A urinary tract infection or UTI is caused by proliferation of bacteria in the kidneys, bladder or connective tubing through which urine flows, such as the ureter and urethra. A variety of antibiotics are prescribed to treat UTIs, depending upon the type of bacteria responsible for the infection, the patient's health and condition, and the possibility of complications. If left untreated, UTIs can progress to the kidneys, leading to potentially fatal consequences.
Best Treatments
Eighty to 85 percent of UTIs are caused by the bacterial pathogen E. coli, with Staphylococcus saprophyticus causing 5 to 10 percent. The best antibiotics to treat a UTI are active against these and other microorganisms which cause UTIs, and do not cause significant side effects, according to MayoClinic.com.
Penicillins
The antimicrobial actions of penicillins, which include amoxicillin, ampicillin and augmentin, are exerted by the ability of these drugs to interfere with the process bacteria use to generate cell walls. These drugs are commonly used to treat UTIs, but resistance of E. coli to penicillins such as ampicillin is now significant due to widespread prescription of these drugs for many years. For this reason, other drug classes or combinations of antibiotics are often prescribed, particularly in hospitals or nursing home environments where bacterial resistance is more widespread, according to the University of Maryland Medical Center.
Cephalosporins
In cases where patients are allergic to penicillin, cephalosporins are often prescribed. Cephalosporins are antibiotics similar to penicillins and also kill bacteria by interfering with cell wall development. Cephalexin, cefadroxil and cefuroxime are cephalosporins which are sometimes prescribed to treat UTIs, according to a November 2003 article published in the "New England Journal of Medicine."
Sulfa Antibiotics
Bacteria are killed by sulfa antibiotics due to inhibition of an enzyme involved in production of an important nutrient, folic acid. The most commonly prescribed sulpha antibiotic for UTIs is Bactrim. However, doctors are increasingly prescribing other antibiotics due to growing bacterial resistance to this drug, according to a June 2010 article published on Medline.
Quinolones
The ability of quinoline antibiotics to inhibit bacterial DNA replication prevents these microorganisms from proliferating. Quinolones commonly prescribed for UTIs include floxacin, ciprofloxacin, norfloxacin, and levofloxacin. Pregnant women are not prescribed quinolone antibiotics, as this class of drugs may cause complications during pregnancy, according to a September 2010 article published in "The New York Times."
