Acute Otitis Media
Trimethoprim has been used for treatment of acute otitis media (AOM) caused by Streptococcus pneumoniae and Haemophilus influenzae. Because Moraxella catarrhalis is resistant to trimethoprim, the drug should not be used if M. catarrhalis is suspected.
The manufacturer states that trimethoprim is not indicated for treatment of AOM in adults or in children younger than 6 months of age. In addition, the drug should not be used for prophylaxis of AOM and should not be given for prolonged periods for treatment of AOM in any age group.
When anti-infective therapy is indicated for treatment of AOM, the American Academy of Pediatrics (AAP) recommends high-dose amoxicillin or amoxicillin and clavulanate potassium as the drugs of first choice for initial treatment and certain cephalosporins (cefdinir, cefpodoxime, cefuroxime, ceftriaxone) as alternatives for initial treatment in penicillin-allergic patients who do not have a history of severe and/or recent penicillin-allergic reactions. Although the fixed combination containing trimethoprim and sulfamethoxazole has been used for treatment of AOM, substantial resistance to the drug has been reported in S. pneumoniae and AAP states that it should not be used as an alternative in patients who do not respond to amoxicillin.
Urinary Tract Infections
Trimethoprim is used for treatment of initial episodes of acute, uncomplicated urinary tract infections caused by susceptible Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter, or coagulase-negative Staphylococcus (including S. saprophyticus).
Although trimethoprim has been used for treatment of acute, uncomplicated cystitis, the value of trimethoprim alone for treatment of acute, uncomplicated urinary tract infections has been questioned because of emergence of an increasing number of trimethoprim-resistant organisms. The fixed combination containing trimethoprim and sulfamethoxazole is used for treatment of urinary tract infections, and has been recommended as a good choice for empiric treatment of acute, uncomplicated cystitis. However, uropathogens with resistance to trimethoprim (with or without sulfamethoxazole) have been reported with increasing frequency.
Prior to initiation of trimethoprim for treatment of acute, uncomplicated urinary tract infections, specimens should be collected for culture and in vitro susceptibility tests; the drug may be initiated before obtaining results. Some clinicians also recommend obtaining follow-up urine cultures after discontinuance of anti-infective therapy to determine whether the bacteria have been eliminated.
Pneumocystis jirovecii Pneumonia
Treatment of Pneumocystis jirovecii Pneumonia
Trimethoprim is used in conjunction with dapsone as an alternative for treatment of mild to moderate Pneumocystis jirovecii (formerly Pneumocystis carinii) pneumonia (PCP). Animal studies suggest that trimethoprim alone is ineffective for treatment of PCP.
The fixed combination containing trimethoprim and sulfamethoxazole is the drug of choice for treatment of mild, moderate, or severe PCP, including PCP in adults, adolescents, and children with human immunodeficiency virus (HIV) infection.
The US Centers for Disease Control and Prevention (CDC), National Institutes of Health (NIH), and Infectious Diseases Society of America (IDSA) state that alternative regimens for treatment of mild to moderate PCP in HIV-infected adults and adolescents when co-trimoxazole cannot be used are dapsone in conjunction with trimethoprim, primaquine in conjunction with clindamycin, or atovaquone alone. These experts state that dapsone in conjunction with trimethoprim may be as effective as co-trimoxazole for treatment of mild to moderate PCP and has fewer adverse effects, but is less convenient because of higher pill burden. Although efficacy and safety data are limited regarding use of dapsone in conjunction with trimethoprim for treatment of PCP in children, some clinicians also recommend the regimen as an alternative for treatment of mild to moderate PCP in children when co-trimoxazole cannot be used. The dapsone and trimethoprim regimen is not included in recommendations for treatment of severe PCP.