Antimicrobial agents generally refer to drugs with bactericidal or antibacterial activity, including various antibiotics, sulfonamides, imidazoles, nitroimidazoles, quinolones and other chemical synthetic drugs. Some products obtained by culturing bacteria, actinomycetes, fungi and other microorganisms, or the same or similar substances produced by chemical semi synthesis method, can also be chemically synthesized.
Antimicrobial agents generally refer to drugs with bactericidal or antibacterial activity, including various antibiotics, sulfonamides, imidazoles, nitroimidazoles, quinolones and other chemical synthetic drugs. Some products obtained by culturing bacteria, actinomycetes, fungi and other microorganisms, or the same or similar substances produced by chemical semi synthesis method, can also be chemically synthesized. Antibiotics can inhibit and kill pathogens at a certain concentration.
Antibiotics are mainly divided into eight categories, of which β— Lactams include penicillins, cephalosporins, carbapenems and enzymes containing inhibitors β— Lactams and monocyclic amides; Aminoglycosides; Tetracyclines; Fluoroquinolones; Folate pathway inhibitors; Chloramphenicol; Glycopeptides include vancomycin and teicoplanin; Macrolides. Rational use of antibiotics should be chosen according to different infectious diseases.
Antibacterial activity of common antibiotics:
Penicillin: gram positive bacteria and gram negative cocci, Haemophilus, various pathogenic spirochetes and most bovine actinomycetes. Classification: Penicillin G, phenoxypenicillin, enzyme resistant penicillin (oxacillin), broad-spectrum penicillin (ampicillin, piperazine penicillin), penicillin acting on Gram-negative bacteria (mexicillin and temoxicillin).
Cephalosporin: it has strong antibacterial effect, resistance to penicillin enzyme, high clinical efficacy, low toxicity and less allergic reaction. It can be divided into three generations: the first generation is mainly used for the infection of Gram-positive bacteria and some Gram-negative bacteria β- La was poorly tolerated. The second generation is for the majority β- La is stable and has a wider antibacterial spectrum than the first generation.
It has a strong effect on Gram-negative bacteria, but its activity on Enterobacter and Pseudomonas aeruginosa is poor. The third generation is for the majority β- La is stable and has strong activity against Gram-negative bacteria, but its effect on G + cocci is not as strong as the first and second generations. Cefoperazone and ceftazidime have good effects on Pseudomonas aeruginosa, and the half-life of ceftriaxone is longer, up to 8 hours.
Cephalosporins: cefoxitin has strong activity against gram-positive, negative, anaerobic or aerobic bacteria β- La is highly stable.
Single ring β- Lactam antibiotics: aztreonam has strong effect on Gram-negative bacteria, stable enzyme and low incidence of cross allergy.
Aminoglycosides: they have good activity against Staphylococcus and aerobic gram-negative bacilli, and some have effect on Mycobacterium tuberculosis and other mycobacteria. There may be cross drug resistance between different varieties, ototoxicity and nephrotoxicity, and can block neuromuscular joints and have the aftereffect of antibiotics.
Tetracyclines: minocycline, doxycycline, tetracycline, oxytetracycline. Broad antibacterial spectrum and convenient oral administration. It is sensitive to Rickettsia, mycoplasma, atypical mycobacterium and Amoeba protozoa.
Macrocyclic lipids: mainly act on Gram-positive bacteria, Gram-negative bacteria, anaerobic bacteria, Legionella, mycoplasma and chlamydia. High tissue concentration. There is incomplete cross resistance.
Lincomycin and clindamycin: gram positive bacteria and anaerobic bacteria.
Polypeptides: vancomycin and norvancomycin. It mainly has strong antibacterial effect on various Gram-positive bacteria: MRSA, MRSE and Enterococcus.
Fluoroquinolones: the first generation: nitidic acid; Second generation: pyridinic acid; The third generation: enoxacin, ofloxacin, pefloxacin, ciprofloxacin, lomefloxacin, etc. Features: broad spectrum, good antibacterial activity against multi drug resistance (other antibiotics), wide body distribution, high tissue concentration, low protein binding rate (14 – 30%), most of which are discharged from the kidney, high urinary drug concentration, long half-life, good oral absorption, and follow-up effect of antibiotics. There was a certain cross resistance among varieties.