Most urinary tract infections (UTIs) are simple and easy to treat. With proper treatment, they rarely lead to serious problems. But sometimes, a UTI can lead to bigger problems.
If a UTI gets "complicated," it means that regular treatment is not enough to get rid of it. Usually, there is something else going on that has caused it to get worse. So the usual treatment of just a few days of antibiotics may not be enough to help you get better. You may need an antibiotic designed specifically for treating a complicated UTI, and you may need to take it for a longer time. If your UTI is severe or the infection is in your kidneys, you might need to be treated with intravenous (IV) antibiotics.
You might have a complicated UTI if you are pregnant or if you have:
- UTIs that keep coming back and can not be controlled with the typical antibiotics
- Problems with kidney function
- A weakened immune system due to HIV, steroid use, or another cause
- A problem with your urinary tract, such as a narrowing of your ureters, which are the tubes that carry urine from your kidneys to your bladder
Zaynich (cefepime/zidebactam) is an IV antibiotic approved in 2026 specifically to treat complicated UTIs, including kidney infections, also known as pyelonephritis.
How Does Zaynich Work for Complicated UTIs?
Zaynich contains two medicines: cefepime and zidebactam. Cefepime is a cephalosporin antibiotic. It targets a specific enzyme used by certain bacteria called penicillin-binding protein 3 (PBP3). This enzyme helps the bacteria make their cell wall. Without a cell wall, the bacteria cannot survive. So it kills the bacteria by preventing them from being able to create their cell wall.
Zidebactam is an antibiotic and a beta-lactamase inhibitor. It blocks another enzyme called penicillin-binding protein 2 (PBP2), which is used by bacteria to make their cell walls. It also blocks an enzyme called beta-lactamase. Beta-lactamase is a substance made by certain bacteria that reduces the effects of antibiotics like cefepime. So it helps kill certain bacteria and also helps to keep cefepime working.
Cefepime and zidebactam work together to keep bacteria from making their cell walls to treat complicated UTIs caused by certain bacteria.
How Was Zaynich Studied for Complicated UTIs?
Researchers conducted one clinical trial to assess the effectiveness of Zaynich. The trial compared two different treatments for complicated UTIs in more than 500 adults. Participants either received Zaynich or meropenem (another IV antibiotic used to treat complicated UTIs). The average age of participants was about 65-68 years. About 90% of participants were White. Other races reported by study participants included Asian, Black or African American, and American Indian or Alaskan Native.
About 68% of the study participants had a complicated UTI, and 32% had pyelonephritis. A small number of participants (about 6%-7%) also had bacteremia, meaning bacteria had spread into the bloodstream.
Participants were randomly assigned to receive either Zaynich or meropenem IV every 8 hours. The main goal of the clinical trial was to see if the treatments successfully resolved UTI symptoms and reduced bacteria in the urine (pee) at a follow-up assessment.
Treatment results were examined at a follow-up visit, which took place 10 days after finishing the antibiotics. During this visit, the researchers looked at two specific outcomes.
- Clinical cure: The researchers checked if the symptoms of the infection from the start of the study had completely gone away. The patient was considered to be clinically cured if all the symptoms of the infection were gone and no new symptoms appeared, without needing extra antibiotics.
- Microbiological response: The researchers tested the urine of the participants to see whether the bacteria causing the infection had dropped in number.
Both of these outcomes were considered together to assess whether the treatment worked. The treatment could only be considered successful if a patient showed improvement in both their symptoms and urine bacteria levels. This combined result, which looks at more than one measure to assess overall treatment success, is known as a composite response.
What Benefits Were Seen?
Zaynich’s effectiveness was measured at a follow-up visit 10 days after finishing the antibiotic treatment. The results showed that Zaynich worked just as well as or better than meropenem to successfully treat complicated UTIs, including pyelonephritis.
The table below summarizes the results shown as the percentages of people who experienced an overall treatment success, a clinical cure, and a microbiological response.
| Zaynich | Meropenem | Difference | |
|---|---|---|---|
| Clinical cure | 96.8% | 94.9% | 1.9% |
| Microbiological response | 91.1% | 70.6% | 20.5% |
| Treatment success (both clinical cure and microbiological response) | 89% | 68.4% | 20.6% |
Of the participants with bacteria in their blood, 98% of those who received Zaynich had a complete response compared to 44% of those who received meropenem.
Results were consistent across patient groups, including by age, gender, race, BMI, kidney function, and type of UTI.
This study supports Zaynich as an effective treatment option for complicated UTIs caused by certain types of bacteria in adults. Keep in mind that your results may be different from what was seen in this study.
What Can I Do to Lower My Risk of UTIs?
Here are some simple things you can do to help prevent a UTI in the first place.
- Drink plenty of fluids. Stay well-hydrated to keep things moving. When you drink water, your bladder fills up regularly, forcing you to empty it more often. This frequent flushing action gives bacteria less time to settle in and cause an infection.
- Wipe properly. Wiping from front to back lowers your risk of transferring bacteria from your anus (where poop comes out) to your urethra (where pee comes out). Fewer bacteria mean less risk of infection.
- Stay clean. Wash your private parts with soap and water before sex. This helps keep bacteria away from the urethra. Empty your bladder after having sex. Peeing helps carry any bacteria that entered the urinary tract back out.
- Avoid irritating products. Keep things gentle by limiting your use of harsh feminine products. Avoid using scented deodorant sprays, powders, and douches that contain chemicals and fragrances, as these types of products can irritate sensitive areas.
Talk to your health care provider about other ways you may be able to help prevent UTIs.