What antibiotics can treat a urinary tract infection?

First choice antibiotics

Empirical antibiotic therapy

The doctor usually treats uncomplicated UTIs with antibiotics without first determining the pathogen spectrum. For this empirical antibiotic therapy, only active ingredients are eligible for which, due to the general resistance situation, it can be assumed that they will work in at least 80 percent of cases. That limits the choice considerably, as Dr. Markus Zieglmeier, pharmacist at the Munich-Bogenhausen Clinic, explained at a symposium at the Interpharm in Berlin: "According to current data from the Robert Koch Institute, Ciprofloxacin has only just barely broken this 80 percent barrier in recent years."

It should therefore be assumed that in the new version of the S3 guideline that is currently being drawn up, ciprofloxacin and the other fluoroquinolones will no longer be recommended as first-choice antibiotics for uncomplicated UTIs. This is already the case today, on the grounds that the fluoroquinolones "(must) be used for other indications and that other, exclusively available antibiotics are also available for the treatment of uncomplicated cystitis". As is well known, the prescription practice looks somewhat different, which has certainly contributed to the worrying increase in the resistance rate.

Against this background, the guideline will probably continue to name only three active ingredients as the first choice: fosfomycin-trometamol, nitrofurantoin and pivotmecillinam. In this indication, fosfomycin should be given as a single dose of 3000 mg. "The absorption of this substance is incomplete and prone to failure," said Zieglmeier. In order to optimize it, it must be taken on an empty stomach. The simultaneous use of agents to increase intestinal peristalsis, such as domperidone or metoclopramide, is contraindicated.

"Fosfomycin is a remarkably low-side antibiotic," Zieglmeier informed. Often only headache, dizziness and weakness are said. Disturbances in the gastrointestinal tract, superinfections of the vagina or diarrhea, on the other hand, rarely occur. The exceptionally good tolerability led to the substance being used frequently. "But the microbiologists are upset, because they need fosfomycin as one of the most important reserve antibiotics in the clinic." There it is used in doses of up to 20 g daily for MRSA infections, among other things.

Lots of caveats with nitrofurantoin

In terms of tolerability, nitrofurantoin is the exact opposite of fosfomycin. Allergic and pseudoallergic reactions are very common in more than 10 percent of cases. It is contraindicated in the case of even slightly impaired kidney function, more precisely from a glomerular filtration rate below 60 ml per minute. In patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, an X-linked recessive inherited enzyme defect, nitrofurantoin leads to hemolytic anemia and is therefore also contraindicated.

"Several million people worldwide have G6PD deficiencies, especially from malaria areas, where it is a selection advantage," explained Zieglmeier. Often those affected do not know anything about it. This should be considered if, for example, an immigrant from sub-Saharan Africa or Asia is to be treated with nitrofurantoin.