Urinary tract infections are extremely common bacterial infections that often cause symptoms of pain with urination; urinary frequency, which is the sensation that one has to empty the bladder, but very little comes out; urgency, or the feeling that one has to get to a bathroom immediately; and urinary incontinence. These infections are much more common in women because the pelvic anatomy of a woman makes her more prone to bacteria entering the bladder. A woman with an uncomplicated urinary tract infection (UTI) may be treated with one of several antibiotics.
Trimethoprim-Sulfamethoxazole (TMP-SMX)
According to University of Texas Southwestern Medical Center obstetrics and gynecology professor Dr. David Hamsell, writing in the gynecology textbook "Williams Gynecology," one of the most common bacteria that cause UTI is E. coli. In such cases, the first choice of therapy is with an antibiotic called trimethoprim-sulfamethoxazole. If a patient has a sulfa allergy, trimethoprim alone may be taken. The recommended course of treatment with TMP-SMX is twice-daily medication taken for three days. Side effects include lack of appetite, nausea, vomiting, itching and rash. Life-threatening situations such as severe skin reactions or liver damage may occur; however, according to the medical database UpToDate, such situations are extremely rare.
Quinolone Antibiotics
Some geographic regions of the country have high levels of resistance of E. coli to TMP-SMX. Resistance occurs when the bacteria have evolved in a way that makes the antibiotic ineffective against them. So, TMP-SMX-resistant E. coli are not impacted by the antibiotic, making TMP-SMX a bad treatment choice for UTI. In such cases, an effective alternative is one of the quinolone antibiotics. Ciprofloxacin, norfloxacin, levofloxacin and gatifloxacin are all members of this class of antibiotic. Ciprofloxacin and norfloxacin are generally given twice daily for three days, while levofloxacin and gatifloxacin should be taken only once daily, also for three days. According to UpToDate, common side effects include nausea and vomiting, as well headache, dizziness and insomnia; a rash may also occur.
Nitrofurantoin
According to Dr. Thomas Hooten, a professor of medicine at the University of Miami Miller School of Medicine, and his colleagues, writing in the medical journal "Clinical Infectious Diseases," there is increasing concern about the resistance of bacteria, including E. coli, to quinolone antibiotics. Similarly to the case of bacterial resistance to TMP-SMX, quinolone resistance arises when the bacteria -- whether they are E. coli or some other bacteria -- mutate and evolve in such a way that they "outsmart" the antibiotic. Bacteria that are resistant to quinolone antibiotics will not be killed or stopped by quinolones; an alternative therapy is needed. Nitrofurantoin is a potential alternative antibiotic if the patient with UTI lives in an area where resistance to TMP-SMX and quinolones is an issue. The therapy regimen for nitrofurantoin is seven days instead of three days. Side effects include nausea, headache and, rarely, lung or liver damage.
References
- "Williams Gynecology"; John O. Schorge et. al.; 2008
- "UpToDate"; Denise S. Basow; 2010
- "Clinical Infectious Diseases"; Acute uncomplicated cystitis in an era of increasing antibiotic resistance: a proposed approach to empirical therapy; T. Hooten et. al.; July 2004
