Third generation cephalosporins

After the first cephalosporin was discovered in 1945, scientists improved the structure of cephalosporins to make them more effective against a wider range of bacteria. Each time the structure changed, a new "generation" of cephalosporins were made. There are five generations of cephalosporins. Third generation cephalosporins were the third generation of cephalosporins to be developed.

Cephalosporins are a large group of antibiotics derived from the mold Acremonium (previously called Cephalosporium). Cephalosporins are bactericidal (kill bacteria) and work in a similar way to penicillins. They bind to and block the activity of enzymes responsible for making peptidoglycan, an important component of the bacterial cell wall. They are called broad-spectrum antibiotics because they are effective against a wide range of bacteria.

What are third-generation cephalosporins used for?

Third generation cephalosporins may be used to treat the following types of infections when caused by susceptible strains of bacteria:

• Bacteremia/septicemia
• Bone and joint infections
• Central nervous system infections
• Gynecological infections
• Intra-abdominal infections
• Lower respiratory tract infections
• Skin and skin structure infections
• Urinary tract infections.

What are the differences between third-generation cephalosporins?

There are differences between third-generation cephalosporins with regards to the bacteria they are effective against. No single third-generation cephalosporin treats all infectious disease scenarios.

Cefotaxime and ceftizoxime (discontinued) offer the best gram-positive coverage out of all the third-generation agents; ceftazidime and cefoperazone (discontinued) are unique in that they provide antipseudomonal coverage.

Ceftriaxone has a long half-life which allows for once daily dosing and may be used for the treatment of gonorrhea, pelvic inflammatory disease, and epididymo-orchitis. It is also an alternative to penicillins for suspected meningitis.

All the third-generation cephalosporins except for cefoperazone (discontinued) penetrate cerebrospinal fluid.

Are third generation cephalosporins safe?

Third generation cephalosporins are generally safe, with low toxicity and good efficacy against susceptible bacteria.

Allergic reactions have been reported with all cephalosporins including third generation cephalosporins and symptoms may include a rash, hives (urticaria), swelling, or rarely, anaphylaxis. Up to 10% of people with a history of penicillin allergy will also be allergic to cephalosporins.

Drug-induced hemolytic anemia has been associated with use of some cephalosporins, including third generation cephalosporins; suspect and investigate further if anemia develops during or after treatment.

Rarely, some people may develop a super-infection due to overgrowth of a naturally occurring bacterium called Clostridium difficile, following use of any antibiotic, including cephalosporins. Symptoms may include severe diarrhea.

Rarely, seizures have been reported with cephalosporins; the risk may be greatest in those with kidney disease.

Cephalosporin should be given exactly as directed. Potentially life-threatening arrhythmias have been reported following rapid bolus administration of cefotaxime, a third generation cephalosporin.

For a complete list of severe side effects, please refer to the individual drug monographs.

What are the side effects of third generation cephalosporins?

Third generation cephalosporins generally cause few side effects. The most common side effects reported include:

• Abdominal pain
• Diarrhea
• Injection site inflammation
• Itchy skin
• Nausea
• Rash
• Vomiting.

Transient increases in liver enzymes have also been reported.

For a complete list of side effects, please refer to the individual drug monographs.