From the Guidelines
For a urinary tract infection with nitrite positivity, the recommended first-line antibiotic regimen is typically nitrofurantoin (Macrobid) 100 mg twice daily for 5 days or trimethoprim-sulfamethoxazole (Bactrim) DS tablet twice daily for 3 days in uncomplicated cases. Nitrite positivity on urinalysis suggests the presence of gram-negative bacteria, particularly Enterobacteriaceae like E. coli, which convert nitrates to nitrites.
Key Considerations
- The choice of antibiotic should be guided by local resistance patterns and patient-specific factors, such as allergy history and renal function 1.
- For patients with contraindications to these medications, alternatives include fosfomycin 3 g single dose or ciprofloxacin 250 mg twice daily for 3 days.
- Pregnant women should receive nitrofurantoin or cephalexin for 7 days.
- For complicated UTIs, including those in men, elderly patients, or those with structural abnormalities, a 7-14 day course may be necessary, potentially with broader-spectrum antibiotics like ciprofloxacin or levofloxacin.
Rationale
- The IDSA/European Society of Clinical Microbiology and Infectious Diseases (ESCMID) guideline recommends treatment durations depending on the type of antibiotic, including 5 days of nitrofurantoin, 3 days of TMP–SMX, or a single dose of fosfomycin 1.
- Fluoroquinolones are highly efficacious in 3-day regimens but have high propensity for adverse effects and thus should not be prescribed empirically and should instead be reserved for patients with a history of resistant organisms 1.
- It's essential to ensure adequate hydration during treatment and to complete the full course of antibiotics even if symptoms resolve earlier.
- Local antibiotic resistance patterns may influence the optimal choice, so clinicians should consider regional guidelines when selecting therapy 1.
From the FDA Drug Label
For the treatment of urinary tract infections due to susceptible strains of the following organisms: Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis and Proteus vulgaris The usual adult dosage in the treatment of urinary tract infections is 1 sulfamethoprim and trimethoprim DS tablet every 12 hours for 10 to 14 days
The recommended antibiotic regimen for a urinary tract infection (UTI) with nitrite positivity is trimethoprim-sulfamethoxazole. The dosage is:
- Adults: 1 DS tablet every 12 hours for 10 to 14 days
- Children: 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days 2 Key points:
- The presence of nitrite in the urine suggests a bacterial infection, and trimethoprim-sulfamethoxazole is effective against common urinary tract pathogens such as Escherichia coli and Klebsiella species.
- The dosage and duration of treatment may vary depending on the severity of the infection and the patient's renal function 2
From the Research
Antibiotic Regimen for UTI with Nitrite Positivity
The presence of nitrite in a urine sample is often an indication of a urinary tract infection (UTI) caused by Gram-negative bacteria, such as Escherichia coli. The recommended antibiotic regimen for UTI with nitrite positivity depends on various factors, including the severity of the infection, patient's health status, and local antimicrobial resistance patterns.
First-Line Treatment Options
- Nitrofurantoin: a 5-day course is recommended for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females 3, 4
- Fosfomycin tromethamine: a 3-g single dose is recommended for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females 3
- Pivmecillinam: a 5-day course is recommended for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females 3
Second-Line Treatment Options
- Oral cephalosporins: such as cephalexin or cefixime 3
- Fluoroquinolones: such as ciprofloxacin, but high rates of resistance preclude their use as empiric treatment in several communities 3, 5
- β-lactams: such as amoxicillin-clavulanate 3
Treatment Options for Resistant Organisms
- ESBL-producing Enterobacteriales: nitrofurantoin, fosfomycin, pivmecillinam, amoxicillin-clavulanate, finafloxacin, and sitafloxacin are recommended 3
- Carbapenem-resistant Enterobacteriales: ceftazidime-avibactam, meropenem/vaborbactam, imipenem/cilastatin-relebactam, colistin, fosfomycin, aztreonam, and cefiderocol are recommended 3
- Multidrug-resistant Pseudomonas spp.: fluoroquinolones, ceftazidime, cefepime, piperacillin-tazobactam, carbapenems, and fosfomycin are recommended 3