From the Guidelines
Ampicillin should not be used for empirical treatment of urinary tract infections (UTIs) due to its relatively poor efficacy and high prevalence of antimicrobial resistance worldwide. The use of ampicillin for UTIs is not recommended as a first-line treatment, as stated in the 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases 1.
Alternative Treatment Options
For uncomplicated UTIs, alternative treatment options include:
- Nitrofurantoin monohydrate/macrocrystals (100 mg twice daily for 5 days)
- Trimethoprim-sulfamethoxazole (160/800 mg twice-daily for 3 days), if local resistance rates do not exceed 20%
- Fosfomycin trometamol (3 g in a single dose)
- Pivmecillinam (400 mg bid for 3–7 days) in regions where it is available
- Fluoroquinolones, such as ofloxacin, ciprofloxacin, and levofloxacin, for important uses other than acute cystitis
Resistance and Treatment Guidance
Ampicillin resistance has developed in many common UTI pathogens, particularly E. coli, which causes about 80% of UTIs 1. Treatment should always be guided by local resistance patterns and, when available, urine culture results. Patients should complete the full course of antibiotics and increase fluid intake to help flush bacteria from the urinary tract.
Special Considerations
In cases where ampicillin must be used based on susceptibility testing, the typical dose is not specified in the provided guidelines, but it is generally recommended to use it with caution due to its inferior efficacy and higher adverse effects compared to other UTI antimicrobials 1.
From the FDA Drug Label
Ampicillin capsules and Ampicillin for oral suspension are indicated in the treatment of infections caused by susceptible strains of the designated organisms listed below: Infections of the genitourinary tract including gonorrhea - E. coli, P. mirabilis, enterococci, Shigella, S. typhosa and other Salmonella and nonpenicillinase-producing N. gonorrhoeae Ampicillin is indicated for the treatment of urinary tract infections (UTIs) caused by susceptible strains of E. coli, P. mirabilis, enterococci, and other organisms.
- The drug label specifies that ampicillin should be used to treat infections caused by susceptible strains of the designated organisms.
- Bacteriology studies should be performed to determine the causative organisms and their susceptibility to ampicillin 2.
From the Research
UTIs and Ampicillin
- There is no direct mention of ampicillin as a treatment option for UTIs in the provided studies 3, 4, 5, 6, 7.
- However, ampicillin is a type of beta-lactam antibiotic, and beta-lactam antibiotics such as amoxicillin-clavulanate are mentioned as treatment options for UTIs due to ESBL-producing Enterobacteriales 3.
- The studies suggest that the choice of antibiotic therapy for UTIs should be based on the stratification into complicated and uncomplicated, as well as upper and lower infections, and on specific risk factors 7.
- The recommended first-line empiric antibiotic therapy for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females includes nitrofurantoin, fosfomycin tromethamine, or pivmecillinam 3.
- Second-line options include oral cephalosporins, fluoroquinolones, and beta-lactams such as amoxicillin-clavulanate 3.
- It is essential to use antimicrobials wisely to avoid resistance development 3.