Antibiotics take advantage of the fact that bacteria cells have certain key differences compared to healthy human cells. As a result there are many different kinds of antibiotics that attack bacteria in different ways. One such class of antibiotic, which can be used for many different kinds of infections, is the cephalosporin class of medications.
Types
According to the Pharmacology Department at the University of Illinois-Chicago, cephalosporins are a type of antibiotic that is commonly divided into four different "generations" of drugs. New generations of cephaloisporins are made by making minor chemical tweaks to the structure of the drug to make it more effective against certain kinds of infections. First generation cephalosporins include cefazolin and cephalexin. Second generation cephalosporins include cefamandole and loracarbef. Examples of third generation cephalosporins are ceftriaxone and cefixime. The only commonly used fourth generation cephalosporin is cefipime.
Efficacy
Cephalosporins are effective against many different kinds of bacteria. The Merck Manual notes that first generation cephalosporins are most effective against gram positive bacteria. Later generations of cephalosporins have enhanced activity against gram negative bacteria. Gram positive and negative describes certain physical properties of bacterial cells in terms of the structure of their cell wall. Common gram positive bacteria include Staph aureus and the Strep family of bacteria, which can cause strep throat and some kinds of pneumonia. Gram negative bacteria include E. coli, H. Influenzae and the cholera bacteria.
Mechanism
Cephalosporins are beta-lactam drugs, which means that they disrupt the integrity of the wall that surrounds all bacterial cells. When the beta-lactam drugs attack bacteria, they punch holes in the wall, which eventually kills off the bacteria.
Limitations
Although cephalosporins are effective against a broad range of different kinds of bacteria, there are some kinds of infections that they are not well suited for treating. Cephalosporins are not effective against enterococci, for example. Enterococci commonly cause urinary tract infections and infections of the cardiac tissue. They also are not effective at treating methicillin-resistant staph infections (MRSA, which can cause abscesses to form in the skin) or anerobic gram-negative bacilli (which commonly infect the intestines). They also are not good at getting into the vitreous humor (the liquid inside the eye) and should not be used for eye infections.
Excretion
Cephalosporins are primarily metabolized by the kidneys and they are excreted in the urine. This means patients with kidney disease or renal insufficiency should get lowered doses of the drug because they will remain in the body for longer. Certain cephalosporins (such as ceftriaxone and cefoperazone) also get excreted in the bile and do not require dose adjustments.
