Characteristics Of Antibiotic Action

Directly acting on bacterial cells

Antibiotics can selectively act on specific links of bacterial cell DNA, RNA and protein synthesis system, interfere with cell metabolism, hinder life activities or stop growth, or even die, which is different from non selective ordinary disinfectants or bactericides. Its antibacterial activity mainly shows three phenomena: bacteriostasis, sterilization and bacteriolysis. 

Selective antibiotic spectrum

The effect of antibiotics is selective, and different antibiotics have different effects on different pathogens. The type of pathogen sensitive to an antibiotic is called the antibiotic spectrum (antibacterial spectrum) of the antibiotic. It only has antibacterial effect on a single strain or genus, and such antibiotics are called narrow spectrum antibiotics. For example, penicillin only has inhibitory effect on gram-positive bacteria. It not only has an effect on bacteria, but also has an inhibitory effect on chlamydia, mycoplasma, rickettsia, spirochetes and protozoa. Such antibiotics are called broad-spectrum antibiotics, such as tetracyclines (chlortetracycline, oxytetracycline, etc.), which have an inhibitory effect on gram-positive and negative, rickettsia, and some viruses and protozoa. 

Effective concentration

Antibiotics are physiologically active substances. All kinds of antibiotics can generally act on pathogenic bacteria at very low concentrations, which is another major feature of antibiotics that distinguishes them from other chemical fungicides. The effective concentrations of various antibiotics to different microorganisms are different, and the minimum inhibitory concentration (MIC) is usually used as the antibacterial strength of antibiotics, referred to as the effective concentration. The lower the effective concentration, the stronger the antibacterial effect. The effective concentration above 100mg/L is the antibiotic with low action intensity, and the effective concentration below 1mg/L is the antibiotic with high action intensity. 

Selective toxicity

Antibiotics are less toxic to humans, animals and plants than microorganisms, which is called selective toxicity. It has specific antagonistic effect on sensitive microorganisms and has a strong effect. More than 10000 times of diluent still has significant bacteriostatic and bactericidal effects