Classes of Cephalosporins

Cephalosporin drugs fall into five classes or generations. Each subsequent generation of these drugs demonstrates greater efficacy against gram-negative bacteria. Cephalosporin drugs are used to treat a wide range of diseases, including strep throat and bronchis, pneumonia, tonsillitis, gonorrhea and staph infections. Cephalosporins are commonly substituted where patients have known penicillin allergy.

First Generation Cephalosporins

• At the time of development, first generation cephalosporins were considered to be broad-range antibiotics used against common gram-positive and gram-negative microbes. However, they exhibited poor efficacy towards the gram-negatives. First generations drugs include, cephalothin, cefazolin, cephapirin, cepadrine, cephalexin, and cefadroxil. They are still used with high confidence against many gram-positive infections.

Second Generation Cephalosporins

• Improvements were made in the laboratory to develop the next generation of cephalosporins, commonly termed second-generation. Coverage was expanded to include more gram-negative microbes while maintaining the successful gram-positive drug coverage. Cephaplosprin drugs in the second generation include cefaclor, cefamandole, cefonid, ceforanide, cefuroxime, cephamycins cefotetin and cefoxitin. Of these, only cefuroxime crosses the blood brain barrier during normal drug action. Cefotetin and cefoxitin are also termed cephamycins.

Third Generation Cephalosporins

• Third generation cephalosporins are drugs capable of penetrating the central nervous system. They are more effective against gram-negative organisms than previous classes of cephalosporins. Efficacy against gram-positive organisms remains good. Third generation drugs include cefotaxime, moxalactam, cefoperazon, ceftiaoxime, ceftazidime, ceftriaxone, cefitofur, and cefixime.

Fourth Generation Cephalosporins

• Fourth generation cephalosporins were developed to target a broader group of aerobic gram-negative bacilli. This expanded coverage was in addition to its previous control over gram-positive organisms.

Fifth Generation Cephalosporins

• Fifth generation cephalosporins were developed in the lab to specifically target against resistant strains of bacteria. In particular, ceftobiprole is effective against methicillin-resistant Staphylococcus aureus (MRSA). Until this drug was introduced, this strain of staph was impossible to contain. Other drugs in this class include cefotetan and cefoxitin, used against anaerobic gram-negative bacilli. This class of drugs is ineffective against enterococci bacteria.