The largest number of urinary tract disorders is caused by urinary tract infections (UTIs), microbial infections of any part of the urinary tract. The infection may be referred to as an upper UTI, such as pyelonephritis, or a lower UTI, such as cystitis, urethritis, or prostatitis. A group of drugs called urinary antiseptics/antiinfectives prevents bacterial growth in the kidneys and bladder, but these drugs are not effective for systemic infections. When given in lower dosages, urinary antiseptics/antiinfectives have a bacteriostatic effect—that is, they inhibit bacterial growth. When given in higher dosages, they also have a bactericidal (bacteria killing) effect. Urinary antiseptics/antiinfectives are presented in this chapter, along with urinary analgesics, which relieve pain and burning in the urinary tract; urinary stimulants, agents that increase the tone of urinary muscles; and urinary antispasmodics/antimuscarinics. Chapter 26 presents further discussions of antibiotics used to treat UTIs, such as fluoroquinolones and sulfonamides. Diuretics are discussed in Chapter 38.
Acute cystitis, a lower UTI, frequently occurs in female patients because of the short urethra. It is more common in women of childbearing age, older women, and young girls. Acute cystitis is commonly caused by Escherichia coli (also called E. coli). Other bacterial causes include the gram-positive Staphylococcus saprophyticus and gram-negative Klebsiella, Proteus, and Pseudomonas species. Symptoms of cystitis include pain and burning on urination and urinary frequency and urgency. A urine culture is usually obtained before the start of any antiinfective/antibiotic drug therapy. In male patients, a lower UTI is most likely prostatitis with symptoms similar to cystitis.
Acute pyelonephritis, an upper UTI, is commonly seen in women of childbearing age, older women, and young girls. E. coli is the most common organism to cause pyelonephritis. Symptoms include chills, high fever, flank pain, pain during urination, urinary frequency and urgency, and pyuria. The bacterial count in the urine is greater than 100,000 bacteria/mL. In severe cases, the patient may be hospitalized and may receive intravenous (IV) antibiotics (e.g., an aminoglycoside or piperacillin-tazobactam).
The most commonly used agents for treating UTIs are nitrofurantoin and trimethoprim-sulfamethoxazole. Treatment may consist of a single double-strength dose of the chosen drug, a 3-day course, or the traditional method of 7 to 14 days of drug dosing. Fosfomycin tromethamine, a nitrofurantoin prototype drug, is effective for UTIs as a single-dose treatment. Other agents used to treat UTIs include third-generation cephalosporins (cefixime, cefpodoxime proxetil, or ceftibuten), fourth-generation cephalosporins (cefepime), fifth-generation cephalosporins (ceftolozane-tazobactam), and fluoroquinolones, such as ofloxacin, ciprofloxacin, and levofloxacin. For uncomplicated UTIs, fluoroquinolones, especially levofloxacin, may be used only when other options are not available. With severe UTIs, IV drug therapy followed by oral drug therapy is usually recommended.
Urinary Antiseptics/Antiinfectives and Antibiotics
Urinary antiseptics/antiinfectives are limited to the treatment of UTIs. Drug action occurs in the renal tubule and bladder, where it is effective in reducing bacterial growth. A urinalysis, as well as a culture and sensitivity test, is usually performed before the initiation of drug therapy. As bactericidal agents, these drugs have the potential to cause superinfections. The urinary antiseptics/antiinfectives are fosfomycin tromethamine, nitrofurantoin, methenamine hippurate, trimethoprim, ertapenem, and the fluoroquinolones.
Nitrofurantoin was first prescribed to treat UTIs in 1953. It is bacteriostatic or bactericidal, depending on the drug dosage, and it is effective against many gram-positive and gram-negative organisms, especially E. coli. It is used to treat cystitis and UTIs.
Nitrofurantoin is well absorbed from the gastrointestinal (GI) tract. The drug is usually taken with food to decrease GI distress, which includes anorexia, nausea, vomiting, abdominal pain, and diarrhea. Decreased absorption occurs when the drug is taken with antacids. Nitrofurantoin is moderately protein bound. With normal renal function, the drug is rapidly eliminated because of its short half-life of 20 minutes; however, it accumulates in the serum with urinary dysfunction.
When nitrofurantoin is given in low doses for prophylactic use, the drug has a bacteriostatic effect. However, higher concentrations of nitrofurantoin cause a bactericidal effect, and it is effective against many gram-positive and gram-negative organisms such as E. coli, Staphylococcus aureus, streptococci, and Neisseria and Klebsiella species. The onset and duration of action are unknown. Peak action occurs 30 minutes after absorption. If sudden onset of dyspnea, chest pain, cough, fever, and chills develops, the patient should contact the health care provider. Symptoms resolve after discontinuing the drug.
The nursing process for nitrofurantoin is applicable to the other urinary antiseptics/antiinfectives.