Fosfomycin fighting antibiotic-resistant bacteria in a stylized urinary tract.

Fosfomycin: The Antibiotic Making a Comeback Against Resistant UTIs in Seniors

Samir D’Costa in Health & Wellness July 2025 • 4 min read.

"A closer look at how fosfomycin is being used to combat tough-to-treat urinary tract infections in the elderly, and what the future holds for this old antibiotic."

Urinary tract infections (UTIs) are a common ailment, especially among older adults. What was once a straightforward condition to treat has become increasingly complex due to the rise of antibiotic-resistant bacteria. This is where fosfomycin, an older antibiotic, is making a comeback, offering a potential solution for these difficult-to-treat infections.

Fosfomycin is a cell-wall active antibiotic known for its bactericidal activity against a wide range of bacteria, both gram-positive and gram-negative. While it has been around for decades, its use has been revitalized as other antibiotics lose their effectiveness. A recent study has investigated the use of fosfomycin in treating ceftriaxone-resistant Enterobacteriaceae urinary tract infections in elderly patients, providing valuable insights into its efficacy and safety.

This article delves into the findings of this research, exploring how fosfomycin is being used in a 1400-bed teaching hospital to combat UTIs caused by resistant bacteria. We'll examine the effectiveness of fosfomycin, potential resistance issues, and what this means for the future of treating UTIs in the elderly.

Fosfomycin: A Powerful Tool Against Resistant UTIs

Fosfomycin fighting antibiotic-resistant bacteria in a stylized urinary tract.

The study focused on patients with cystitis caused by ceftriaxone-resistant Enterobacteriaceae, a type of bacteria increasingly resistant to common antibiotics. These patients were given a 3g dose of fosfomycin trometamol (FT), an oral formulation of the drug. For complicated cystitis, patients sometimes received 3g of FT every other day for a total of three doses. The study tracked the outcomes of these patients, looking at both clinical and microbiological cures.

Clinical cure was defined as the resolution of symptoms, while microbiological cure meant no bacteria growth was observed in repeated cultures after therapy. The researchers also monitored for any adverse reactions to fosfomycin and documented the development of antibiotic resistance.

High Clinical Success Rate: The study found that 71.3% of patients achieved clinical cure with fosfomycin, experiencing no reported adverse drug events.
Microbiological Cure: Microbiological cure was documented in 60% of patients.
Resistance Development: A significant concern was the development of resistance to fosfomycin in 30% of patients with recurrent UTIs within three months.
Prior Antibiotic Use: In patients who previously received antibiotics, the clinical cure rate was 71.6%.
Dosage Impact: Patients receiving a single dose of fosfomycin had a similar clinical cure rate (71.6%), but a higher percentage developed recurrent infections.

These findings highlight the potential of fosfomycin as a valuable treatment option, but also underscore the importance of monitoring for resistance development, especially with repeat usage.

The Future of Fosfomycin and UTIs

The study's findings suggest that fosfomycin remains an effective antibiotic for treating UTIs, particularly those caused by resistant bacteria in older adults. However, the emergence of resistance is a significant concern that needs to be addressed. Strategies to minimize resistance development might include:

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Fosfomycin offers a valuable tool in the fight against antibiotic-resistant UTIs, but its long-term effectiveness depends on careful management and responsible use. Further research is needed to optimize treatment strategies and minimize the development of resistance, ensuring that this older antibiotic remains a viable option for future generations.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.ijantimicag.2018.10.008, Alternate LINK

Title: Outcomes Of Fosfomycin Use In Ceftriaxone-Resistant Enterobacteriaceae Urinary Tract Infection In The Elderly

Subject: Pharmacology (medical)

Journal: International Journal of Antimicrobial Agents

Publisher: Elsevier BV

Authors: Wei Ming Quek, Christine B. Teng, Yan Zhi Tan, Kelly Chong, David C. Lye, Tat Ming Ng

Published: 2019-02-01

Everything You Need To Know

Why is fosfomycin being used more often now to treat urinary tract infections (UTIs) in seniors?

Fosfomycin is making a comeback due to the increasing prevalence of antibiotic-resistant bacteria, particularly in urinary tract infections (UTIs) among older adults. It's a cell-wall active antibiotic effective against a wide range of bacteria, including both gram-positive and gram-negative types. Its resurgence is linked to the decline in effectiveness of other antibiotics against resistant strains.

What exactly were the definitions of 'clinical cure' and 'microbiological cure' in the context of the study on fosfomycin?

In the study, clinical cure with fosfomycin was defined as the resolution of UTI symptoms in patients. Microbiological cure meant that repeated cultures after fosfomycin therapy showed no bacterial growth. These two measures were critical in assessing the overall effectiveness of the treatment.

What were the main findings of the study regarding the effectiveness and potential drawbacks of using fosfomycin for UTIs?

The study revealed a clinical cure rate of 71.3% with fosfomycin and a microbiological cure rate of 60%. However, a notable concern was the development of resistance to fosfomycin in 30% of patients with recurrent UTIs within three months, which highlights the need for caution in repeat usage. Single dose showed same cure rate, but higher rate of re-infection.

Why is there a worry about bacteria becoming resistant to fosfomycin, and what steps might be taken to lower the risk of this happening?

The development of resistance to fosfomycin is a significant concern, particularly with repeat usage. Strategies to minimize resistance may include employing fosfomycin judiciously, implementing antibiotic stewardship programs, and exploring combination therapies to prevent resistance from emerging. Further, the study hints at different resistance outcomes depending on dosage, which is an important detail to consider.

The research centered on cystitis from ceftriaxone-resistant Enterobacteriaceae. Does that mean the findings apply to all types of UTIs or other infections, and how broadly can we apply these results?

The study primarily focused on patients with cystitis (bladder infection) caused by ceftriaxone-resistant Enterobacteriaceae. This means the results are most directly applicable to this specific type of UTI. The study does not offer specific data on other types of UTIs (e.g., kidney infections) or infections caused by different bacteria. However, the study does state fosfomycin can treat gram-positive and gram-negative bacteria. More research would be needed to determine fosfomycin's effectiveness in those scenarios.