Cephalosporins

     The first cephalosporin was developed in 1964.  The compounds that were used to develop these antibiotics were isolated from a sewer on an island in the Mediterranean sea by an Italian scientist.  Like the penicillins, there are four classes of cephalosporins.  As mentioned above there is some cross reactivity between penicillin and cephalosporins in regard to allergies. 

    The first-generation cephalosporins have approximately a 10% cross reactivity with penicillin.  It is a question of debate whether there is cross reactivity with second or third-generation cephalosporins.  If the reaction is severe, such as breathing difficulty, swelling of the throat or hives, then the use of cephalosporins should not be used in the face of a penicillin allergy. 

     Two commonly used oral first generation cephalosporins are (see table) cephalexin (Keflex) and cefadroxil (Duricef).  First-generation cephalosporins cover gram-positive bacteria well and have limited activity against gram-negative bacteria. 

     Second or third-generation cephalosporins work well for many different bacterial infections. The second and third-generation cephalosporins add coverage of gram-negative bacteria.

     There is one fourth-generation cephalosporin that is given through the IV.  It is used for urinary tract infections, kidney infections, pneumonia, skin infections and abdominal infections. 

What do they treat?  

      The most commonly used first generation cephalosporin is cephalexin (Keflex).  It effectively treats gram-positive infections.  This means that it is effective for the treatment of many streptococcal infections and staphylococcal infections. 

     It is commonly used for skin infections as well as some respiratory infections such as strep throat.  It is not a commonly used drug for most respiratory infections other than strep throat.   While it is very effective in the treatment of strep throat it is not recommended as a first-line drug. 

     Second-generation cephalosporins retain gram-positive coverage but adds in some gram-negative coverage.  This means that they can treat more infections.  They are commonly used for respiratory tract infections including sinus infections and ear infections.    

     The third-generation cephalosporins have even better gram-negative coverage. This class is made up of some oral medications and a commonly used injectable medication called ceftriaxone (Rocephin).  Rocephin is a popular drug in this class as it is used with some frequency in the doctor's office for more severe infections.  Other medications in this class are available as an intravenous (IV) preparation. 

     This class is used to treat many respiratory tract infections.  There is a lot of variability within this class.  Some of the drugs are only given through the IV and are used for some very severe infections.  Some antibiotics in this class are used to treat kidney infections, pneumonias, gonorrhea, meningitis and some infections in the stomach.

     See the antibiotic table for a breakdown of specific medications commonly used in the doctor’s office and what they treat. 

Common side effects

    As a class, side effects from cephalosporins are not common.  Common side effects include:

• Diarrhea
• Nausea
• Rash

Less common side effects include:

• Dizziness
• Electrolyte disturbance
• Headache
• Thrush
• Vaginal yeast infections
• Diarrhea secondary to Clostridium difficile  
• Fever
• Vomiting

     Some specific side effects to be aware of include:

• Cefdinir (Omnicef) can turn the stool especially if taken with iron.
• Ceftriaxone (Rocephin) can cause considerable pain upon injection and it is sometimes mixed with a numbing agent such as lidocaine.
• Loracarbef (Lorabid) and cefprozil (Cefzil) cause the least amount of diarrhea.
• Loracarbef (Lorabid) and cefpodoxime (Vantin) are the best tasting antibiotics. 

Key points

• Cephalosporins have four generations.
• If you have a skin infection the use of cephalexin (Keflex) is a good choice.
• Cephalosporins do not cover methicillin-resistant Staphylococcal Aureus, which is a common cause of skin infections. 
• The second-generation cephalosporins cover a wide range of infections and can be used in a variety of respiratory infections. 
• Ceftriaxone is often used in some who is very sick in the doctor’s office with a bad ear infection or pneumonia.  It is sometimes given everyday and will require daily visits to the doctor's office.  This is often done in someone who is on the border of being hospitalized.