How to Distinguish Mycins?

Erythromycin, chloramphenicol, and clindamycin are all called “mycins”. What are the differences in their effects?

There are many drugs with the word “mycin”, such as erythromycin, chloramphenicol, clindamycin, gentamicin, etc. are very common. So, how should these “mycins” be distinguished? How is the clinical application different?

Table of Mycins

Macrolide Antibiotics

Representative drugs: erythromycin, azithromycin, clarithromycin, clarithromycin, roxithromycin, telithromycin, etc.

Antibacterial spectrum: mainly against most Gram-positive bacteria, anaerobic cocci, and some Gram-negative bacteria.

Uses: To treat respiratory tract, urinary tract, skin and soft tissue infections and other diseases caused by Gram-positive bacteria and some Gram-negative bacteria, mycoplasma, Helicobacter pylori, sensitive bacteria, etc. In addition, erythromycin can be used to treat penicillin-resistant bacterial infections and is suitable for patients who are allergic to penicillin.

Clinical application

Recent studies have shown that macrolide antibiotics can be used to treat mycobacterium (including mycobacterium tuberculosis and atypical mycobacterium) and pseudomonas aeruginosa infections in addition to being effective against cocci, anaerobes, legionella, mycoplasma and chlamydia. It can prevent the formation of Pseudomonas aeruginosa biofilm, and has synergistic bactericidal effect when combined with quinolones. According to the opinion in the Guidelines for the Treatment of Adult Community-Acquired Pneumonia revised by the American Thoracic Society in 2001, it is only possible that the combination of bactericides and rapid bacteriostatic agents in the reproductive period is antagonistic. The clinical data shows that the combination of the two can help improve the prognosis.

Macrolide antibiotics have good tissue penetration, the concentration in lung tissue can reach several times of the blood drug concentration, and the tissue half-life is also far higher than the serum half-life, so it has good clinical effect in the treatment of G+, G – cocci and G+bacilli lung infection, and because of its high intracellular drug concentration, in order to treat mycoplasma, chlamydia The drug of choice for Legionella infection.

Application in secondary prevention of cardio-cerebrovascular diseases: Many studies have found that Helicobacter pylori and Chlamydia pneumoniae can be detected in atherosclerotic plaque of patients, so it is believed that Helicobacter pylori and Chlamydia pneumoniae infection are closely related to coronary heart disease. It is suggested that Helicobacter pylori infection is a risk factor for coronary heart disease. It shows that clarithromycin has secondary prevention effect in this kind of patients. However, the secondary prevention effect of macrolides in cardio-cerebrovascular diseases needs further study.

The research of macrolides used in the treatment of peptic ulcer has been reported repeatedly. This therapeutic effect is related to the antibacterial activity of these drugs against Helicobacter pylori. The combination of macrolides and antacids can eradicate Helicobacter pylori in the stomach of patients with gastric ulcer, and has become the treatment recommended by many scholars. In addition, many studies have shown that macrolide antibiotics are also gastric peristalsis, which can increase gastric emptying and can be used for the treatment of non-ulcerative dyspepsia. Long-term intravenous injection of erythromycin is a practical, safe and effective method for the treatment of gastroparesis.


Lincomycin Antibiotics

Representative drugs: lincomycin, clindamycin, etc.

Antibacterial spectrum: mainly against Gram-positive bacteria, non-enterococci, some aerobic Gram-negative cocci and various anaerobic bacteria.

Uses: Treat acute and chronic osteomyelitis, joint infection, mixed infection of anaerobic and aerobic bacteria such as peritonitis, pelvic inflammatory disease, otitis media, sinusitis, etc. caused by Staphylococcus aureus.

Scope of application

Aminoglycoside Antibiotics

Representative drugs: streptomycin, neomycin, gentamicin, kanamycin, spectinomycin, etc.

Antibacterial spectrum: broad antibacterial spectrum, strong antibacterial activity against various aerobic Gram-negative bacilli including Pseudomonas aeruginosa; against penicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, methicillin-resistant epidermis Staphylococcus and other Gram-positive cocci also have good antibacterial effect. Some drugs are highly effective against Mycobacterium tuberculosis, but less effective against Gram-positive bacilli and Gram-negative cocci.

Uses: To treat systemic infections caused by sensitive aerobic gram-negative bacilli; to treat severe infections caused by gram-positive cocci should be combined with penicillin and other β-lactam antibiotics and rifampin. In addition, streptomycin can be used to treat tuberculosis.

Scope of application
It is mainly used for systemic infection caused by sensitive aerobic gram-negative bacteria. Especially for the common gram-negative bacteria such as Pseudomonas aeruginosa, Klebsiella and Escherichia coli, it has a long post-antibiotic effect (PAE), so it is used to treat serious infections caused by aerobic gram-negative bacteria, such as meningitis, respiratory tract infection, urinary tract infection, skin and soft tissue infection, gastrointestinal tract infection, burn infection and bone and joint infection. For severe infections caused by gram-negative bacilli such as septicemia, pneumonia, meningitis, etc., aminoglycosides alone may fail. At this time, other antibacterial drugs with strong antibacterial activity against gram-negative bacilli, such as broad-spectrum semi-synthetic penicillin, third-generation cephalosporins and fluoroquinolones, need to be used in combination.


