What are the different generations of cephalosporins?

Posted on  March 28, 2021, Edited by Jason, Category  

What are cephalosporins?

Cephalosporins are a class of antibiotics widely used clinically. Like penicillin, they are all beta lactam antibiotics.

People usually divide microorganisms into 8 categories: bacteria, viruses, fungi, actinomycetes, rickettsiae, mycoplasma, chlamydia, and spirochetes. These microorganisms can cause us to get sick under certain conditions, but "cephalosporin" only has a killing effect on bacteria and is ineffective against the other 7 microorganisms.

Bacteria are divided into more than 40 types. Each infectious disease may be caused by one or several types of bacteria; there are more than 50 kinds of "cephalosporins" that can be used now, and each type of bacteria is sensitive to different "cephalosporins". This makes it almost impossible to choose a suitable "cephalosporin" to treat diseases, so how should "cephalosporins" be selected reasonably?

Through experiments, it was found that almost all bacteria can be divided into two major categories through "Gram stain", namely, Gram-positive bacteria (G+) and Gram-negative bacteria (G-). Gram-positive bacteria and gram-negative bacteria are very different in the structure of the cell wall and so on, so the sensitivity to different antibiotics is different. For example, most gram-positive bacteria are sensitive to penicillin, while gram-negative bacteria are not sensitive to penicillin, but to streptomycin and chloramphenicol.

So people divide "cephalosporins" into five generations based on their antibacterial spectrum and antibacterial activity. In this way, when choosing drugs, doctors can make a wise choice based on the structural characteristics of the bacteria and the action characteristics of the drugs.

Cephalosporin classification

The formal name of "cephalosporin" is cephalosporin antibiotics. It is a series of semi-synthetic antibiotics obtained by transformation of cephalosporin C isolated from the culture broth close to Penicillium. The mechanism of action is the same as that of penicillins, inhibiting the formation of bacterial cell walls to achieve the purpose of sterilization.

It is a bactericide. Compared with penicillins, its advantages include: wider antibacterial range; little or no cross-allergic reaction with penicillin, and lower allergic reactions caused by penicillins; beta lactamase produced by acid and various bacteria (A substance that destroys penicillin and cephalosporin) is more stable. Due to its low adverse reactions and toxic side effects, it has developed rapidly since its first clinical application in the early 1960s, and many varieties have been produced. Cephalosporins have been developed for five generations. Many people believe that the higher the generation, the more expensive and the better the curative effect. In fact, this is a misunderstanding. Cephalosporins are mainly divided into different generations according to their development sequence, antibacterial spectrum, stability to beta lactamase, and toxicity to kidneys.


1. First generation cephalosporin

A. Representative drugs

Cefalotin sodium, cephalexin, cefadroxil, cefazolin, cefradine, cefathiamidine, cefaclor, ceftazidime, Cephaloglycin, cefacetonitrile, cefpirin, cefotiazole.

B. Introduction

The first generation cephalosporin was launched in the early 1960s. In terms of antibacterial performance, the bacteria sensitive to the first generation of cephalosporins mainly include β-hemolytic streptococcus and other streptococci, including Streptococcus pneumonia (but enterococcus resistant), Staphylococcus (including enzyme-producing strains) Haemophilus influenzae, Escherichia coli, Klebsiella, Proteus mirabilis, Salmonella, Shigella, etc. Different varieties of cephalosporins can have their own antibacterial characteristics. For example, cephalothin has better antibacterial effect on gram-positive bacteria, while cefazolin has a certain effect on some gram-negative bacteria. However, the first generation cephalosporins are less resistant to the beta lactamase of gram-negative bacteria. Therefore, gram-negative bacteria are more resistant to antibiotics of this generation.

The first-generation cephalosporins are not effective against indole-positive Proteus, Citrobacter, Aerobacter, Pseudomonas, Serratia, Bacteroides, Streptococcus faecalis (except Cefathiamidine) and other microorganisms.

Commonly used varieties of antibiotics of this generation include cefazolin, cephalexin, cefradine, cefadroxil and so on. Among them, cefazolin can only be used for injection, the others can be used for oral administration. Cefalotin, cefotaxime, cefacetonitrile, cefpirin, etc. have been used less or not.

2. Second generation cephalosporin

A. Representative drugs

Cefuroxime sodium, cefuroxime axetil, cefmendol, cefaclor, cefotiam, cefmetazole, cefprozil, cefonisi, cefradit.

B. Introduction     

The antibacterial efficacy of the second generation cephalosporin against gram-positive bacteria is similar to or lower than that of the first-generation cephalosporins, while the effect on gram-negative bacteria is excellent.

  • Strong enzyme resistance. Some gram-negative bacteria (such as Escherichia coli, Proteus mirabilis, etc.) are easily resistant to the first-generation cephalosporins. Second-generation cephalosporins are often effective against these resistant strains.
  • Broad antibacterial spectrum. The antibacterial spectrum of the second-generation cephalosporins has been expanded compared with the first-generation. It has antibacterial effects on Neisseria, some indole-positive Proteus, some Citrobacter, and some Enterobacter.

3. 3rd generation cephalosporin

A. Representative drugs

Cefotaxime sodium, cefoperazone, ceftazidime, ceftriaxone, ceftizoxime, cefmenoxime, cefpiramide, cefotetan, cefixime, cefpodoxime proxetil, ceftimeproxil, cefodizime, cephalosporin Titium, Cefdinir, Cefteram, Ceflanel, Laoxycephalosporin, Ceftibutene, Cefminol, Cefprozil.

