From the Guidelines
Positive nitrites in a urine test should be treated with antibiotics, unless the urinalysis shows negative nitrite and negative leukocyte esterase, or if there are no symptoms or signs of a urinary tract infection, as indicated by recent guidelines 1. When treating positive nitrites, the following symptoms and signs should be considered:
- Frequency, incontinence, urgency
- Costovertebral angle pain/tenderness of recent onset
- Change in urine color, change in urine odor, cloudy urine, macroscopically hematuria
- Nocturia, decreased urinary output, dysuria, suprapubic pain, urinary retention
- Agitation, aggression, mental status change without clinical suspicion of delirium
- Decreased fluid intake, decreased dietary intake, nausea, malaise, fatigue, weakness, dizziness, syncope, decreased functional status, ADL decreased mobility The treatment should involve a 3-7 day course of antibiotics, such as nitrofurantoin (Macrobid) 100mg twice daily, trimethoprim-sulfamethoxazole (Bactrim) DS twice daily, or fosfomycin (Monurol) as a single 3g dose, as recommended by recent studies 1. It's essential to note that the presence of nitrites indicates that bacteria in the urine have converted nitrates to nitrites, which is particularly common with gram-negative bacteria like E. coli, and completing the full course of antibiotics is crucial to prevent recurrence or antibiotic resistance 1. If symptoms persist after 48-72 hours of treatment, patients should seek further medical evaluation, as culture and sensitivity testing may be needed to identify the specific bacteria and appropriate antibiotic, as suggested by guidelines 1.
From the Research
Treatment of Positive Nitrites
- Positive nitrites are an indication of a urinary tract infection (UTI) 2
- The treatment of UTI typically involves antimicrobial therapy, with the goal of ameliorating symptoms 3
- First-line treatments for UTI include:
- Nitrofurantoin is a wide-spectrum antibiotic that is effective against drug-resistant uropathogens and has a low frequency of utilization, making it a good choice for treating UTI 4
- A 5-day course of nitrofurantoin has been shown to be more effective than a single dose of fosfomycin in achieving clinical and microbiologic resolution of UTI 5
- The choice of antimicrobial therapy should take into account factors such as pharmacokinetics, spectrum of activity, resistance prevalence, potential for adverse effects, and duration of therapy 3
Considerations for Treatment
- Asymptomatic bacteriuria should not be treated with antibiotics, especially in older women 2
- In symptomatic women, even growth as low as 10^2 colony-forming unit/mL could reflect infection 2
- Resistance is increasing to fluoroquinolones, beta-lactams, and trimethoprim-sulfamethoxazole, making nitrofurantoin a good alternative 2
- Urine culture is the gold standard for detection of UTI, but may not always be necessary for diagnosis 2