Cephalosporins

Cephalosporins are a type of β-lactam antibiotic closely related to the penicillins. They are bactericidal, with the same MOA as other beta-lactams.Cephalosporins disrupt synthesis of the peptidoglycan layer of bacterial cell walls. Peptidoglycan is a strong structural molecule specific to the cells walls of bacteria. With the cell wall structure compromised, the bactericidal result is lysis and death of the cell. Our cells do not have cells walls or peptidoglycan, therefore, B-lactam antibiotics are able to target bacterial cells without harming human cells.

Cephalosporins are categorized by "generation," a classification that relates to their antimicrobial properties. There are four generations; each newer generation of cephalosporins having greater gram-negative antimicrobial effectiveness than the generation before. The later the generation, the greater the cephalosporin’s effectiveness against resistant bacterial strains.

MODE OF ACTION

Cephalosporins affect the bacterial cell wall, making it defective and unstable. This action is similar to the action of penicillin. The cephalosporins are usually bactericidal (capable of destroying bacteria).

USES

The cephalosporins are used in the treatment of infections caused by susceptible microorganisms. Examples of microorganisms that may be susceptible to the cephalosporins include streptococci, staphylococci.

ADVERSE REACTIONS

The most common adverse reactions seen with administration of the cephalosporins are gastrointestinal disturbances, such as nausea, vomiting, and diarrhea. Hypersensitivity (allergic) reactions may occur with administration of the cephalosporins and range from mild to life threatening. Mild hypersensitivity reactions include pruritus, urticaria, and skin rashes. More serious hypersensitivity reactions include Stevens- Johnson syndrome (fever, cough, muscular aches and pains, headache, and the appearance of lesions on the skin, mucous membranes, and eyes), hepatic and renal dysfunction, aplasticanemia (anemia due to deficient red blood cell production), and epidermal necrolysis (death of the epidermal layer of the skin). Because of the close relation of the cephalosporins to penicillin, a patient allergic to penicillin also may be allergic to the cephalosporins. Other adverse reactions that may be seen with administration of the cephalosporins are headache, dizziness, nephrotoxicity (damage to the kidneys by a toxic substance), malaise, heartburn, and fever. Intramuscular (IM) administration often results in pain, tenderness,and inflammation at the injection site. Intravenous (IV) administration has resulted in thrombophlebitis and phlebitis. Therapy with cephalosporins may result in a bacterial or fungal superinfection. Diarrhea may be an indication of pseudomembranous colitis, which is one type of bacterial superinfection.

PRECAUTIONS

The nurse should use cephalosporins cautiously in patients with renal or hepatic impairment and in patients with bleeding disorders. Safety of cephalosporin administration has not been established in pregnancy or lactation; these drugs are assigned to Pregnancy Category B.

INTERACTIONS

The risk of nephrotoxicity increases when the cephalosporins are administered with the aminoglycosides. The risk for bleeding increases when the cephalosporins are taken with oral anticoagulants. A disulfiram-like reaction may occur if alcohol is consumed within 72 hours after cephalosporin administration. Symptoms of a disulfiram-like reactions include flushing, throbbing in the head and neck, respiratory difficulty, vomiting, sweating, chest pain, and hypotension. Severe reactions may cause arrhythmias and unconsciousness. When the cephalosporins are administered with the aminoglycosides, the risk for nephrotoxicity increases.

There are five generations of cephalosporins, with increasing expanded coverage to include gram-negative infections. Cephalosporins treat many infections, including strep throat, ear infections, urinary tract infections, skin infections, and meningitis. The fifth generation cephalosporin ceftaroline (Teflaro) is active against methicillin resistant Staphylococcus aureus (MRSA).Common antibiotics in the penicillin class include:

cefuroxime (Ceftin)

ceftriaxone (Rocephin)
Cefdinir (Omnicef)