B. Introduction

The antibacterial efficacy of the third generation cephalosporin against gram-positive bacteria is generally lower than that of the first generation (some varieties are similar), while the effect on gram-negative bacteria is more superior than that of the second-generation cephalosporins.

  • Expansion of the antibacterial spectrum. The antibacterial spectrum of the third generation cephalosporins has been expanded compared with the second generation, and it is effective against Pseudomonas aeruginosa, Serratia, Acinetobacter, Peptococcus, and some Bacteroides fragilis (different varieties The antibacterial efficacy of the drugs is not the same). It is invalid for Streptococcus faecalis, Clostridium difficile, etc.
  • Strong enzyme resistance. For some Gram-negative strains resistant to the first or second generation cephalosporins, the third generation cephalosporins are often effective.

4. 4th generation cephalosporin

A. Representative drugs

Cefepime, Cefpirome, Cefazuran.

B. Introduction

The third generation cephalosporins have weak effects on Gram-positive bacteria and cannot be used to control Staphylococcus aureus infections. In recent years, some new varieties, such as Cefpirome, have been discovered that not only have the antibacterial properties of the third generation cephalosporins, but also have antibacterial effects on staphylococci. They are called the fourth generation cephalosporins.

5. 5th generation cephalosporin

A. Representative drugs

Ceftaroline, cefepime, etc.

B. Introduction

The fifth generation cephalosporins have stronger effects on Gram-positive bacteria than the previous four generations, especially on methicillin-resistant Staphylococcus aureus, vancomycin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, penicillin-resistant Streptococcus pneumonia and some anaerobic bacteria. The effect on Gram-negative bacteria is similar to the fourth-generation cephalosporin.

It is highly stable to most β-lactamases, but can be hydrolyzed by most metal beta lactamases and extended-spectrum beta lactamases. Its target of action is PBP2a, which is mainly used for complicated skin and soft tissue infections, diabetic foot infections caused by gram-negative bacteria, community-acquired pneumonia, and hospital-acquired pneumonia.

Common cephalosporins


1. Cephalexin

Cephalexin is a semi-synthetic first-generation oral cephalosporin antibiotic drug that can inhibit the synthesis of cell walls, make the cell contents swell, rupture and dissolve, and kill bacteria.

This product is a semi-synthetic first-generation oral cephalosporin. Its antibacterial spectrum is basically the same as that of cefalotin and ceftazidime, and its antibacterial effect is weaker than the two. However, the product is characterized by acid resistance and good oral absorption. It has a good antibacterial effect on resistant Staphylococcus aureus.

Cephalexin uses: It is mainly used for Gram-positive and negative bacterial infections, such as: influenza, hemorrhagic sepsis, streptococcal disease, swine erysipelas, anthrax, emphysema gangrene, malignant edema, actinomycosis, necrotic bacillosis, leptospirosis Septic high fever (41-43 °C) or persistent low temperature (below 37 °C) caused by spirochetes, indigestion, drinking cold water, lethargy, lame walking, blue ears, tears, etc. It is also used to treat various inflammatory diseases, such as: infectious pleuropneumonia, pulmonary pneumonia, atrophic rhinitis, blue ear disease, mastitis, metritis, stomatitis, urethritis, etc.

2. Cefaclor

Cefixime is a third generation cephalosporin antibiotic for oral use. It is suitable for the treatment of respiratory, urinary and biliary infections caused by sensitive bacteria. Cefixime is highly stable to the beta lactamase produced by gram-negative bacilli. Its antibacterial effect on gram-negative bacilli is stronger than that of the first and second generation cephalosporins, and its antibacterial effect on gram-positive cocci is not as good as that of the first and second generation cephalosporins. At present, the cefixime drugs approved by the State Food and Drug Administration come in various dosage forms such as tablets, capsules, dispersible tablets, dry suspensions and granules, all of which are prescription drugs.

Cefixime is used to treat the following infections caused by sensitive bacteria: respiratory infections, such as bronchitis, pneumonia, etc.; urinary system infections, such as pyelonephritis, cystitis, urethritis, etc.; biliary tract infections, such as cholecystitis, cholangitis; Otitis media, sinusitis, scarlet fever, etc.

3. Ceftobiprole

MRSA is one of the common clinical pathogens, and most of the cephalosporins that have been marketed are ineffective. The world's first anti-MRSA cephalosporin drug Ceftobiprole developed by Basilea Pharmaceutica, Switzerland, was approved for marketing in Canada on June 30, 2008.

Ceftobiprole is a pyrrolidone cephalosporin drug. It has antibacterial activity against gram-positive bacteria, gram-negative bacteria and anaerobic bacteria. It is the first cephalosporin drug effective against MRSA and VRSA, and its application prospects are broad, regarded as a member of the fifth-generation cephalosporin drugs. Compared with cefepime, Ceftobiprole has a wider antibacterial spectrum for gram-positive bacteria, while has a similar antibacterial spectrum of gram-negative bacteria to cefepime.


Cephalosporin has undergone great development since it went on the market. For different types of bacteria, from the first generation cephalosporin to the fifth generation cephalosporin, their antibacterial spectrum and stability vary.

BALLYA provides a betalactam cephalexin combo test kit to tell you if there are beta lactams residues and cephalosporin residues in dairy products you eat every day.


Recent Posts

Proudly designed by BALLYA
linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram