Different generations of cephalosporin drugs


Cephalosporins are one of the most prescribed drug classes in the world. You have most likely met these antibiotics , even if you don't know their name. For example, among other things, keflex (cephalexin) is used to treat skin infections . Rocephin (ceftriaxone) is also used to treat pneumonia .

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What are cephalosporins?

Cephalosporins were first discovered in sewage off the coast of Sardinia in 1945. In 1964, the first cephalosporin was prescribed .

Cephalosporins are structurally similar to other antibiotics. Like penicillins, cephalosporins have a beta-lactam ring attached to the dihydothiazole ring. Several side chains hang from this diidothiazole ring, the composition of which gives different cephalosporins with different pharmacology and antimicrobial activity.

Cephalosporins have three different mechanisms of action:

  • Binding to specific penicillin-binding proteins.
  • Suppression of cell wall synthesis.
  • Activation of autolytic (self-destructive) enzymes of the bacterial cell wall.

Cephalosporins are divided into five generations. However, different cephalosporins of the same generation are sometimes chemically unrelated and have different spectra of activity (eg, cephamycins).

The generalization taught by many healthcare professionals is that with successive generations of cephalosporins, coverage of gram-positive decreases and coverage of gram-negative increases.

1-3% of all people are allergic to cephalosporins. In reality, however, this number is likely higher because people with penicillin allergies are not often prescribed cephalosporins .

First generation cephalosporins

First-generation cephalosporins are oral and intravenous. They are active against Viridans streptococci, group A hemolytic streptococci, Staphylococcus aureus, Escherichia coli , Klebsiella and Proteus bacteria. Like all other cephalosporins, first-generation cephalosporins have no effect on enterococci.

Examples of first-generation cephalosporins include the following:

  • Cephalexin (Keflex)
  • Cephradine
  • Cefadroxil
  • Cefazolin (intravenous and intramuscular)

In general, first-generation cephalosporins can be used to fight skin and other soft tissue infections, respiratory and urinary tract infections. First-generation intravenous cephalosporins can be used as prophylaxis after clean surgical procedures.

The prevalence of MRSA has reduced the efficacy of first-generation cephalosporins for prevention and treatment.

Second generation cephalosporins

In general, second-generation cephalosporins are more active against gram-negative organisms, making them more useful in many clinical situations.

For example, second-generation cephalosporins are active against Proteus and Klebsiella strains. Second-generation cephalosporins also fight H. influenza, a cause of pneumonia, sepsis, and meningitis. However, first-generation cephalosporins are generally better for treating gram-positive infections.

Examples of second-generation cephalosporins include the following:

  • Cefoxitin
  • Cefotetan
  • Cefuroxime (tablets and injections)
  • Cefprozil

Second-generation cephalosporins treat the following:

  • Sinusitis
  • Otitis media (ear infection)
  • Mixed anaerobic infections, including peritonitis and diverticulitis
  • Prevention after colorectal surgery

Second-generation cephalosporins are not active against Pseudomonas aeruginosa.

Third-generation cephalosporins

The main advantage of third and fourth generation antibiotics is the significantly expanded coverage against gram-negative bacteria. Additionally, third-generation cephalosporin ceftazidime is active against Pseudomonas aeruginosa , a bacterium that can cause skin infections in people with normal immune systems (for example, after exposure to an insufficiently chlorinated hot tub or swimming pool), as well as pneumonia, blood infections. , and so on in humans, with a weakened immune system. P. aeruginosa is more common in patients who have been hospitalized for a week or more). Infections can be very complex and life threatening.

There are several third-generation cephalosporins. Talking about all of them is beyond the scope of this article. Instead, let's focus on ceftriaxone (rocefin), which has many uses, including:

  • Lower respiratory tract infections
  • Skin and soft tissue.
  • Gonorrhea without complications
  • Urinary tract infections
  • Otitis media
  • Pelvic inflammatory disease
  • Surgical prophylaxis
  • Bacterial sepsis (blood poisoning)
  • Meningitis
  • Bone infections
  • Joint infections
  • Intra-abdominal infections

Fourth generation cephalosporin

Cefepime is the only available fourth generation cephalosporin (FDA approved). Like the third-generation cephalosporin ceftazidime, cefepime is active against Pseudomonas aeruginosa. Furthermore, cefepime is more active against Enterobacter and Citrobacterr bacteria. Finally, cefepime has a gram-positive effect comparable to ceftriaxone.

Some of the clinical uses of cefepime are:

  • Moderate to severe pneumonia
  • Severe urinary tract infection.
  • Skin and soft tissue.
  • Complicated intra-abdominal infections

Fifth generation cephalosporin

In 2010, the FDA approved ceftaroline (Teflaro), the only fifth- or advanced-generation cephalosporin. Like cefepime, ceftaroline is a powerful antibiotic that should be used for serious infections. In particular, it is active against multi-drug resistant infections such as MRSA (methicillin-resistant S. aureus ) and VRSA ( vancomycin-resistant S. aureus) . This medication is also used by injection and is indicated to treat community-acquired pneumonia and serious skin and soft tissue infections. Fortunately, ceftaroline is safe and does not induce resistance.

Get the word of drug information

As you will now understand, cephalosporins are a surprisingly diverse class of antibiotics with wide coverage. However, as with most antibiotics, antibiotic resistance is a concern for many physicians, epidemiologists, public health officials, and patients.

Bacterial resistance is due in part to overprescribing; however, we, as patients, can also help combat the development of resistance. For example, you should not always expect or demand that your doctor prescribe antibiotics to treat an infection that may well be viral. (Antibiotics are not effective against viruses.) Also, when prescribing antibiotics, it is imperative that you complete the entire cycle, even if you "feel better."

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