From the Guidelines
If the patient's symptoms have improved with fosfomycin treatment for a UTI, you generally do not need to prescribe additional penicillin, even if the urine culture shows Staphylococcus sensitive to penicillin. Fosfomycin is a single-dose treatment that remains active in the urinary tract for several days and is effective against many urinary pathogens, including Staphylococcus species, as recommended by the American College of Physicians in 2021 1. Clinical improvement indicates the infection is resolving with the current therapy. The best practice advice from the American College of Physicians suggests prescribing short-course antibiotics with either nitrofurantoin for 5 days, trimethoprim–sulfamethoxazole (TMP–SMZ) for 3 days, or fosfomycin as a single dose for women with uncomplicated bacterial cystitis 1. Some key points to consider include:
- Fosfomycin's efficacy in treating UTIs, including those caused by Staphylococcus species
- The importance of clinical response in guiding treatment decisions, rather than relying solely on culture results
- The potential for asymptomatic bacteriuria following treatment, which may not require additional antibiotics if the patient is clinically improved However, it's essential to monitor the patient's symptoms and adjust the treatment plan if necessary. If symptoms worsen or return after completing fosfomycin, then consider switching to penicillin based on the culture results. The decision to change antibiotics should be guided by clinical response rather than culture results alone, as asymptomatic bacteriuria following treatment doesn't necessarily require additional antibiotics if the patient is clinically improved 1.
From the Research
Fosfomycin Treatment for UTI
- Fosfomycin is a bactericidal antibiotic with broad-spectrum activity, including against multidrug-resistant Gram-negative bacteria 2.
- It has been shown to be effective in treating urinary tract infections (UTIs), including those caused by Escherichia coli, Klebsiella pneumoniae, and Enterococcus faecalis 3, 4.
- Fosfomycin susceptibility rates are high for non-ESBL and ESBL E. coli, as well as for other Enterobacterales and gram-positive organisms, including Staphylococcus aureus 3.
Treatment of Staphylococcus aureus UTI
- Fosfomycin has been shown to be effective against Staphylococcus aureus, with high susceptibility rates 3.
- However, the use of fosfomycin as a single agent for the treatment of Staphylococcus aureus UTI may be limited by the potential for resistance development 5.
- Penicillin is often recommended for the treatment of Staphylococcus aureus infections, but fosfomycin may be a viable alternative in cases where penicillin is not effective or cannot be used 3, 4.
Clinical Decision-Making
- In cases where a patient's symptoms have improved with fosfomycin treatment, but urine culture results indicate the presence of a pathogen that is susceptible to penicillin, the decision to switch to penicillin should be based on individual patient factors and clinical judgment 4, 5.
- Factors to consider include the severity of the infection, the patient's overall health status, and the potential for resistance development 2, 6.
- Further studies are needed to fully evaluate the efficacy and safety of fosfomycin for the treatment of UTIs, including those caused by Staphylococcus aureus 3, 5.