Learning Outcomes
By the end of this section, you should be able to:
- 35.1.1 Identify the characteristics of urinary anti-infective drugs used for urinary and bladder disorders.
- 35.1.2 Explain the indications, actions, adverse reactions, contraindications, and interactions of urinary anti-infective drugs used for urinary and bladder disorders.
- 35.1.3 Describe nursing implications of urinary anti-infective drugs used for urinary and bladder disorders.
- 35.1.4 Explain the client education related to urinary anti-infective drugs used for urinary and bladder disorders.
Urinary anti-infectives are a class of drugs specifically used to treat infections of the urinary tract, including the bladder, urethra, ureters, and kidneys (Figure 35.2). They are designed to target and eliminate the bacteria or other microorganisms causing urinary infection.
In this section of the chapter, common urinary anti-infectives will be discussed in greater detail. The choice of medication depends on various factors, such as type of infection, its severity, the presence of underlying conditions, client allergies, and local resistance patterns. The health care provider will prescribe the appropriate urinary anti-infective for the client based on these criteria.
Culture and susceptibility studies should be performed prior to starting urinary anti-infectives. These studies should also be considered when selecting and modifying antibacterial therapy. In the absence of these studies, local epidemiology and susceptibility patterns (e.g., the institutional antibiogram) should be considered for the empiric selection of therapy.
Nitrofurantoin
Nitrofurantoin is specifically indicated for treating urinary tract infections (UTIs) due to susceptible strains of Escherichia coli, enterococci, Staphylococcus aureus, and certain susceptible strains of Klebsiella and Enterobacter species (Squadrito & del Portal, 2023).
Adverse reactions can include chronic, subacute, or acute pulmonary hypersensitivity; hepatic reactions, including hepatitis; neurologic conditions such as asthenia, vertigo, headache, and drowsiness; exfoliative dermatitis; erythema multiforme; and gastrointestinal reactions such as nausea, vomiting, abdominal pain, and anorexia. A typical effect of nitrofurantoin is brown discoloration of the urine.
Nitrofurantoin is contraindicated in clients with impaired renal function, impaired hepatic function, or known hypersensitivity. This drug should not be prescribed to pregnant clients after the 37th week of pregnancy, during labor, or when the onset of labor is imminent, because it can lead to a decrease in the fetus’s or newborn’s red blood cell count. Nitrofurantoin is also contraindicated during lactation and for newborns 1 month old or younger. Nitrofurantoin should be used cautiously in older clients due to potential impaired renal and hepatic function. It is contraindicated in all clients with a creatinine clearance of less than 60 mL due to the increased risk of toxicity because of impaired excretion of the drug. (Nitrofurantoin is in the Beers Criteria® list of medications with specific guidelines for use in older clients.)
Clinical Tip
Nitrofurantoin and Urine Color
Nitrofurantoin may turn the urine brown. This is an expected effect of the medication and does not harm the client.
Trimethoprim and Sulfamethoxazole
The combination of trimethoprim and sulfamethoxazole (TMP/SMX) is indicated to treat UTIs due to susceptible strains of Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis, and Proteus vulgaris (Kemnic & Coleman, 2022). However, it is recommended that initial episodes of uncomplicated UTIs be treated with a single effective antibacterial agent rather than this combination.
The most common adverse reactions are gastrointestinal disturbances, such as nausea, vomiting, and anorexia; photosensitivity; and allergic skin reactions such as rash and urticaria. More serious adverse reactions include severe cutaneous reactions, including Stevens–Johnson syndrome, as well as fulminant hepatic necrosis, blood dyscrasias, hyperkalemia, and anaphylaxis or circulatory shock.
TMP/SMX is contraindicated in clients with hypersensitivity to trimethoprim, sulfonamides, or any of their constituents (commonly referred to as “sulfa drugs”); a history of drug-induced immune thrombocytopenia with the use of trimethoprim and/or sulfonamides; megaloblastic anemia due to folate deficiency; or severe renal or hepatic insufficiency. It is also contraindicated in infants younger than 2 months of age and in clients taking dofetilide.
Clinical Tip
TMP/SMX and Photosensitivity
TMP/SMX may cause photosensitivity. Nurses should instruct clients to avoid direct sunlight due to the increased risk of sunburn or skin rash with exposure.
Fosfomycin Tromethamine
Fosfomycin tromethamine granules for oral solution are indicated for clients with uncomplicated UTIs (acute cystitis) due to susceptible strains of Escherichia coli and Enterococcus faecalis (Abbott et al., 2020; DailyMed, Fosfomycin tromethamine, 2022).
Adverse effects include diarrhea, vaginitis, nausea, headache, dizziness, asthenia, and dyspepsia. Fosfomycin tromethamine is contraindicated in clients with known sensitivity to the drug or any of its components.
Methenamine Hippurate
Methenamine hippurate tablets are indicated for prophylactic or suppressive treatment of frequently recurring UTIs when long-term therapy is considered necessary. This drug should be used only after other appropriate antimicrobial agents have eradicated the infection (DailyMed, Methenamine hippurate, 2021; Heltveit-Olsen et al., 2022).
Minimal adverse effects have been reported with the use of this drug, including nausea, upset stomach, dysuria, and rash. Contraindications include severe renal or hepatic insufficiency and severe dehydration.
