Ciprofloxacin and levofloxacin are no longer recommended for the treatment of gonococcal infection in the USA, as resistance is now common; however, gemifloxacin may be used in combination with azithromycin as an alternate to ceftriaxone. Levofloxacin and ofloxacin are recommended by the Centers for Disease Control and Prevention as alternative treatment options for chlamydial urethritis or cervicitis. Ciprofloxacin, levofloxacin, or moxifloxacin is occasionally used as part of a treatment regimen for tuberculosis and non-tuberculous mycobacterial infections. These agents are suitable for eradication of meningococci from carriers and for prophylaxis of bacterial infection in neutropenic cancer patients.
With their enhanced Gram-positive activity and activity against atypical pneumonia agents (chlamydiae, Mycoplasma, and Legionella), levofloxacin, gemifloxacin, and moxifloxacin— so-called respiratory fluoroquinolones—are effective for treatment of lower respiratory tract infections.
Fluoroquinolones are generally well tolerated. The most common effects are nausea, vomiting, and diarrhea. Occasionally, headache, dizziness, insomnia, skin rash, or abnormal liver function tests develop. Photosensitivity has been reported with lomefloxacin and pefloxacin. Prolongation of the QTc interval may occur with gatifloxacin, levofloxacin, gemifloxacin, and moxifloxacin; these drugs should be avoided or used with caution in patients with known QTc interval prolongation or uncorrected hypokalemia; in those receiving class 1A (eg, quinidine or procainamide) or class 3 antiarrhythmic agents (sotalol, ibutilide, amiodarone); and in patients receiving other agents known to increase the QTc interval (eg, erythromycin, tricyclic antidepressants). Gatifloxacin has been associated with hyperglycemia in diabetic patients and with hypoglycemia in patients also receiving oral hypoglycemic agents. Because of these serious effects (including some fatalities), gatifloxacin was withdrawn from sale in the United States in 2006.
In animal models, fluoroquinolones may damage growing cartilage and cause an arthropathy. Thus, these drugs have not been recommended as first-line agents for patients under 18 years of age. However, there is a growing consensus that fluoroquinolones may be used in children if needed (eg, for treatment of pseudomonal infections in patients with cystic fibrosis). Tendinitis, a complication in adults, can be serious because of the risk of tendon rupture. Risk factors for tendinitis include advanced age, renal insufficiency, and concurrent steroid use. Fluoroquinolones should be avoided during pregnancy in the absence of specific data documenting their safety. Oral or intravenously administered fluoroquinolones have also been associated with peripheral neuropathy. Neuropathy can occur at any time during treatment with fluoroquinolones and may persist for months to years after the drug is stopped. In some cases it may be permanent. Although many potential adverse effects are uncommon, the FDA called for updated warnings for all fluoroquinolones in 2016, stating that these agents should be reserved for patients who do not have alternative options, particularly in less severe infections such as upper respiratory infections or uncomplicated cystitis.
Sulfadiazine: Oral; first-line therapy for toxoplasmosis when combined with pyrimethamine
Trimethoprim: Oral; used alone only for lower urinary tract infections; may be safely prescribed to patients with sulfonamide allergy
Pyrimethamine: Oral; first-line therapy for toxoplasmosis when combined with sulfadiazine; coadminister with leucovorin to limit bone marrow toxicity