentration (micrograms per milliliter). 

The microdilution method was employed for antibacterial and antifungal activity tests. Media were placed into each well of the 96 well-microplate. Extract solutions at 1,024 pg/ml were added into first raw of microplates and twofold dilutions of the compounds (512-0.25 pg/ml) were made by dispensing the solutions to the remaining wells. Ten microliters of culture suspensions were inoculated into all the wells. The sealed microplates were incubated at 35°C for 24 and 48 h in humid chamber. The lowest concentration of the extracts that completely inhibit macroscopic growth was determined and minimum inhibitory concentrations (MICs) were... 

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. 

Figure 10. Microcalorimetric growth experiments with Escherichia coli in the presence of antibiotics (1.6 pg/ml = twice the minimum inhibitory concentration), added at the time indicated by the arrow, a, tetracycline b, doxycycline 0, control experiment. Obviously doxycycline suppressed the growth more efficiently than tetracycline. Adapted from Mcirdh et al. (1976).

Molnar, Beladii, and Foldes [69] studied antimycobacterial activity of five phenothiazine derivatives including chlorpromazine, levomeprazine, promazine, promethazine, and diethazine. The growth of Mycobacterium tuberculosis, Mycobacterium bovis, and Mycobacterium butyricum was found to be inhibited by chlorpromazine at practically identical concentrations. The minimum inhibitory concentrations for Mycobacterium tuberculosis were chlorpromazine and levomeprazine 10 xg/ml diethazine and promethazine 20 xg/ml whilst chlorpromazine sulphoxide was ineffective even at 100 xg/ml. Chlorpromazine and promethazine exerted a measurable bactericidal activity on Mycobacterium tuberculosis at 50 xg/ml total destruction of the organism and loss of acid fastness in part of the cells were shown at 300 xg/ml. Preliminary studies in mouse experiments revealed that phenothiazine derivatives were ineffective. 

In the laboratory, the relationship between an antimicrobial drug and a pathogen is described by the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The MIC is the lowest drug concentration that inhibits bacterial growth. The MBC is the lowest drug concentration that kills 99.9% of the bacteria. 

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