From the Guidelines
For a urinalysis positive for nitrites and leukocyte esterase, the most appropriate antibiotic options are nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin, as recommended by the AUA/CUA/SUFU guideline 1. These antibiotics are considered first-line therapy due to their effectiveness in treating urinary tract infections (UTIs) and lower likelihood of producing collateral damage compared to second-line agents. Key considerations in choosing a UTI treatment include the local antibiogram, resistance prevalence, and potential for collateral damage, as highlighted in the IDSA 2011 guidelines and the AUA systematic review 1. Some specific treatment options include:
- Nitrofurantoin 100mg twice daily for 5 days
- Trimethoprim-sulfamethoxazole one tablet twice daily for 3 days
- Fosfomycin 3g single dose It is essential to note that the treatment duration should be as short as reasonable, generally no longer than seven days, and patients should complete the full course of antibiotics even if symptoms resolve quickly 1. Additionally, patients should drink plenty of fluids and seek medical attention if symptoms worsen or don't improve within 48 hours of starting treatment. In cases of complicated UTIs or pyelonephritis, or when first-line agents are not suitable due to resistance or allergy, alternative therapies such as fluoroquinolones or cephalosporins may be considered, but the choice of antibiotic should always be guided by the most recent and highest quality evidence, such as the AUA/CUA/SUFU guideline 1.
From the FDA Drug Label
To reduce the development of drug-resistant bacteria and maintain the effectiveness of sulfamethoxazole and trimethoprim tablets and other antibacterial drugs, sulfamethoxazole and trimethoprim tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria 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 Urinary Tract Infections can be treated with trimethoprim-sulfamethoxazole.
- The presence of nitrites and leukocyte esterase in the urinalysis suggests a bacterial infection.
- Escherichia coli is a common cause of urinary tract infections and is susceptible to trimethoprim-sulfamethoxazole 2. Therefore, trimethoprim-sulfamethoxazole is a good antibiotic option for this patient.
From the Research
Urinalysis Results and Antibiotic Treatment
- A urinalysis showing positive results for nitrites and leukocyte esterase can indicate a urinary tract infection (UTI) 3, 4.
- The presence of nitrites and leukocyte esterase in urine can be used to diagnose UTIs, but it may not be helpful in choosing an initial antibiotic 5.
- The study found that the resistance rate was higher in the nitrite positive group for certain antibiotics, such as TMP/SMX and ampicillin with or without sulbactam 5.
Antibiotic Options
- The use of nitrofurantoin or cephalexin for the treatment of cystitis was found to be optimum, and in the presence of negative leukoesterase, nitrofurantoin was preferable to cephalexin 5.
- For uncomplicated symptomatic urinary tract infections, a positive value for nitrites and leukocyte esterase by urine dipstick can be treated without the need for a urine culture 3.
Diagnostic Methods
- Leukocyte esterase is a useful marker that can be used in establishing a diagnosis of urinary tract infections (UTIs) 6.
- Microfluidic paper-based devices can be used for the sensitive detection of leukocyte esterase in human urine, allowing for quantitative determination and early detection of UTIs 6.
- The positive predictive value of a positive nitrite test result was 96%, and the addition of results of the leukocyte esterase test did not improve the diagnostic accuracy of the nitrite test 4.