Polypeptide Antibiotics

Representative drugs: vancomycin, norvancomycin, polymyxins, etc.

Antibacterial spectrum: narrow antibacterial spectrum, polymyxins are effective against some Gram-negative bacilli such as Escherichia coli, Klebsiella, Salmonella, Shigella and Pseudomonas aeruginosa. Vancomycin and norvancomycin have a strong bactericidal effect on Gram-positive bacteria, especially against Bacteroides fragilis and Clostridium.

Uses: Polymyxins can be used for topical treatment of Pseudomonas aeruginosa infection in ears, eyes, skin, mucous membranes and burns caused by sensitive bacteria, and for oral preparation before intestinal surgery. Vancomycin and norvancomycin can be used to treat serious infections caused by methicillin-resistant staphylococci, such as pneumonia, sepsis, endocarditis, osteomyelitis, and colitis.

Tetracycline Antibiotics

Representative drugs: tetracycline, oxytetracycline, aureomycin, demeclocycline, doxycycline, etc.

Antibacterial spectrum: broad antibacterial spectrum, including common gram-positive and gram-negative aerobic bacteria, anaerobic bacteria, rickettsia, spirochetes, mycoplasma, etc.

Uses: This class of drugs has special effects on the treatment of typhus and scrub typhus caused by rickettsia. It is the first choice medicine for inflammation, salpingitis and trachoma, etc. It also has good effect on plague, cholera, Brucellosis, granuloma inguinale, etc.

Clinical application
It is used for the clinical treatment of rickettsia disease, chlamydia disease, mycoplasma disease and spirochete disease. Doxycycline is generally the first choice in clinical practice.

Tetracycline can be the first choice for typhus, murine typhus, reburning typhus, Rickettsia disease and tsutsugamushi disease. It also has good effect on SARS caused by Coxsrickettsia.

Tetracycline has curative effect on psittacosis caused by Chlamydia psittaci, pneumonia caused by Chlamydia pneumoniae, nonspecific urethritis, cervicitis, venereal lymphogranuloma, trachoma, etc. caused by Chlamydia trachomatis by oral or local application. Doxycycline is the first choice.

It has good effect on atypical pneumonia and nonspecific urethritis caused by mycoplasma pneumoniae.

The most effective drug is to treat chronic migratory erythema caused by Spirochaeta burgdorferi and relapsing fever caused by Spirochaeta.

treatment of inguinal granuloma caused by Sheath bacillus granuloma, cholera caused by Vibrio cholerae and brucellosis caused by Brucella are the first choice drugs.

Chloramphenicol Antibiotics

Representative drugs: chloramphenicol, thiamphenicol

Antibacterial Spectrum: Similar to Tetracycline.

Uses: Chloramphenicol can be used to treat severe infections such as typhoid fever, paratyphoid fever, and influenza bacillary meningitis caused by sensitive bacteria; it can be used locally to treat trachoma, conjunctivitis, and superficial ear infections. Thiamphenicol is mainly used clinically to treat typhoid, paratyphoid and other Salmonella infections.

Antibacterial range
Chloramphenicol has broad-spectrum antibacterial effect. Among aerobic gram-positive bacteria, they are sensitive to Streptococcus viridis, Diphtheria, Bacillus anthracis, Staphylococcus aureus, Streptococcus haemolyticus and Streptococcus pneumoniae, but relatively insensitive to Group D Streptococcus; Among aerobic gram-negative bacteria, it has good antibacterial effect on influenza bacteria, Shigella, pertussis, gonococcus and meningococcus, and is also sensitive to Salmonella, Escherichia coli, Proteus mirabilis, Vibrio cholerae, while it is not very sensitive to Serratia marcescens, Enterobacter and Klebsiella pneumoniae. Many anaerobic bacteria, including enterococcus, streptococcus, clostridium perfringens, clostridium, and bacteroides fragilis, can be inhibited by them. In addition, it is effective against most of rickettsia, chlamydia and mycoplasts, but has no inhibitory effect on Pseudomonas aeruginosa, indole-positive Proteus, tuberculosis, fungi, viruses and protozoa. After long-term clinical application of chloramphenicol, various kinds of bacteria can develop resistance to it to varying degrees, but the degree of resistance varies from place to time. The main mechanism of drug resistance is that the plasmid with drug resistance genetic gene in the bacteria mediates the production of chloramphenicol acetyltransferase, which acetylates the 3-hydroxy position of the propylene glycol gene in chloramphenicol. Therefore, chloramphenicol cannot bind with the 50S subunit of the bacterial ribosome and lose its activity. This drug resistance genetic gene can also be transferred to sensitive bacteria of the same or different genera through combination or translocation to make them become drug resistant bacteria. However, the strains that have acquired drug resistance can disappear and become sensitive bacteria again after stopping the drug for a period of time.


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