Cephalosporins are a broad-spectrum class of beta-lactam antibiotics used to treat a wide variety of bacterial infections, such as pneumonia, skin infections, and urinary tract infections. They derive from the fungus Acremonium and work by inhibiting the synthesis of the bacterial cell wall. The drugs are categorized into different generations, with each successive generation offering a broader spectrum of activity, particularly against gram-negative bacteria. Below is a breakdown of the names of cephalosporins by their generation.
First-Generation Cephalosporins
These drugs are primarily effective against gram-positive bacteria, including most Staphylococcus and Streptococcus species, but have limited activity against gram-negative organisms. They are often used for uncomplicated skin and soft tissue infections, as well as for surgical prophylaxis.
- Cefazolin (Ancef, Kefzol): Administered parenterally (injection) and is a common choice for surgical prophylaxis.
- Cephalexin (Keflex): A popular oral option for treating skin infections and urinary tract infections.
- Cefadroxil (Duricef): Oral cephalosporin with similar uses to cephalexin.
- Cephapirin (Cefadyl): Administered parenterally.
Second-Generation Cephalosporins
Second-generation cephalosporins offer enhanced activity against certain gram-negative bacteria, including Haemophilus influenzae, Enterobacter aerogenes, and Neisseria species, while retaining some gram-positive coverage. This generation is sometimes used for respiratory tract infections and complicated urinary tract infections.
- Cefuroxime (Ceftin, Zinacef): Available in both oral and parenteral forms and can cross the blood-brain barrier.
- Cefaclor (Ceclor): An oral medication used for various infections.
- Cefprozil (Cefzil): An oral agent used for respiratory and skin infections.
- Cefoxitin (Mefoxin): A parenteral cephamycin that offers additional coverage against anaerobic bacteria.
- Cefotetan (Cefotan): Also a cephamycin with anaerobic coverage.
Third-Generation Cephalosporins
This generation is known for its extended spectrum against gram-negative bacteria and improved stability against beta-lactamase enzymes. Some third-generation cephalosporins can penetrate the central nervous system, making them useful for treating meningitis.
- Ceftriaxone (Rocephin): A highly effective parenteral drug used for serious infections, including meningitis, pneumonia, and gonorrhea.
- Cefotaxime (Claforan): Parenteral agent that, like ceftriaxone, is effective for meningitis and other severe infections.
- Ceftazidime (Fortaz): A third-generation drug with important activity against Pseudomonas aeruginosa.
- Cefdinir (Omnicef): A widely used oral agent for respiratory and skin infections.
- Cefixime (Suprax): An oral option used for urinary tract and ear infections.
- Cefpodoxime (Vantin): An oral agent with good absorption.
Fourth-Generation Cephalosporins
Fourth-generation cephalosporins feature a broad-spectrum of activity, combining the gram-positive coverage of earlier generations with the enhanced gram-negative coverage of the third-generation, including activity against Pseudomonas aeruginosa.
- Cefepime (Maxipime): The primary fourth-generation cephalosporin in the US, used for severe hospital-acquired infections and reserved for multi-drug resistant organisms.
Fifth-Generation Cephalosporins
Representing the newest class, fifth-generation cephalosporins are notable for their ability to combat difficult-to-treat infections, especially those caused by Methicillin-Resistant Staphylococcus aureus (MRSA).
- Ceftaroline (Teflaro): An injectable antibiotic used for community-acquired pneumonia and skin and soft tissue infections involving MRSA.
- Ceftolozane/Tazobactam (Zerbaxa): A combination drug that includes a beta-lactamase inhibitor, expanding its spectrum against resistant gram-negative bacteria, including Pseudomonas aeruginosa.
- Ceftobiprole (Zevtera): Approved in some regions and pending approval in the US, with activity against MRSA and E. faecalis.
- Cefiderocol (Fetroja): A siderophore cephalosporin approved for complicated urinary tract infections and pneumonia caused by resistant gram-negative bacteria.
Comparison of Cephalosporin Generations
| Generation | Typical Names (Generic/Brand) | Primary Coverage | Common Uses | Administration Route |
|---|---|---|---|---|
| First | Cephalexin (Keflex), Cefazolin (Ancef) | Most gram-positive cocci | Skin infections, surgical prophylaxis | Oral, Parenteral |
| Second | Cefaclor, Cefuroxime (Ceftin), Cefoxitin | Increased gram-negative, retained gram-positive (less potent) | Respiratory tract infections, some UTIs | Oral, Parenteral |
| Third | Ceftriaxone (Rocephin), Cefdinir (Omnicef), Ceftazidime (Fortaz) | Broad gram-negative, including CNS penetration | Meningitis, pneumonia, gonorrhea | Oral, Parenteral |
| Fourth | Cefepime (Maxipime) | Broad-spectrum, covers Pseudomonas aeruginosa | Severe hospital-acquired infections | Parenteral |
| Fifth | Ceftaroline (Teflaro), Ceftobiprole | Broad-spectrum, including MRSA | Community-acquired pneumonia (MRSA), skin infections | Parenteral |
Potential Side Effects and Precautions
While cephalosporins are generally well-tolerated, side effects can occur, and certain precautions are necessary. Common side effects are generally mild and include nausea, vomiting, abdominal pain, and lack of appetite. More serious side effects can also happen, such as hypersensitivity reactions (rashes, hives, anaphylaxis), which are more common with earlier generations.
One significant point of concern is the potential for cross-reactivity in patients with a penicillin allergy. Early studies showed a higher risk, but modern research indicates that for most cephalosporins, especially third-generation and beyond, the risk of cross-reactivity is very low. However, patients with a documented severe (anaphylactic) penicillin allergy should still use caution, and a physician should evaluate the risk.
Neurotoxicity, such as encephalopathy or seizures, is another potential risk, particularly in patients with pre-existing central nervous system disorders or renal impairment where dose adjustments are not made. Specific cephalosporins, such as cefotetan and ceftriaxone, have also been associated with drug-induced immune hemolytic anemia and biliary sludge formation, respectively. For patients on warfarin, some cephalosporins can interact and increase the risk of bleeding.
Conclusion
Cephalosporins represent a versatile and crucial class of antibiotics, with a diverse list of names distributed across five distinct generations. The progressive increase in gram-negative coverage and resistance to beta-lactamase as generations advance allows clinicians to select an appropriate agent for various infections, from common skin ailments to severe, multi-drug resistant conditions. While generally safe, awareness of the specific names and their generational properties, along with potential side effects and precautions like penicillin allergy cross-reactivity and renal function concerns, is vital for effective and safe treatment. For the most up-to-date and authoritative information, consulting reputable medical resources such as the National Institutes of Health (NIH) is recommended.