Table 35.1 lists common urinary anti-infectives and typical routes and dosing for adult clients.
| Drug | Routes and Dosage Ranges |
|---|---|
| Nitrofurantoin (Furadantin, Macrobid, Macrodantin) |
100 mg orally twice daily. Long-term suppressive therapy: 50–100 mg orally at bedtime. Therapy should be continued for 1 week or at least 3 days after sterility of urine is obtained. |
| Trimethoprim and sulfamethoxazole (TMP/SMX) (Bactrim, Septra) |
Regular-strength tablet: one 400 mg/80 mg tablet orally twice daily. Double-strength tablet: one 800 mg/160 mg tablet orally twice daily. |
| Fosfomycin tromethamine (Monurol) |
1 sachet (3 g) of granules in 3–4 oz of water for oral solution, taken immediately after combining. Do not use hot water. |
| Methenamine hippurate (Hiprex) |
1 tablet (1 g) orally twice daily (morning and night). |
Adverse Effects and Contraindications
Common adverse effects of urinary anti-infectives include nausea, vomiting, abdominal pain, anorexia, rash, headache, photosensitivity, and dizziness. Serious adverse effects can occur with certain urinary anti-infectives, including exfoliative dermatitis, Stevens–Johnson syndrome, and fulminant hepatic necrosis.
Contraindications include renal and hepatic insufficiency and hypersensitivity to the drug or any of its components. Certain urinary anti-infectives are contraindicated in clients with blood dyscrasias and in specific pediatric populations.
Table 35.2 is a drug prototype table for urinary anti-infectives featuring TMP/SMX. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.
| Drug Class Anti-infective Mechanism of Action Inhibits the bacterial synthesis of tetrahydrofolic acid, which is necessary in the synthesis of thymidine, purines, and bacterial DNA |
Drug Dosage Regular-strength tablet: one 400 mg/80 mg tablet orally twice daily. Double-strength tablet: one 800 mg/160 mg tablet orally twice daily. |
| Indications Treatment of UTIs due to susceptible strains of the following organisms: Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis, and Proteus vulgaris Therapeutic Effects Elimination of bacteria that cause UTIs |
Drug Interactions Dofetilide Warfarin Nonsteroidal anti-inflammatory drugs Phenytoin Methotrexate Cyclosporine Digoxin Amantadine Food Interactions No significant interactions |
| Adverse Effects Nausea, vomiting, anorexia Rash, urticaria Severe cutaneous reactions Fulminant hepatic necrosis Blood dyscrasias Photosensitivity Hyperkalemia |
Contraindications Hypersensitivity History of drug-induced immune thrombocytopenia with use of trimethoprim and/or sulfonamides Megaloblastic anemia due to folate deficiency Infants younger than 2 months of age Severe renal or hepatic insufficiency Caution: May cause Clostridioides difficile–associated diarrhea |
Nursing Implications
The nurse should do the following for clients who are taking urinary anti-infectives:
- Before administering the drug, check the client’s medical history, current drug list, and allergies.
- Before administering the drug, confirm the results of baseline laboratory tests, including, but not limited to, urinalysis, urine culture and sensitivity, complete blood cell count, and renal and hepatic function levels.
- For clients receiving nitrofurantoin, monitor for acute and subacute signs of respiratory reactions, such as dyspnea, chest pain, chills, fever, and cough, and notify the health care provider if these develop.
- For clients receiving TMP/SMX, monitor for early signs of blood dyscrasias, such as sore throat, fever, or pallor, and notify the health care provider if these develop.
- Monitor intake, output, and urine specific gravity. Report significant decreases in urinary output to the health care provider.
- Report any signs of superinfection, such as stomatitis, anogenital discharge, or itching, to the health care provider.
- Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.
Client Teaching Guidelines
The client taking a urinary anti-infective should:
- Increase their daily fluid intake (avoiding substances that cause diuresis, such as caffeine), if not contraindicated, to avoid the development of kidney stones.
- Rinse their mouth out thoroughly after taking nitrofurantoin because this drug may stain the teeth.
- Ask the health care provider before taking certain urinary anti-infectives, such as nitrofurantoin, if they are pregnant, are thinking of becoming pregnant, are breastfeeding, or are considering giving these medications to an infant younger than 1 month of age because they may cause serious adverse effects such as blood dyscrasias, anemia, and fetal abnormalities.
- Avoid excessive exposure to sunlight when taking TMP/SMX because photosensitivity may occur, and sun exposure may cause sunburn or skin rash.
The client taking a urinary anti-infective should not:
- Crush tablets or open capsules unless directed by a pharmacist because these drugs may cause esophageal or stomach irritation.
- Stop taking the drug unless directed by the health care provider. Drugs in this class help eliminate bacteria in the body and can result in a worsening infection if the drug course is stopped early. Stopping early may also contribute to antibiotic resistance.
FDA Black Box Warning
Urinary Anti-infectives
Nitrofurantoin may cause acute, subacute, or chronic pulmonary reactions (such as diffuse interstitial pneumonitis or pulmonary fibrosis, or both). Monitoring for these conditions is warranted.
Trimethoprim and sulfamethoxazole (TMP/SMX) may cause acute eosinophilic pneumonia, acute and delayed lung injury, interstitial lung disease, and acute respiratory failure resulting in prolonged mechanical ventilation, extracorporeal membrane oxygenation (ECMO), the need for lung transplantation, or death. Monitoring for these conditions is warranted.